Question

有没有办法在Windows 10（UWP应用）中将笔画从InkCanvas保存到png / jpg图像？

Answer 1

我知道这是一篇很老的帖子，但我发现这是为那些可能需要它的人做的。

如果您不想将InkCanvas保存到文件或GIF，请在内存中操作它。我实际上有三个选项。注意，对于其中一些，您需要添加对Win2D.uwp的引用，可以通过搜索确切的名称在NuGet上找到它。它由Microsoft提供。

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;
    }
}

如果您只需要像素的字节数组，那么您就完成了。但是，如果您现在要生成图像，则使用WriteableBitmap执行此操作。以下是可以调用的同步和异步方法。

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;
}

最后，这是一个异步方法，我正在使用它来在位图上进行裁剪，如果你想这样做的话。这种方法的关键在于注意如何使用这种方法，首先不必将像素字节作为数组。您只需从画布中获取笔画，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。

Answer 2

当然，只需将笔划容器保存到流中并将其写入文件即可。

if (inkCanvas.InkPresenter.StrokeContainer.GetStrokes().Count > 0)
{
    var savePicker = new Windows.Storage.Pickers.FileSavePicker();
    savePicker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.PicturesLibrary;
    savePicker.FileTypeChoices.Add("PNG", new System.Collections.Generic.List<string> { ".png" });

    Windows.Storage.StorageFile file = await savePicker.PickSaveFileAsync();
    if (null != file)
    {
        try
        {
            using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
            {
                await inkCanvas.InkPresenter.StrokeContainer.SaveAsync(stream);
            }
        }
        catch (Exception ex)
        {
        }
    }
}

可以找到更多InkCanvas样本here。

Answer 3

你所要求的是拍摄屏幕快照。在这种情况下，RenderTargetBitmap似乎可以提供帮助。它可以将任意UIElement渲染为位图。您可以参考我的回复post。

在Windows 10中将InkCanvas笔划保存为png / jpg图像

3 个答案: