Drawable、Bitmap、byte[]之间的转换

android在处理一写图片资源的时候，会进行一些类型的转换:

1 Drawable → Bitmap 的简单方法

 ((BitmapDrawable)res.getDrawable(R.drawable.youricon)).getBitmap();

2 Drawable → Bitmap

 public static Bitmap drawableToBitmap(Drawable drawable) {  

     Bitmap bitmap = Bitmap.createBitmap(rawable.getIntrinsicWidth(), drawable.getIntrinsicHeight(), drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565);
     Canvas canvas = new Canvas(bitmap);
     //canvas.setBitmap(bitmap);
     drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
     drawable.draw(canvas);
     return bitmap;
 }  

3 Bitmap→Drawable的简单方法

 BitmapDrawable bitmapDrawable = (BitmapDrawable)bitmap;
 Drawable drawable = (Drawable)bitmapDrawable;     

 Bitmap bitmap = new Bitmap (...);
 Drawable drawable = new BitmapDrawable(bitmap); 

4 从资源中获取Bitmap

 Resources res = getResources();
 Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.pic);

5 Bitmap → byte[]

 private byte[] Bitmap2Bytes(Bitmap bm) {
     ByteArrayOutputStream baos = new ByteArrayOutputStream();
     bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
     return baos.toByteArray();
 }  

6 byte[] → Bitmap

private Bitmap Bytes2Bimap(byte[] b) {
    if (b.length!=0) {
        return BitmapFactory.decodeByteArray(b, 0, b.length);
    } else {
        return null;
    }
}