Custom SwipeRefresh

CircleImageView.java

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RadialGradient;
import android.graphics.Shader;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.OvalShape;
import android.support.v4.view.ViewCompat;
import android.view.animation.Animation;
import android.widget.ImageView;

/**
 * Private class created to work around issues with AnimationListeners being
 * called before the animation is actually complete and support shadows on older
 * platforms.
 *
 * @hide
 */
class CircleImageView extends ImageView {

    private static final int KEY_SHADOW_COLOR = 0x1E000000;
    private static final int FILL_SHADOW_COLOR = 0x3D000000;
    // PX
    private static final float X_OFFSET = 0f;
    private static final float Y_OFFSET = 1.75f;
    private static final float SHADOW_RADIUS = 3.5f;
    private static final int SHADOW_ELEVATION = 4;

    private Animation.AnimationListener mListener;
    private int mShadowRadius;

    public CircleImageView(Context context, int color, final float radius) {
        super(context);
        final float density = getContext().getResources().getDisplayMetrics().density;
        final int diameter = (int) (radius * density * 2);
        final int shadowYOffset = (int) (density * Y_OFFSET);
        final int shadowXOffset = (int) (density * X_OFFSET);

        mShadowRadius = (int) (density * SHADOW_RADIUS);

        ShapeDrawable circle;
        if (elevationSupported()) {
            circle = new ShapeDrawable(new OvalShape());
            ViewCompat.setElevation(this, SHADOW_ELEVATION * density);
        } else {
            OvalShape oval = new OvalShadow(mShadowRadius, diameter);
            circle = new ShapeDrawable(oval);
            ViewCompat.setLayerType(this, ViewCompat.LAYER_TYPE_SOFTWARE, circle.getPaint());
            circle.getPaint().setShadowLayer(mShadowRadius, shadowXOffset, shadowYOffset,
                    KEY_SHADOW_COLOR);
            final int padding = mShadowRadius;
            // set padding so the inner image sits correctly within the shadow.
            setPadding(padding, padding, padding, padding);
        }
        circle.getPaint().setColor(color);
        setBackgroundDrawable(circle);
    }

    private boolean elevationSupported() {
        return android.os.Build.VERSION.SDK_INT >= 21;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (!elevationSupported()) {
            setMeasuredDimension(getMeasuredWidth() + mShadowRadius*2, getMeasuredHeight()
                    + mShadowRadius*2);
        }
    }

    public void setAnimationListener(Animation.AnimationListener listener) {
        mListener = listener;
    }

    @Override
    public void onAnimationStart() {
        super.onAnimationStart();
        if (mListener != null) {
            mListener.onAnimationStart(getAnimation());
        }
    }

    @Override
    public void onAnimationEnd() {
        super.onAnimationEnd();
        if (mListener != null) {
            mListener.onAnimationEnd(getAnimation());
        }
    }

    /**
     * Update the background color of the circle image view.
     *
     * @param colorRes Id of a color resource.
     */
    public void setBackgroundColorRes(int colorRes) {
        setBackgroundColor(getContext().getResources().getColor(colorRes));
    }

    @Override
    public void setBackgroundColor(int color) {
        if (getBackground() instanceof ShapeDrawable) {
            ((ShapeDrawable) getBackground()).getPaint().setColor(color);
        }
    }

    private class OvalShadow extends OvalShape {
        private RadialGradient mRadialGradient;
        private Paint mShadowPaint;
        private int mCircleDiameter;

        public OvalShadow(int shadowRadius, int circleDiameter) {
            super();
            mShadowPaint = new Paint();
            mShadowRadius = shadowRadius;
            mCircleDiameter = circleDiameter;
            mRadialGradient = new RadialGradient(mCircleDiameter / 2, mCircleDiameter / 2,
                    mShadowRadius, new int[] {
                            FILL_SHADOW_COLOR, Color.TRANSPARENT
                    }, null, Shader.TileMode.CLAMP);
            mShadowPaint.setShader(mRadialGradient);
        }

        @Override
        public void draw(Canvas canvas, Paint paint) {
            final int viewWidth = CircleImageView.this.getWidth();
            final int viewHeight = CircleImageView.this.getHeight();
            canvas.drawCircle(viewWidth / 2, viewHeight / 2, (mCircleDiameter / 2 + mShadowRadius),
                    mShadowPaint);
            canvas.drawCircle(viewWidth / 2, viewHeight / 2, (mCircleDiameter / 2), paint);
        }
    }
}

MaterialProgressDrawable.java

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.drawable.Animatable;
import android.graphics.drawable.Drawable;
import android.support.annotation.IntDef;
import android.support.annotation.NonNull;
import android.support.v4.view.animation.FastOutSlowInInterpolator;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.animation.Animation;
import android.view.animation.Interpolator;
import android.view.animation.LinearInterpolator;
import android.view.animation.Transformation;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.util.ArrayList;

/**
 * Fancy progress indicator for Material theme.
 *
 * @hide
 */
class MaterialProgressDrawable extends Drawable implements Animatable {
    private static final Interpolator LINEAR_INTERPOLATOR = new LinearInterpolator();
    private static final Interpolator MATERIAL_INTERPOLATOR = new FastOutSlowInInterpolator();

    private static final float FULL_ROTATION = 1080.0f;
    @Retention(RetentionPolicy.CLASS)
    @IntDef({LARGE, DEFAULT})
    public @interface ProgressDrawableSize {}
    // Maps to ProgressBar.Large style
    public static final int LARGE = 0;
    // Maps to ProgressBar default style
    public static final int DEFAULT = 1;

    // Maps to ProgressBar default style
    private static final int CIRCLE_DIAMETER = 40;
    private static final float CENTER_RADIUS = 8.75f; //should add up to 10 when + stroke_width
    private static final float STROKE_WIDTH = 2.5f;

    // Maps to ProgressBar.Large style
    private static final int CIRCLE_DIAMETER_LARGE = 56;
    private static final float CENTER_RADIUS_LARGE = 12.5f;
    private static final float STROKE_WIDTH_LARGE = 3f;

    private final int[] COLORS = new int[] {
        Color.BLACK
    };

    /**
     * The value in the linear interpolator for animating the drawable at which
     * the color transition should start
     */
    private static final float COLOR_START_DELAY_OFFSET = 0.75f;
    private static final float END_TRIM_START_DELAY_OFFSET = 0.5f;
    private static final float START_TRIM_DURATION_OFFSET = 0.5f;

    /** The duration of a single progress spin in milliseconds. */
    private static final int ANIMATION_DURATION = 1332;

    /** The number of points in the progress "star". */
    private static final float NUM_POINTS = 5f;
    /** The list of animators operating on this drawable. */
    private final ArrayList<Animation> mAnimators = new ArrayList<Animation>();

    /** The indicator ring, used to manage animation state. */
    private final Ring mRing;

    /** Canvas rotation in degrees. */
    private float mRotation;

    /** Layout info for the arrowhead in dp */
    private static final int ARROW_WIDTH = 10;
    private static final int ARROW_HEIGHT = 5;
    private static final float ARROW_OFFSET_ANGLE = 5;

    /** Layout info for the arrowhead for the large spinner in dp */
    private static final int ARROW_WIDTH_LARGE = 12;
    private static final int ARROW_HEIGHT_LARGE = 6;
    private static final float MAX_PROGRESS_ARC = .8f;

    private Resources mResources;
    private View mParent;
    private Animation mAnimation;
    private float mRotationCount;
    private double mWidth;
    private double mHeight;
    boolean mFinishing;

    public MaterialProgressDrawable(Context context, View parent) {
        mParent = parent;
        mResources = context.getResources();

        mRing = new Ring(mCallback);
        mRing.setColors(COLORS);

        updateSizes(DEFAULT);
        setupAnimators();
    }

    private void setSizeParameters(double progressCircleWidth, double progressCircleHeight,
            double centerRadius, double strokeWidth, float arrowWidth, float arrowHeight) {
        final Ring ring = mRing;
        final DisplayMetrics metrics = mResources.getDisplayMetrics();
        final float screenDensity = metrics.density;

        mWidth = progressCircleWidth * screenDensity;
        mHeight = progressCircleHeight * screenDensity;
        ring.setStrokeWidth((float) strokeWidth * screenDensity);
        ring.setCenterRadius(centerRadius * screenDensity);
        ring.setColorIndex(0);
        ring.setArrowDimensions(arrowWidth * screenDensity, arrowHeight * screenDensity);
        ring.setInsets((int) mWidth, (int) mHeight);
    }

