读取sd卡下图片，由图片路径转换为bitmap

01 public Bitmap convertToBitmap(String path, int w, int h) {
02             BitmapFactory.Options opts = new BitmapFactory.Options();
03             // 设置为ture只获取图片大小
04             opts.inJustDecodeBounds = true;
05             opts.inPreferredConfig = Bitmap.Config.ARGB_8888;
06             // 返回为空
07             BitmapFactory.decodeFile(path, opts);
08             int width = opts.outWidth;
09             int height = opts.outHeight;
10             float scaleWidth = 0.f, scaleHeight = 0.f;
11             if (width > w || height > h) {
12                 // 缩放
13                 scaleWidth = ((float) width) / w;
14                 scaleHeight = ((float) height) / h;
15             }
16             opts.inJustDecodeBounds = false;
17             float scale = Math.max(scaleWidth, scaleHeight);
18             opts.inSampleSize = (int)scale;
19             WeakReference<Bitmap> weak = new WeakReference<Bitmap>(BitmapFactory.decodeFile(path, opts));
20             return Bitmap.createScaledBitmap(weak.get(), w, h, true);
21         }

其中w和h你需要转换的大小

path转换为bitmap:上面方法即可；
imageview获取drawable并转换为 bitmap ：Bitmap bt= ((BitmapDrawable) mImageview.getDrawable()).getBitmap();
resourceid转换为bitmap：Bitmap bt = BitmapFactory.decodeResource(getResources(), R.drawable.resourceid);
Drawable转换为bitmap：Bitmap bt= ((BitmapDrawable) Drawable).getBitmap();
因为BitmapDrawable是继承Drawable，所以可以灵活的转换

作者：sanmee

补充：移动开发 , Android ,