我正在尝试在我的应用拍摄的照片上加水印。我能想到的最简单的方法是使用FrameworkElement
来构建图层,然后使用RenderTargetBitmap
来创建带有水印的图像。
这是我的XAML的示例。
<ScrollViewer x:Name="Zoom" Grid.Column="1" HorizontalScrollMode="Enabled" VerticalScrollMode="Enabled" VerticalScrollBarVisibility="Hidden" HorizontalScrollBarVisibility="Hidden" ZoomMode="Enabled">
<Border x:Name="BgBorder">
<Grid x:Name="ImageGird" SizeChanged="ImageGird_SizeChanged">
<Grid x:Name="CaptureGird">
<Image x:Name="CapturedImage" Stretch="None" Source="ms-appx:///Assets/Photo.jpg" />
<StackPanel x:Name="Watermark" VerticalAlignment="Top" HorizontalAlignment="Left" Background="#6FFFFFFF" Margin="10">
<TextBlock Text="Name" Foreground="Black" Margin="10,2.5,10,2.5" />
<TextBlock Text="12345" Foreground="Black" Margin="10,2.5,10,2.5"/>
<TextBlock Text="54321" Foreground="Black" Margin="10,2.5,10,2.5" />
</StackPanel>
</Grid>
</Grid>
</Border>
</ScrollViewer>
由于他们需要的图像分辨率高,因此将其包裹在A中,ScrollViewer
因此可以将其缩小,但是当我尝试使用以下代码创建该图像的位图时,渲染的位图会小于FrameworkElement
private async void Button_Click(object sender, RoutedEventArgs e)
{
try
{
var displayI = DisplayInformation.GetForCurrentView();
var renderTargetBitmap = new RenderTargetBitmap();
await renderTargetBitmap.RenderAsync(ImageGird, (int)ImageGird.ActualWidth, (int)ImageGird.ActualHeight);
IBuffer pixels = await renderTargetBitmap.GetPixelsAsync();
CapturedImage2.Source = renderTargetBitmap;
Debug.WriteLine("Button_Click: ImageGrid: " + ImageGird.ActualWidth + "x" + ImageGird.ActualHeight + " RenderTargetBitmap: " + renderTargetBitmap.PixelWidth + "x" + renderTargetBitmap.PixelHeight);
}
catch (Exception )
{
}
}
调试输出是
Button_Click: ImageGrid: 5344x3008 RenderTargetBitmap: 4096x2306
谁能告诉我为什么渲染的位图比我从中创建它的实际元素小得多?
还有给图像加水印的更好方法吗?
感谢@AJBauer向我指出Win2D,我设法非常优雅地解决了这个问题。
/// <summary>
/// Create a watermarked image from an image stream
/// </summary>
/// <param name="sender">Jpeg image stream.</param>
private async Task<ImageSource> CreateWaterMarkedImage(IRandomAccessStream stream)
{
// Ensure our stream is at the beginning.
stream.Seek(0);
// Create our Win2D in memory renderer.
CanvasDevice device = CanvasDevice.GetSharedDevice();
CanvasRenderTarget offscreen = new CanvasRenderTarget(device, (float)ImageGird.ActualWidth, (float)ImageGird.ActualHeight, 96);
// Create our Win2D bitmap
CanvasBitmap bmp = await CanvasBitmap.LoadAsync(offscreen, stream, 96);
// Create a text formatter for our watermark
var format = new CanvasTextFormat()
{
FontSize = 40,
HorizontalAlignment = CanvasHorizontalAlignment.Left,
VerticalAlignment = CanvasVerticalAlignment.Top,
WordWrapping = CanvasWordWrapping.Wrap,
FontFamily = "Arial",
FontWeight = FontWeights.SemiBold
};
// Get a Win2D drawing session instance
using (CanvasDrawingSession ds = offscreen.CreateDrawingSession())
{
// Layer our resulting Watermarked image.
ds.DrawImage(bmp);
// Create the Win2D text layout so we can get the bounds.
var tl = new CanvasTextLayout(ds, "Name\r\n12345\r\n54321", format, 1000, 1000);
// Create a background for the text
ds.FillRectangle(10, 10, (float)tl.DrawBounds.Width + 20f, (float)tl.DrawBounds.Height + 20f, new Color() { A = 0x6F, R = 0xFF, G = 0xFF, B = 0xFF });
// Add the text layout.
ds.DrawTextLayout(tl, 10, 10, Colors.Black);
// Clear up the memory.
tl.Dispose();
}
// Create our bitmap so we can return an ImageSource
BitmapImage im = new BitmapImage();
using (InMemoryRandomAccessStream oStream = new InMemoryRandomAccessStream())
{
// Save the Win2D canvas renderer a stream.
await offscreen.SaveAsync(oStream, CanvasBitmapFileFormat.Jpeg, 1.0f);
stream.Seek(0);
// Stream our Win2D pixels into the Bitmap
await im.SetSourceAsync(oStream);
Debug.WriteLine("CreateWaterMarkedImage: ImageGrid: " + ImageGird.ActualWidth + "x" + ImageGird.ActualHeight + " Bitmap: " + im.PixelWidth + "x" + im.PixelHeight);
}
// Tidy Up.
format.Dispose();
bmp.Dispose();
offscreen.Dispose();
device.Dispose();
return im;
}
结果调试给了我。
CreateWaterMarkedImage: ImageGrid: 5344x3008 Bitmap: 5344x3008
如果已设置,Image
UIElement
则显示带水印的图像的来源。
CapturedImage2.Source = await CreateWaterMarkedImage(photoStream);
此示例非常适合我的需求,但是,如果您使用Win2D XAML控件,那么任何人都应该可以轻松对其进行调整。
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