    /**
     * Set the overall size for the progress spinner. This updates the radius
     * and stroke width of the ring.
     *
     * @param size One of {@link MaterialProgressDrawable.LARGE} or
     *            {@link MaterialProgressDrawable.DEFAULT}
     */
    public void updateSizes(@ProgressDrawableSize int size) {
        if (size == LARGE) {
            setSizeParameters(CIRCLE_DIAMETER_LARGE, CIRCLE_DIAMETER_LARGE, CENTER_RADIUS_LARGE,
                    STROKE_WIDTH_LARGE, ARROW_WIDTH_LARGE, ARROW_HEIGHT_LARGE);
        } else {
            setSizeParameters(CIRCLE_DIAMETER, CIRCLE_DIAMETER, CENTER_RADIUS, STROKE_WIDTH,
                    ARROW_WIDTH, ARROW_HEIGHT);
        }
    }

    /**
     * @param show Set to true to display the arrowhead on the progress spinner.
     */
    public void showArrow(boolean show) {
        mRing.setShowArrow(show);
    }

    /**
     * @param scale Set the scale of the arrowhead for the spinner.
     */
    public void setArrowScale(float scale) {
        mRing.setArrowScale(scale);
    }

    /**
     * Set the start and end trim for the progress spinner arc.
     *
     * @param startAngle start angle
     * @param endAngle end angle
     */
    public void setStartEndTrim(float startAngle, float endAngle) {
        mRing.setStartTrim(startAngle);
        mRing.setEndTrim(endAngle);
    }

    /**
     * Set the amount of rotation to apply to the progress spinner.
     *
     * @param rotation Rotation is from [0..1]
     */
    public void setProgressRotation(float rotation) {
        mRing.setRotation(rotation);
    }

    /**
     * Update the background color of the circle image view.
     */
    public void setBackgroundColor(int color) {
        mRing.setBackgroundColor(color);
     }

    /**
     * Set the colors used in the progress animation from color resources.
     * The first color will also be the color of the bar that grows in response
     * to a user swipe gesture.
     *
     * @param colors
     */
    public void setColorSchemeColors(int... colors) {
        mRing.setColors(colors);
        mRing.setColorIndex(0);
    }

    @Override
    public int getIntrinsicHeight() {
        return (int) mHeight;
    }

    @Override
    public int getIntrinsicWidth() {
        return (int) mWidth;
    }

    @Override
    public void draw(Canvas c) {
        final Rect bounds = getBounds();
        final int saveCount = c.save();
        c.rotate(mRotation, bounds.exactCenterX(), bounds.exactCenterY());
        mRing.draw(c, bounds);
        c.restoreToCount(saveCount);
    }

    @Override
    public void setAlpha(int alpha) {
        mRing.setAlpha(alpha);
    }

    public int getAlpha() {
        return mRing.getAlpha();
    }

    @Override
    public void setColorFilter(ColorFilter colorFilter) {
        mRing.setColorFilter(colorFilter);
    }

    @SuppressWarnings("unused")
    void setRotation(float rotation) {
        mRotation = rotation;
        invalidateSelf();
    }

    @SuppressWarnings("unused")
    private float getRotation() {
        return mRotation;
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }

    @Override
    public boolean isRunning() {
        final ArrayList<Animation> animators = mAnimators;
        final int N = animators.size();
        for (int i = 0; i < N; i++) {
            final Animation animator = animators.get(i);
            if (animator.hasStarted() && !animator.hasEnded()) {
                return true;
            }
        }
        return false;
    }

    @Override
    public void start() {
        mAnimation.reset();
        mRing.storeOriginals();
        // Already showing some part of the ring
        if (mRing.getEndTrim() != mRing.getStartTrim()) {
            mFinishing = true;
            mAnimation.setDuration(ANIMATION_DURATION/2);
            mParent.startAnimation(mAnimation);
        } else {
            mRing.setColorIndex(0);
            mRing.resetOriginals();
            mAnimation.setDuration(ANIMATION_DURATION);
            mParent.startAnimation(mAnimation);
        }
    }

    @Override
    public void stop() {
        mParent.clearAnimation();
        setRotation(0);
        mRing.setShowArrow(false);
        mRing.setColorIndex(0);
        mRing.resetOriginals();
    }

    private float getMinProgressArc(Ring ring) {
        return (float) Math.toRadians(
                ring.getStrokeWidth() / (2 * Math.PI * ring.getCenterRadius()));
    }

    // Adapted from ArgbEvaluator.java
    private int evaluateColorChange(float fraction, int startValue, int endValue) {
        int startInt = (Integer) startValue;
        int startA = (startInt >> 24) & 0xff;
        int startR = (startInt >> 16) & 0xff;
        int startG = (startInt >> 8) & 0xff;
        int startB = startInt & 0xff;

        int endInt = (Integer) endValue;
        int endA = (endInt >> 24) & 0xff;
        int endR = (endInt >> 16) & 0xff;
        int endG = (endInt >> 8) & 0xff;
        int endB = endInt & 0xff;

        return (int)((startA + (int)(fraction * (endA - startA))) << 24) |
                (int)((startR + (int)(fraction * (endR - startR))) << 16) |
                (int)((startG + (int)(fraction * (endG - startG))) << 8) |
                (int)((startB + (int)(fraction * (endB - startB))));
    }

    /**
     * Update the ring color if this is within the last 25% of the animation.
     * The new ring color will be a translation from the starting ring color to
     * the next color.
     */
    private void updateRingColor(float interpolatedTime, Ring ring) {
        if (interpolatedTime > COLOR_START_DELAY_OFFSET) {
            // scale the interpolatedTime so that the full
            // transformation from 0 - 1 takes place in the
            // remaining time
            ring.setColor(evaluateColorChange((interpolatedTime - COLOR_START_DELAY_OFFSET)
                    / (1.0f - COLOR_START_DELAY_OFFSET), ring.getStartingColor(),
                    ring.getNextColor()));
        }
    }

    private void applyFinishTranslation(float interpolatedTime, Ring ring) {
        // shrink back down and complete a full rotation before
        // starting other circles
        // Rotation goes between [0..1].
        updateRingColor(interpolatedTime, ring);
        float targetRotation = (float) (Math.floor(ring.getStartingRotation() / MAX_PROGRESS_ARC)
                + 1f);
        final float minProgressArc = getMinProgressArc(ring);
        final float startTrim = ring.getStartingStartTrim()
                + (ring.getStartingEndTrim() - minProgressArc - ring.getStartingStartTrim())
                * interpolatedTime;
        ring.setStartTrim(startTrim);
        ring.setEndTrim(ring.getStartingEndTrim());
        final float rotation = ring.getStartingRotation()
                + ((targetRotation - ring.getStartingRotation()) * interpolatedTime);
        ring.setRotation(rotation);
    }

    private void setupAnimators() {
        final Ring ring = mRing;
        final Animation animation = new Animation() {
                @Override
            public void applyTransformation(float interpolatedTime, Transformation t) {
                if (mFinishing) {
                    applyFinishTranslation(interpolatedTime, ring);
                } else {
                    // The minProgressArc is calculated from 0 to create an
                    // angle that matches the stroke width.
                    final float minProgressArc = getMinProgressArc(ring);
                    final float startingEndTrim = ring.getStartingEndTrim();
                    final float startingTrim = ring.getStartingStartTrim();
                    final float startingRotation = ring.getStartingRotation();

                    updateRingColor(interpolatedTime, ring);

                    // Moving the start trim only occurs in the first 50% of a
                    // single ring animation
                    if (interpolatedTime <= START_TRIM_DURATION_OFFSET) {
                        // scale the interpolatedTime so that the full
                        // transformation from 0 - 1 takes place in the
                        // remaining time
                        final float scaledTime = (interpolatedTime)
                                / (1.0f - START_TRIM_DURATION_OFFSET);
                        final float startTrim = startingTrim
                                + ((MAX_PROGRESS_ARC - minProgressArc) * MATERIAL_INTERPOLATOR
                                        .getInterpolation(scaledTime));
                        ring.setStartTrim(startTrim);
                    }

