对于CSS，垂直边界崩溃，但为什么浮动的div不会折叠垂直边缘？(For CSS, vertical margin collapses, but why floated divs don't collapse vertical margins?)

 你在这里做的是复制整个屏幕并在坐标Rect(442,440,792,520);处绘制Rect(442,440,792,520); 在你的新位图中......哪个是画布上的。 
 
 坐标Rect(442,440,792,520)对应于你想要从源位图获得的部分。 你想把它复制到你的新位图的“内部”，所以在rect Rect(0,0,350,80) 
 
 你可以简单地调整你的矩形： 
 
 rect_source := Rect(442,440,792,520);
 rect_destination := Rect(0,0,350,80);
 
 其余的代码看起来是正确的。 

What you are doing here is copying the whole screen and draw it at coordinate Rect(442,440,792,520); in your new bitmap... Which is off its canvas.
 
The coordinate Rect(442,440,792,520) correspond to the part you want to get from the source bitmap. You want to copy it "inside" your new bitmap, so within the rect Rect(0,0,350,80)
 
You can simply adjust your rect like this :
 
 rect_source := Rect(442,440,792,520);
 rect_destination := Rect(0,0,350,80);
 
The rest of your code seems correct.