CSC 160 Computer Programming for Non-Majors Images: Another Form of Symbolic Data Prof. Adam M. Wittenstein

Data Type: Image (Shapes or Pictures) A third type of symbolic data. Fun to process images. Images are values like numbers, symbols, or strings – they can be used inside expressions. Usually given names, since the same image can be used with several different functions. Like symbols, images don't have any specific meaning, but we tend to connect them easily with the intended information.

Inserting Images To insert an image into a program, move the blinking caret to the place in your program where you want the image, and select the Insert Image item from the Special menu. DrScheme will then provide a dialog for selecting an image file. After you have selected a file, the image will be inserted at the blinking caret.

Another teachpack: “world.ss” This teachpack has some functions to create shapes. --Wherever a function takes in a "mode", you may use either the string “solid” or the symbol “outline”. --Wherever a function takes in an “image-color”, enter the color as a string. For example, “blue” or “Blue” or “red”. rectangle : num num mode image-color -> image circle : num mode image-color -> image triangle : num mode image-color -> image (NOTE: The triangle function is only for equilateral triangles.)

Other “world.ss” functions image-width : image -> number --to obtain an image's width in pixels image-height : image -> number --to obtain an image's height in pixels overlay : image image image... -> image --to add the pixels of the second image onto the first image, lining up the pinholes (centers)

Next time… The “tiles.ss” teachpack --Download it from the website: --In DrScheme, Language->Add Teachpack-> Right-click on “tiles”. This extracts another “tiles” file. Install this file. Writing our own image functions