                    // Moving the end trim starts after 50% of a single ring
                    // animation completes
                    if (interpolatedTime > END_TRIM_START_DELAY_OFFSET) {
                        // scale the interpolatedTime so that the full
                        // transformation from 0 - 1 takes place in the
                        // remaining time
                        final float minArc = MAX_PROGRESS_ARC - minProgressArc;
                        float scaledTime = (interpolatedTime - START_TRIM_DURATION_OFFSET)
                                / (1.0f - START_TRIM_DURATION_OFFSET);
                        final float endTrim = startingEndTrim
                                + (minArc * MATERIAL_INTERPOLATOR.getInterpolation(scaledTime));
                        ring.setEndTrim(endTrim);
                    }

                    final float rotation = startingRotation + (0.25f * interpolatedTime);
                    ring.setRotation(rotation);

                    float groupRotation = ((FULL_ROTATION / NUM_POINTS) * interpolatedTime)
                            + (FULL_ROTATION * (mRotationCount / NUM_POINTS));
                    setRotation(groupRotation);
                }
            }
        };
        animation.setRepeatCount(Animation.INFINITE);
        animation.setRepeatMode(Animation.RESTART);
        animation.setInterpolator(LINEAR_INTERPOLATOR);
        animation.setAnimationListener(new Animation.AnimationListener() {

                @Override
            public void onAnimationStart(Animation animation) {
                mRotationCount = 0;
            }

                @Override
            public void onAnimationEnd(Animation animation) {
                // do nothing
            }

                @Override
            public void onAnimationRepeat(Animation animation) {
                ring.storeOriginals();
                ring.goToNextColor();
                ring.setStartTrim(ring.getEndTrim());
                if (mFinishing) {
                    // finished closing the last ring from the swipe gesture; go
                    // into progress mode
                    mFinishing = false;
                    animation.setDuration(ANIMATION_DURATION);
                    ring.setShowArrow(false);
                } else {
                    mRotationCount = (mRotationCount + 1) % (NUM_POINTS);
                }
            }
        });
        mAnimation = animation;
    }

    private final Callback mCallback = new Callback() {
        @Override
        public void invalidateDrawable(Drawable d) {
            invalidateSelf();
        }

        @Override
        public void scheduleDrawable(Drawable d, Runnable what, long when) {
            scheduleSelf(what, when);
        }

        @Override
        public void unscheduleDrawable(Drawable d, Runnable what) {
            unscheduleSelf(what);
        }
    };

    private static class Ring {
        private final RectF mTempBounds = new RectF();
        private final Paint mPaint = new Paint();
        private final Paint mArrowPaint = new Paint();

        private final Callback mCallback;

        private float mStartTrim = 0.0f;
        private float mEndTrim = 0.0f;
        private float mRotation = 0.0f;
        private float mStrokeWidth = 5.0f;
        private float mStrokeInset = 2.5f;

        private int[] mColors;
        // mColorIndex represents the offset into the available mColors that the
        // progress circle should currently display. As the progress circle is
        // animating, the mColorIndex moves by one to the next available color.
        private int mColorIndex;
        private float mStartingStartTrim;
        private float mStartingEndTrim;
        private float mStartingRotation;
        private boolean mShowArrow;
        private Path mArrow;
        private float mArrowScale;
        private double mRingCenterRadius;
        private int mArrowWidth;
        private int mArrowHeight;
        private int mAlpha;
        private final Paint mCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        private int mBackgroundColor;
        private int mCurrentColor;

        public Ring(Callback callback) {
            mCallback = callback;

            mPaint.setStrokeCap(Paint.Cap.SQUARE);
            mPaint.setAntiAlias(true);
            mPaint.setStyle(Paint.Style.STROKE);

            mArrowPaint.setStyle(Paint.Style.FILL);
            mArrowPaint.setAntiAlias(true);
        }

        public void setBackgroundColor(int color) {
            mBackgroundColor = color;
        }

        /**
         * Set the dimensions of the arrowhead.
         *
         * @param width Width of the hypotenuse of the arrow head
         * @param height Height of the arrow point
         */
        public void setArrowDimensions(float width, float height) {
            mArrowWidth = (int) width;
            mArrowHeight = (int) height;
        }

        /**
         * Draw the progress spinner
         */
        public void draw(Canvas c, Rect bounds) {
            final RectF arcBounds = mTempBounds;
            arcBounds.set(bounds);
            arcBounds.inset(mStrokeInset, mStrokeInset);

            final float startAngle = (mStartTrim + mRotation) * 360;
            final float endAngle = (mEndTrim + mRotation) * 360;
            float sweepAngle = endAngle - startAngle;

            mPaint.setColor(mCurrentColor);
            c.drawArc(arcBounds, startAngle, sweepAngle, false, mPaint);

            drawTriangle(c, startAngle, sweepAngle, bounds);

            if (mAlpha < 255) {
                mCirclePaint.setColor(mBackgroundColor);
                mCirclePaint.setAlpha(255 - mAlpha);
                c.drawCircle(bounds.exactCenterX(), bounds.exactCenterY(), bounds.width() / 2,
                        mCirclePaint);
            }
        }

        private void drawTriangle(Canvas c, float startAngle, float sweepAngle, Rect bounds) {
            if (mShowArrow) {
                if (mArrow == null) {
                    mArrow = new Path();
                    mArrow.setFillType(Path.FillType.EVEN_ODD);
                } else {
                    mArrow.reset();
                }

                // Adjust the position of the triangle so that it is inset as
                // much as the arc, but also centered on the arc.
                float inset = (int) mStrokeInset / 2 * mArrowScale;
                float x = (float) (mRingCenterRadius * Math.cos(0) + bounds.exactCenterX());
                float y = (float) (mRingCenterRadius * Math.sin(0) + bounds.exactCenterY());

                // Update the path each time. This works around an issue in SKIA
                // where concatenating a rotation matrix to a scale matrix
                // ignored a starting negative rotation. This appears to have
                // been fixed as of API 21.
                mArrow.moveTo(0, 0);
                mArrow.lineTo(mArrowWidth * mArrowScale, 0);
                mArrow.lineTo((mArrowWidth * mArrowScale / 2), (mArrowHeight
                        * mArrowScale));
                mArrow.offset(x - inset, y);
                mArrow.close();
                // draw a triangle
                mArrowPaint.setColor(mCurrentColor);
                c.rotate(startAngle + sweepAngle - ARROW_OFFSET_ANGLE, bounds.exactCenterX(),
                        bounds.exactCenterY());
                c.drawPath(mArrow, mArrowPaint);
            }
        }

        /**
         * Set the colors the progress spinner alternates between.
         *
         * @param colors Array of integers describing the colors. Must be non-<code>null</code>.
         */
        public void setColors(@NonNull int[] colors) {
            mColors = colors;
            // if colors are reset, make sure to reset the color index as well
            setColorIndex(0);
        }

        /**
         * Set the absolute color of the progress spinner. This is should only
         * be used when animating between current and next color when the
         * spinner is rotating.
         *
         * @param color int describing the color.
         */
        public void setColor(int color) {
            mCurrentColor = color;
        }

        /**
         * @param index Index into the color array of the color to display in
         *            the progress spinner.
         */
        public void setColorIndex(int index) {
            mColorIndex = index;
            mCurrentColor = mColors[mColorIndex];
        }

        /**
         * @return int describing the next color the progress spinner should use when drawing.
         */
        public int getNextColor() {
            return mColors[getNextColorIndex()];
        }

        private int getNextColorIndex() {
            return (mColorIndex + 1) % (mColors.length);
        }

        /**
         * Proceed to the next available ring color. This will automatically
         * wrap back to the beginning of colors.
         */
        public void goToNextColor() {
            setColorIndex(getNextColorIndex());
        }

        public void setColorFilter(ColorFilter filter) {
            mPaint.setColorFilter(filter);
            invalidateSelf();
        }

        /**
         * @param alpha Set the alpha of the progress spinner and associated arrowhead.
         */
        public void setAlpha(int alpha) {
            mAlpha = alpha;
        }

        /**
         * @return Current alpha of the progress spinner and arrowhead.
         */
        public int getAlpha() {
            return mAlpha;
        }

        /**
         * @param strokeWidth Set the stroke width of the progress spinner in pixels.
         */
        public void setStrokeWidth(float strokeWidth) {
            mStrokeWidth = strokeWidth;
            mPaint.setStrokeWidth(strokeWidth);
            invalidateSelf();
        }

        @SuppressWarnings("unused")
        public float getStrokeWidth() {
            return mStrokeWidth;
        }

        @SuppressWarnings("unused")
        public void setStartTrim(float startTrim) {
            mStartTrim = startTrim;
            invalidateSelf();
        }

        @SuppressWarnings("unused")
        public float getStartTrim() {
            return mStartTrim;
        }

        public float getStartingStartTrim() {
            return mStartingStartTrim;
        }

        public float getStartingEndTrim() {
            return mStartingEndTrim;
        }

        public int getStartingColor() {
            return mColors[mColorIndex];
        }

