Drawable转换为Bitmap两种方法

如果通过网络加载了一张位图，想拿到这张位图的Bitmap，有两种办法，至于那种好，可能要看是在什么情况下了

1，根据已有的Drawable创建一个新的Bitmap:

private Bitmap bitmap;
private void drawableToBitamp(Drawable drawable)
     {
        int w = drawable.getIntrinsicWidth();
         int h = drawable.getIntrinsicHeight();
         System.out.println("Drawable转Bitmap");
         Bitmap.Config config = 
                 drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                         : Bitmap.Config.RGB_565;
         bitmap = Bitmap.createBitmap(w,h,config);
         //注意，下面三行代码要用到，否在在View或者surfaceview里的canvas.drawBitmap会看不到图
         Canvas canvas = new Canvas(bitmap);   
         drawable.setBounds(0, 0, w, h);   
         drawable.draw(canvas);
     }

2,直接从现有的Drawable中取出Bitmap:

 private Bitmap bitmap;
 
 private void drawableToBitamp(Drawable drawable)
     {
         BitmapDrawable bd = (BitmapDrawable) drawable;
         bitmap = bd.getBitmap();
     }