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;  
    }  
}