如何：对区域使用命中测试
更新：2007 年 11 月
命中检测的目的是确定光标是否位于给定对象（如图标或按钮）上。
示例
下面的示例通过合并两个矩形区域创建形状为加号的区域。假设变量 point 中保存最近单击过的位置。该代码查看 point 是否位于形状为加号的区域。如果该点位于该区域（命中），则该区域将用不透明的红色画笔填充。否则，该区域将用半透明的红色画笔填充。
Dim point As New Point(60, 10)
' Assume that the variable "point" contains the location of the
' most recent mouse click.
' To simulate a hit, assign (60, 10) to point.
' To simulate a miss, assign (0, 0) to point.
Dim solidBrush As New SolidBrush(Color.Black)
Dim region1 As New [Region](New Rectangle(50, 0, 50, 150))
Dim region2 As New [Region](New Rectangle(0, 50, 150, 50))
' Create a plus-shaped region by forming the union of region1 and region2.
' The union replaces region1.
region1.Union(region2)
If region1.IsVisible(point, e.Graphics) Then
' The point is in the region. Use an opaque brush.
solidBrush.Color = Color.FromArgb(255, 255, 0, 0)
Else
' The point is not in the region. Use a semitransparent brush.
solidBrush.Color = Color.FromArgb(64, 255, 0, 0)
End If
e.Graphics.FillRegion(solidBrush, region1)
Point point = new Point(60, 10);
// Assume that the variable "point" contains the location of the
// most recent mouse click.
// To simulate a hit, assign (60, 10) to point.
// To simulate a miss, assign (0, 0) to point.
SolidBrush solidBrush = new SolidBrush(Color.Black);
Region region1 = new Region(new Rectangle(50, 0, 50, 150));
Region region2 = new Region(new Rectangle(0, 50, 150, 50));
// Create a plus-shaped region by forming the union of region1 and
// region2.
// The union replaces region1.
region1.Union(region2);
if (region1.IsVisible(point, e.Graphics))
{
// The point is in the region. Use an opaque brush.
solidBrush.Color = Color.FromArgb(255, 255, 0, 0);
}
else
{
// The point is not in the region. Use a semitransparent brush.
solidBrush.Color = Color.FromArgb(64, 255, 0, 0);
}
e.Graphics.FillRegion(solidBrush, region1);
编译代码
前面的示例是为使用 Windows 窗体而设计的，它需要 PaintEventHandler 的参数 PaintEventArgse。