Pad++ Programmer's Guide

REGION MANAGEMENT AND SCREEN UPDATING

Only the portions of the screen that change get rendered. This makes many operations much faster. Specifically, modifying or dragging individual items, or panning the view is much more efficient. Notably, zooming is no faster - and still requires re-rendering the entire view.

This screen updating is controlled by region management which uses the concepts of damage and repair. When an item changes, the region within its bounding box is automatically damaged. The act of damaging a region adds it to a list that gets scheduled for repair. The repair doesn't happen until either the system is idle, or the update command is called. Many commands implicitly damage items, but damage can be triggered manually with the damage command.

Pad++ Programmer's Guide - 20 JUN 1997

Copyright Computer Science Department, The University of New Mexico

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