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Volume 6A: Motif Programming Manual
book

Volume 6A: Motif Programming Manual

by David Brennan, Dan Heller, Paula Ferguson
September 1993
Intermediate to advanced content levelIntermediate to advanced
1014 pages
28h 26m
English
O'Reilly Media, Inc.
Content preview from Volume 6A: Motif Programming Manual
Let's take another look at the PG&E scenario that we discussed at the beginning of the chapter. As you recall, the
problem with that particular situation was that the database could retrieve 20% of the county (the work window), but
the graphic resolution was such that only 10% of it could be displayed at one time (the viewport). The fundamental
problem with the application−defined scrolling mode is that the work window cannot be a different size from the
viewport. However, we can work around this problem by complying with the restriction that the work window and
viewport are the same size, but we can use the enlarged pixmap idea from the source code to accomplish the task.
Each database query can be converted and rendered into a sufficiently large pixmap, which can then be rendered into
the work window as necessary. If the scrolling is small enough, another part of the pixmap can be rendered into the
work window, instead of performing a completely new database lookup.
10.5 Working With Keyboard Traversal in ScrolledWindows
As we described in Chapter 8, Manager Widgets, manager widgets play a significant role in handling keyboard
traversal mechanisms. As a manager, the ScrolledWindow supports keyboard traversal. However, one significant
difference is that the widgets in a ScrolledWindow may not be visible at all times. In Motif 1.1, the toolkit does not
provide a mechanism to allow keyboard traversal to widgets that are not visible. While it might be possible to
implement this feature, it ...
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Publisher Resources

ISBN: 9780596000431