简单谈谈Resource，Drawable和Bitmap之间的转换

一直接触这些东西，还是归个类整理一下比较好。

Resource -> Drawable

Drawable draw1 = this.getResources().getDrawable(R.drawable.icon);

Drawable -> Bitmap

1.

static Bitmap drawableToBitmap(Drawable drawable) // drawable 转换成bitmap
{
    int width = drawable.getIntrinsicWidth();// 取drawable的长宽
    int height = drawable.getIntrinsicHeight();
    Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ?Bitmap.Config.ARGB_8888:Bitmap.Config.RGB_565;// 取drawable的颜色格式
    Bitmap bitmap = Bitmap.createBitmap(width, height, config);// 建立对应bitmap
    Canvas canvas = new Canvas(bitmap);// 建立对应bitmap的画布
    drawable.setBounds(0, 0, width, height);
    drawable.draw(canvas);// 把drawable内容画到画布中
    return bitmap;
}  

2.

Bitmap bitmap = ((android.graphics.drawable.BitmapDrawable) pm.getApplicationIcon(appInfo)).getBitmap();