以编程方式生成视图并捕获位图

Question

I'm programmatically generating a view in Android. The parent view is a RelativeLayout and I'm adding subviews dynamically (eg TextView and ImageView ).

If I add the view to my activity's main view then it displays fine (just as expected). Using this code.

LinearLayout mainView = (LinearLayout)findViewById(R.id.mainView);
mainView.addView(dynamicallyGeneratedView);

I don't want to add the view as a subview though, I just want to turn it into a bitmap. So I do the following:

view.measure(View.MeasureSpec.UNSPECIFIED,View.MeasureSpec.UNSPECIFIED);
Bitmap b = Bitmap.createBitmap(view.getMeasuredWidth(), view.getMeasuredHeight(), Bitmap.Config.ARGB_8888);
Canvas c = new Canvas(b);
view.draw(c);

But when I add this bitmap to an ImageView it doesn't show anything.

What am I doing wrong? I want to generate a view, turn it into a bitmap but not display it on the screen.

Any help would be appreciated.

Answer 1

Well, you definitely do not have a call to layout() after measure() , which AFAIK is required here.

Whether you can get away with View.MeasureSpec.UNSPECIFIED and stuff like getMeasuredWidth() , I can't say, as I haven't tried that. Whenever I have manually measured and laid out a View , I have always used actual sizes, such as:

root=inflater.inflate(R.layout.add, null);
root.measure(800, 480);
root.layout(0, 0, 800, 480);

If your Bitmap presently has a useful size, but just does not have any content, try layout() with the size before you draw to the Canvas . If your Bitmap wound up with some less-than-useful size (eg, one or both dimensions are 0), you will probably need to specify an actual size rather than go UNSPECIFIED .