旋转位图会导致OutOfMemoryException异常 [英] Rotating bitmap causes outOfMemoryException

问题描述

我旋转一个位图这样一来，每个按钮点击图片旋转90度

I am rotating a bitmap this way, on every button click the image rotates 90 degrees

Matrix matrix = new Matrix();
matrix.postRotate(90);
rotated = Bitmap.createBitmap(rotated, 0, 0,
        rotated.getWidth(), rotated.getHeight(), matrix, true);
iv.setImageBitmap(rotated);

我想这与大量的图片，但现在之一导致OutOfMemoryError异常。有没有一种方法，以prevent呢？当然，我可以叫循环，但后来我失去了位图，必须从ImageView的再次获取。我不认为，这将使任何区别。

I tried this with a lot of images, but now one caused an OutOfMemoryError. Is there a way to prevent this? Of course I can call recycle, but then I lose the bitmap and have to get it again from the imageview. I don't think that will make any difference.

推荐答案

我有建议给你。

1）如果您有任何内存饥饿的任务，方法和可能的话使用带有的AsyncTask 。
2）声明对象为的WeakReference 。这会给你机会，使用后释放内存。参见下面的例子。

1) When you have any memory hunger task, use in methods and if possible with AsyncTask.
2) Declare objects as WeakReference. This will give you chance to release memory after use. See below example.

public class RotateTask extends AsyncTask<Void, Void, Bitmap> {
    private WeakReference<ImageView> imgInputView;
    private WeakReference<Bitmap> rotateBitmap;

    public RotateTask(ImageView imgInputView){
        this.imgInputView = new WeakReference<ImageView>(imgInputView);
    }

    @Override
    protected void onPreExecute() {
        //if you want to show progress dialog
    }

    @Override
    protected Bitmap doInBackground(Void... params) {
        Matrix matrix = new Matrix();
        matrix.postRotate(90);
        rotateBitmap = new WeakReference<Bitmap>(Bitmap.createBitmap(rotated, 0, 0,rotated.getWidth(), rotated.getHeight(), matrix, true));
        return rotateBitmap.get();
    }

    @Override
    protected void onPostExecute(Bitmap result) {
        //dismiss progress dialog
        imgInputView.get().setImageBitmap(result);
    }
}

该任务有各方面的意见和对象的WeakReference 。当这项任务完成后，所有使用该任务的记忆是免费的。试试这个办法。我用我的应用程序。

This task has all the views and object as WeakReference. When this task is completed, all the memory used by this Task is free. Try this approach. I used in my application.

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