在Android画布上绘制路径或形状的交集

Question

如何绘制两个矩形和路径的交集。看看这张图片。

图1是我现在拥有的。图2是我想要实现的。这是我的看法的代码：

public class MyView extends View { 

    public MyView(Context context) { 
     super(context); 
    } 

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

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

    @Override 
    protected void onDraw(Canvas canvas) { 
     super.onDraw(canvas); 

     Paint paintRectA = new Paint(); 
     Paint paintRectB = new Paint(); 
     Paint paintPath = new Paint(); 

     paintRectA.setColor(Color.BLUE); 
     paintRectB.setColor(Color.RED); 
     paintPath.setColor(Color.CYAN); 

     RectF rectA = new RectF(0, 0, 50, 100); 
     RectF rectB = new RectF(50, 0, 100, 100); 

     Path path = new Path(); 
     path.lineTo(100, 0); 
     path.quadTo(50, 100, 0, 0); 
     path.close(); 

     canvas.drawRect(rectA, paintRectA); 
     canvas.drawRect(rectB, paintRectB); 
     canvas.drawPath(path, paintPath); 
    } 
} 

Answer 1

此代码将绘制图片＃2

@Override 
protected void onDraw(Canvas canvas) { 
    super.onDraw(canvas); 

    RectF rectA = new RectF(0, 0, 150, 300); 
    RectF rectB = new RectF(150, 0, 300, 300); 

    Path path = new Path(); 
    path.lineTo(300, 0); 
    path.quadTo(150, 300, 0, 0); 
    path.close(); 

    Bitmap bmp = Bitmap.createBitmap(300, 300, Bitmap.Config.ARGB_8888); 
    Canvas bitmapCanvas = new Canvas(bmp); 

    Paint paintPath = new Paint(Paint.ANTI_ALIAS_FLAG); 
    bitmapCanvas.drawPath(path, paintPath); 

    Paint paint = new Paint(); 
    paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN)); 

    paint.setColor(Color.BLUE); 
    bitmapCanvas.drawRect(rectA, paint); 

    paint.setColor(Color.RED); 
    bitmapCanvas.drawRect(rectB, paint); 

    paint.setXfermode(null); 
    canvas.drawBitmap(bmp, 0, 0, paint); 
}