Customized Segmented button

attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>
	<declare-styleable name="SegmentedButton">
		<attr name="gradientNormal" format="reference"/>
		<attr name="gradientChecked" format="reference"/>
	</declare-styleable>
</resources>

SegmentedButton.java

/**
 * Customization of the RadioButton in order to allow behaviour
 * and appearance like the iOS ones.
 *
 * Inspired from http://blog.bookworm.at/2010/10/segmented-controls-in-android.html
 */
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.drawable.GradientDrawable;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Paint.Style;
import android.graphics.drawable.GradientDrawable;
import android.graphics.drawable.GradientDrawable.Orientation;
import android.util.AttributeSet;
import android.widget.RadioButton;

// a day read this
// http://kahdev.wordpress.com/2008/09/13/making-a-custom-android-button-using-a-custom-view/
// copy from LabelView custom view example from sample code
public class SegmentedButton extends RadioButton {
	private float mX;
	private float mTextWidth;
	private float mCurrentWidth;
	private float mCurrentHeight;
	private int mAscent;
	private String mText;
	private Paint mTextPaint;

	private GradientDrawable mGradient = new GradientDrawable(Orientation.TOP_BOTTOM, new int[] { 0xffdcdcdc, 0xff111111 });;
	private GradientDrawable mGradientChecked = new GradientDrawable(Orientation.TOP_BOTTOM, new int[] { 0xffa5a5a5, 0xff000000 });;

	public SegmentedButton(Context context) {
		super(context);

		init(context, null, 0);
	}

	public SegmentedButton(Context context, AttributeSet attrs) {
		super(context, attrs);

		init(context, attrs, 0);
	}

	/**
	 * This methods inits the style configuration.
	 *
	 * For some reason if not called explicitely the checking doesn't work.
	 */
	protected void init(Context context, AttributeSet attrs, int defStyle) {
		// retrieve text for the button
		mText = getText().toString();
		mTextPaint = new Paint();
		mTextPaint.setAntiAlias(true);
		mTextPaint.setTextSize(14);
		mTextPaint.setColor(0xFF000000);
		setPadding(3, 3, 3, 3);

		TypedArray a =
			context.obtainStyledAttributes(
				attrs,
				R.styleable.SegmentedButton,
				defStyle,
				0);


		/*
		 * TODO: text align, padding, margin, text color etc...
		 */
		final int N = a.getIndexCount();
		for (int i = 0; i < N; i++) {
		    int attr = a.getIndex(i);
		    switch (attr) {
			case R.styleable.SegmentedButton_gradientNormal:
			    mGradient = (GradientDrawable)a.getDrawable(attr);
			    break;
			case R.styleable.SegmentedButton_gradientChecked:
			    mGradientChecked = (GradientDrawable)a.getDrawable(attr);
			    break;
		    }
		}
	}

	public SegmentedButton(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);

		init(context, attrs, defStyle);
	}

	@Override
	public void onDraw(Canvas canvas) {
		if (isChecked()) {
			GradientDrawable grad = mGradient;
			grad.setBounds(0, 0, this.getWidth(), this.getHeight());
			grad.draw(canvas);
		} else {
			GradientDrawable grad = mGradientChecked;
			grad.setBounds(0, 0, this.getWidth(), this.getHeight());
			grad.draw(canvas);
		}

		Rect bounds = new Rect();
		mTextPaint.getTextBounds(mText, 0, mText.length(), bounds);
		canvas.drawText(mText, -bounds.width()/2 + getWidth()/2, getPaddingTop() - mAscent, mTextPaint);

		Paint paint = new Paint();
		paint.setColor(Color.BLACK);
		paint.setStyle(Style.STROKE);
		Rect rect = new Rect(0, 0, this.getWidth(), this.getHeight());
		canvas.drawRect(rect, paint);
	}

	/*
	@Override
	protected void onSizeChanged(int w, int h, int ow, int oh) {
		android.util.Log.i("onSizeChanged", "miao");
		super.onSizeChanged(w, h, ow, oh);
		mX = w * 0.5f; // remember the center of the screen
	}*/

	@Override
	public void onMeasure(int width, int height) {
		android.util.Log.i("onMeasure", "width: " + width + " height: " + height);

		mAscent = (int)mTextPaint.ascent();

		//setMeasuredDimension(getMeasurement(width, bounds.width()), getMeasuredHeight());
		setMeasuredDimension(
			getMeasurement(width, (int)mTextPaint.measureText(mText)),
			getMeasurement(
				height,
				(int)mTextPaint.descent()-mAscent+getPaddingTop() + getPaddingBottom())
		);

		//setMeasuredDimension((int)mCurrentWidth, (int)mCurrentHeight);
		//super.onMeasure(width, height);
	}

	private int getMeasurement(int measureSpec, int preferred) {
		int specSize = MeasureSpec.getSize(measureSpec);
		int measurement = 0;

		switch(MeasureSpec.getMode(measureSpec)) {
			case MeasureSpec.EXACTLY:
				// This means the width of this view has been given.
				measurement = specSize;
				break;
		     case MeasureSpec.AT_MOST:
			     // Take the minimum of the preferred size and what
			     // we were told to be.
			     measurement = Math.min(preferred, specSize);
			     break;
		     default:
			     measurement = preferred;
			     break;
		}

		return measurement;
    }
}