;;; -*- Mode:gate; Fonts:(CPTFONT); Base:10 -*-

=Node: Nodes with Functions

=Function: (load "gateway:source;function-demo")

=Text:

The following two nodes have functions associated with them using
the =Function: facility.  Any time one uses this facility, it is
important to be explicit in naming the package and checking if
the function is bound, if any required subsystems are loaded.

In order to run these demos, you must first load
"gateway:source;function-demo".  Conveniently, the function of
THIS node is to load that file, so you should click on Execute
Function in the Miscellaneous section of the menu, or simply hit
Hyper-Super-X.  Of course, you only need to do that once for this
session.  The graphics can be run as many times as you want. 
 
The first node just draws random circles on the screen, using a
variant of the old DRF code.

The second finds an illustration made with an experimental paint
facility (sorry, not available in release 3.0) and displays it on
the main Gateway screen.

=Node: DRF Example

=Function: (zwei:DRF)
 
=Text:

To run DRF on this screen, click on Execute Function in the
Miscellaneous section of the menu, or simply hit Hyper-Super-X

The screen should get twenty random circles drawn on it.  The
code for DRF looks like:

(defun DRF (&optional
	    (number-of-circles 20)
	    (window zwei:display-pane-1))
  (let* ((w (send window :width))
	 (h (send window :height))
	 (a (fix (// (sqrt (* w h)) 4)))
		;proportional to window area
	 )
    (loop for i from 0 to number-of-circles
	  do (send window
		   :draw-circle
		   (random w)
		   (random h)
		   (random a))
	  )))

=Node: Picture Example

=Function: (zwei:get-gi "gateway:data;amusing-demo-drawing.qfasl")

=Text:

When you run this function, the
illustration is found, either as
an already loaded image (see the
variable GD:*Gateway-images*) or
by searching in the gateway
directory for a file of the
appropriate type.  Once the bit
array is located, we BITBLT it to
the main gateway screen using the
TV:ALU-IOR operation.  This
overlays the image with the text
already printed, which can be
useful.  When full picture
handling capability is developed
in future, optional Gateway
modules, a wider range of
features will be considered.
Suggestions are always welcome.

=Node: Function Calling Demos

=Nodelist:

@ Nodes with Functions
@ DRF Example
@ Picture Example