背景
从 API 11 开始，您可以在解码新位图时重复使用位图，这样解码器就不需要重新创建全新的大型对象。
这是使用类似以下代码的代码（取自本教程）完成的：
mCurrentBitmap = Bitmap.createBitmap(imageWidth,imageHeight,Bitmap.Config.ARGB_8888);
bitmapOptions.inJustDecodeBounds = false;
bitmapOptions.inBitmap = mCurrentBitmap;
bitmapOptions.inSampleSize = 1;
mCurrentBitmap = BitmapFactory.decodeResource(getResources(),imageResId, bitmapOptions);
优势非常明显：在某些情况下使用更少的内存，对 GC 的压力更小，并且具有更好的性能，因为您不需要创建更多的大对象。
唯一的问题是两个图像必须具有相同的大小和配置。
问题
即使代码与项目本身的资源（在 res 文件夹中）完美配合，在处理放入内部存储的图像文件时，我似乎总是会遇到下一个错误：
java.lang.IllegalArgumentException: Problem decoding into existing bitmap
我已经为位图选项尝试了多个不同的标志：
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
我还尝试了 BitmapFactory 的 decodeFile 和 decodeStream。
这是显示存在问题的示例代码（基于我写过的示例）：
@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
为什么我不断收到此错误，我该如何解决？
我发现了一些类似的问题，但没有一个答案。