Bug 88670

Summary:

StyledText scrolling spends most of its time setting top caret

Product:

[Eclipse Project] Platform

Reporter:

Tod Creasey <Tod_Creasey>

Component:

SWT

Assignee:

Felipe Heidrich <eclipse.felipe>

Status:

RESOLVED INVALID

QA Contact:

Severity:

normal

Priority:

CC:

steve_northover

Version:

3.1

Keywords:

performance

Target Milestone:

---

Hardware:

OS:

Windows XP

Whiteboard:

Attachments:

Description	Flags
Scrolling trace	none

Description Tod Creasey

2005-03-21 14:51:22 EST

20050315

When you scroll a large scrolled text quite a bit of time is spent calculating the
top index.

STEPS
1) Open StyledText.java
2) Starting at the top of the editor select the scroll bar and scroll to the bottom

Optimize It trace to follow

Comment 1 Tod Creasey

2005-03-21 14:52:10 EST

Created attachment 19062 [details]
Scrolling trace

Comment 2 Felipe Heidrich

2005-03-21 17:16:25 EST

When the top index changes the StyledText needs update the horizontal 
scrollbar. In order to do that it needs to know the width of all visible 
lines. The new lines at bottom (supposing you are scrolling from the top to 
bottom) are created and initialized during this process. The creation of these 
new lines is what is taking time.

Even if you comment out all the code that is setting the scrollbar it won't 
improve the performance, it will only change the place where the time is 
spent. Instead of spending time creating lines during the scrolling the 
process will spend time creating lines during the paint.

NOTE: StyledText caches the visible lines. The time used to created & 
initialized a line when it becomes visible is necessary.
NOTE: We already put a lot of effort to optimize the time to create and 
initialize lines.

Comment 3 Veronika Irvine

2005-03-22 13:07:18 EST

Felipe, if there is nothing more that can be optimized, maybe this bug should 
be closed.  Perhaps take another look just to be sure first.

Comment 4 Felipe Heidrich

2005-04-07 16:18:45 EDT

Nothing I can in here. Closing.