获取系统图片资源 drawable和bitmap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，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;

}

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);

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();

}

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 ;

}

}