c# - 在 Windows 10 中将 InkCanvas 笔画保存为 png/jpg 图像

Question

有没有办法在 Windows 10(UWP 应用程序)中将 InkCanvas 中的笔画保存为 png/jpg 图像？

Answer 1

我知道这是一篇旧帖子，但以下是我发现如何为其他可能需要它的人做到这一点的方法。

如果您不想将 InkCanvas 保存为文件或 GIF，请在内存中对其进行操作。我实际上有以下三个选择。请注意，对于其中的某些内容，您将需要添加对 Win2D.uwp 的引用，可以通过搜索确切的名称在 NuGet 上找到该引用。它由 Microsoft 提供。

1. 将 InkCanvas 转换为字节数组:

   private byte[] ConvertInkCanvasToByteArray()
   {
       var canvasStrokes = cvsSignature.InkPresenter.StrokeContainer.GetStrokes();
   
       if (canvasStrokes.Count > 0)
       {
           var width = (int)cvsSignature.ActualWidth;
           var height = (int)cvsSignature.ActualHeight;
           var device = CanvasDevice.GetSharedDevice();
           var renderTarget = new CanvasRenderTarget(device, width,
               height, 96);
   
           using (var ds = renderTarget.CreateDrawingSession())
           {
               ds.Clear(Windows.UI.Colors.White);
               ds.DrawInk(cvsSignature.InkPresenter.StrokeContainer.GetStrokes());
           }
   
           return renderTarget.GetPixelBytes();
       }
       else
       {
           return null;
       }
   }
   

2. 如果您需要的只是像素的字节数组，那么您就完成了。但是，如果您现在想要生成图像，则可以使用 WriteableBitmap 来执行此操作。以下是可以调用来执行此操作的同步和异步方法。

   private WriteableBitmap GetSignatureBitmapFull()
   {
       var bytes = ConvertInkCanvasToByteArray();
   
       if (bytes != null)
       {
           var width = (int)cvsSignature.ActualWidth;
           var height = (int)cvsSignature.ActualHeight;
   
           var bmp = new WriteableBitmap(width, height);
           using (var stream = bmp.PixelBuffer.AsStream())
           {
               stream.Write(bytes, 0, bytes.Length);
               return bmp;
           }
       }
       else
           return null;
   }
   
   private async Task<WriteableBitmap> GetSignatureBitmapFullAsync()
   {
       var bytes = ConvertInkCanvasToByteArray();
   
       if (bytes != null)
       {
           var width = (int)cvsSignature.ActualWidth;
           var height = (int)cvsSignature.ActualHeight;
   
           var bmp = new WriteableBitmap(width, height);
           using (var stream = bmp.PixelBuffer.AsStream())
           {
               await stream.WriteAsync(bytes, 0, bytes.Length);
               return bmp;
           }
       }
       else
           return null;
   }
   

3. 最后，这里有一个异步方法，如果您想的话，我可以使用它在位图上进行裁剪。此方法的关键是请注意，使用此方法，您不必首先以数组形式获取像素字节。您只需从 Canvas 中获取笔画，然后将其直接保存到内存流中

   private async Task<WriteableBitmap> GetSignatureBitmapCropped()
   {
       try
       {
           var canvasStrokes = cvsSignature.InkPresenter.StrokeContainer.GetStrokes();
   
           if (canvasStrokes.Count > 0)
           {
               var bounds = cvsSignature.InkPresenter.StrokeContainer.BoundingRect;
               var xOffset = (uint)Math.Round(bounds.X);
               var yOffset = (uint)Math.Round(bounds.Y);
               var pixelWidth = (int)Math.Round(bounds.Width);
               var pixelHeight = (int)Math.Round(bounds.Height);
   
               using (var memStream = new InMemoryRandomAccessStream())
               {
                   await cvsSignature.InkPresenter.StrokeContainer.SaveAsync(memStream);
   
                   var decoder = await BitmapDecoder.CreateAsync(memStream);
   
                   var transform = new BitmapTransform();
                   var newBounds = new BitmapBounds();
                   newBounds.X = 0;
                   newBounds.Y = 0;
                   newBounds.Width = (uint)pixelWidth;
                   newBounds.Height = (uint)pixelHeight;
                   transform.Bounds = newBounds;
   
                   var pdp = await decoder.GetPixelDataAsync(
                       BitmapPixelFormat.Bgra8,
                       BitmapAlphaMode.Straight,
                       transform,
                       ExifOrientationMode.IgnoreExifOrientation,
                       ColorManagementMode.DoNotColorManage);
   
                   var pixels = pdp.DetachPixelData();
   
                   var cropBmp = new WriteableBitmap(pixelWidth, pixelHeight);
   
                   using (var stream = cropBmp.PixelBuffer.AsStream())
                   {
                       await stream.WriteAsync(pixels, 0, pixels.Length);
                   }
                   return cropBmp;
               }
           }
           else
           {
               return null;
           }
       }
       catch (Exception ex)
       {
           return null;
       }
   }
   

希望这有助于在 Windows 10 Universal 中使用 InkCanvas 时提供一些替代方案。