Graphics.IsVisible Method (PointF)


Indicates whether the specified PointF structure is contained within the visible clip region of this Graphics.

Namespace:   System.Drawing
Assembly:  System.Drawing (in System.Drawing.dll)

Public Function IsVisible (
	point As PointF
) As Boolean


Type: System.Drawing.PointF

PointF structure to test for visibility.

Return Value

Type: System.Boolean

true if the point specified by the point parameter is contained within the visible clip region of this Graphics; otherwise, false.

The following code example is designed for use with Windows Forms, and it requires PaintEventArgse, 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 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 IsVisiblePointF(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 Single = 100.0F
    Dim y1 As Single = 100.0F
    Dim x2 As Single = 200.0F
    Dim y2 As Single = 200.0F
    Dim point1 As New PointF(x1, y1)
    Dim point2 As New PointF(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, _
        10.0F, 10.0F)
    End If
    If e.Graphics.IsVisible(point2) Then
        e.Graphics.FillEllipse(New SolidBrush(Color.Blue), x2, y2, _
        10.0F, 10.0F)
    End If
End Sub

.NET Framework
Available since 1.1
Return to top