Drawable、 Bitmap、byte[] 的相互转换

android 在处理一些图片资源时，会进行一些类型的转换，现整理一下:

1. Drawable --> Bitmap

public static Bitmap drawableToBitmap(Drawable drawable){

Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight(),

drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_888 : Bitmap.Config.RGB_565);

Canvas canvas = new Canvas(bitmap);

drawable.setBounds(0,0,drawable.getIntrinsicWidth(),drawable.getIntrinsicHeight());

drawable.draw(canvas);

return bitmap;

}

2. Bitmap ---> Drawable

Bitmap bitmap = new Bitmap (...);

Drawable drawable = new BitmapDrawable(bitmap);

3. 从资源中获取Bitmap

Resources res = getResources();

Bitmap bm = BitmapFactory.decodeResource(res,R.drawable.pic);

4. Bitmap --> byte[]

private byte[] Bitmap2Bytes(Bitmap bm) {

ByteArrayOutputStream baos = new ByteArrayOutputStream();

bm.compress(Bitmap.CompressFormat.PNG,100,baos);

return baos.toByteArray();

}

5. byte[] --> Bitmap

private Bitmap Bytes2Bitmap(byte[] b) {

if(b.length != 0)

return BitmapFactory.decodeByteArray(b,0,b.length);

else

return null;

}