CDC::Arc
Draws an elliptical arc.
BOOL Arc( int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4 ); BOOL Arc( LPCRECT lpRect, POINT ptStart, POINT ptEnd );
Parameters
- x1
- Specifies the x-coordinate of the upper-left corner of the bounding rectangle (in logical units).
- y1
- Specifies the y-coordinate of the upper-left corner of the bounding rectangle (in logical units).
- x2
- Specifies the x-coordinate of the lower-right corner of the bounding rectangle (in logical units).
- y2
- Specifies the y-coordinate of the lower-right corner of the bounding rectangle (in logical units).
- x3
- Specifies the x-coordinate of the point that defines the arc's starting point (in logical units). This point does not have to lie exactly on the arc.
- y3
- Specifies the y-coordinate of the point that defines the arc's starting point (in logical units). This point does not have to lie exactly on the arc.
- x4
- Specifies the x-coordinate of the point that defines the arc's endpoint (in logical units). This point does not have to lie exactly on the arc.
- y4
- Specifies the y-coordinate of the point that defines the arc's endpoint (in logical units). This point does not have to lie exactly on the arc.
- lpRect
- Specifies the bounding rectangle (in logical units). You can pass either an LPRECT or a CRect object for this parameter.
- ptStart
- Specifies the x- and y-coordinates of the point that defines the arc's starting point (in logical units). This point does not have to lie exactly on the arc. You can pass either a POINT structure or a CPoint object for this parameter.
- ptEnd
- Specifies the x- and y-coordinates of the point that defines the arc's ending point (in logical units). This point does not have to lie exactly on the arc. You can pass either a POINT structure or a CPoint object for this parameter.
Return Value
Nonzero if the function is successful; otherwise 0.
Remarks
The arc drawn by using the function is a segment of the ellipse defined by the specified bounding rectangle.
The actual starting point of the arc is the point at which a ray drawn from the center of the bounding rectangle through the specified starting point intersects the ellipse. The actual ending point of the arc is the point at which a ray drawn from the center of the bounding rectangle through the specified ending point intersects the ellipse. The arc is drawn in a counterclockwise direction. Since an arc is not a closed figure, it is not filled. Both the width and height of the rectangle must be greater than 2 units and less than 32,767 units.
Example
void CCurvesView::OnDraw(CDC* pDC)
{
// Fill the client area with a thin circle. The circle's
// interior is not filled. The circle's perimeter is
// blue from 6 o'clock to 3 o'clock and red from 3
// o'clock to 6 o'clock.
// Get the client area.
CRect rectClient;
GetClientRect(rectClient);
// Make a couple of pens.
CPen penBlue;
CPen penRed;
CPen* pOldPen;
penBlue.CreatePen(PS_SOLID | PS_COSMETIC, 1, RGB(0, 0, 255));
penRed.CreatePen(PS_SOLID | PS_COSMETIC, 1, RGB(255, 0, 0));
// Draw from 3 o'clock to 6 o'clock, counterclockwise,
// in a blue pen.
pOldPen = pDC->SelectObject(&penBlue);
pDC->Arc(rectClient,
CPoint(rectClient.right, rectClient.CenterPoint().y),
CPoint(rectClient.CenterPoint().x, rectClient.right));
// Draw from 6 o'clock to 3 o'clock, counterclockwise,
// in a red pen.
pDC->SelectObject(&penRed);
// Keep the same parameters, but reverse start
// and end points.
pDC->Arc(rectClient,
CPoint(rectClient.CenterPoint().x, rectClient.right),
CPoint(rectClient.right, rectClient.CenterPoint().y));
// Restore the previous pen.
pDC->SelectObject(pOldPen);
}
See Also
CDC Overview | Class Members | Hierarchy Chart | CDC::Chord | Arc | POINT | RECT
