java – 试图缩小Android中的位图无法正常工作

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.

以下是我的代码的两个片段：

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,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：

以下是我的代码的两个片段：

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,options);
            if (options.outHeight > options.outWidth) {
                options.inSampleSize = calculateInSampleSize(options,options);

            //This log statement outputs around 1000 Now. 
            Log.d("bitmap",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;
        }

解决方法

你需要两次调用.decodeByteArray(..)！一旦获得宽度和高度,.inJustDecodeBounds设置为true,然后再使用.inSampleSize获取实际缩放的Bitmap,代码中的options.outHeight和options.outWidth可能为零.

调用BitmapFactory.decodeByteArray(myImageByteArray,options);在检查出高度和宽度之前.

编辑

从Google’s Android Dev site看一下这个例子：

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

请注意,在调用decodeResources(…)之后使用了options.outHeight.您必须修复代码.

原文地址：https://www.jb51.cc/android/128905.html