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 CDCView::DrawArc(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);
}

Requirements

Header: afxwin.h

See Also

Reference

CDC Class

Hierarchy Chart

CDC::Chord

Arc

POINT Structure

RECT Structure