尝试在Android中缩小位图不起作用

我试图缩小一个位图。 简而言之，图像最初来自宽度为4016的ByteArray。在用工厂选项缩小图像后，它仍然报告宽度为4016的图像。

这里是我的代码的两个剪辑：

Bitmap myBitmap = null;
        @Override
        protected byte[] doInBackground(Object... params) {


            final BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;

            if (options.outHeight > options.outWidth) {
                options.inSampleSize = calculateInSampleSize(options, 640, 960);
            } else {
                options.inSampleSize = calculateInSampleSize(options, 960, 640);
            }

            options.inJustDecodeBounds = false;

            //myImageByteArray is 4016 wide
            myBitmap = BitmapFactory.decodeByteArray(myImageByteArray, 0, myImageByteArray.length, options);

            //This log statement outputs 4016!!! Shouldn't it be smaller since I just decoded the byteArray with options?
            Log.d("bitmap", myBitmap.getWidth()+"");

}

        public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
            // Raw height and width of image
            final int height = options.outHeight;
            final int width = options.outWidth;
            int inSampleSize = 1;

            if (height > reqHeight || width > reqWidth) {

                // Calculate ratios of height and width to requested height and
                // width
                final int heightRatio = Math.round((float) height / (float) reqHeight);
                final int widthRatio = Math.round((float) width / (float) reqWidth);

                // Choose the smallest ratio as inSampleSize value, this will
                // guarantee
                // a final image with both dimensions larger than or equal to
                // the
                // requested height and width.
                inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
            }

            return inSampleSize;
        }

更新：

这里是我的代码的两个剪辑：

Bitmap myBitmap = null;
        @Override
        protected byte[] doInBackground(Object... params) {


            final BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            //myImageByteArray is 4016 wide
            myBitmap = BitmapFactory.decodeByteArray(myImageByteArray, 0, myImageByteArray.length, options);
            if (options.outHeight > options.outWidth) {
                options.inSampleSize = calculateInSampleSize(options, 640, 960);
            } else {
                options.inSampleSize = calculateInSampleSize(options, 960, 640);
            }

            options.inJustDecodeBounds = false;

            //myImageByteArray is 4016 wide
            myBitmap = BitmapFactory.decodeByteArray(myImageByteArray, 0, myImageByteArray.length, options);

            //This log statement outputs around 1000 now. 
            Log.d("bitmap", myBitmap.getWidth()+"");

}

        public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
            // Raw height and width of image
            final int height = options.outHeight;
            final int width = options.outWidth;
            int inSampleSize = 1;

            if (height > reqHeight || width > reqWidth) {

                // Calculate ratios of height and width to requested height and
                // width
                final int heightRatio = Math.round((float) height / (float) reqHeight);
                final int widthRatio = Math.round((float) width / (float) reqWidth);

                // Choose the smallest ratio as inSampleSize value, this will
                // guarantee
                // a final image with both dimensions larger than or equal to
                // the
                // requested height and width.
                inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
            }

            return inSampleSize;
        }

---

你需要调用.decodeByteArray(..)两次！ 一旦获得宽度和高度，将.inJustDecodeBounds设置为true ，然后再使用.inSampleSize获取实际缩放的位图，则代码中的options.outHeight和options.outWidth可能为零。

调用BitmapFactory.decodeByteArray(myImageByteArray, 0, myImageByteArray.length, options); 在检查出outHeight和outWidth之前。

编辑

看一下谷歌Android Dev站点的这个例子：

BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeResource(getResources(), R.id.myimage, options);
int imageHeight = options.outHeight;
int imageWidth = options.outWidth;

注意在调用decodeResources(...) 之后使用了options.outHeight 。 这你必须修复你的代码。

---

您没有用设置其“outHeight”和“outWidth”的任何内容填充bitmapOptions。

你应该看看谷歌的位图教程：

http://developer.android.com/training/displaying-bitmaps/load-bitmap.html

为了决定缩放到什么值，您需要知道与目标大小相比的图像大小。 这就是为什么你需要做两次解码。

顺便说一句，还有另一种缩小图像的方法，正如我在这里展示的 。

链接地址: http://www.djcxy.com/p/18277.html

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