A Slide-out Navigation Implementation for Android

DecorDrawerWrapper.java

/*
 * Copyright (c) 2012 Eddie Ringle <[email protected]>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification, are permitted
 * provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this list of conditions
 * and the following disclaimer.
 * Redistributions in binary form must reproduce the above copyright notice, this list of conditions
 * and the following disclaimer in the documentation and/or other materials provided with the
 * distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
 * FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY
 * WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.util.DisplayMetrics;
import android.util.TypedValue;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AccelerateDecelerateInterpolator;
import android.widget.FrameLayout;
import android.widget.ListView;
import android.widget.Scroller;

/**
 * DecorDrawerWrapper
 *
 * An implementation of the slide-out navigation pattern.
 *
 * @author Eddie Ringle ([email protected])
 */
public class DecorDrawerWrapper extends FrameLayout {
    private static final int SCROLL_DURATION = 250;

    private static final float TOUCH_TARGET_WIDTH_DIP = 48.0f;

    private boolean mDrawerOpened = false;
    private boolean mDrawerMoving = false;

    private int mDecorOffsetX = 0;
    private int mTouchTargetWidth;

    private Drawable mShadowDrawable;

    private Handler mScrollerHandler;
    private Scroller mScroller;

    private ViewGroup mDecorView;
    private ViewGroup mDecorContent;
    private ViewGroup mDrawerContent;

    private IDrawerCallbacks mDrawerCallbacks;

    public static interface IDrawerCallbacks {
        public void onDrawerOpened();

        public void onDrawerClosed();
    }

    public DecorDrawerWrapper(Activity activity, int drawerLayout) {
        super(activity);

        final DisplayMetrics dm = activity.getResources().getDisplayMetrics();

        mTouchTargetWidth = Math.round(TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
                                                                 TOUCH_TARGET_WIDTH_DIP, dm));

        mShadowDrawable = getResources().getDrawable(R.drawable.decor_shadow);
        mShadowDrawable.setBounds(-mTouchTargetWidth / 6, 0, 0, dm.heightPixels);

        mScrollerHandler = new Handler();
        mScroller = new Scroller(activity, new AccelerateDecelerateInterpolator());

        mDecorView = (ViewGroup) activity.getWindow().getDecorView();
        mDecorContent = (ViewGroup) mDecorView.getChildAt(0);
        mDrawerContent = (ViewGroup) LayoutInflater.from(activity).inflate(drawerLayout, null);

        /* TODO: Make this a configurable attribute */
        mDecorContent.setBackgroundColor(Color.WHITE);

        mDrawerContent.setPadding(0, 0, mTouchTargetWidth, 0);

        /*
         * Remove DecorView's children and re-appropriate them under this ViewGroup,
         * along with the drawer contents.
         */
        mDecorView.removeAllViews();
        addView(mDrawerContent);
        addView(mDecorContent);
        mDecorView.addView(this);
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        mDrawerContent.layout(left, top, right, bottom);
        mDecorContent.layout(mDecorContent.getLeft(), 0, mDecorContent.getLeft() + right, bottom);
    }

    @Override
    public boolean onInterceptTouchEvent(MotionEvent ev) {
        /* We always return false from this method */
        return false;
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);

        if (mDrawerOpened || mDrawerMoving) {
            canvas.save();
            canvas.translate(mDecorContent.getLeft(), 0);
            mShadowDrawable.draw(canvas);
            canvas.restore();
        }
    }

    public void toggleDrawer(final boolean animate) {
        if (!mDrawerOpened) {
            openDrawer(animate);
        } else {
            closeDrawer(animate);
        }
    }

    public void toggleDrawer() {
        toggleDrawer(true);
    }

    public void openDrawer(final boolean animate) {
        if (mDrawerOpened || mDrawerMoving) return;

        mDrawerMoving = true;

        final int widthPixels = getResources().getDisplayMetrics().widthPixels;
        mScroller.startScroll(0, 0, (widthPixels - mTouchTargetWidth), 0, SCROLL_DURATION);
        mDecorOffsetX = 0;

        mScrollerHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                final boolean scrolling = mScroller.computeScrollOffset();
                mDecorContent.offsetLeftAndRight(mScroller.getCurrX() - mDecorOffsetX);
                mDecorOffsetX = mScroller.getCurrX();
                postInvalidate();

                if (!scrolling) {
                    mDrawerMoving = false;
                    mDrawerOpened = true;
                    if (mDrawerCallbacks != null) {
                        mScrollerHandler.post(new Runnable() {
                            @Override
                            public void run() {
                                enableDisableViewGroup((ViewGroup) mDecorContent
                                        .findViewById(android.R.id.content), false);
                                mDrawerCallbacks.onDrawerOpened();
                            }
                        });
                    }
                } else {
                    mScrollerHandler.postDelayed(this, 16);
                }
            }
        }, 16);
    }

    public void openDrawer() {
        openDrawer(true);
    }

    public void closeDrawer(final boolean animate) {
        if (!mDrawerOpened || mDrawerMoving) return;

        mDrawerMoving = true;

        final int widthPixels = getResources().getDisplayMetrics().widthPixels;
        mScroller.startScroll(0, 0, -(widthPixels - mTouchTargetWidth), 0, SCROLL_DURATION);
        mDecorOffsetX = 0;

        mScrollerHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                final boolean scrolling = mScroller.computeScrollOffset();
                mDecorContent.offsetLeftAndRight(mScroller.getCurrX() - mDecorOffsetX);
                mDecorOffsetX = mScroller.getCurrX();
                postInvalidate();

                if (!scrolling) {
                    mDrawerMoving = false;
                    mDrawerOpened = false;
                    if (mDrawerCallbacks != null) {
                        mScrollerHandler.post(new Runnable() {
                            @Override
                            public void run() {
                                enableDisableViewGroup((ViewGroup) mDecorContent
                                        .findViewById(android.R.id.content), true);
                                mDrawerCallbacks.onDrawerClosed();
                            }
                        });
                    }
                } else {
                    mScrollerHandler.postDelayed(this, 16);
                }
            }
        }, 16);
    }

    public void closeDrawer() {
        closeDrawer(true);
    }

    public boolean isDrawerOpened() {
        return mDrawerOpened;
    }

    public boolean isDrawerMoving() {
        return mDrawerMoving;
    }

    public void setDrawerCallbacks(final IDrawerCallbacks callbacks) {
        mDrawerCallbacks = callbacks;
    }

    public IDrawerCallbacks getDrawerCallbacks() {
        return mDrawerCallbacks;
    }

    public static void enableDisableViewGroup(ViewGroup viewGroup, boolean enabled) {
        int childCount = viewGroup.getChildCount();
        for (int i = 0; i < childCount; i++) {
            View view = viewGroup.getChildAt(i);
            if (view.isFocusable()) view.setEnabled(enabled);
            if (view instanceof ViewGroup) {
                enableDisableViewGroup((ViewGroup) view, enabled);
            } else if (view instanceof ListView) {
                if (view.isFocusable()) view.setEnabled(enabled);
                ListView listView = (ListView) view;
                int listChildCount = listView.getChildCount();
                for (int j = 0; j < listChildCount; j++) {
                    if (view.isFocusable()) listView.getChildAt(j).setEnabled(false);
                }
            }
        }
    }
}