试图缩小Android中的Bitmap无法正常工作

Question

我正在尝试缩小位图.简而言之,图像最初来自宽度为4016的ByteArray.在使用工厂选项缩小图像后,它仍会报告宽度为4016的图像.

这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;
        }

Answer 1

您需要拨打.decodeByteArray(..)两次电话！.inJustDecodeBounds一旦获得设置为的宽度和高度true，然后再次.inSampleSize获得实际缩放的位图，options.outHeight并且options.outWidth在您的代码中可能为零。

BitmapFactory.decodeByteArray(myImageByteArray, 0, myImageByteArray.length, options);检查之前先打电话outHeight，然后outWidth。

编辑

看一下Google 的 Android 开发网站上的这个示例：

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

请注意，在调用之后options.outHeight使用。您必须在代码中修复此问题。decodeResources(...)