graphics.h File Reference

Functions
void	InitGraphics ()
void	MovePen (double x, double y)
void	DrawLine (double dx, double dy)
void	DrawArc (double r, double start, double sweep)
double	GetWindowWidth ()
double	GetWindowHeight ()
double	GetCurrentX ()
double	GetCurrentY ()

---

Function Documentation

void DrawArc	(	double	r,
		double	start,
		double	sweep
	)

This procedure draws a circular arc, which always begins at the current point. The arc itself has radius r, and starts at the angle specified by the parameter start, relative to the center of the circle. This angle is measured in degrees counterclockwise from the 3 o'clock position along the x-axis, as in traditional mathematics. For example, if start is 0, the arc begins at the 3 o'clock position; if start is 90, the arc begins at the 12 o'clock position; and so on. The fraction of the circle drawn is specified by the parameter sweep, which is also measured in degrees. If sweep is 360, DrawArc draws a complete circle; if sweep is 90, it draws a quarter of a circle. If the value of sweep is positive, the arc is drawn counterclockwise from the current point. If sweep is negative, the arc is drawn clockwise from the current point. The current point at the end of the DrawArc operation is the final position of the pen along the arc.

Examples: DrawArc(r, 0, 360) Draws a circle to the left of the current point. DrawArc(r, 90, 180) Draws the left half of a semicircle starting from the 12 o'clock position. DrawArc(r, 0, 90) Draws a quarter circle from the 3 o'clock to the 12 o'clock position. DrawArc(r, 0, -90) Draws a quarter circle from the 3 o'clock to the 6 o'clock position. DrawArc(r, -90, -90) Draws a quarter circle from the 6 o'clock to the 9 o'clock position.

void DrawLine	(	double	dx,
		double	dy
	)

This procedure draws a line extending from the current point by moving the pen dx inches in the x direction and dy inches in the y direction. The final position becomes the new current point.

double GetCurrentX

(

)

These functions return the current x and y positions.

double GetCurrentY

(

)

double GetWindowHeight

(

)

double GetWindowWidth

(

)

These functions return the width and height of the graphics window, in inches.

void InitGraphics

(

)

This procedure creates the graphics window on the screen. The call to InitGraphics must precede any calls to other functions in this package and must also precede any printf output. In most cases, the InitGraphics call is the first statement in the function main.

void MovePen	(	double	x,
		double	y
	)

This procedure moves the current point to the position (x, y), without drawing a line. The model is that of the pen being lifted off the graphics window surface and then moved to its new position.

---