Show a basic storage type to handle a simple RGB raster graphics image,
and some primitive associated functions.

If possible provide a function to allocate an uninitialised image,
given its width and height, and provide 3 additional functions:

   one to fill an image with a plain RGB color,
   one to set a given pixel with a color,
   one to get the color of a pixel.


(If there are specificities about the storage or the allocation, explain those.)

These functions are used as a base for the articles in the category raster graphics operations, 
and a basic output function to check the results
is available in the article write ppm file.




graphsize 30,30
call fill(rgb(255,0,0))
call setpixel(10,10,rgb(0,255,255))
print "pixel 10,10 is " + pixel(10,10)
print "pixel 20,20 is " + pixel(20,10)
 
imgsave "BASIC256_bitmap.png"
end
 
subroutine fill(c)
color c
rect 0,0,graphwidth, graphheight
end subroutine
 
subroutine setpixel(x,y,c)
color c
plot x,y
end subroutine