Graphics.IsVisible Method (Point)

The following code example is designed for use with Windows Forms, and it requires PaintEventArgs e, which is a parameter of the Paint event handler. The code performs the following actions:

• Creates a rectangular clipping region and sets it as the clipping region for the graphics object of the form using Replace.

• Creates two points, one inside the clipping region and one outside.

• Tests each of the points for visibility and draws only the visible one.

The result is one small red circle, which is within the clip region.

Private Sub IsVisiblePoint(ByVal e As PaintEventArgs)

    ' Set clip region. 
    Dim clipRegion As New [Region](New Rectangle(50, 50, 100, 100))
    e.Graphics.SetClip(clipRegion, CombineMode.Replace)

    ' Set up coordinates of points. 
    Dim x1 As Integer = 100
    Dim y1 As Integer = 100
    Dim x2 As Integer = 200
    Dim y2 As Integer = 200
    Dim point1 As New Point(x1, y1)
    Dim point2 As New Point(x2, y2)

    ' If point is visible, fill ellipse that represents it. 
    If e.Graphics.IsVisible(point1) Then
        e.Graphics.FillEllipse(New SolidBrush(Color.Red), x1, y1, _
        10, 10)
    End If 
    If e.Graphics.IsVisible(point2) Then
        e.Graphics.FillEllipse(New SolidBrush(Color.Blue), x2, y2, _
        10, 10)
    End If 
End Sub

.NET Framework

.NET Framework Client Profile

Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Reference