From: Lyle Johnson <ljohnson@...>
Date: 2002-03-26T06:59:46+09:00
Subject: Re: FXDCWindow, event, screen...

> - I don't exactly understand the use of FXDC or FXDCWindow.
> I saw FXDCWindow.new(canvas) and FXDCWindow.new(canvas, event), but
> FXDCWindow.html (in fox-api's doc) doesn't explain the constructor's
> parameters.

The two-argument constructor for FXDCWindow (where you pass an FXEvent as
the second argument) clips any drawing commands against the event's "expose"
rectangle. So, for example, if you're handling a SEL_PAINT message (which is
generated by FOX when part or all of a window is "exposed") you'd want to
use this constructor. If you're doing some drawing outside of one of these
SEL_PAINT events, or for whatever other reasons you don't want the drawing
to be clipped against this rectangle, you can just use the one-argument
constructor for FXDCWindow and draw all over the thing.

> - I want to get screen parameters (width & height, colors, ...) from a
ruby
> program, but I don't know where to look at...

By "screen", do you mean the entire desktop? If so, you may be able to use
the FXRootWindow class to get some of this information, e.g.

    rootWindow = getApp().root
    puts "root window width = #{rootWindow.width}, height =
#{rootWindow.height}"

> - I'd like to understand how does a ".connect" run when an event happens.

This page:

    http://fxruby.sourceforge.net/doc/events.html

from the FXRuby documentation describes how to use connect() to connect
events generated by widgets to code blocks (or methods). For some more
background you might also check out the documentation on FOX's
target-message system:

    http://www.fox-toolkit.org/messages.html

Hope this helps,

Lyle