读取sd卡下图片，由图片路径转换为bitmap

public Bitmap convertToBitmap(String path, int w, int h) {             BitmapFactory.Options opts = new BitmapFactory.Options();             // 设置为ture只获取图片大小             opts.inJustDecodeBounds = true;             opts.inPreferredConfig = Bitmap.Config.ARGB_8888;             // 返回为空             BitmapFactory.decodeFile(path, opts);             int width = opts.outWidth;             int height = opts.outHeight;             float scaleWidth = 0.f, scaleHeight = 0.f;             if (width > w || height > h) {                 // 缩放                 scaleWidth = ((float) width) / w;                 scaleHeight = ((float) height) / h;             }             opts.inJustDecodeBounds = false;             float scale = Math.max(scaleWidth, scaleHeight);             opts.inSampleSize = (int)scale;             WeakReference<Bitmap> weak = new WeakReference<Bitmap>(BitmapFactory.decodeFile(path, opts));             return Bitmap.createScaledBitmap(weak.get(), w, h, true);         }

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