Android图片缩放

static Drawable zoomDrawable(Drawable drawable, int w, int h)   
     {   
              int width = drawable.getIntrinsicWidth();   
              int height= drawable.getIntrinsicHeight();   
               Bitmap oldbmp = drawableToBitmap(drawable); // drawable转换成bitmap   
               Matrix matrix = new Matrix();   // 创建操作图片用的Matrix对象   
              float scaleWidth = ((float)w / width);   // 计算缩放比例   
              float scaleHeight = ((float)h / height);   
               matrix.postScale(scaleWidth, scaleHeight);         // 设置缩放比例   
               Bitmap newbmp = Bitmap.createBitmap(oldbmp, 0, 0, width, height, matrix, true);       // 建立新的bitmap，其内容是对原bitmap的缩放后的图   
              return new BitmapDrawable(newbmp);       // 把bitmap转换成drawable并返回   
     }   
   
    static Bitmap drawableToBitmap(Drawable drawable) // drawable 转换成bitmap   
     {   
              int width = drawable.getIntrinsicWidth();   // 取drawable的长宽   
              int height = drawable.getIntrinsicHeight();   
               Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888:Bitmap.Config.RGB_565;         // 取drawable的颜色格式   
               Bitmap bitmap = Bitmap.createBitmap(width, height, config);     // 建立对应bitmap   
               Canvas canvas = new Canvas(bitmap);         // 建立对应bitmap的画布   
               drawable.setBounds(0, 0, width, height);   
               drawable.draw(canvas);      // 把drawable内容画到画布中   
              return bitmap;   
     }   
}