OutlineContainer.java

package com.marshalchen.common.uimodule.jazzyviewpager;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.Rect;
import android.graphics.drawable.Animatable;
import android.util.AttributeSet;
import android.view.animation.AnimationUtils;
import android.view.animation.Interpolator;
import android.widget.FrameLayout;

import com.marshalchen.common.uimodule.widgets.R;


public class OutlineContainer extends FrameLayout implements Animatable {

	private Paint mOutlinePaint;
	
	private boolean mIsRunning = false;
    private long mStartTime;
	private float mAlpha = 1.0f;
	private static final long ANIMATION_DURATION = 500;
	private static final long FRAME_DURATION = 1000 / 60;
	private final Interpolator mInterpolator = new Interpolator() {
		public float getInterpolation(float t) {
			t -= 1.0f;
			return t * t * t + 1.0f;
		}
	};

	public OutlineContainer(Context context) {
		super(context);
		init();
	}
	public OutlineContainer(Context context, AttributeSet attrs) {
		super(context, attrs);
		init();
	}
	public OutlineContainer(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		init();
	}

	private void init() {
		mOutlinePaint = new Paint();
		mOutlinePaint.setAntiAlias(true);
		mOutlinePaint.setStrokeWidth(Util.dpToPx(getResources(), 2));
		mOutlinePaint.setColor(getResources().getColor(R.color.holo_blue_dark));
		mOutlinePaint.setStyle(Style.STROKE);

		int padding = Util.dpToPx(getResources(), 10);
		setPadding(padding, padding, padding, padding);
	}

	@Override
	protected void dispatchDraw(Canvas canvas) {
		super.dispatchDraw(canvas);
		int offset = Util.dpToPx(getResources(), 5);
		if (mOutlinePaint.getColor() != JazzyViewPager.sOutlineColor) {
			mOutlinePaint.setColor(JazzyViewPager.sOutlineColor);
		}
		mOutlinePaint.setAlpha((int)(mAlpha * 255));
		Rect rect = new Rect(offset, offset, getMeasuredWidth()-offset, getMeasuredHeight()-offset);
		canvas.drawRect(rect, mOutlinePaint);
	}
	
	public void setOutlineAlpha(float alpha) {
		mAlpha = alpha;
	}

	@Override
	public boolean isRunning() {
		return mIsRunning;
	}

	@Override
	public void start() {
		if (mIsRunning)
			return;
		mIsRunning = true;
		mStartTime = AnimationUtils.currentAnimationTimeMillis();	
		post(mUpdater);
	}

	@Override
	public void stop() {
		if (!mIsRunning)
			return;
		mIsRunning = false;
	}
	
	private final Runnable mUpdater = new Runnable() {
        @Override
        public void run() {
            long now = AnimationUtils.currentAnimationTimeMillis();
            long duration = now - mStartTime;
            if (duration >= ANIMATION_DURATION) {
                mAlpha = 0.0f;
                invalidate();
                stop();
                return;
            } else {
            	mAlpha = mInterpolator.getInterpolation(1 - duration / (float) ANIMATION_DURATION);
                invalidate();
            }
            postDelayed(mUpdater, FRAME_DURATION);
        }
    };

}