android - Android Studio-旋转图像时如何避免OutOfMemoryError

Question

当我以最简单的形式旋转图像时，如何避免OutOfMemoryError。我是Android Studio和Java的新手。这是图像旋转的静态方法

public static Bitmap rotateBitmap(Bitmap bitmap, int orientation, Context context) {

        Matrix matrix = new Matrix();
        switch (orientation) {
            case ExifInterface.ORIENTATION_NORMAL:
                return bitmap;
            case ExifInterface.ORIENTATION_FLIP_HORIZONTAL:
                matrix.setScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_ROTATE_180:
                matrix.setRotate(180);
                break;
            case ExifInterface.ORIENTATION_FLIP_VERTICAL:
                matrix.setRotate(180);
                matrix.postScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_TRANSPOSE:
                matrix.setRotate(90);
                matrix.postScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_ROTATE_90:
                matrix.setRotate(90);
                break;
            case ExifInterface.ORIENTATION_TRANSVERSE:
                matrix.setRotate(-90);
                matrix.postScale(-1, 1);
                break;
            case ExifInterface.ORIENTATION_ROTATE_270:
                matrix.setRotate(-90);
                break;
            default:
                return bitmap;
        }
        try {
            Bitmap bmRotated = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth()/2, bitmap.getHeight()/2, matrix, true);
            bitmap.recycle();
            return bmRotated;
        }
        catch (OutOfMemoryError e) {
            e.printStackTrace();
            Toast.makeText(context, "Error:"  + e, Toast.LENGTH_SHORT).show();

            return null;
        }
    }

Answer 1

我不知道您的用例是什么，但是您无需借助矩阵就可以进行简单的轮换。用大位图耗尽内存很容易。

另一方面，这将以0到360度之间的任意随机量旋转任何给定的imageview，而开销却相当低:

        display = (ImageView) findViewById(R.id.someview);
        int randomRot;
        Random rand = new Random();
        randomRot=rand.nextInt(360);
        display.setRotation((float) randomRot);