在矩形外部填充画布

发布于 2024-10-17 18:46:04 字数 170 浏览 1 评论 0原文

我想填充画布上矩形之外的区域。我用来

 canvas.drawRect(pTopLeft.x, pTopLeft.y, pBotRight.x, pBotRight.y, paint);

绘制矩形，但不知道如何填充矩形/剪辑之外。

谢谢杰夫

原文

I want to fill the area outside a rectangle on a canvas. I use

 canvas.drawRect(pTopLeft.x, pTopLeft.y, pBotRight.x, pBotRight.y, paint);

to draw the rectangle, but can't figure out how to fill outside the rectangle/clip.

Thanks
Geoff

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平安喜乐 2024-10-24 18:46:04

谢谢 ted 和 trojanfoe - 我想出的最好的解决方案是

    Point pTopLeft = new Point();
    Point pBotRight = new Point();

    //TODO:set x,y for points

    Rect rHole = new Rect(pTopLeft.x, pTopLeft.y, pBotRight.x, pBotRight.y);
    //assume current clip is full canvas
    //put a hole in the current clip
    canvas.clipRect(rHole,  Region.Op.DIFFERENCE);
    //fill with semi-transparent red
    canvas.drawARGB(50, 255, 0, 0);
    //restore full canvas clip for any subsequent operations
    canvas.clipRect(new Rect(0, 0, canvas.getWidth(), canvas.getHeight())
                    , Region.Op.REPLACE);

Thanks ted and trojanfoe - the neatest solution I've come up with is

    Point pTopLeft = new Point();
    Point pBotRight = new Point();

    //TODO:set x,y for points

    Rect rHole = new Rect(pTopLeft.x, pTopLeft.y, pBotRight.x, pBotRight.y);
    //assume current clip is full canvas
    //put a hole in the current clip
    canvas.clipRect(rHole,  Region.Op.DIFFERENCE);
    //fill with semi-transparent red
    canvas.drawARGB(50, 255, 0, 0);
    //restore full canvas clip for any subsequent operations
    canvas.clipRect(new Rect(0, 0, canvas.getWidth(), canvas.getHeight())
                    , Region.Op.REPLACE);

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鹿港小镇 2024-10-24 18:46:04

你不会在剪辑之外填充；这就是剪辑要防止的事情！如果要填充矩形外部和绘图层边界内部的空间，请构造四个辅助矩形：

Rect above = new Rect(0, 0, canvas.getWidth(), pTopLeft.y);
Rect left = new Rect(0, pTopLeft.y, pTopLeft.x, pBotRight.y);
Rect right = new Rect(pBotRight.x, pTopLeft.y, canvas.getWidth(), pBotRight.y);
Rect bottom = new Rect(0, pBotRight.y, canvas.getWidth(), canvas.getHeight());

然后填充它们。

You aren't going to fill outside the clip; that's the kind of thing clip is there to prevent! If you want to fill the space outside a rect and inside the drawing layer bounds, construct four auxiliary rects:

Rect above = new Rect(0, 0, canvas.getWidth(), pTopLeft.y);
Rect left = new Rect(0, pTopLeft.y, pTopLeft.x, pBotRight.y);
Rect right = new Rect(pBotRight.x, pTopLeft.y, canvas.getWidth(), pBotRight.y);
Rect bottom = new Rect(0, pBotRight.y, canvas.getWidth(), canvas.getHeight());

Then fill these.

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萌逼全场 2024-10-24 18:46:04

ICS及以上...

canvas.clipRect(rHole,  Region.Op.DIFFERENCE);

XOR、Difference 和 ReverseDifference 剪辑模式是
如果启用硬件加速，则被 ICS 忽略。
只需在您的视图中禁用 2D 硬件加速即可：
myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

参考Android：如何在API15中使用clipRect

ICS and above ...

canvas.clipRect(rHole,  Region.Op.DIFFERENCE);

XOR, Difference and ReverseDifference clip modes are
ignored by ICS if hardware acceleration is enabled.
Just disable 2D hardware acceleration in your view:
myView.setLayerType(View.LAYER_TYPE_SOFTWARE, null);

Reference Android: Howto use clipRect in API15

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