The following example creates an elliptical
path and draws that
path with a wide yellow pen. Then the code tests each point in an array to see whether the point touches the outline (as it would be drawn by the wide yellow pen) of the
path. Points that touch the outline are painted green, and points that don't touch the outline are painted red.
C++
VOID Example_IsOutlineVisibleExample(HDC hdc)
{
Graphics graphics(hdc);
INT j;
Pen yellowPen(Color(255, 255, 255, 0), 20);
SolidBrush brush(Color(255, 255, 0, 0));
// Create and draw a path.
GraphicsPath path;
path.AddEllipse(50, 50, 200, 100);
graphics.DrawPath(&yellowPen, &path);
// Create an array of three points, and determine whether each
// point in the array touches the outline of the path.
// If a point touches the outline, paint it green.
// If a point does not touch the outline, paint it red.
PointF[] = {
PointF(230, 138),
PointF(100, 120),
PointF(150, 170)};
for(j = 0; j <= 2; ++j)
{
if(path.IsOutlineVisible(points[j].X, points[j].Y, &yellowPen, NULL))
brush.SetColor(Color(255, 0, 255, 0));
else
brush.SetColor(Color(255, 255, 0, 0));
graphics.FillEllipse(&brush, points[j].X - 3.0f, points[j].Y - 3.0f, 6.0f, 6.0f);
}
}
SUB GDIP_IsOutlineVisible (BYVAL hdc AS DWORD)
LOCAL hStatus AS LONG
LOCAL pGraphics AS DWORD
LOCAL pPath AS DWORD
LOCAL pYellowPen AS DWORD
LOCAL pBrush AS DWORD
DIM pts(2) AS POINTF
LOCAL result AS LONG
LOCAL i AS LONG
hStatus = GdipCreateFromHDC(hdc, pGraphics)
hStatus = GdipCreatePen1(GDIP_ARGB(255, 255, 255, 0), 20, %UnitWorld, pYellowPen)
hStatus = GdipCreateSolidFill(GDIP_ARGB(255, 255, 0, 0), pBrush)
' // Create and draw a path.
hStatus = GdipCreatePath(%FillModeAlternate, pPath)
hStatus = GdipAddPathEllipse(pPath, 50, 50, 200, 100)
hStatus = GdipDrawPath(pGraphics, pYellowPen, pPath)
' // Create an array of three points, and determine whether each
' // point in the array touches the outline of the path.
' // If a point touches the outline, paint it green.
' // If a point does not touch the outline, paint it red.
pts(0).x = 230 : pts(0).y = 138
pts(1).x = 100 : pts(1).y = 120
pts(2).x = 150 : pts(2).y = 170
FOR i = 0 TO 2
hStatus = GdipIsOutlineVisiblePathPoint(pPath, pts(i).x, pts(i).y, pYellowPen, %NULL, result)
IF result THEN
hStatus = GdipSetSolidFillColor(pBrush, GDIP_ARGB(255, 0, 255, 0))
ELSE
hStatus = GdipSetSolidFillColor(pBrush, GDIP_ARGB(255, 255, 0, 0))
END IF
hStatus = GdipFillEllipse(pGraphics, pBrush, pts(i).x - 3, pts(i).y - 3, 6, 6)
NEXT
' // Cleanup
IF pYellowPen THEN GdipDeletePen(pYellowPen)
IF pPath THEN GdipDeletePath(pPath)
IF pGraphics THEN GdipDeleteGraphics(pGraphics)
END SUB
(http://www.jose.it-berater.org/captures/GdipIsOutlineVisiblePathPoint.png)