Fundamentals Overview IDE (Editor) Syntax Variables Data Types Declarations Scope Special Values Operators

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Additional Capabilities Keyboard Sound Graphics Concepts Screen (text) Screen (drawing) Gaming (sprites) Event Trapping Errors System Calls

Screen - Drawing Commands
In an earlier tutorial section graphics concepts and the capabilities QBasic supports were covered. In this section we'll cover the actual commands which control screen content.

Here is a list of the QBasic graphics drawing functions.

Screen/Color Control	cls, color
Points	pset, preset, point
Pre-Set Shapes	circle, line
Random Shapes	draw, paint

Screen Modes
Screen modes were discussed in an earlier section. All of the examples on this page assume that the mode has been set to screen mode 12, although all of the commands will work in any graphics mode. Here's the command to set the screen mode.

    screen 12        ' set screen to 640x480, 16 colors
    cls              ' clears the screen

CLS and COLOR Functions
... in work

Points
... in work

Shapes - Lines, Boxes, Circles, Ellipses
... in work

DRAWing Custom Shapes
... in work

Filling Screen Areas - Paint
... in work

Drawing Commands Reference
The following functions are available to display graphics.

• circle - draws a circle, arc or ellipse

     
      circle (0,0),50,12    # center at 0,0, radius=50, color=12
      

• cls - clears the screen of all graphics and text

     
      cls           # clear entire screen
      cls 0         # clear entire screen
      cls 1         # clears viewport (screen if no viewport set)
      cls 2         # clears text viewport
      

• color - sets the screen display colors (foreground, background, border)

     
      color fg%, bg%, border%        # syntax
  
      Color values:
      0   Black       8   Gray
      1   Blue        9   Light Blue
      2   Green       10  Light Green
      3   Cyan        11  Light Cyan
      4   Red         12  Light Red
      5   Magenta     13  Light Magenta
      6   Brown       14  Yellow
      7   White       15  High-intensity white
      

• draw - draws point to oint composite lines

     
      draw "F60 L120 E60"
      

• line - draws a line or a (filled) box

     
      line (1,1)-(10,10),15,BF
      

• paint - fills closed areas on the screen with a color

     
      paint (5,5),15
      

• point - returns cursor coordinates or color of a specified pixel

     
      point (n%)                   # returns coordinates of cursor
                                     n%=0 - viewport x coordinates
                                     n%=1 - viewport y coordinates
                                     n%=2 - window x coordinates
                                     n%=3 - window x coordinates
        
      result% = point ((x%,y%)     # returns color of pixel at xy
      

• preset - set the color of a pixel

     
      preset(5,20),15     # reverses the current fg/bg
      

• pset - set the color of a pixel

     
      pset (5,20),15      # uses current fg/bg
      

If you have any suggestions or correction, please let me know.