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.




|img1 img2|
"a depth24 RGB image"
img1 := Image width:100 height:200 depth:24.
img1 fillRectangle:(0@0 corner:100@100) with:Color red.
img1 fillRectangle:(0@100 corner:100@100) with:(Color rgbValue: 16rFF00FF).
img1 colorAt:(10 @ 10) put:(Color green).
img1 saveOn:'sampleFile.png'.
 
img1 displayOn:Transcript window graphicsContext.
Transcript showCR:(img1 colorAt:(100 @ 10) ).
 
"a depth8 palette image"
img2 := Image width:100 height:200 depth:8.
img2 colorMap:{ Color black. Color red . Color green }. 
img2 fillRectangle:(0@0 corner:100@100) with:Color red.
img2 fillRectangle:(0@100 corner:100@100) with: 16r02.
img2 colorAt:(10 @ 10) put:(Color green).
img2 saveOn:'sampleFile.gif'.
 
img2 displayOn:Transcript window graphicsContext.
Transcript showCR:(img2 colorAt:(100 @ 10) ).
 