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CDC::Arc

Visual Studio 2010

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

C++


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

Reference

Other Resources

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