/Demo/turtle/demohelp.txt

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 4
 5      xturtleDemo - Help
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 7  ----------------------------------------------
 8
 9  This document has two sections:
10
11  (1) How to use the demo viewer
12  (2) How to add your own demos to the demo repository
13
14
15  (1) How to use the demo viewer.
16
17  Select a demoscript from the example menu.
18  The (syntax coloured) source code appears in the left
19  source code window. IT CANNOT BE EDITED, but ONLY VIEWED!
20
21  - Press START button to start the demo.
22  - Stop execution by pressing the STOP button.
23  - Clear screen by pressing the CLEAR button.
24  - Restart by pressing the START button again.
25
26  SPECIAL demos are those which run EVENTDRIVEN.
27  (For example clock.py - or oldTurtleDemo.py which
28  in the end expects a mouse click.):
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30      Press START button to start the demo.
31
32      - Until the EVENTLOOP is entered everything works
33      as in an ordinary demo script.
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35      - When the EVENTLOOP is entered, you control the
36      application by using the mouse and/or keys (or it's
37      controlled by some timer events)
38      To stop it you can and must press the STOP button.
39
40      While the EVENTLOOP is running, the examples menu is disabled.
41
42      - Only after having pressed the STOP button, you may
43      restart it or choose another example script.
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45   * * * * * * * *
46   In some rare situations there may occur interferences/conflicts
47   between events concerning the demo script and those concerning the
48   demo-viewer. (They run in the same process.) Strange behaviour may be
49   the consequence and in the worst case you must close and restart the
50   viewer.
51   * * * * * * * *
52
53
54   (2) How to add your own demos to the demo repository
55
56   - scriptname: must begin with tdemo_ ,
57     so it must have the form tdemo_<your-script-name>.py
58
59   - place: same directory as xturtleDemo.py or some
60     subdirectory, the name of which must also begin with
61     tdemo_.....
62
63   - requirements on source code:
64       code must contain a main() function which will
65       be executed by the viewer (see provided example scripts)
66       main() may return a string which will be displayed
67       in the Label below the source code window (when execution
68       has finished.) 
69
70       !! For programs, which are EVENT DRIVEN, main must return
71       !! the string "EVENTLOOP". This informs the viewer, that the
72       !! script is still running and must be stopped by the user!
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