        @SuppressWarnings("unused")
        public void setEndTrim(float endTrim) {
            mEndTrim = endTrim;
            invalidateSelf();
        }

        @SuppressWarnings("unused")
        public float getEndTrim() {
            return mEndTrim;
        }

        @SuppressWarnings("unused")
        public void setRotation(float rotation) {
            mRotation = rotation;
            invalidateSelf();
        }

        @SuppressWarnings("unused")
        public float getRotation() {
            return mRotation;
        }

        public void setInsets(int width, int height) {
            final float minEdge = (float) Math.min(width, height);
            float insets;
            if (mRingCenterRadius <= 0 || minEdge < 0) {
                insets = (float) Math.ceil(mStrokeWidth / 2.0f);
            } else {
                insets = (float) (minEdge / 2.0f - mRingCenterRadius);
            }
            mStrokeInset = insets;
        }

        @SuppressWarnings("unused")
        public float getInsets() {
            return mStrokeInset;
        }

        /**
         * @param centerRadius Inner radius in px of the circle the progress
         *            spinner arc traces.
         */
        public void setCenterRadius(double centerRadius) {
            mRingCenterRadius = centerRadius;
        }

        public double getCenterRadius() {
            return mRingCenterRadius;
        }

        /**
         * @param show Set to true to show the arrow head on the progress spinner.
         */
        public void setShowArrow(boolean show) {
            if (mShowArrow != show) {
                mShowArrow = show;
                invalidateSelf();
            }
        }

        /**
         * @param scale Set the scale of the arrowhead for the spinner.
         */
        public void setArrowScale(float scale) {
            if (scale != mArrowScale) {
                mArrowScale = scale;
                invalidateSelf();
            }
        }

        /**
         * @return The amount the progress spinner is currently rotated, between [0..1].
         */
        public float getStartingRotation() {
            return mStartingRotation;
        }

        /**
         * If the start / end trim are offset to begin with, store them so that
         * animation starts from that offset.
         */
        public void storeOriginals() {
            mStartingStartTrim = mStartTrim;
            mStartingEndTrim = mEndTrim;
            mStartingRotation = mRotation;
        }

        /**
         * Reset the progress spinner to default rotation, start and end angles.
         */
        public void resetOriginals() {
            mStartingStartTrim = 0;
            mStartingEndTrim = 0;
            mStartingRotation = 0;
            setStartTrim(0);
            setEndTrim(0);
            setRotation(0);
        }

        private void invalidateSelf() {
            mCallback.invalidateDrawable(null);
        }
    }
}

SwipeRefreshLayout.java

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.support.annotation.ColorInt;
import android.support.annotation.ColorRes;
import android.support.v4.view.MotionEventCompat;
import android.support.v4.view.NestedScrollingChild;
import android.support.v4.view.NestedScrollingChildHelper;
import android.support.v4.view.NestedScrollingParent;
import android.support.v4.view.NestedScrollingParentHelper;
import android.support.v4.view.ViewCompat;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.DecelerateInterpolator;
import android.view.animation.Transformation;
import android.widget.AbsListView;

/**
 * The SwipeRefreshLayout should be used whenever the user can refresh the
 * contents of a view via a vertical swipe gesture. The activity that
 * instantiates this view should add an OnRefreshListener to be notified
 * whenever the swipe to refresh gesture is completed. The SwipeRefreshLayout
 * will notify the listener each and every time the gesture is completed again;
 * the listener is responsible for correctly determining when to actually
 * initiate a refresh of its content. If the listener determines there should
 * not be a refresh, it must call setRefreshing(false) to cancel any visual
 * indication of a refresh. If an activity wishes to show just the progress
 * animation, it should call setRefreshing(true). To disable the gesture and
 * progress animation, call setEnabled(false) on the view.
 * <p>
 * This layout should be made the parent of the view that will be refreshed as a
 * result of the gesture and can only support one direct child. This view will
 * also be made the target of the gesture and will be forced to match both the
 * width and the height supplied in this layout. The SwipeRefreshLayout does not
 * provide accessibility events; instead, a menu item must be provided to allow
 * refresh of the content wherever this gesture is used.
 * </p>
 */
public class SwipeRefreshLayout extends ViewGroup implements NestedScrollingParent,
    NestedScrollingChild {
    // Maps to ProgressBar.Large style
    public static final int LARGE = MaterialProgressDrawable.LARGE;
    // Maps to ProgressBar default style
    public static final int DEFAULT = MaterialProgressDrawable.DEFAULT;

    private static final String TAG = SwipeRefreshLayout.class.getSimpleName();

    private static final int MAX_ALPHA = 255;
    private static final int STARTING_PROGRESS_ALPHA = (int) (.3f * MAX_ALPHA);

    private static final int CIRCLE_DIAMETER = 40;
    private static final int CIRCLE_DIAMETER_LARGE = 56;

    private static final float DECELERATE_INTERPOLATION_FACTOR = 2f;
    private static final int INVALID_POINTER = -1;
    private static final float DRAG_RATE = .5f;

    // Max amount of circle that can be filled by progress during swipe gesture,
    // where 1.0 is a full circle
    private static final float MAX_PROGRESS_ANGLE = .8f;

    private static final int SCALE_DOWN_DURATION = 150;

    private static final int ALPHA_ANIMATION_DURATION = 300;

    private static final int ANIMATE_TO_TRIGGER_DURATION = 200;

    private static final int ANIMATE_TO_START_DURATION = 200;

    // Default background for the progress spinner
    private static final int CIRCLE_BG_LIGHT = 0xFFFAFAFA;
    // Default offset in dips from the top of the view to where the progress spinner should stop
    private static final int DEFAULT_CIRCLE_TARGET = 64;

    private View mTarget; // the target of the gesture
    private android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener mListener;
    private boolean mRefreshing = false;
    private int mTouchSlop;
    private float mTotalDragDistance = -1;
    // If nested scrolling is enabled, the total amount that needed to be
    // consumed by this as the nested scrolling parent is used in place of the
    // overscroll determined by MOVE events in the onTouch handler
    private float mTotalUnconsumed;
    private final NestedScrollingParentHelper mNestedScrollingParentHelper;
    private final NestedScrollingChildHelper mNestedScrollingChildHelper;
    private final int[] mParentScrollConsumed = new int[2];

    private int mMediumAnimationDuration;
    private int mCurrentTargetOffsetTop;
    // Whether or not the starting offset has been determined.
    private boolean mOriginalOffsetCalculated = false;

    private float mInitialMotionY;
    private float mInitialDownY;
    private boolean mIsBeingDragged;
    private int mActivePointerId = INVALID_POINTER;
    // Whether this item is scaled up rather than clipped
    private boolean mScale;

    // Target is returning to its start offset because it was cancelled or a
    // refresh was triggered.
    private boolean mReturningToStart;
    private final DecelerateInterpolator mDecelerateInterpolator;
    private static final int[] LAYOUT_ATTRS = new int[] {
        android.R.attr.enabled
    };

    private CircleImageView mCircleView;
    private int mCircleViewIndex = -1;

    protected int mFrom;

    private float mStartingScale;

    protected int mOriginalOffsetTop;

    private MaterialProgressDrawable mProgress;

    private Animation mScaleAnimation;

    private Animation mScaleDownAnimation;

    private Animation mAlphaStartAnimation;

    private Animation mAlphaMaxAnimation;

    private Animation mScaleDownToStartAnimation;

    private float mSpinnerFinalOffset;

    private boolean mNotify;

    private int mCircleWidth;

    private int mCircleHeight;

    // Whether the client has set a custom starting position;
    private boolean mUsingCustomStart;

    private Animation.AnimationListener mRefreshListener = new Animation.AnimationListener() {
        @Override
        public void onAnimationStart(Animation animation) {
        }

        @Override
        public void onAnimationRepeat(Animation animation) {
        }

        @Override
        public void onAnimationEnd(Animation animation) {
            if (mRefreshing) {
                // Make sure the progress view is fully visible
                mProgress.setAlpha(MAX_ALPHA);
                mProgress.start();
                if (mNotify) {
                    if (mListener != null) {
                        mListener.onRefresh();
                    }
                }
            } else {
                mProgress.stop();
                mCircleView.setVisibility(View.GONE);
                setColorViewAlpha(MAX_ALPHA);
                // Return the circle to its start position
                if (mScale) {
                    setAnimationProgress(0 /* animation complete and view is hidden */);
                } else {
                    setTargetOffsetTopAndBottom(mOriginalOffsetTop - mCurrentTargetOffsetTop,
                            true /* requires update */);
                }
            }
            mCurrentTargetOffsetTop = mCircleView.getTop();
        }
    };

    private void setColorViewAlpha(int targetAlpha) {
        mCircleView.getBackground().setAlpha(targetAlpha);
        mProgress.setAlpha(targetAlpha);
    }

