不规则图形按钮非透明区的点击

/** 
 * 不规则"图形按钮控件" 
 * 
 */  
public class TrapezoidImageButton extends ImageButton {  
  
    public TrapezoidImageButton(Context context, AttributeSet attrs, int defStyle) {  
    super(context, attrs, defStyle);  
    }  
  
    public TrapezoidImageButton(Context context, AttributeSet attrs) {  
    super(context, attrs);  
    }  
  
    public TrapezoidImageButton(Context context) {  
    super(context);  
    }  
      
    @Override  
    public boolean onTouchEvent(MotionEvent event) {  
    if (isTouchPointInView(event.getX(),event.getY())||  
        event.getAction() != MotionEvent.ACTION_DOWN){  
        return super.onTouchEvent(event);  
    }else{  
        return false;  
    }  
    }  
  
    protected boolean isTouchPointInView(float localX, float localY){  
    Bitmap bitmap = Bitmap.createBitmap(getWidth(), getHeight(), Config.ARGB_8888);  
    Canvas canvas = new Canvas(bitmap);  
    draw(canvas);  
    int x = (int)localX;  
    int y = (int)localY;  
    if (x < 0 || x >= getWidth())  
        return false;  
    if (y < 0 || y >= getHeight())  
        return false;  
    int pixel = bitmap.getPixel(x,y);  
    if ((pixel&0xff000000) != 0){ //点在非透明区  
        return true;  
    }else{  
        return false;  
    }  
    }  
}