Chord Function

Declare Function Chord Lib "gdi32.dll" (ByVal hdc As Long, ByVal nLeftRect As Long, ByVal nTopRect As Long, ByVal nRightRect As Long, ByVal nBottomRect As Long, ByVal nXRadial1 As Long, ByVal nYRadial1 As Long, ByVal nXRadial2 As Long, ByVal nYRadial2 As Long) As Long

Platforms

Windows 95: Supported.
Windows 98: Supported.
Windows NT: Requires Windows NT 3.1 or later.
Windows 2000: Supported.
Windows CE: Not Supported.

Description & Usage

Chord draws an elliptical chord on a device. The chord is drawn using the device's currently selected pen and is filled using its currently selected brush. The chord consists of a line segment connecting two points along an ellipse; the area between the chord and the ellipse's edge is filled (going counterclockwise around the ellipse). The start and end points of the chord's elliptical arc are determined by two radials (drawn from the ellipse's center out to a point). The point where a radial and the ellipse intersect is the start or end point of the chord's arc.

Return Value

If an error occured, the function returns 0 (Windows NT, 2000: use GetLastError to get the error code). If successful, the function returns a non-zero value.

Visual Basic-Specific Issues

None.

Parameters

hdc: A handle to a device context to the device to draw the chord on.
nLeftRect: The x-coordinate of the upper-left corner of the ellipse's bounding rectangle.
nTopRect: The y-coordinate of the upper-left corner of the ellipse's bounding rectangle.
nRightRect: The x-coordinate of the lower-right corner of the ellipse's bounding rectangle.
nBottomRect: The y-coordinate of the lower-right corner of the ellipse's bounding rectangle.
nXRadial1: The x-coordinate of the point along the radial determining the starting point of the chord.
nYRadial1: The y-coordinate of the point along the radial determining the starting point of the chord.
nXRadial2: The x-coordinate of the point along the radial determining the ending point of the chord.
nYRadial2: The y-coordinate of the point along the radial determining the ending point of the chord.

Example

' This code is licensed according to the terms and conditions listed here.

' Draw a chord on window Form1.  The ellipse has a bounding rectangle
' of (10,20)-(210,120).  The chord will have endpoints on the ellipse of (210,70)
' and (110,20) -- i.e., the "upper-right" portion of the ellipse.  Draw the chord using
' Form1's current brush and pen.
Dim retval As Long  ' return value

' Draw the chord as specified above.
retval = Chord(Form1.hDC, 10, 20, 210, 120, 210, 70, 110, 20)