Android图片资源转换代码

android在处理一写图片资源的时候，会进行一些类型的转换，现在有空整理一下：
1、Drawable → Bitmap
public static Bitmap drawableToBitmap(Drawable drawable) {
 Bitmap bitmap = Bitmap.createBitmap(
  drawable.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;
}

2、从资源中获取Bitmap
 Resources res=getResources();
 Bitmap bmp=BitmapFactory.decodeResource(res, R.drawable.pic);

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

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