a splite image example

SpliteImageView.java

package com.fanpage.tedliang.shaderexample;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ImageView;

public class SpliteImageView extends ImageView {

    private float originY;
    private float deltaY;
    Bitmap rightBottom;
    Bitmap leftup;
    Bitmap leftBottom;
    Bitmap rightup;

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

    }

    public SpliteImageView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public SpliteImageView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    public boolean onTouchEvent(MotionEvent motionEvent) {
        int action = motionEvent.getAction();
        if (action == MotionEvent.ACTION_DOWN) {
            originY = motionEvent.getY();

        } else if (action == MotionEvent.ACTION_MOVE) {
            deltaY = Math.abs(originY - motionEvent.getY());
        } else if (action == MotionEvent.ACTION_CANCEL || action == MotionEvent.ACTION_UP) {
            deltaY = 0;
            originY = 0;
        }
        invalidate();
        return true;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        if (rightBottom == null) {
            rightBottom = createRightDown();
            leftup = createLeftUp();
            leftBottom = createLeftDown();
            rightup = createRightUp();

        }
        canvas.drawBitmap(leftup, -deltaY, -deltaY, null);
        canvas.drawBitmap(rightBottom, deltaY, deltaY, null);
        canvas.drawBitmap(leftBottom, -deltaY, deltaY, null);
        canvas.drawBitmap(rightup, deltaY, -deltaY, null);
    }

    private Bitmap createRightUp() {
        Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
        Canvas myCanvas = new Canvas(bitmap);
        myCanvas.clipRect(new Rect(getWidth() / 2, 0, getWidth(), getHeight() / 2));
        super.onDraw(myCanvas);
        return bitmap;
    }

    private Bitmap createLeftDown() {
        Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
        Canvas myCanvas = new Canvas(bitmap);
        myCanvas.clipRect(new Rect(0, getHeight() / 2, getWidth() / 2, getHeight()));
        super.onDraw(myCanvas);
        return bitmap;
    }

    private Bitmap createRightDown() {
        Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
        Canvas myCanvas = new Canvas(bitmap);
        myCanvas.clipRect(new Rect(getWidth() / 2, getHeight() / 2, getWidth(), getHeight()));
        super.onDraw(myCanvas);
        return bitmap;
    }

    private Bitmap createLeftUp() {
        Bitmap bitmap = Bitmap.createBitmap(getWidth() / 2, getHeight() / 2, Bitmap.Config.ARGB_8888);
        Canvas myCanvas = new Canvas(bitmap);
        super.onDraw(myCanvas);
        return bitmap;
    }
}