    /**
     * The refresh indicator starting and resting position is always positioned
     * near the top of the refreshing content. This position is a consistent
     * location, but can be adjusted in either direction based on whether or not
     * there is a toolbar or actionbar present.
     *
     * @param scale Set to true if there is no view at a higher z-order than
     *            where the progress spinner is set to appear.
     * @param start The offset in pixels from the top of this view at which the
     *            progress spinner should appear.
     * @param end The offset in pixels from the top of this view at which the
     *            progress spinner should come to rest after a successful swipe
     *            gesture.
     */
    public void setProgressViewOffset(boolean scale, int start, int end) {
        mScale = scale;
        mCircleView.setVisibility(View.GONE);
        mOriginalOffsetTop = mCurrentTargetOffsetTop = start;
        mSpinnerFinalOffset = end;
        mUsingCustomStart = true;
        mCircleView.invalidate();
    }

    /**
     * The refresh indicator resting position is always positioned near the top
     * of the refreshing content. This position is a consistent location, but
     * can be adjusted in either direction based on whether or not there is a
     * toolbar or actionbar present.
     *
     * @param scale Set to true if there is no view at a higher z-order than
     *            where the progress spinner is set to appear.
     * @param end The offset in pixels from the top of this view at which the
     *            progress spinner should come to rest after a successful swipe
     *            gesture.
     */
    public void setProgressViewEndTarget(boolean scale, int end) {
        mSpinnerFinalOffset = end;
        mScale = scale;
        mCircleView.invalidate();
    }

    /**
     * One of DEFAULT, or LARGE.
     */
    public void setSize(int size) {
        if (size != MaterialProgressDrawable.LARGE && size != MaterialProgressDrawable.DEFAULT) {
            return;
        }
        final DisplayMetrics metrics = getResources().getDisplayMetrics();
        if (size == MaterialProgressDrawable.LARGE) {
            mCircleHeight = mCircleWidth = (int) (CIRCLE_DIAMETER_LARGE * metrics.density);
        } else {
            mCircleHeight = mCircleWidth = (int) (CIRCLE_DIAMETER * metrics.density);
        }
        // force the bounds of the progress circle inside the circle view to
        // update by setting it to null before updating its size and then
        // re-setting it
        mCircleView.setImageDrawable(null);
        mProgress.updateSizes(size);
        mCircleView.setImageDrawable(mProgress);
    }

    /**
     * Simple constructor to use when creating a SwipeRefreshLayout from code.
     *
     * @param context
     */
    public SwipeRefreshLayout(Context context) {
        this(context, null);
    }

    /**
     * Constructor that is called when inflating SwipeRefreshLayout from XML.
     *
     * @param context
     * @param attrs
     */
    public SwipeRefreshLayout(Context context, AttributeSet attrs) {
        super(context, attrs);

        mTouchSlop = ViewConfiguration.get(context).getScaledTouchSlop();

        mMediumAnimationDuration = getResources().getInteger(
                android.R.integer.config_mediumAnimTime);

        setWillNotDraw(false);
        mDecelerateInterpolator = new DecelerateInterpolator(DECELERATE_INTERPOLATION_FACTOR);

        final TypedArray a = context.obtainStyledAttributes(attrs, LAYOUT_ATTRS);
        setEnabled(a.getBoolean(0, true));
        a.recycle();

        final DisplayMetrics metrics = getResources().getDisplayMetrics();
        mCircleWidth = (int) (CIRCLE_DIAMETER * metrics.density);
        mCircleHeight = (int) (CIRCLE_DIAMETER * metrics.density);

        createProgressView();
        ViewCompat.setChildrenDrawingOrderEnabled(this, true);
        // the absolute offset has to take into account that the circle starts at an offset
        mSpinnerFinalOffset = DEFAULT_CIRCLE_TARGET * metrics.density;
        mTotalDragDistance = mSpinnerFinalOffset;
        mNestedScrollingParentHelper = new NestedScrollingParentHelper(this);

        mNestedScrollingChildHelper = new NestedScrollingChildHelper(this);
        setNestedScrollingEnabled(true);
    }

    protected int getChildDrawingOrder(int childCount, int i) {
        if (mCircleViewIndex < 0) {
            return i;
        } else if (i == childCount - 1) {
            // Draw the selected child last
            return mCircleViewIndex;
        } else if (i >= mCircleViewIndex) {
            // Move the children after the selected child earlier one
            return i + 1;
        } else {
            // Keep the children before the selected child the same
            return i;
        }
    }

    private void createProgressView() {
        mCircleView = new CircleImageView(getContext(), CIRCLE_BG_LIGHT, CIRCLE_DIAMETER/2);
        mProgress = new MaterialProgressDrawable(getContext(), this);
        mProgress.setBackgroundColor(CIRCLE_BG_LIGHT);
        mCircleView.setImageDrawable(mProgress);
        mCircleView.setVisibility(View.GONE);
        addView(mCircleView, 0);
    }

    /**
     * Set the listener to be notified when a refresh is triggered via the swipe
     * gesture.
     */
    public void setOnRefreshListener(
        android.support.v4.widget.SwipeRefreshLayout.OnRefreshListener listener) {
        mListener = listener;
    }

    /**
     * Pre API 11, alpha is used to make the progress circle appear instead of scale.
     */
    private boolean isAlphaUsedForScale() {
        return android.os.Build.VERSION.SDK_INT < 11;
    }

    /**
     * Notify the widget that refresh state has changed. Do not call this when
     * refresh is triggered by a swipe gesture.
     *
     * @param refreshing Whether or not the view should show refresh progress.
     */
    public void setRefreshing(boolean refreshing) {
        if (refreshing && mRefreshing != refreshing) {
            // scale and show
            mRefreshing = refreshing;
            int endTarget = 0;
            if (!mUsingCustomStart) {
                endTarget = (int) (mSpinnerFinalOffset + mOriginalOffsetTop);
            } else {
                endTarget = (int) mSpinnerFinalOffset;
            }
            setTargetOffsetTopAndBottom(endTarget - mCurrentTargetOffsetTop,
                    true /* requires update */);
            mNotify = false;
            startScaleUpAnimation(mRefreshListener);
        } else {
            setRefreshing(refreshing, false /* notify */);
        }
    }

    private void startScaleUpAnimation(Animation.AnimationListener listener) {
        mCircleView.setVisibility(View.VISIBLE);
        if (android.os.Build.VERSION.SDK_INT >= 11) {
            // Pre API 11, alpha is used in place of scale up to show the
            // progress circle appearing.
            // Don't adjust the alpha during appearance otherwise.
            mProgress.setAlpha(MAX_ALPHA);
        }
        mScaleAnimation = new Animation() {
            @Override
            public void applyTransformation(float interpolatedTime, Transformation t) {
                setAnimationProgress(interpolatedTime);
            }
        };
        mScaleAnimation.setDuration(mMediumAnimationDuration);
        if (listener != null) {
            mCircleView.setAnimationListener(listener);
        }
        mCircleView.clearAnimation();
        mCircleView.startAnimation(mScaleAnimation);
    }

