为什么我总是重复使用位图时变得异常？ [英] Why do I keep getting exception when re-using bitmaps?

问题描述

这是API 11起，您可以重新使用位图，当你去code换新，让德codeR不需要重新创建全新的大对象。

starting from API 11, you can re-use bitmaps when you decode new ones, so that the decoder won't need to re-create totally new large objects.

这是使用这样的事情code完成（从本教程 ）：

this is done using something like this code (taken from this tutorial) :

mCurrentBitmap = Bitmap.createBitmap(imageWidth,imageHeight,Bitmap.Config.ARGB_8888);
bitmapOptions.inJustDecodeBounds = false;
bitmapOptions.inBitmap = mCurrentBitmap;
bitmapOptions.inSampleSize = 1;
mCurrentBitmap = BitmapFactory.decodeResource(getResources(),imageResId, bitmapOptions);

的优势是相当明显的：在某些情况下使用较少的内存，在GC越来越少pressure，并具有更好的性能，因为你并不需要创建更多的大对象

the advantage is quite obvious: using less memory in some cases, getting less pressure on the GC, and having a better performance because you don't need to create a lot more large objects.

，唯一的缺点是，这两个图像必须是相同尺寸和配置的。

the only catch is that both images must be of the same size and config.

尽管code项目本身工作完全正常使用的资源（res文件夹），我似乎处理的图像文件，我已经把进入内部存储时，总是得到下一个错误：

even though the code works perfectly fine with resources in the project itself (in the res folder), i seem to always get the next error when handling image files i've put into the internal storage :

java.lang.IllegalArgumentException: Problem decoding into existing bitmap

我试过多种不同的标志位图选项：

i've tried multiple different flags for the bitmap options:

bitmapOptions.inPurgeable = true;
bitmapOptions.inInputShareable = true;
bitmapOptions.inMutable = true;
bitmapOptions.inScaled = false;
bitmapOptions.inSampleSize = 1;
bitmapOptions.inPreferredConfig = Config.RGB_565; //i've set the created bitmap to be of this type too, of course

我也尝试都失codeFILE并为BitmapFactory德codeStream。

i've also tried both decodeFile and decodeStream for the BitmapFactory.

下面是一个示例code，表示有（根据样本我已经写）一个问题：

here's a sample code to show there is a problem (based on the sample i've written about) :

@Override
public void onCreate(final Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_bitmap_allocation);

    final int[] imageIDs = { R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d, R.drawable.e, R.drawable.f };

    final CheckBox checkbox = (CheckBox) findViewById(R.id.checkbox);
    final TextView durationTextview = (TextView) findViewById(R.id.loadDuration);
    final ImageView imageview = (ImageView) findViewById(R.id.imageview);

    // Create bitmap to be re-used, based on the size of one of the bitmaps
    mBitmapOptions = new BitmapFactory.Options();
    mBitmapOptions.inJustDecodeBounds = true;
    BitmapFactory.decodeResource(getResources(), R.drawable.a, mBitmapOptions);
    mCurrentBitmap = Bitmap.createBitmap(mBitmapOptions.outWidth, mBitmapOptions.outHeight, Bitmap.Config.ARGB_8888);
    mBitmapOptions.inJustDecodeBounds = false;
    mBitmapOptions.inBitmap = mCurrentBitmap;
    mBitmapOptions.inSampleSize = 1;
    mBitmapOptions.inPreferredConfig = Config.ARGB_8888;
    BitmapFactory.decodeResource(getResources(), R.drawable.a, mBitmapOptions);
    imageview.setImageBitmap(mCurrentBitmap);

    // When the user clicks on the image, load the next one in the list
    imageview.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(final View v) {
            mCurrentIndex = (mCurrentIndex + 1) % imageIDs.length;
            Options bitmapOptions = new Options();
            bitmapOptions.inPreferredConfig = Config.ARGB_8888;
            if (checkbox.isChecked()) {
                // Re-use the bitmap by using BitmapOptions.inBitmap
                bitmapOptions = mBitmapOptions;
                bitmapOptions.inBitmap = mCurrentBitmap;
            }
            final long startTime = System.currentTimeMillis();
            //
            File tempFile = null;
            try {
                tempFile = File.createTempFile("temp", ".webp", getApplicationContext().getCacheDir());
                FileOutputStream fileOutputStream;
                final Bitmap bitmap = BitmapFactory.decodeResource(getResources(), imageIDs[mCurrentIndex]);
                bitmap.compress(CompressFormat.WEBP, 100, fileOutputStream = new FileOutputStream(tempFile));
                fileOutputStream.flush();
                fileOutputStream.close();
            final InputStream inputStream = new FileInputStream(tempFile);
            mCurrentBitmap = BitmapFactory.decodeStream(inputStream,null,bitmapOptions);
            inputStream.close();
            } catch (final IOException e1) {
                e1.printStackTrace();
            }
            imageview.setImageBitmap(mCurrentBitmap);

            // One way you can see the difference between reusing and not is through the
            // timing reported here. But you can also see a huge impact in the garbage
            // collector if you look at logcat with and without reuse. Avoiding garbage
            // collection when possible, especially for large items like bitmaps,
            // is always a good idea.
            durationTextview.setText("Load took " + (System.currentTimeMillis() - startTime));
        }
    });
}

问题

为什么我不断收到这个错误，我怎么能解决这个问题？

the question

why do i keep getting this error, and how can i fix it?

我已经发现了一些类似的问题，但什么都没有回答。

i've found some similar questions, but none had an answer.

推荐答案

看来，当使用WebP档案同此凉技巧的问题。

it seems that the problem with this cool tip when using webP files.

我只需要使用JPG或PNG。

i just need to use either jpg or png.

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