VISIO::CANVAS
(int grid, int xpos, int ypos, int xsize, int ysize)
Description: Creates a
drawing canvas . The canvas is created on grid 'grid', it has
coordinates 'xpos' and 'ypos', and the width is determined by 'xsize'
and the height by 'ysize'. The actual amount of pixels in x-direction
and y-direction may vary but can be retrieved using the visio::canvas_width and the visio::canvas_height
commands. The coordinates (0,0) refer to the uppermost left corner of
the canvas. Furthermore the canvas has by default a white background
color. This can be changed by the command visio::canvas_bg_color.
There can be more instances of a canvas on one window with a maximum of
256. The ID of the created canvas is returned to the BASIC program.
Example: canvas
= VISIO::CANVAS (grid, 10, 10, 80, 80)