    /**
     * Pre API 11, this does an alpha animation.
     * @param progress
     */
    private void setAnimationProgress(float progress) {
        if (isAlphaUsedForScale()) {
            setColorViewAlpha((int) (progress * MAX_ALPHA));
        } else {
            ViewCompat.setScaleX(mCircleView, progress);
            ViewCompat.setScaleY(mCircleView, progress);
        }
    }

    private void setRefreshing(boolean refreshing, final boolean notify) {
        if (mRefreshing != refreshing) {
            mNotify = notify;
            ensureTarget();
            mRefreshing = refreshing;
            if (mRefreshing) {
                animateOffsetToCorrectPosition(mCurrentTargetOffsetTop, mRefreshListener);
            } else {
                startScaleDownAnimation(mRefreshListener);
            }
        }
    }

    private void startScaleDownAnimation(Animation.AnimationListener listener) {
        mScaleDownAnimation = new Animation() {
            @Override
            public void applyTransformation(float interpolatedTime, Transformation t) {
                setAnimationProgress(1 - interpolatedTime);
            }
        };
        mScaleDownAnimation.setDuration(SCALE_DOWN_DURATION);
        mCircleView.setAnimationListener(listener);
        mCircleView.clearAnimation();
        mCircleView.startAnimation(mScaleDownAnimation);
    }

    private void startProgressAlphaStartAnimation() {
        mAlphaStartAnimation = startAlphaAnimation(mProgress.getAlpha(), STARTING_PROGRESS_ALPHA);
    }

    private void startProgressAlphaMaxAnimation() {
        mAlphaMaxAnimation = startAlphaAnimation(mProgress.getAlpha(), MAX_ALPHA);
    }

    private Animation startAlphaAnimation(final int startingAlpha, final int endingAlpha) {
        // Pre API 11, alpha is used in place of scale. Don't also use it to
        // show the trigger point.
        if (mScale && isAlphaUsedForScale()) {
            return null;
        }
        Animation alpha = new Animation() {
            @Override
            public void applyTransformation(float interpolatedTime, Transformation t) {
                mProgress
                        .setAlpha((int) (startingAlpha+ ((endingAlpha - startingAlpha)
                                * interpolatedTime)));
            }
        };
        alpha.setDuration(ALPHA_ANIMATION_DURATION);
        // Clear out the previous animation listeners.
        mCircleView.setAnimationListener(null);
        mCircleView.clearAnimation();
        mCircleView.startAnimation(alpha);
        return alpha;
    }

    /**
     * @deprecated Use {@link #setProgressBackgroundColorSchemeResource(int)}
     */
    @Deprecated
    public void setProgressBackgroundColor(int colorRes) {
        setProgressBackgroundColorSchemeResource(colorRes);
    }

    /**
     * Set the background color of the progress spinner disc.
     *
     * @param colorRes Resource id of the color.
     */
    public void setProgressBackgroundColorSchemeResource(@ColorRes int colorRes) {
        setProgressBackgroundColorSchemeColor(getResources().getColor(colorRes));
    }

    /**
     * Set the background color of the progress spinner disc.
     *
     * @param color
     */
    public void setProgressBackgroundColorSchemeColor(@ColorInt int color) {
        mCircleView.setBackgroundColor(color);
        mProgress.setBackgroundColor(color);
    }

    /**
     * Set the color resources used in the progress animation from color resources.
     * The first color will also be the color of the bar that grows in response
     * to a user swipe gesture.
     *
     * @param colorResIds
     */
    public void setColorSchemeResources(@ColorRes int... colorResIds) {
        final Resources res = getResources();
        int[] colorRes = new int[colorResIds.length];
        for (int i = 0; i < colorResIds.length; i++) {
            colorRes[i] = res.getColor(colorResIds[i]);
        }
        setColorSchemeColors(colorRes);
    }

    /**
     * Set the colors used in the progress animation. The first
     * color will also be the color of the bar that grows in response to a user
     * swipe gesture.
     *
     * @param colors
     */
    @ColorInt
    public void setColorSchemeColors(int... colors) {
        ensureTarget();
        mProgress.setColorSchemeColors(colors);
    }

    /**
     * @return Whether the SwipeRefreshWidget is actively showing refresh
     *         progress.
     */
    public boolean isRefreshing() {
        return mRefreshing;
    }

    private void ensureTarget() {
        // Don't bother getting the parent height if the parent hasn't been laid
        // out yet.
        if (mTarget == null) {
            for (int i = 0; i < getChildCount(); i++) {
                View child = getChildAt(i);
                if (!child.equals(mCircleView)) {
                    mTarget = child;
                    break;
                }
            }
        }
    }

    /**
     * Set the distance to trigger a sync in dips
     *
     * @param distance
     */
    public void setDistanceToTriggerSync(int distance) {
        mTotalDragDistance = distance;
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        final int width = getMeasuredWidth();
        final int height = getMeasuredHeight();
        if (getChildCount() == 0) {
            return;
        }
        if (mTarget == null) {
            ensureTarget();
        }
        if (mTarget == null) {
            return;
        }

        int circleWidth = mCircleView.getMeasuredWidth();
        int circleHeight = mCircleView.getMeasuredHeight();
        mCircleView.layout((width / 2 - circleWidth / 2), mCurrentTargetOffsetTop,
            (width / 2 + circleWidth / 2), mCurrentTargetOffsetTop + circleHeight);

        final View child = mTarget;
        final int childLeft = getPaddingLeft();
        final int childTop = getPaddingTop();
        final int childWidth = width - getPaddingLeft() - getPaddingRight();
        final int childHeight = height - getPaddingTop() - getPaddingBottom();
        child.layout(childLeft, childTop, childLeft + childWidth, childTop + childHeight);

    }

    @Override
    public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        if (mTarget == null) {
            ensureTarget();
        }
        if (mTarget == null) {
            return;
        }
        mTarget.measure(MeasureSpec.makeMeasureSpec(
                getMeasuredWidth() - getPaddingLeft() - getPaddingRight(),
                MeasureSpec.EXACTLY), MeasureSpec.makeMeasureSpec(
                getMeasuredHeight() - getPaddingTop() - getPaddingBottom(), MeasureSpec.EXACTLY));
        mCircleView.measure(MeasureSpec.makeMeasureSpec(mCircleWidth, MeasureSpec.EXACTLY),
                MeasureSpec.makeMeasureSpec(mCircleHeight, MeasureSpec.EXACTLY));
        if (!mUsingCustomStart && !mOriginalOffsetCalculated) {
            mOriginalOffsetCalculated = true;
            mCurrentTargetOffsetTop = mOriginalOffsetTop = -mCircleView.getMeasuredHeight();
        }
        mCircleViewIndex = -1;
        // Get the index of the circleview.
        for (int index = 0; index < getChildCount(); index++) {
            if (getChildAt(index) == mCircleView) {
                mCircleViewIndex = index;
                break;
            }
        }
    }

    /**
     * Get the diameter of the progress circle that is displayed as part of the
     * swipe to refresh layout. This is not valid until a measure pass has
     * completed.
     *
     * @return Diameter in pixels of the progress circle view.
     */
    public int getProgressCircleDiameter() {
        return mCircleView != null ?mCircleView.getMeasuredHeight() : 0;
    }

    /**
     * @return Whether it is possible for the child view of this layout to
     *         scroll up. Override this if the child view is a custom view.
     */
    public boolean canChildScrollUp() {
        if (android.os.Build.VERSION.SDK_INT < 14) {
            if (mTarget instanceof AbsListView) {
                final AbsListView absListView = (AbsListView) mTarget;
                return absListView.getChildCount() > 0
                        && (absListView.getFirstVisiblePosition() > 0 || absListView.getChildAt(0)
                                .getTop() < absListView.getPaddingTop());
            } else {
                return ViewCompat.canScrollVertically(mTarget, -1) || mTarget.getScrollY() > 0;
            }
        } else {
            return ViewCompat.canScrollVertically(mTarget, -1);
        }
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        ensureTarget();

        final int action = MotionEventCompat.getActionMasked(ev);

        if (mReturningToStart && action == MotionEvent.ACTION_DOWN) {
            mReturningToStart = false;
        }

        if (!isEnabled() || mReturningToStart || canChildScrollUp() || mRefreshing) {
            // Fail fast if we're not in a state where a swipe is possible
            return false;
        }

        switch (action) {
            case MotionEvent.ACTION_DOWN:
                setTargetOffsetTopAndBottom(mOriginalOffsetTop - mCircleView.getTop(), true);
                mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
                mIsBeingDragged = false;
                final float initialDownY = getMotionEventY(ev, mActivePointerId);
                if (initialDownY == -1) {
                    return false;
                }
                mInitialDownY = initialDownY;
                break;

            case MotionEvent.ACTION_MOVE:
                if (mActivePointerId == INVALID_POINTER) {
                    Log.e(TAG, "Got ACTION_MOVE event but don't have an active pointer id.");
                    return false;
                }

                final float y = getMotionEventY(ev, mActivePointerId);
                if (y == -1) {
                    return false;
                }
                final float yDiff = y - mInitialDownY;
                if (yDiff > mTouchSlop && !mIsBeingDragged) {
                    mInitialMotionY = mInitialDownY + mTouchSlop;
                    mIsBeingDragged = true;
                    mProgress.setAlpha(STARTING_PROGRESS_ALPHA);
                }
                break;

            case MotionEventCompat.ACTION_POINTER_UP:
                onSecondaryPointerUp(ev);
                break;

