android实现图片按任意路径截取

public class MyView extends View {
private Drawable mDrawable;
private Path mPath;
private float mX = -1;
private float mY = -1;
private float mPastX;
private float mPastY;

public MyView(Context context) {
super(context);
// TODO Auto-generated constructor stub
mPath = new Path();
}

public void setDrawable(Drawable pDrawable){
mDrawable = pDrawable;
}

@Override
protected void onDraw(Canvas canvas) {
// TODO Auto-generated method stub
super.onDraw(canvas);
Log.i("xiao", "onDraw");
mDrawable.setBounds(0, 0, getWidth(), getHeight());
Rect lRect = mDrawable.getBounds();
Log.i("xiao", "lRect.left =  " + lRect.left + " top = " + lRect.top + " right = " + lRect.right + " bottom = " + lRect.bottom);
if(!mPath.isEmpty()){
Log.i("xiao", "!mPath.isEmpty()");
canvas.clipPath(mPath);
//mDrawable.draw(canvas);
}

mDrawable.draw(canvas);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
Log.i("xiao", "onTouchEvent");
int lAction = event.getAction();
if(mX != -1){
mPastX = mX;
mPastY = mY;
}
mX = event.getX();
mY = event.getY();
switch(lAction){
case MotionEvent.ACTION_DOWN:
mPath.reset();
mPath.moveTo(mX, mY);
break;
case MotionEvent.ACTION_MOVE:
mPath.quadTo(mPastX, mPastY, (mX + mPastX) / 2, (mY + mPastY) / 2);
break;
case MotionEvent.ACTION_UP:
mPath.lineTo(mX, mY);
mX = -1;
mY = -1;
invalidate();
break;
default:

break;
}
return true;
}
}

private MyView mView;

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);

mView = new MyView(this);
mView.setDrawable(this.getResources().getDrawable(R.drawable.test1));
this.setContentView(mView);
}