Image-manipulation functions defined in tiles-world

Many of the functions in tiles-world are documented in DrScheme's help desk, so I won't repeat their full descriptions here: type either "image.ss" or "world.ss" into the search field of DrScheme's help desk. The ones you're most likely to use from "image.ss" are

• rectangle : int int mode image-color -> image
• circle : int mode image-color -> image
• ellipse : int int mode image-color -> image
• triangle : int mode image-color -> image
• line : int int image-color -> image
• add-line : image int int int int image-color -> image
• text : string size image-color -> image
• overlay : image image image ... -> image
• overlay/xy : image int int image -> image
• image-inside? : image image -> boolean
• find-image : image image -> posn
• image-width : image -> number
• image-height : image -> number
• pinhole-x : image -> number
• pinhole-y : image -> number
• move-pinhole : image number number -> image
• image->color-list : image -> list-of-color
• color-list->image : list-of-color int int int int -> image
• make-color : int int int -> color
• color? : anything -> boolean
• color-red : color -> int
• color-green : color -> int
• color-blue : color -> int

The functions from "world.ss" are

• big-bang : Number Number Number World -> true
• on-tick-event : (World -> World) -> true
• on-key-event : (KeyEvent World -> World) -> true
• end-of-time : -> World
• nw:rectangle : Number Number Mode Color -> Image
  (just like rectangle but with the pinhole at the top left rather than in the center)
• empty-scene : Number Number -> Scene
• place-image : Image Number Number Scene -> Scene
• run-movie : (Listof Image) -> true

In addition, tiles-world provides several other useful functions:

image-above : image image -> image

produces an image with the first image "above" (i.e. closer to the top of the screen) the second. The pinholes are lined up in the x dimension; the pinhole of the result is halfway between the pinholes of the two images.

image-beside : image image -> image

produces an image with the first image to the left of the second. The pinholes are lined up in the y dimension; the pinhole of the result is halfway between the pinholes of the two images.

reflect-vert : image -> image

Reflects the given image top-to-bottom.

reflect-horiz : image -> image

Reflects the given image left-to-right and bottom.

reflect-main-diag : image -> image

Reflects the given image across the diagonal from top-left to bottom-right; in other words, it swaps top-right with bottom-left.

reflect-other-diag : image -> image

Reflects the given image across the diagonal from top-right to bottom-left; in other words, it swaps top-left with bottom-right.

rotate-cw : image -> image

Rotates the given image 90 degrees clockwise around its pinhole.

rotate-ccw : image -> image

Rotates the given image 90 degrees counterclockwise around its pinhole.

rotate-180 : image -> image

Rotates the given image 180 degrees around its pinhole.

show-pinhole : image -> image

Adds a small black dot to the image so you can see where the pinhole is (useful in debugging).

on-redraw-event : (World -> Image) -> true

(on-redraw-event draw-world) installs the draw-world function to be called on the current world every time the screen needs refreshing; the result will appear in the animation window in place of whatever was there before.