尽管使用减少的样本大小，但 BitmapFactory.decodeStream 内存不足 [英] BitmapFactory.decodeStream out of memory despite using reduced sample size

问题描述

我已经阅读了很多关于解码位图内存分配问题的相关帖子，但使用官网提供的代码仍然无法找到解决以下问题的方法.

I have read many related posts concerning memory allocation problems with decoding bitmaps, but am still unable to find the solution to the following problem even after using the code provided in the official website.

这是我的代码:

public static Bitmap decodeSampledBitmapFromResource(InputStream inputStream, int reqWidth, int reqHeight) {

    ByteArrayOutputStream baos = new ByteArrayOutputStream();
    byte[] buffer = new byte[1024];
    int len;
    try {
        while ((len = inputStream.read(buffer)) > -1) {
        baos.write(buffer, 0, len);
        }
        baos.flush();
        InputStream is1 = new ByteArrayInputStream(baos.toByteArray());
        InputStream is2 = new ByteArrayInputStream(baos.toByteArray());

        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeStream(is1, null, options);

        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
        options.inPurgeable = true;
        options.inInputShareable = true;
        options.inJustDecodeBounds = false;
        options.inPreferredConfig = Bitmap.Config.ARGB_8888;
        return BitmapFactory.decodeStream(is2, null, options);

    } catch (Exception e) {
        e.printStackTrace();

        return null;
    }
}

public static 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;
}

bitmap = decodeSampledBitmapFromResource(inputStream, 600, 600); 

我在这一行中收到3250016 字节分配内存不足错误":

I am getting "Out of memory error on a 3250016 - byte allocation" in this line:

return BitmapFactory.decodeStream(is2, null, options);

在我看来，3.2 MB 足够小，可以分配.我哪里错了?我该如何解决这个问题?

It would seem to me that 3.2 MB is small enough to be allocated. Where am I going wrong? How can I solve this?

编辑

在研究此解决方案后这里由 N-Joy 提供，它在所需大小 300 下运行良好，但我需要的大小是 800，所以我仍然收到错误消息.

After looking into this solution HERE by N-Joy it works fine with Required size 300 but my required size is 800, so i am still getting the error.

推荐答案

decodeSampledBitmapFromResource 方法内存效率不高，因为它使用 3 个流:ByteArrayOutputStream baos，ByteArrayInputStream is1和 ByteArrayInputStream is2，每个都存储相同的图像流数据(每个一个字节数组).

The method decodeSampledBitmapFromResource is not memory efficient because it uses 3 streams: the ByteArrayOutputStream baos, ByteArrayInputStream is1 and ByteArrayInputStream is2, each of those stores the same stream data of the image (one byte array for each).

当我使用我的设备 (LG nexus 4) 进行测试以将 SD 卡上的 2560x1600 图像解码为目标大小 800 时，需要这样的事情:

And when I test with my device (LG nexus 4) to decode an 2560x1600 image on SDcard to target size 800 it takes something like this:

03-13 15:47:52.557: E/DecodeBitmap(11177): dalvikPss (beginning) = 1780
03-13 15:47:53.157: E/DecodeBitmap(11177): dalvikPss (decoding) = 26393
03-13 15:47:53.548: E/DecodeBitmap(11177): dalvikPss (after all) = 30401 time = 999

我们可以看到:分配了太多内存(28.5 MB)只是为了解码 4096000 个像素图像.

We can see: too much memory allocated (28.5 MB) just to decode 4096000 a pixel image.

解决方案:我们读取 InputStream 并将数据直接存储到一个字节数组中，并使用此字节数组进行其余工作.
示例代码:

Solution: we read the InputStream and store the data directly into one byte array and use this byte array for the rest work.
Sample code:

public Bitmap decodeSampledBitmapFromResourceMemOpt(
            InputStream inputStream, int reqWidth, int reqHeight) {

        byte[] byteArr = new byte[0];
        byte[] buffer = new byte[1024];
        int len;
        int count = 0;

        try {
            while ((len = inputStream.read(buffer)) > -1) {
                if (len != 0) {
                    if (count + len > byteArr.length) {
                        byte[] newbuf = new byte[(count + len) * 2];
                        System.arraycopy(byteArr, 0, newbuf, 0, count);
                        byteArr = newbuf;
                    }

                    System.arraycopy(buffer, 0, byteArr, count, len);
                    count += len;
                }
            }

            final BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            BitmapFactory.decodeByteArray(byteArr, 0, count, options);

            options.inSampleSize = calculateInSampleSize(options, reqWidth,
                    reqHeight);
            options.inPurgeable = true;
            options.inInputShareable = true;
            options.inJustDecodeBounds = false;
            options.inPreferredConfig = Bitmap.Config.ARGB_8888;

            int[] pids = { android.os.Process.myPid() };
            MemoryInfo myMemInfo = mAM.getProcessMemoryInfo(pids)[0];
            Log.e(TAG, "dalvikPss (decoding) = " + myMemInfo.dalvikPss);

            return BitmapFactory.decodeByteArray(byteArr, 0, count, options);

        } catch (Exception e) {
            e.printStackTrace();

            return null;
        }
    }

进行计算的方法:

public void onButtonClicked(View v) {
        int[] pids = { android.os.Process.myPid() };
        MemoryInfo myMemInfo = mAM.getProcessMemoryInfo(pids)[0];
        Log.e(TAG, "dalvikPss (beginning) = " + myMemInfo.dalvikPss);

        long startTime = System.currentTimeMillis();

        FileInputStream inputStream;
        String filePath = Environment.getExternalStorageDirectory()
                .getAbsolutePath() + "/test2.png";
        File file = new File(filePath);
        try {
            inputStream = new FileInputStream(file);
//          mBitmap = decodeSampledBitmapFromResource(inputStream, 800, 800);
            mBitmap = decodeSampledBitmapFromResourceMemOpt(inputStream, 800,
                    800);
            ImageView imageView = (ImageView) findViewById(R.id.image);
            imageView.setImageBitmap(mBitmap);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
        myMemInfo = mAM.getProcessMemoryInfo(pids)[0];
        Log.e(TAG, "dalvikPss (after all) = " + myMemInfo.dalvikPss
                + " time = " + (System.currentTimeMillis() - startTime));
    }

结果:

03-13 16:02:20.373: E/DecodeBitmap(13663): dalvikPss (beginning) = 1823
03-13 16:02:20.923: E/DecodeBitmap(13663): dalvikPss (decoding) = 18414
03-13 16:02:21.294: E/DecodeBitmap(13663): dalvikPss (after all) = 18414 time = 917

这篇关于尽管使用减少的样本大小，但 BitmapFactory.decodeStream 内存不足的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！