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出于某种原因，当我将手机设置为横向模式时，相机预览是颠倒的（水平翻转）。我正在使用 Xamarin 移植的示例项目；AVCam条码。

我最终通过在横向使用 GeometryFlipped 提出了一个半完整的修复。但是，现在绘制的条形码在横向模式下没有绘制在正确的位置。

  1. 这是设备/操作系统问题还是示例不完整？

  2. 纠正此问题的推荐方法是什么？

    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 ();
        });
    }
}

编辑

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 ();
    }
}
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1 回答 1

2

设备和视频方向对于横向具有不同的含义。

文档说（用于视频）：

案例景观左

表示视频应水平定向，右上。

案例景观右

指示视频应水平放置，左上角。

但设备方向说：

案例景观左

设备处于横向模式，设备直立，主页按钮位于右侧。

案例景观右

设备处于横向模式，设备直立，主页按钮位于左侧。

因此，您需要更改为：

case UIDeviceOrientation.LandscapeLeft:
    return LandscapeRight;
case UIDeviceOrientation.LandscapeRight:
    return LandscapeLeft;
于 2017-11-04T01:24:01.320 回答