The SimpleCxxLib package

class GArc : public GObject

• The coordinates of the bounding rectangle (x, y, width, height)
• The angle at which the arc starts (start)
• The number of degrees that the arc covers (sweep)

All angles in a GArc description are measured in degrees moving counterclockwise from the +x axis. Negative values for either start or sweep indicate motion in a clockwise direction.

The following diagram illustrates the interpretation of these parameters for the arc shown in red:

Constructor detail

GArc(double width, double height, double start, double sweep);
GArc(double x, double y, double width, double height, double start, double sweep);

Creates a new GArc object consisting of an elliptical arc. The first form creates a GArc whose origin is the point (0, 0); the second form positions the GArc at the point (x, y).

The following screenshots show several examples of how the GArc constructor interprets the start and sweep parameters:

In the code fragments underneath each of these diagrams, r is the radius of the circular arc, and cx and cy are the coordinates of the center or the window.

Usage:

GArc *arc = new GArc(width, height, start, sweep);
GArc *arc = new GArc(x, y, width, height, start, sweep);

Method detail

void setStartAngle(double start);

arc->setStartAngle(start);

double getStartAngle() const;

double angle = arc->getStartAngle();

void setSweepAngle(double start);

arc->setSweepAngle(start);

double getSweepAngle() const;

double angle = arc->getSweepAngle();

GPoint getStartPoint() const;

GPoint pt = arc->getStartPoint();

GPoint getEndPoint() const;

GPoint pt = arc->getEndPoint();

void setFrameRectangle(const GRectangle & rect);
void setFrameRectangle(double x, double y, double width, double height);

arc->setFrameRectangle(rect);
arc->setFrameRectangle(x, y, width, height);

GRectangle getFrameRectangle() const;

GRectangle rect = arc->getFrameRectangle();

void setFilled(bool flag);

Sets the fill status for the arc, where false is outlined and true is filled. If a GArc is unfilled, the figure consists only of the arc itself. If a GArc is filled, the figure consists of the pie-shaped wedge formed by connecting the endpoints of the arc to the center. As an example, the following program draws a 270-degree arc starting at 45 degrees, filled in yellow, much like the character in the PacMan video game:

   int main() {
      GWindow gw;
      cout << "This program draws the PacMan character." << endl;
      double cx = gw.getWidth() / 2;
      double cy = gw.getHeight() / 2;
      double r = 25;
      GArc *pacman = new GArc(cx - r, cy - r, 2 * r, 2 * r, 45, 270);
      pacman->setFilled(true);
      pacman->setFillColor("YELLOW");
      gw.add(pacman);
      return 0;
   }

The program results in the following picture:

Usage:

arc->setFilled(flag);

bool isFilled() const;

if (arc->isFilled()) ...

void setFillColor(string color);
void setFillColor(int rgb);

arc->setFillColor(color);

string getFillColor() const;

string color = arc->getFillColor();