Android：从图库加载的位图在ImageView中旋转

Question

当我将媒体库中的图像加载到位图中时，一切正常，除了将相机在垂直握住手机的情况下拍摄的照片旋转之外，即使在垂直方向上看起来是垂直的，我也总是得到水平的照片。画廊。为什么会这样，如何正确加载呢？

Answer 1

这是一个完整的解决方案（可从Facebook SDK的Hackbook示例中找到）。它的优点是不需要访问文件本身。如果要从内容解析器加载图像，这将非常有用（例如，如果您的应用正在响应共享照片的意图）。

public static int getOrientation(Context context, Uri photoUri) {

    /* it's on the external media. */

    Cursor cursor = context.getContentResolver().query(photoUri,

            new String[] { MediaStore.Images.ImageColumns.ORIENTATION }, null, null, null);

    if (cursor.getCount() != 1) {

        return -1;

    }

    cursor.moveToFirst();

    return cursor.getInt(0);

}

然后，您可以如下获得旋转的位图。这段代码还将图片缩小（不幸的是）到MAX_IMAGE_DIMENSION。否则可能会耗尽内存。

public static Bitmap getCorrectlyOrientedImage(Context context, Uri photoUri) throws IOException {

    InputStream is = context.getContentResolver().openInputStream(photoUri);

    BitmapFactory.Options dbo = new BitmapFactory.Options();

    dbo.inJustDecodeBounds = true;

    BitmapFactory.decodeStream(is, null, dbo);

    is.close();

    int rotatedWidth, rotatedHeight;

    int orientation = getOrientation(context, photoUri);

    if (orientation == 90 || orientation == 270) {

        rotatedWidth = dbo.outHeight;

        rotatedHeight = dbo.outWidth;

    } else {

        rotatedWidth = dbo.outWidth;

        rotatedHeight = dbo.outHeight;

    }

    Bitmap srcBitmap;

    is = context.getContentResolver().openInputStream(photoUri);

    if (rotatedWidth > MAX_IMAGE_DIMENSION || rotatedHeight > MAX_IMAGE_DIMENSION) {

        float widthRatio = ((float) rotatedWidth) / ((float) MAX_IMAGE_DIMENSION);

        float heightRatio = ((float) rotatedHeight) / ((float) MAX_IMAGE_DIMENSION);

        float maxRatio = Math.max(widthRatio, heightRatio);

        // Create the bitmap from file

        BitmapFactory.Options options = new BitmapFactory.Options();

        options.inSampleSize = (int) maxRatio;

        srcBitmap = BitmapFactory.decodeStream(is, null, options);

    } else {

        srcBitmap = BitmapFactory.decodeStream(is);

    }

    is.close();

    /*

     * if the orientation is not 0 (or -1, which means we don't know), we

     * have to do a rotation.

     */

    if (orientation > 0) {

        Matrix matrix = new Matrix();

        matrix.postRotate(orientation);

        srcBitmap = Bitmap.createBitmap(srcBitmap, 0, 0, srcBitmap.getWidth(),

                srcBitmap.getHeight(), matrix, true);

    }

    return srcBitmap;

}

Answer 2

在这篇文章中，借助这篇文章帮助解决了我的问题：

            Bitmap myBitmap = getBitmap(imgFile.getAbsolutePath());

            try {

                ExifInterface exif = new ExifInterface(imgFile.getAbsolutePath());

                int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, 1);

                Log.d("EXIF", "Exif: " + orientation);

                Matrix matrix = new Matrix();

                if (orientation == 6) {

                    matrix.postRotate(90);

                }

                else if (orientation == 3) {

                    matrix.postRotate(180);

                }

                else if (orientation == 8) {

                    matrix.postRotate(270);

                }

                myBitmap = Bitmap.createBitmap(myBitmap, 0, 0, myBitmap.getWidth(), myBitmap.getHeight(), matrix, true); // rotating bitmap

            }

            catch (Exception e) {

            }

            ImageView img = (ImageView) findViewById(R.id.imgTakingPic);

            img.setImageBitmap(myBitmap);

希望它可以节省别人的时间！