9 The graphmath Library

The graphmath library defines patterns for making graphical computations: point, rectangle, matrix, region, etc. Each of these patterns defines several operations.

• point is used for making calculatiuons on 2D positions.

• rectangle is used for making calculations with 2D rectangles

• matrix is used for making calculations with coordinat system transformations.

• region is used for making calculations with 2D regions (i.e. areas in 2D, bounded by a polygon.) Please note that this pattern is not implemented yet.

9.1 Using the graphmath Library

Remember that in order to utilize this extension to Lidskjalv, the fragment graphmath must be included as follows:

ORIGIN '~beta/guienv/guienv'; INCLUDE '~beta/guienv/graphmath' --- program: descriptor --- guienv(# p1, p2: @point; ... do ... p1 -> p2.inset -> ...; ... #)

9.2 Examples of Use of the graphmath Fragment

This example gives an example of how to use the containsPoint operation of a rectangle.

Program 8: containspoint.bet

ORIGIN '~beta/guienv/guienv'; (* This demo gives an example of how to use the containsPoint * operation of a rectangle. *) --- program: descriptor --- guienv (# theWindow: @window (# hitZone: @rectangle; open:: (# do 'Graphmath Demo' -> title; (40,40) -> position; (300,300) -> size; ((0,0), (30,30)) -> hitZone #); eventHandler:: (# onAboutToClose:: (# do terminate #); onMouseDown:: (# do (if localPosition -> hitZone.containsPoint then 'Mouse down in Hit Zone.' -> screen.putline if) #) #) #) do theWindow.open #)