Canvas.clipPath(Path)未按预期剪切

Question

我正在尝试将画布绘制操作剪切成弧形楔形.但是,在将剪切路径设置为画布后,我没有得到预期的结果.

为了说明,这是我正在做的事情:

path.reset();

//Move to point #1
path.moveTo(rect.centerX(), rect.centerY());

//Per the documentation, this will draw a connecting line from the current
//position to the starting position of the arc (at 0 degrees), add the arc
//and my current position now lies at #2.
path.arcTo(rect, 0, -30);

//This should then close the path, finishing back at the center point (#3)
path.close();

这是有效的,当我简单地绘制这个路径(canvas.drawPath(path, paint))时,它会绘制如上所示的楔形.但是,当我将此路径设置为画布的剪切路径并将其绘制到其中时:

//I've tried it with and without the Region.Op parameter
canvas.clipPath(path, Region.Op.REPLACE);
canvas.drawColor(Color.BLUE);

我得到以下结果(仅留下楔形以显示参考):

所以它似乎剪切到了它的边界矩形Path,而不是它Path自身.有什么想法在这里发生了什么？

编辑就像更新一样,我发现了一种更有效的方法,可以实现硬件加速.首先,将整个图像(您要裁剪)绘制到屏幕外位图中.做一个BitmapShader使用此Bitmap,该着色器设置为一个Paint,然后使用该绘制楔形路径Paint对象:

drawMyBitmap(bitmap);
Shader shader = new BitmapShader(bitmap, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setShader(shader);

@Override
public void onDraw(Canvas canvas) {
    canvas.drawArc(rect,         //The rectangle bounding the circle
                   startAngle,   //The angle (CW from 3 o'clock) to start
                   sweepAngle,   //The angle (CW from 3 o'clock) of the arc
                   true,         //Boolean of whether to draw a filled arc (wedge)
                   paint         //The paint with the shader attached
    );
}

Answer 1

您使用的是HC还是以上或其他使用硬件加速？

如果是这样,则不支持clipPath并且存在问题.

developer.android.com/guide/topics/graphics/hardware-accel.html.