Android View.getDrawingCache 返回空值，只有空值 [英] Android View.getDrawingCache returns null, only null

问题描述

有没有人可以试着向我解释一下原因

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!!!
}

总是记录绘图缓存为空，并将位图设置为空?

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

我是否必须在设置缓存之前实际绘制视图?

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

谢谢！

推荐答案

我也遇到了这个问题，找到了这个答案:

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

这篇关于Android View.getDrawingCache 返回空值，只有空值的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！