从画布或 BitmapFactory.createBitmap(src,x,y,w,h) 错误绘制的 Android 位图

Question

在 Android 上，我正在尝试将从相机拍摄的图像位图裁剪为小于拍摄的原始照片的固定宽度/宽度，但是当我创建裁剪后的图像时，结果总是会旋转（即使没有矩阵已定义）见http://i.imgur.com/MppWH69l.png 为原始图像，http://i.imgur.com/C4WVtwZl.png 为裁剪后的图像，该图像正在旋转且显示不正确。

createBitmap 方法为什么会在目标位图中旋转要绘制的位图。

相关代码如下

try {       int dstWidth = params[0].intValue();
            int dstHeight = params[1].intValue();
            int targetSize = Math.min(dstWidth, dstHeight);
            BitmapFactory.Options options = new BitmapFactory.Options();
            options.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(getActivity().getContentResolver().openInputStream(mPhotoUri), null, options); 
//calculate min inSampleSize for avoiding memory problems
            options.inSampleSize = calculateImageInSampleSize(options, targetSize, targetSize);
            options.inJustDecodeBounds = false;
            Bitmap originalPhotoBitmap = BitmapFactory.decodeStream(getActivity().getContentResolver()
                    .openInputStream(mPhotoUri), null, options);
            mOriginalBitmap = Bitmap.createBitmap(originalPhotoBitmap, originalPhotoBitmap.getWidth() - targetSize,
                                                        originalPhotoBitmap.getHeight() - targetSize, targetSize, targetSize);
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }

//codefor inSampleSize calculation from http://developer.android.com/training/displaying-bitmaps/load-bitmap.html#load-bitmap

private int calculateImageInSampleSize(BitmapFactory.Options originalSize, int targetWidth, int targetHeight) {
    final int width = originalSize.outWidth;
    final int height = originalSize.outHeight;
    int inSampleSize = 1;

    if (height > targetHeight || width > targetWidth) {
        final int halfHeight = height /2;
        final int halfWidth = width /2;

        while ((halfHeight /inSampleSize) > targetHeight &&
                (halfWidth / inSampleSize) > targetWidth) {
            inSampleSize *= 2;
        }
    }

    return inSampleSize;
}

Answer 1

每个设备在相机中遵循不同的方向，所以你按照这个例子解决了你的问题

private Bitmap imageRotating(String filePath){
    try{
        ExifInterface exif = new ExifInterface(filePath);
        int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, ExifInterface.ORIENTATION_UNDEFINED);

        return rotateBitmap(decodeSampledBitmapFromResource(filePath,150,224), orientation);
    }
    catch(Exception e){
        e.printStackTrace();
        return null;
    }
}

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

    try{
        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(), bitmap.getHeight(), matrix, true);
            bitmap.recycle();
            return bmRotated;
        }
        catch (OutOfMemoryError e) {
            e.printStackTrace();
            return null;
        }
    }
    catch (Exception e) {
        e.printStackTrace();
        return null;
    }
}