Please use FireFox to view this page

Visual Basic 6 definition

Declare Function CreatePolygonRgn Lib "gdi32.dll" (lpPoint As POINT_TYPE, ByVal nCount As Long, ByVal nPolyFillMode As Long) As Long

Visual Basic .NET definition

Declare Function CreatePolygonRgn Lib "gdi32" (ByRef lpPoint As POINTAPI, ByVal nCount As Integer, ByVal nPolyFillMode As Integer) As Integer

C# definition

[DllImport("gdi32")] public static extern int CreatePolygonRgn(ref POINTAPI lpPoint, int nCount, int nPolyFillMode)

Description

Platforms: Win 32s, Win 95/98, Win NT CreatePolygonRgn creates a polygonal region and provides a handle to it. The polygon is defined by an array of points specifying its vertices. Note that the polygon fill mode must explictly be specified, instead of using the one set for whatever device the region is used with. The function returns the handle to the newly created region if successful, or 0 if an error occured. CreatePolygonRgn Creates a polygonal region. System.Drawing.Drawing2D.GraphicsPath constructorSystem.Drawing.Drawing2D.GraphicsPath.AddPolygonSystem.Drawing.Region.Region(System.Drawing.Drawing2D.GraphicsPath)

Parameters

lpPoint An array holding the vertices of the polygonal region. Specify each point in order only once. nCount The number of elements in the array passed as lpPoint. nPolyFillMode Exactly one of the following flags specifying the polygon fill mode to use for the polygonal region: ALTERNATE = 1 Alternates between filling and not filling contiguous sections whose boundaries are determined by the edge(s) of the polygon crossing through the polygon's interior. WINDING = 2 Any section inside the polygon is filled, regardless of any intra-polygonal boundaries and edges.

Further Information:

For further information on Windows API functions such as these, and how to use these API's in your C# and VB.NET applications, please refer to the book 'Network programming in .NET' (Buy at Amazon UK) (Buy at Amazon US)

Visual Basic 6 example source code
' Invert the pixels within a triangular region on window Form1. The triangular ' region has vertices (150,150), (250, 200), and (100, 200). Note how the points are loaded ' into the array of vertices. Dim vertex(0 To 2) As POINT_TYPE ' array of region's vertices Dim hrgn As Long ' handle to the triangular region Dim retval As Long ' return value ' Load the vertices of the triangular region into the array. vertex(0).x = 150: vertex(0).y = 150 ' 1st point: (150,150) vertex(1).x = 250: vertex(1).y = 200 ' 2nd point: (250,200) vertex(2).x = 100: vertex(2).y = 200 ' 3rd point: (100,200) ' Create the polygonal region based on the array of vertices. hrgn = CreatePolygonRgn(vertex(0), 3, ALTERNATE) ' for a triangle, fill mode is irrelevant ' Invert the pixels within the triangular region on Form1. retval = InvertRgn(Form1.hDC, hrgn) ' Delete the region to free up resources. retval = DeleteObject(hrgn)
C# example source code

Provide a code example

C#
VB.NET
VB6