[425] in java-interest
Re: DisplayItemWindow
daemon@ATHENA.MIT.EDU (Jonathan Payne)
Wed Jun 21 12:56:48 1995
Date: Wed, 21 Jun 1995 09:30:55 -0700
From: jpayne@starwave.com (Jonathan Payne)
To: ptyma@top.cis.syr.edu
Cc: java-interest@java.sun.com
In-Reply-To: <9506210310.AA00628@java.sun.com> (message from Paul Tyma on Tue, 20 Jun 95 23:09:43 EDT)
Here's the story with DisplayItem's and Windows.
In order to use DisplayItems, you must use a DisplayItemWindow. A
DisplayItem is just a small object with a location and size, that
responds to input events from the mouse and keyboard. It doesn't have
a native window associated with it at all. They were meant to be
incredibly cheap, so that each little chunk of text of an html
document could be one. You must use a DisplayItemWindow to display
DisplayItems, since it's smart enough to forward mouse and keyboard
events to the right child, taking into consideration scrolling, etc.
Scrolling is accomplished by changing the origin of the
DisplayItemWindow, as far as the DisplayItem's are concerned, that is.
In other words, when you scroll 10 pixels, a single variable called
ScrollY or something in DisplayItemWindow is changed, as opposed to
all the DisplayItem's having their y location changed.
This is one of the reasons that real, native Windows don't do so well
inside DisplayItemWindows. In fact, we went through hell to get
native widgets to scroll as nicely as our fake, DisplayItem widgets
already did effortlessly. But we only did that so that we could get
html forms to work nicely.
When you find bugs in the handling of native children inside Window
objects, don't be surprised. This was a toolkit-on-demand effort,
"great" new discoveries about the wonders of X and Motif were made
practically every day, etc. I personally wanted to kill myself.
Just kidding.
> Date: Tue, 20 Jun 95 23:09:43 EDT
> From: Paul Tyma <ptyma@top.cis.syr.edu>
> Organization: Syracuse University, Comp. Sci.
> Sender: owner-java-interest@java.sun.com
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> Anybody have any example code making a frame and popping
> up DisplayItems in it. I got the frame up, but its kinda
> stubborn after that.
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