android在处理图片资源的时候，Drawable、Bitmap、byte[]之间的转换

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;   
       }   
}