WPF上用GDI图形画圆

Question

我需要在 WPF 窗体上用 GDI 图形绘制一个圆圈。我不能用 windows 形式做到这一点，所以我添加了一个 using. 我无法使用 WPF 中的 Elipse 控件。我的老师让我这样做的。

这是我的代码：

public void MakeLogo()
{
    System.Drawing.SolidBrush myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Green);
    System.Drawing.Graphics formGraphics = this.CreateGraphics();
    formGraphics.FillEllipse(myBrush, new System.Drawing.Rectangle(0, 0, 200, 300));
    myBrush.Dispose();
    formGraphics.Dispose();
}

这是错误：

MainWindow' does not contain a definition for 'CreateGraphics' and no extension method 'CreateGraphics' accepting a first argument of type 'MainWindow' could be found (are you missing a using directive or an assembly reference?)

Answer 1

您不能直接在 WPF 中使用 GDI，要实现您的需要，请使用 WindowsFormsHost。添加对 System.Windows.Forms 和 WindowsFormsIntegration 的引用，像这样将其添加到 xaml（里面应该有一些东西，比如 Panel 或其他）：

<Window x:Class="WpfApplication1.MainWindow"
                xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
                xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
                xmlns:local="clr-namespace:WpfApplication1"
                mc:Ignorable="d"
                xmlns:wf="clr-namespace:System.Windows.Forms;assembly=System.Windows.Forms"
                Title="MainWindow" Height="350" Width="525">
        <!--whatever goes here-->
        <WindowsFormsHost x:Name="someWindowsForm">
            <wf:Panel></wf:Panel>
        </WindowsFormsHost>
        <!--whatever goes here-->
    </Window>

然后你的 code-behind 看起来像这样，你会没事的

    SolidBrush myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Green);
    Graphics formGraphics = this.someWindowsForm.Child.CreateGraphics();
    formGraphics.FillEllipse(myBrush, new System.Drawing.Rectangle(0, 0, 200, 300)); 
    myBrush.Dispose();
    formGraphics.Dispose();

UPD：在这里使用 using 语句是个好主意：

using (var myBrush = new System.Drawing.SolidBrush(System.Drawing.Color.Green))
            {
                using (var formGraphics = this.someForm.Child.CreateGraphics())
                {
                    formGraphics.FillEllipse(myBrush, new System.Drawing.Rectangle(0, 0, 200, 300));
                }
            }

WPF上用GDI图形画圆

Drawing a circle with GDI graphics on WPF

c#

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visual-studio