            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL:
                Log.d(TAG, "onInterceptTouchEvent() called with: " + "ev = [" + ev + "]");
                mIsBeingDragged = false;
                mActivePointerId = INVALID_POINTER;
                break;
        }

        return mIsBeingDragged;
    }

    private float getMotionEventY(MotionEvent ev, int activePointerId) {
        final int index = MotionEventCompat.findPointerIndex(ev, activePointerId);
        if (index < 0) {
            return -1;
        }
        return MotionEventCompat.getY(ev, index);
    }

    @Override
    public void requestDisallowInterceptTouchEvent(boolean b) {
        // if this is a List < L or another view that doesn't support nested
        // scrolling, ignore this request so that the vertical scroll event
        // isn't stolen
        if ((android.os.Build.VERSION.SDK_INT < 21 && mTarget instanceof AbsListView)
                || (mTarget != null && !ViewCompat.isNestedScrollingEnabled(mTarget))) {
            // Nope.
        } else {
            super.requestDisallowInterceptTouchEvent(b);
        }
    }

    // NestedScrollingParent

    @Override
    public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
        if (isEnabled() && (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0) {
            // Dispatch up to the nested parent
            startNestedScroll(nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL);
            return true;
        }
        return false;
    }

    @Override
    public void onNestedScrollAccepted(View child, View target, int axes) {
        // Reset the counter of how much leftover scroll needs to be consumed.
        mNestedScrollingParentHelper.onNestedScrollAccepted(child, target, axes);
        mTotalUnconsumed = 0;
    }

    @Override
    public void onNestedPreScroll(View target, int dx, int dy, int[] consumed) {
        // If we are in the middle of consuming, a scroll, then we want to move the spinner back up
        // before allowing the list to scroll
        if (dy > 0 && mTotalUnconsumed > 0) {
            if (dy > mTotalUnconsumed) {
                consumed[1] = dy - (int) mTotalUnconsumed;
                mTotalUnconsumed = 0;
            } else {
                mTotalUnconsumed -= dy;
                consumed[1] = dy;

            }
            moveSpinner(mTotalUnconsumed);
        }

        // Now let our nested parent consume the leftovers
        final int[] parentConsumed = mParentScrollConsumed;
        if (dispatchNestedPreScroll(dx - consumed[0], dy - consumed[1], parentConsumed, null)) {
            consumed[0] += parentConsumed[0];
            consumed[1] += parentConsumed[1];
        }
    }

    @Override
    public int getNestedScrollAxes() {
        return mNestedScrollingParentHelper.getNestedScrollAxes();
    }

    @Override
    public void onStopNestedScroll(View target) {
        mNestedScrollingParentHelper.onStopNestedScroll(target);
        // Finish the spinner for nested scrolling if we ever consumed any
        // unconsumed nested scroll
        if (mTotalUnconsumed > 0) {
            finishSpinner(mTotalUnconsumed);
            mTotalUnconsumed = 0;
        }
        // Dispatch up our nested parent
        stopNestedScroll();
    }

    @Override
    public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed,
            int dyUnconsumed) {
        if (dyUnconsumed < 0) {
            dyUnconsumed = Math.abs(dyUnconsumed);
            mTotalUnconsumed += dyUnconsumed;
            moveSpinner(mTotalUnconsumed);
        }
        // Dispatch up to the nested parent
        dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dxConsumed, null);
    }

    // NestedScrollingChild

    @Override
    public boolean onNestedPreFling(View target, float velocityX, float velocityY) {
        return false;
    }

    @Override
    public boolean onNestedFling(View target, float velocityX, float velocityY, boolean consumed) {
        return false;
    }

    @Override
    public void setNestedScrollingEnabled(boolean enabled) {
        mNestedScrollingChildHelper.setNestedScrollingEnabled(enabled);
    }

    @Override
    public boolean isNestedScrollingEnabled() {
        return mNestedScrollingChildHelper.isNestedScrollingEnabled();
    }

    @Override
    public boolean startNestedScroll(int axes) {
        return mNestedScrollingChildHelper.startNestedScroll(axes);
    }

    @Override
    public void stopNestedScroll() {
        mNestedScrollingChildHelper.stopNestedScroll();
    }

    @Override
    public boolean hasNestedScrollingParent() {
        return mNestedScrollingChildHelper.hasNestedScrollingParent();
    }

    @Override
    public boolean dispatchNestedScroll(int dxConsumed, int dyConsumed, int dxUnconsumed,
            int dyUnconsumed, int[] offsetInWindow) {
        return mNestedScrollingChildHelper.dispatchNestedScroll(dxConsumed, dyConsumed,
                dxUnconsumed, dyUnconsumed, offsetInWindow);
    }

    @Override
    public boolean dispatchNestedPreScroll(int dx, int dy, int[] consumed, int[] offsetInWindow) {
        return mNestedScrollingChildHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow);
    }

    @Override
    public boolean dispatchNestedFling(float velocityX, float velocityY, boolean consumed) {
        return mNestedScrollingChildHelper.dispatchNestedFling(velocityX, velocityY, consumed);
    }

    @Override
    public boolean dispatchNestedPreFling(float velocityX, float velocityY) {
        return mNestedScrollingChildHelper.dispatchNestedPreFling(velocityX, velocityY);
    }

    private boolean isAnimationRunning(Animation animation) {
        return animation != null && animation.hasStarted() && !animation.hasEnded();
    }

    private void moveSpinner(float overscrollTop) {
        mProgress.showArrow(true);
        float originalDragPercent = overscrollTop / mTotalDragDistance;

        float dragPercent = Math.min(1f, Math.abs(originalDragPercent));
        float adjustedPercent = (float) Math.max(dragPercent - .4, 0) * 5 / 3;
        float extraOS = Math.abs(overscrollTop) - mTotalDragDistance;
        float slingshotDist = mUsingCustomStart ? mSpinnerFinalOffset - mOriginalOffsetTop
                : mSpinnerFinalOffset;
        float tensionSlingshotPercent = Math.max(0, Math.min(extraOS, slingshotDist * 2)
                / slingshotDist);
        float tensionPercent = (float) ((tensionSlingshotPercent / 4) - Math.pow(
                (tensionSlingshotPercent / 4), 2)) * 2f;
        float extraMove = (slingshotDist) * tensionPercent * 2;

        int targetY = mOriginalOffsetTop + (int) ((slingshotDist * dragPercent) + extraMove);
        // where 1.0f is a full circle
        if (mCircleView.getVisibility() != View.VISIBLE) {
            mCircleView.setVisibility(View.VISIBLE);
        }
        if (!mScale) {
            ViewCompat.setScaleX(mCircleView, 1f);
            ViewCompat.setScaleY(mCircleView, 1f);
        }
        if (overscrollTop < mTotalDragDistance) {
            if (mScale) {
                setAnimationProgress(overscrollTop / mTotalDragDistance);
            }
            if (mProgress.getAlpha() > STARTING_PROGRESS_ALPHA
                    && !isAnimationRunning(mAlphaStartAnimation)) {
                // Animate the alpha
                startProgressAlphaStartAnimation();
            }
            float strokeStart = adjustedPercent * .8f;
            mProgress.setStartEndTrim(0f, Math.min(MAX_PROGRESS_ANGLE, strokeStart));
            mProgress.setArrowScale(Math.min(1f, adjustedPercent));
        } else {
            if (mProgress.getAlpha() < MAX_ALPHA && !isAnimationRunning(mAlphaMaxAnimation)) {
                // Animate the alpha
                startProgressAlphaMaxAnimation();
            }
        }
        float rotation = (-0.25f + .4f * adjustedPercent + tensionPercent * 2) * .5f;
        mProgress.setProgressRotation(rotation);
        setTargetOffsetTopAndBottom(targetY - mCurrentTargetOffsetTop, true /* requires update */);
    }

    private void finishSpinner(float overscrollTop) {
        if (overscrollTop > mTotalDragDistance) {
            setRefreshing(true, true /* notify */);
        } else {
            // cancel refresh
            mRefreshing = false;
            mProgress.setStartEndTrim(0f, 0f);
            Animation.AnimationListener listener = null;
            if (!mScale) {
                listener = new Animation.AnimationListener() {

                    @Override
                    public void onAnimationStart(Animation animation) {
                    }

                    @Override
                    public void onAnimationEnd(Animation animation) {
                        if (!mScale) {
                            startScaleDownAnimation(null);
                        }
                    }

                    @Override
                    public void onAnimationRepeat(Animation animation) {
                    }

