通过

如何：对区域使用命中测试

  • 项目

命中测试的目的是确定光标是否位于指定对象（例如图标或按钮）上。

示例

以下示例通过形成两个矩形区域的并集来创建加号形状区域。 假设变量 point 保留最近一次单击的位置。 代码将检查 point 是否位于加号形状区域。 如果点位于区域中（命中），则使用不透明的红色画笔填充该区域。 否则，将使用半透明红色画笔填充该区域。

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);

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)

编译代码

前面的示例专用于 Windows 窗体，它需要 PaintEventArgs e，这是 PaintEventHandler 的参数。

另请参阅