缩放后的 Android 位图/画布偏移 [英] Android Bitmap/Canvas offset after scale

问题描述

如果我有一个画布，我在上面画一个位图，如下所示:

If I have a canvas, on which I draw a Bitmap like this:

canvas.drawBitmap(bmLargeImage, srcRect, destRect, paint);

然后我缩放位图:

canvas.scale(1.5f, 1.5f, 450, 250);

我想在缩放后获取位图的位置.如果缩放前的位置是 (0, 0)，缩放后有一个偏移量，我需要这个偏移量.. 我怎样才能得到它?

I want to get the position of the Bitmap after the scale. If the position before scale was (0, 0), after scale there is a offset and I need that offset.. how can I get it?

感谢并为这个简单的问题感到抱歉，这里是新手...

Thanks and sorry for the simple question, newbie here...

推荐答案

好吧，让我们试着找出最好的公式

Ok lets try to work out the best formula for this

canvas.scale(scaleX, scaleY, pivotX, pivotY);  

if (scaleX >= 1){    
  objectNewX = objectOldX + (objectOldX - pivotX)*(scaleX - 1); 
}else{   
  objectNewX = objectOldX - (objectOldX - pivotX)*(1 - scaleX); 
}

objectNewY 也是如此.位图的新宽度和高度当然是旧尺寸和比例的倍数.

The same for objectNewY. The new width and height of the bitmap would of course be the multiple of the old size and scale.

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