在 .Net 中使用 GDI+ 勾勒出路径

如何使用 GDI+ 绘制图形路径？例如，我将两个相交的矩形添加到 GraphicsPath 中。我只想绘制所得图形路径的轮廓。

请注意，我不想填充该区域，我只想绘制轮廓。

Example:

没有有效的方法来绘制大纲。然而，GDI+ 确实有一个名为 GdipWindingModeOutline 的函数可以完全做到这一点。这是MSDN参考这段代码可以解决这个问题：

// Declaration required for interop
[DllImport(@"gdiplus.dll")]
public static extern int GdipWindingModeOutline( HandleRef path, IntPtr matrix, float flatness );

void someControl_Paint(object sender, PaintEventArgs e)
{
    // Create a path and add some rectangles to it
    GraphicsPath path = new GraphicsPath();
    path.AddRectangles(rectangles.ToArray());

    // Create a handle that the unmanaged code requires. nativePath private unfortunately
    HandleRef handle = new HandleRef(path, (IntPtr)path.GetType().GetField("nativePath", BindingFlags.NonPublic | BindingFlags.Instance).GetValue(path));
    // Change path so it only contains the outline
    GdipWindingModeOutline(handle, IntPtr.Zero, 0.25F);
    using (Pen outlinePen = new Pen(Color.FromArgb(255, Color.Red), 2))
    {
        g.DrawPath(outlinePen, path);
    }
}