Question

出于某种原因，当我将手机定位到横向模式时，相机预览会颠倒（水平翻转）。我正在使用Xamarin移植的示例项目; AVCamBarcode

我最终通过横向使用GeometryFlip来完成半个完整的修复。但是，现在绘制的条形码不会以横向模式在正确的位置绘制。

这是设备/操作系统问题还是样本不完整？

建议的解决方法是什么？

public override void ViewWillTransitionToSize (CGSize toSize, IUIViewControllerTransitionCoordinator coordinator)
{
    base.ViewWillTransitionToSize (toSize, coordinator);

    var videoPreviewLayerConnection = PreviewView.VideoPreviewLayer.Connection;
    if (videoPreviewLayerConnection != null) {
        var deviceOrientation = UIDevice.CurrentDevice.Orientation;
        if (!deviceOrientation.IsPortrait () && !deviceOrientation.IsLandscape ())
            return;

        var newVideoOrientation = VideoOrientationFor (deviceOrientation);
        var oldSize = View.Frame.Size;
        var oldVideoOrientation = videoPreviewLayerConnection.VideoOrientation;
        videoPreviewLayerConnection.VideoOrientation = newVideoOrientation;

        //THIS IS THE HALF FIX I CAME UP WITH
        if (deviceOrientation.IsLandscape())
            videoPreviewLayerConnection.VideoPreviewLayer.GeometryFlipped = true;
        else
            videoPreviewLayerConnection.VideoPreviewLayer.GeometryFlipped = false;
        //END FIX

        // When we transition to the new size, we need to adjust the region
        // of interest's origin and size so that it stays anchored relative
        // to the camera.
        coordinator.AnimateAlongsideTransition (context => {
            var oldRegion = PreviewView.RegionOfInterest;
            var newRegion = new CGRect ();

            if (oldVideoOrientation == LandscapeRight && newVideoOrientation == LandscapeLeft) {
                newRegion = oldRegion.WithX (oldSize.Width - oldRegion.X - oldRegion.Width);
            } else if (oldVideoOrientation == LandscapeRight && newVideoOrientation == Portrait) {
                newRegion.X = toSize.Width - oldRegion.Y - oldRegion.Height;
                newRegion.Y = oldRegion.X;
                newRegion.Width = oldRegion.Height;
                newRegion.Height = oldRegion.Width;
            } else if (oldVideoOrientation == LandscapeLeft && newVideoOrientation == LandscapeRight) {
                newRegion = oldRegion.WithX (oldSize.Width - oldRegion.X - oldRegion.Width);
            } else if (oldVideoOrientation == LandscapeLeft && newVideoOrientation == Portrait) {
                newRegion.X = oldRegion.Y;
                newRegion.Y = oldSize.Width - oldRegion.X - oldRegion.Width;
                newRegion.Width = oldRegion.Height;
                newRegion.Height = oldRegion.Width;
            } else if (oldVideoOrientation == Portrait && newVideoOrientation == LandscapeRight) {
                newRegion.X = oldRegion.Y;
                newRegion.Y = toSize.Height - oldRegion.X - oldRegion.Width;
                newRegion.Width = oldRegion.Height;
                newRegion.Height = oldRegion.Width;
            } else if (oldVideoOrientation == Portrait && newVideoOrientation == LandscapeLeft) {
                newRegion.X = oldSize.Height - oldRegion.Y - oldRegion.Height;
                newRegion.Y = oldRegion.X;
                newRegion.Width = oldRegion.Height;
                newRegion.Height = oldRegion.Width;
            }

            PreviewView.SetRegionOfInterestWithProposedRegionOfInterest (newRegion);
        }, context => {
            sessionQueue.DispatchAsync (() => {
                metadataOutput.RectOfInterest = PreviewView.VideoPreviewLayer.MapToLayerCoordinates (PreviewView.RegionOfInterest);
            });
            // Remove the old metadata object overlays.
            RemoveMetadataObjectOverlayLayers ();
        });
    }
}

修改

AVCaptureVideoOrientation VideoOrientationFor (UIDeviceOrientation deviceOrientation)
{
    switch (deviceOrientation) {
    case UIDeviceOrientation.Portrait:
        return Portrait;
    case UIDeviceOrientation.PortraitUpsideDown:
        return PortraitUpsideDown;
    case UIDeviceOrientation.LandscapeLeft:
        return LandscapeLeft;
    case UIDeviceOrientation.LandscapeRight:
        return LandscapeRight;
    default:
        throw new InvalidProgramException ();
    }
}

Answer 1

设备和视频方向对景观有不同的含义。

The docs say (for video)：

案例landscapeLeft

表示视频应水平定向，位于右上方。

案例landscapeRight

表示视频应水平定向，位于左上方。

但device orientation说：

案例landscapeLeft

设备处于横向模式，设备直立，主页按钮位于右侧。

案例landscapeRight

设备处于横向模式，设备直立，主页按钮位于左侧。

所以，你需要改为：

case UIDeviceOrientation.LandscapeLeft:
    return LandscapeRight;
case UIDeviceOrientation.LandscapeRight:
    return LandscapeLeft;

iOS VideoPreview格局颠倒

1 个答案: