如何将 CanvasControl 的内容添加到 MediaClip

Question

我正在创建一个 uwp 应用程序，用户输入的文本会转换为视频叠加层。用户加载视频，输入文本，预览带有文本的视频，然后他们可以保存带有叠加层的视频。现在它适用于图像叠加层，但不适用于文本。我正在尝试使用 win2d 来格式化文本。但是，我不知道如何将 win2d canvas 控件放入 windows.media.editing 媒体剪辑中。

我想我可以转到 CanvasControl > 某种位图 > 图像 > MediaClip，但媒体剪辑只能通过存储文件或直接 3d 表面创建。任何事情都会有帮助！这是我第一次尝试在游戏引擎之外写东西。

当前将canvas控件转换为位图的部分：

private async void btnAddOverlay_Click(object sender, RoutedEventArgs e)
        {

            var bitmap = new RenderTargetBitmap();
            await bitmap.RenderAsync(canvasControl);
            IBuffer pixelBuffer = await bitmap.GetPixelsAsync();
            byte[] pixels = pixelBuffer.ToArray();
            SoftwareBitmap outputBitmap = SoftwareBitmap.CreateCopyFromBuffer
            (
                pixelBuffer,
                BitmapPixelFormat.Bgra8,
                bitmap.PixelWidth,
                bitmap.PixelHeight
            );
        }

将图像叠加到视频中的旧部分。（overlayImageFile是存储文件，我只是不知道如何将outputBitmap转换成存储文件来制作媒体剪辑。）

private async void CreateOverlays()
        {
            // Create a clip from video and add it to the composition
            var baseVideoClip = await MediaClip.CreateFromFileAsync(pickedFile);
            composition = new MediaComposition();
            composition.Clips.Add(baseVideoClip);

            // Create a clip from image
            var overlayImageClip = await MediaClip.CreateFromImageFileAsync(overlayImageFile,timeSpan);

            // Put image in upper left corner, retain its native aspect ratio
            Rect imageOverlayPosition;
            imageOverlayPosition.Height = mediaElement.ActualHeight / 3;
            imageOverlayPosition.Width = (double)imageBitmap.PixelWidth / (double)imageBitmap.PixelHeight * imageOverlayPosition.Height;
            imageOverlayPosition.X = 0;
            imageOverlayPosition.Y = 0;

            // Make the clip from the image an overlay
            var imageOverlay = new MediaOverlay(overlayImageClip);
            imageOverlay.Position = imageOverlayPosition;
            imageOverlay.Opacity = 0.8;

            // Make a new overlay layer and add the overlay to it
            var overlayLayer = new MediaOverlayLayer();
            overlayLayer.Overlays.Add(imageOverlay);
            composition.OverlayLayers.Add(overlayLayer);

            //Render to MediaElement
            mediaElement.Position = TimeSpan.Zero;
            mediaStreamSource = composition.GeneratePreviewMediaStreamSource((int)mediaElement.ActualWidth, (int)mediaElement.ActualHeight);
            mediaElement.SetMediaStreamSource(mediaStreamSource);
            txbNotification.Text = "Overlay creaeted";
        }

Windows 媒体剪辑 Class: https://docs.microsoft.com/en-us/uwp/api/windows.media.editing.mediaclip?view=winrt-19041

Answer 1

I just don't know how to convert outputBitmap to a storage file to make a media clip from it.

得到RenderTargetBitmap后，不需要转换为SoftwareBitmap。您可以通过BitmapEncoder将像素数据存储为指定格式的文件。这是方法：

private async void btnAddOverlay_Click(object sender, RoutedEventArgs e)
{
    RenderTargetBitmap renderTargetBitmap = new RenderTargetBitmap();
    await renderTargetBitmap.RenderAsync(canvasControl);

    var pixelBuffer = await renderTargetBitmap.GetPixelsAsync();
    var pixels = pixelBuffer.ToArray();
    var displayInformation = DisplayInformation.GetForCurrentView();

    // Create the file in local folder
    var file = await ApplicationData.Current.LocalFolder.CreateFileAsync("TempCanvas.png", CreationCollisionOption.ReplaceExisting);
    
    // Write data
    using (var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
    {
        var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, stream);
        encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Premultiplied, (uint)renderTargetBitmap.PixelWidth, (uint)renderTargetBitmap.PixelHeight, displayInformation.RawDpiX, displayInformation.RawDpiY, pixels);
        await encoder.FlushAsync();
    }
}

需要时，您可以使用以下代码获取保存的图片：

var file = await ApplicationData.Current.LocalFolder.GetFileAsync("TempCanvas.png");

Answer 2

这只是另一种可能的方式

如果您使用的是 win2d，则可以使用

MediaClip.CreateFromSurface(IDirect3DSurface, TimeSpan) 函数和

您可以将 canvas 渲染目标直接传递给此方法

这样您就不必将位图保存到文件

因此您必须创建离线 canvas 设备然后是 canvas 渲染目标然后在上面画文字然后将该渲染目标传递给函数它将生成用于叠加的媒体剪辑

如何将 CanvasControl 的内容添加到 MediaClip

How to add contents of CanvasControl to a MediaClip

c#

windows

uwp

video-processing

win2d