如何将使用 InkCanvas 在画布上完成的工作保存到 UWP C# 中的图像文件?
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【中文标题】如何将使用 InkCanvas 在画布上完成的工作保存到 UWP C# 中的图像文件?【英文标题】:how to save work done on canvas using InkCanvas to an image file in UWP C#? 【发布时间】:2021-05-26 16:56:54 【问题描述】:我想将我在画布上完成的工作保存在我的 UWP 应用中。我正在使用 InkCanvas 在画布内的选定图像上绘制线条,并且我想将画布工作保存到新的图像文件中。
我在尝试保存文件后得到一张空白图像。我尝试了两种保存文件的方法。
工作完成:
xaml 代码
<Button Click="ShowPopup" Content="click me"/>
<Popup x:Name="IMG_G" Width="600" Height="300" HorizontalAlignment="Left" ManipulationMode="All">
<Grid x:Name="img_grid" Height="300" Background="ThemeResource ApplicationPageBackgroundThemeBrush" ManipulationMode="Scale">
<Image VerticalAlignment="Top" HorizontalAlignment="Left"
x:Name="img" Stretch="Fill" Height="300" ManipulationMode="All">
</Image>
<Canvas x:Name="selectionCanvas" Width="600" Background="Transparent" Height="300"/>
<InkCanvas x:Name="inker" />
<InkToolbar x:Name="img_inktoolbar" TargetInkCanvas="x:Bind inker"
VerticalAlignment="Top">
</InkToolbar>
</Grid>
</Popup>
<Button Content="Save"
Width="100"
Height="25"
HorizontalAlignment="Center"
VerticalAlignment="Center" Click="BtnSave_Click"/>
代码背后
public DrawLines()
InitializeComponent();
inker.InkPresenter.InputDeviceTypes = CoreInputDeviceTypes.Mouse | CoreInputDeviceTypes.Touch;
inker.InkPresenter.UnprocessedInput.PointerPressed += StartLine;
inker.InkPresenter.UnprocessedInput.PointerMoved += ContinueLine;
inker.InkPresenter.UnprocessedInput.PointerReleased += CompleteLine;
inker.InkPresenter.InputProcessingConfiguration.RightDragAction = InkInputRightDragAction.LeaveUnprocessed;
private async void ShowPopup(object sender, RoutedEventArgs e)
var _filePicker = new FileOpenPicker();
_filePicker.SuggestedStartLocation = PickerLocationId.Desktop;
_filePicker.ViewMode = PickerViewMode.Thumbnail;
_filePicker.FileTypeFilter.Add(".bmp");
_filePicker.FileTypeFilter.Add(".jpg");
StorageFile _file = await _filePicker.PickSingleFileAsync();
IRandomAccessStream imageStream = await _file.OpenAsync(FileAccessMode.Read);
BitmapImage bmpimage = new BitmapImage();
await bmpimage.SetSourceAsync(imageStream);
img.Source = bmpimage;
IMG_G.IsOpen = true;
private void StartLine(InkUnprocessedInput sender, PointerEventArgs args)
line = new Line();
line.X1 = args.CurrentPoint.RawPosition.X;
line.Y1 = args.CurrentPoint.RawPosition.Y;
line.X2 = args.CurrentPoint.RawPosition.X;
line.Y2 = args.CurrentPoint.RawPosition.Y;
line.Stroke = new SolidColorBrush(Colors.Purple);
line.StrokeThickness = 4;
selectionCanvas.Children.Add(line);
private void ContinueLine(InkUnprocessedInput sender, PointerEventArgs args)
line.X2 = args.CurrentPoint.RawPosition.X;
line.Y2 = args.CurrentPoint.RawPosition.Y;
private void CompleteLine(InkUnprocessedInput sender, PointerEventArgs args)
List<InkPoint> points = new List<InkPoint>();
InkStrokeBuilder builder = new InkStrokeBuilder();
InkPoint pointOne = new InkPoint(new Point(line.X1, line.Y1), 0.5f);
points.Add(pointOne);
InkPoint pointTwo = new InkPoint(new Point(line.X2, line.Y2), 0.5f);
points.Add(pointTwo);
InkStroke stroke = builder.CreateStrokeFromInkPoints(points, System.Numerics.Matrix3x2.Identity);
InkDrawingAttributes ida = inker.InkPresenter.CopyDefaultDrawingAttributes();
stroke.DrawingAttributes = ida;
inker.InkPresenter.StrokeContainer.AddStroke(stroke);
selectionCanvas.Children.Remove(line);
保存文件的方法一
private async void BtnSave_Click(object sender, RoutedEventArgs e)
StorageFolder pictureFolder = KnownFolders.SavedPictures;
var file = await pictureFolder.CreateFileAsync("test2.bmp", CreationCollisionOption.ReplaceExisting);
CanvasDevice device = CanvasDevice.GetSharedDevice();
CanvasRenderTarget renderTarget = new CanvasRenderTarget(device, (int)img.ActualWidth, (int)img.ActualHeight, 96);
//get image's path
StorageFolder folder = ApplicationData.Current.LocalFolder;
//Get the same image file copy which i selected to draw on in ShowPopup() but I actually wanted to get the edited canvas
StorageFile Ifile = await folder.GetFileAsync("Datalog_2020_09_22_10_44_59_2_3_5_RSF.bmp");
var inputFile = Ifile.Path;
