圆形颜色变换

发布于 2024-08-16 09:47:55 字数 327 浏览 3 评论 0原文

有没有办法将 colorTransform 应用于圆形而不是矩形中的 BitmapData？

我不想像下面的代码那样通过减少 Alpha 通道来擦除图像的矩形部分，而是想以圆形的形式进行擦除。

 _bitmap.colorTransform(new Rectangle(mouseX-d/2, mouseY-d/2, d, d),
 new ColorTransform(1, 1, 1, .5, 0, 0, 0, 1));

我确实有一些循环像素、提取 alpha 值并使用 setPixel 的代码，但它比 colorTransform 函数明显慢得多。

原文

Is there a way to apply a colorTransform to a BitmapData in a circle rather than in a rectangle?

Instead of erasing rectangular parts of an image by reducing the alpha channel as in the code below, I'd like to do it in circles.

 _bitmap.colorTransform(new Rectangle(mouseX-d/2, mouseY-d/2, d, d),
 new ColorTransform(1, 1, 1, .5, 0, 0, 0, 1));

I do have some code which loops through the pixels, extracts the alpha value and uses setPixel but it seams significantly slower than the colorTransform function.

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栖迟 2024-08-23 09:47:55

尝试使用绘图 API (flash.display.Graphics) 创建一个圆，然后使用 BlendMode.ERASE 将其绘制到位图数据上。如果我理解正确的话，这可能会解决你的问题。

var circle : Shape = new Shape;
circle.graphics.beginFill(0xffcc00, 1);
circle.graphics.drawEllipse(-50, -50, 100, 100);

// Create a transformation matrix for the draw() operation, with
// a translation matching the mouse position.
var mtx : Matrix = new Matrix();
mtx.translate(mouseX, mouseY);

// Draw circle at mouse position with the ERASE blend mode, to
// set affected pixels to alpha=0.
myBitmap.draw(circle, mtx, null, BlendMode.ERASE);

我不能 100% 确定 ERASE 混合模式能够与 draw() 命令配合使用，但我不明白为什么它不能。请让我知道结果如何！

Try creating a circle using the drawing API (flash.display.Graphics) and then drawing that onto the bitmap data with BlendMode.ERASE. That might solve your problem, if I understand it correctly.

var circle : Shape = new Shape;
circle.graphics.beginFill(0xffcc00, 1);
circle.graphics.drawEllipse(-50, -50, 100, 100);

// Create a transformation matrix for the draw() operation, with
// a translation matching the mouse position.
var mtx : Matrix = new Matrix();
mtx.translate(mouseX, mouseY);

// Draw circle at mouse position with the ERASE blend mode, to
// set affected pixels to alpha=0.
myBitmap.draw(circle, mtx, null, BlendMode.ERASE);

I'm not 100% sure that the ERASE blend mode works satisfyingly with the draw() command, but I can't see why it shouldn't. Please let me know how it works out!

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