由网友(改变是痛苦，不改变是受苦)分享简介：会有人请尽量向我解释为什么Would anyone please try to explain to me whypublic void addView(View child) {child.setDrawingCacheEnabled(true);child.setWillNotCacheDrawing(fals...

会有人请尽量向我解释为什么

Would anyone please try to explain to me why

public void addView(View child) {
  child.setDrawingCacheEnabled(true);
  child.setWillNotCacheDrawing(false);
  child.setWillNotDraw(false);
  child.buildDrawingCache();
  if(child.getDrawingCache() == null) { //TODO Make this work!
    Log.w("View", "View child's drawing cache is null");
  }
  setImageBitmap(child.getDrawingCache()); //TODO MAKE THIS WORK!!!
}

始终记录了绘图缓存为空，并设置位为空？

ALWAYS logs that the drawing cache is null, and sets the bitmap to null?

我一定要实际绘制视图的缓存设置过吗？

Do I have to actually draw the view before the cache is set?

谢谢！

推荐答案

我也有这个问题，并发现了这样的回答：

I was having this problem also and found this answer:

v.setDrawingCacheEnabled(true);

// this is the important code :)  
// Without it the view will have a dimension of 0,0 and the bitmap will be null          
v.measure(MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED), 
            MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED));
v.layout(0, 0, v.getMeasuredWidth(), v.getMeasuredHeight()); 

v.buildDrawingCache(true);
Bitmap b = Bitmap.createBitmap(v.getDrawingCache());
v.setDrawingCacheEnabled(false); // clear drawing cache