C Graphics Primitives

1
C Graphics Primitives

• April 15th

2

• void clearscreen(int c)
• clear the screen to background color c
• If c lt 0 screen white
• If c gt 1 screen black

3

• void moveto(int x, int y)
• Cursor moves to position (x,y) (without drawing
  anything on the screen)
• The value x must be between 0 and maxX
• The value y must be between 0 and maxY

4

• int getmaxx()
• Return the integer value of maxX for the screen
• int getmaxy()
• Return the integer value of maxX for the screen

5
Example

• void main ()
• int x,y
• x getmaxx()
• y getmaxy()
• moveto(x/2, y/2)

6

• void setcolor(int c)
• Set the color of the pen that will be drawing
  lines and shapes on screen to color c
• If c lt 0 pen color white
• If c gt 1 pen color black
• Note white pen on white screen (also black pen
  on black screen) will not show up (can be used
  to erase)

7

• void lineto(int x, int y)
• Draw a straight line from current position of
  cursor to position (x,y) on screen using current
  pen color
• Example
• clearscreen(0) //screen white
• setcolor(1) //pen black
• moveto(20,20) //move cursor to (20,20)
• lineto(100,100)

8

• void rectangle(int x1, int y1, int x2, int y2)
• Draw a rectangle with upper left corner at
  position (x1, y1) and lower right corner (x2, y2)

9

• void circle(int x, int y, int r)
• Draw a circle with center at (x,y) and radius r

10

• void writedraw(type value, int x, int y)
• - where type can be int, char or a text (string)
• - display the value at position (x,y) on screen
• Example
• ...
• writedraw(3, 10, 10)
• writedraw(Stop right here!!, 100, 100)
• writedraw(a, 25, 25)

11

• void getmouse(int x, int y)
• Get into x and y the current mouse coordinates at
  the instant when the mouse is clicked
• Example
• int x, y
• getmouse(x,y)
• if (x lt 100 y lt 100)
• writedraw( Bingo! You clicked in the upper
  left corner!, 10, 10)
• else
• writedraw(soryytry again, 10, 10)

12
Click here to exit
Stop!