C# 如何在 WPF 中将位图渲染到画布中？
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How to render bitmap into canvas in WPF?
提问by void.pointer
I've subclassed Canvasso that I can override its Renderfunction. I need to know how I can load a bitmap in WPF and render that to the canvas. I'm completely new to WPF and I haven't found any tutorials that show you how to do something so seemingly trivial. Step-by-step instructions with examples would be great.
我已经子类化，Canvas以便我可以覆盖它的Render功能。我需要知道如何在 WPF 中加载位图并将其渲染到画布上。我对 WPF 完全陌生，我还没有找到任何教程来向您展示如何做一些看似微不足道的事情。带有示例的分步说明会很棒。
采纳答案by Tarydon
This should get you started:
这应该让你开始：
class MyCanvas : Canvas {
protected override void OnRender (DrawingContext dc) {
BitmapImage img = new BitmapImage (new Uri ("c:\demo.jpg"));
dc.DrawImage (img, new Rect (0, 0, img.PixelWidth, img.PixelHeight));
}
}
回答by mg007
If you do want to paint background of canvas, I would recommend using ImageBrushas Background, 'coz that's simple as you dont need to subclass Canvasto override Onender.
如果您确实想绘制画布背景，我建议使用ImageBrushas Background，'因为这很简单，因为您不需要子类Canvas来覆盖Onender.
But I'll give you a demo source-code for what you have asked:
但我会给你一个演示源代码，用于你所问的问题：
Create a class (I've called it ImageCanvas)
创建一个类（我称之为ImageCanvas）
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace WpfApplication1
{
public class ImageCanvas : Canvas
{
public ImageSource CanvasImageSource
{
get { return (ImageSource)GetValue(CanvasImageSourceProperty); }
set { SetValue(CanvasImageSourceProperty, value); }
}
public static readonly DependencyProperty CanvasImageSourceProperty =
DependencyProperty.Register("CanvasImageSource", typeof(ImageSource),
typeof(ImageCanvas), new FrameworkPropertyMetadata(default(ImageSource)));
protected override void OnRender(System.Windows.Media.DrawingContext dc)
{
dc.DrawImage(CanvasImageSource, new Rect(this.RenderSize));
base.OnRender(dc);
}
}
}
Now you can use it like this:
现在你可以像这样使用它：
<Window x:Class="WpfApplication1.Window1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1" Title="Window1" Height="300" Width="300">
<Grid>
<local:ImageCanvas CanvasImageSource="/Splash.png">
<TextBlock Text="Hello From Mihir!" />
</local:ImageCanvas>
</Grid>
</Window>
回答by user7116
In WPF it is a rare case that you would need to override OnRenderespecially if all you wanted to do was draw a BMP to a background:
在 WPF 中，您需要覆盖的情况很少见，OnRender特别是如果您只想将 BMP 绘制到背景：
<Canvas>
<Canvas.Background>
<ImageBrush ImageSource="Resources\background.bmp" />
</Canvas.Background>
<!-- ... -->
</Canvas>