                };
            }
            animateOffsetToStartPosition(mCurrentTargetOffsetTop, listener);
            mProgress.showArrow(false);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent ev) {
        final int action = MotionEventCompat.getActionMasked(ev);

        if (mReturningToStart && action == MotionEvent.ACTION_DOWN) {
            mReturningToStart = false;
        }

        if (!isEnabled() || mReturningToStart || canChildScrollUp()) {
            // Fail fast if we're not in a state where a swipe is possible
            return false;
        }

        switch (action) {
            case MotionEvent.ACTION_DOWN:
                mActivePointerId = MotionEventCompat.getPointerId(ev, 0);
                mIsBeingDragged = false;
                break;

            case MotionEvent.ACTION_MOVE: {
                final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
                if (pointerIndex < 0) {
                    Log.e(TAG, "Got ACTION_MOVE event but have an invalid active pointer id.");
                    return false;
                }

                final float y = MotionEventCompat.getY(ev, pointerIndex);
                final float overscrollTop = (y - mInitialMotionY) * DRAG_RATE;
                if (mIsBeingDragged) {
                    if (overscrollTop > 0) {
                        moveSpinner(overscrollTop);
                    } else {
                        return false;
                    }
                }
                break;
            }
            case MotionEventCompat.ACTION_POINTER_DOWN: {
                final int index = MotionEventCompat.getActionIndex(ev);
                mActivePointerId = MotionEventCompat.getPointerId(ev, index);
                break;
            }

            case MotionEventCompat.ACTION_POINTER_UP:
                onSecondaryPointerUp(ev);
                break;

            case MotionEvent.ACTION_UP:
            case MotionEvent.ACTION_CANCEL: {
                Log.d(TAG, "onTouchEvent() called with: " + "ev = [" + ev + "]");
                if (mActivePointerId == INVALID_POINTER) {
                    if (action == MotionEvent.ACTION_UP) {
                        Log.e(TAG, "Got ACTION_UP event but don't have an active pointer id.");
                    }
                    return false;
                }
                final int pointerIndex = MotionEventCompat.findPointerIndex(ev, mActivePointerId);
                final float y = MotionEventCompat.getY(ev, pointerIndex);
                final float overscrollTop = (y - mInitialMotionY) * DRAG_RATE;
                mIsBeingDragged = false;
                finishSpinner(overscrollTop);
                mActivePointerId = INVALID_POINTER;
                return false;
            }
        }

        return true;
    }

    private void animateOffsetToCorrectPosition(int from, Animation.AnimationListener listener) {
        mFrom = from;
        mAnimateToCorrectPosition.reset();
        mAnimateToCorrectPosition.setDuration(ANIMATE_TO_TRIGGER_DURATION);
        mAnimateToCorrectPosition.setInterpolator(mDecelerateInterpolator);
        if (listener != null) {
            mCircleView.setAnimationListener(listener);
        }
        mCircleView.clearAnimation();
        mCircleView.startAnimation(mAnimateToCorrectPosition);
    }

    private void peek(int from, Animation.AnimationListener listener) {
        mFrom = from;
        mPeek.reset();
        mPeek.setDuration(500);
        mPeek.setInterpolator(mDecelerateInterpolator);
        if (listener != null) {
            mCircleView.setAnimationListener(listener);
        }
        mCircleView.clearAnimation();
        mCircleView.startAnimation(mPeek);
    }

    private void animateOffsetToStartPosition(int from, Animation.AnimationListener listener) {
        if (mScale) {
            // Scale the item back down
            startScaleDownReturnToStartAnimation(from, listener);
        } else {
            mFrom = from;
            mAnimateToStartPosition.reset();
            mAnimateToStartPosition.setDuration(ANIMATE_TO_START_DURATION);
            mAnimateToStartPosition.setInterpolator(mDecelerateInterpolator);
            if (listener != null) {
                mCircleView.setAnimationListener(listener);
            }
            mCircleView.clearAnimation();
            mCircleView.startAnimation(mAnimateToStartPosition);
        }
    }

    private final Animation mAnimateToCorrectPosition = new Animation() {
        @Override
        public void applyTransformation(float interpolatedTime, Transformation t) {
            int targetTop = 0;
            int endTarget = 0;
            if (!mUsingCustomStart) {
                endTarget = (int) (mSpinnerFinalOffset - Math.abs(mOriginalOffsetTop));
            } else {
                endTarget = (int) mSpinnerFinalOffset;
            }
            targetTop = (mFrom + (int) ((endTarget - mFrom) * interpolatedTime));
            int offset = targetTop - mCircleView.getTop();
            setTargetOffsetTopAndBottom(offset, false /* requires update */);
            mProgress.setArrowScale(1 - interpolatedTime);
        }
    };

    private final Animation mPeek = new Animation() {
        @Override
        public void applyTransformation(float interpolatedTime, Transformation t) {
            int targetTop = 0;
            int endTarget = 0;
            if (!mUsingCustomStart) {
                endTarget = (int) (mSpinnerFinalOffset - Math.abs(mOriginalOffsetTop));
            } else {
                endTarget = (int) mSpinnerFinalOffset; //mSpinnerFinalOffset;
            }
            targetTop = (mFrom + (int) ((endTarget - mFrom) * interpolatedTime));
            int offset = targetTop - mCircleView.getTop();
            setTargetOffsetTopAndBottom(offset, false /* requires update */);
            mProgress.setArrowScale(1 - interpolatedTime);
        }
    };

    private void moveToStart(float interpolatedTime) {
        int targetTop = 0;
        targetTop = (mFrom + (int) ((mOriginalOffsetTop - mFrom) * interpolatedTime));
        int offset = targetTop - mCircleView.getTop();
        setTargetOffsetTopAndBottom(offset, false /* requires update */);
    }

    private final Animation mAnimateToStartPosition = new Animation() {
        @Override
        public void applyTransformation(float interpolatedTime, Transformation t) {
            moveToStart(interpolatedTime);
        }
    };

    private void startScaleDownReturnToStartAnimation(int from,
            Animation.AnimationListener listener) {
        mFrom = from;
        if (isAlphaUsedForScale()) {
            mStartingScale = mProgress.getAlpha();
        } else {
            mStartingScale = ViewCompat.getScaleX(mCircleView);
        }
        mScaleDownToStartAnimation = new Animation() {
            @Override
            public void applyTransformation(float interpolatedTime, Transformation t) {
                float targetScale = (mStartingScale + (-mStartingScale  * interpolatedTime));
                setAnimationProgress(targetScale);
                moveToStart(interpolatedTime);
            }
        };
        mScaleDownToStartAnimation.setDuration(SCALE_DOWN_DURATION);
        if (listener != null) {
            mCircleView.setAnimationListener(listener);
        }
        mCircleView.clearAnimation();
        mCircleView.startAnimation(mScaleDownToStartAnimation);
    }

    private float targetTranslateY = 0;

    private void setTargetOffsetTopAndBottom(int offset, boolean requiresUpdate) {
        if (targetTranslateY >= mTotalDragDistance && offset > 0) {
            return;
        }
        final boolean quickMove =
            requiresUpdate && (targetTranslateY == 0 && offset >= mTotalDragDistance);
        targetTranslateY += offset;
        if (targetTranslateY == mTotalDragDistance) {
            targetTranslateY =
                mTotalDragDistance; // This to make sure we not scroll over mTotalDragDistance
        }
        if (quickMove) {
            mTarget.animate().setDuration(ANIMATE_TO_START_DURATION).translationY(targetTranslateY);
        } else {
            mTarget.setTranslationY(targetTranslateY);
        }

        mCircleView.bringToFront();
        mCircleView.offsetTopAndBottom(offset);
        mCurrentTargetOffsetTop = mCircleView.getTop();
        if (requiresUpdate && android.os.Build.VERSION.SDK_INT < 11) {
            invalidate();
        }
        Log.d(TAG, "setTargetOffsetTopAndBottom() called with: "
            + "targetTranslateY = ["
            + targetTranslateY
            + "], requiresUpdate = ["
            + requiresUpdate
            + "]");
        if (targetTranslateY == 0) {
            ViewCompat.setScaleX(mCircleView, 0);
            ViewCompat.setScaleY(mCircleView, 0);
        }
    }

    private void onSecondaryPointerUp(MotionEvent ev) {
        final int pointerIndex = MotionEventCompat.getActionIndex(ev);
        final int pointerId = MotionEventCompat.getPointerId(ev, pointerIndex);
        if (pointerId == mActivePointerId) {
            // This was our active pointer going up. Choose a new
            // active pointer and adjust accordingly.
            final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
            mActivePointerId = MotionEventCompat.getPointerId(ev, newPointerIndex);
        }
    }
}