using (var ds = renderTarget.CreateDrawingSession())
ds.Clear(Colors.White);
CanvasBitmap image = await CanvasBitmap.LoadAsync(device, inputFile);
//var image = img2.Source;
// I want to use this too, but I have no idea about this
ds.DrawImage(image);
ds.DrawInk(inker.InkPresenter.StrokeContainer.GetStrokes());
// save results
using (var fileStream = await file.OpenAsync(FileAccessMode.ReadWrite))
await renderTarget.SaveAsync(fileStream, CanvasBitmapFileFormat.Jpeg, 1f);
结果
想要的结果
注意:箭头是我在图片上画的
我用这种方法得到的结果
test2.bmp(图像由于某种原因被放大)
保存文件的方法二
private async void BtnSave_Click(object sender, RoutedEventArgs e)
RenderTargetBitmap bitmap = new RenderTargetBitmap();
await bitmap.RenderAsync(selectionCanvas);
Debug.WriteLine($"Capacity = (uint)bitmap.PixelWidth, Length=(uint)bitmap.PixelHeight");
var pixelBuffer = await bitmap.GetPixelsAsync();
Debug.WriteLine($"Capacity = pixelBuffer.Capacity, Length=pixelBuffer.Length");
byte[] pixels = pixelBuffer.ToArray();
var displayInformation = DisplayInformation.GetForCurrentView();
StorageFolder pictureFolder = KnownFolders.SavedPictures;
var file = await pictureFolder.CreateFileAsync("test2.bmp", CreationCollisionOption.ReplaceExisting);
using (var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.BmpEncoderId, stream);
encoder.SetPixelData(BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
(uint)bitmap.PixelWidth,
(uint)bitmap.PixelHeight,
displayInformation.RawDpiX,
displayInformation.RawDpiY,
pixels);
await encoder.FlushAsync();
这种方法的结果
由于某种原因,我得到了全黑图像
test2.bmp
我们将不胜感激。对方法 2 的任何帮助都会更好。
【问题讨论】:
【参考方案1】:如何将使用 InkCanvas 在画布上完成的工作保存到 UWP C# 中的图像文件中?
您无需使用RenderTargetBitmap
将 InkCanvas 保存到图像。 UWP InkCanvas
具有 SaveAsync 方法,可以将StrokeContainer
流直接保存到图像文件。例如。
async void OnSaveAsync(object sender, RoutedEventArgs e)
// We don't want to save an empty file
if (inkCanvas.InkPresenter.StrokeContainer.GetStrokes().Count > 0)
var savePicker = new FileSavePicker();
savePicker.SuggestedStartLocation = PickerLocationId.PicturesLibrary;
savePicker.FileTypeChoices.Add("png with embedded ISF", new[] ".png" );
StorageFile file = await savePicker.PickSaveFileAsync();
if (null != file)
try
using (IRandomAccessStream stream = await file.OpenAsync(FileAccessMode.ReadWrite))
// Truncate any existing stream in case the new file
// is smaller than the old file.
stream.Size = 0;
await inkCanvas.InkPresenter.StrokeContainer.SaveAsync(stream);
catch (Exception ex)
else
更多细节请参考UWPsimple ink代码示例场景3
更新
我在尝试保存文件后得到一个空白图像。
上面的代码只能保存InkCanvas
的笔画,我检查了你的代码,发现你没有在selectionCanvas
中放置任何元素。所以selectionCanvas
的RenderTargetBitmap
将变黑为空。请尝试使用img_grid
替换。
抱歉,现在 InkToolbar 也与我所做的墨水更改一起被复制到图像上:(
这是设计使然,RenderTargetBitmap
将渲染所有查看过的元素,对于您的场景,我们建议您制作矩形以覆盖InkToolbar
或将 img_inktoolbar Visibility 设置为 Collapsed,然后再捕获屏幕并在完成后重置它.
【讨论】:
您好,感谢您的宝贵时间。我尝试使用inkCanvas.InkPresenter.StrokeContainer.SaveAsync(stream);
但我得到的只是墨水笔触,图像变得透明,即我得到的只是墨水笔触,没有图像背景【参考方案2】:
我对方法 2 做了一些改变,得到了想要的结果
保存文件的方法二
private async void BtnSave_Click(object sender, RoutedEventArgs e)
// In order to hide the InkToolbar before the saving the image
img_inktoolbar.Visibility = Visibility.Collapsed;
RenderTargetBitmap bitmap = new RenderTargetBitmap();
await bitmap.RenderAsync(img_grid);
Debug.WriteLine($"Capacity = (uint)bitmap.PixelWidth, Length=(uint)bitmap.PixelHeight");
var pixelBuffer = await bitmap.GetPixelsAsync();
Debug.WriteLine($"Capacity = pixelBuffer.Capacity, Length=pixelBuffer.Length");
byte[] pixels = pixelBuffer.ToArray();
var displayInformation = DisplayInformation.GetForCurrentView();
StorageFolder pictureFolder = KnownFolders.SavedPictures;
var file = await pictureFolder.CreateFileAsync("test2.bmp", CreationCollisionOption.ReplaceExisting);
using (var stream = await file.OpenAsync(FileAccessMode.ReadWrite))
var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.BmpEncoderId, stream);
encoder.SetPixelData(BitmapPixelFormat.Bgra8,
BitmapAlphaMode.Ignore,
(uint)bitmap.PixelWidth,
(uint)bitmap.PixelHeight,
displayInformation.RawDpiX,
displayInformation.RawDpiY,
pixels);
await encoder.FlushAsync();
【讨论】:
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