571536 – Remove obsolete USE_DOUBLE_BUFFER=true in BufferedCanvas

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Bug 571536 - Remove obsolete USE_DOUBLE_BUFFER=true in BufferedCanvas

Summary: Remove obsolete USE_DOUBLE_BUFFER=true in BufferedCanvas

Status:	RESOLVED FIXED

Alias:	None

Product:	Platform
Classification:	Eclipse Project
Component:	Team (show other bugs)
Version:	4.18
Hardware:	PC Linux

Importance:	P3 normal (vote)
Target Milestone:	4.20 M1
Assignee:	Lars Vogel
QA Contact:

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Depends on:
Blocks:

Reported:	2021-02-26 06:37 EST by Lars Vogel
Modified:	2021-03-15 08:24 EDT (History)
CC List:	2 users (show)

See Also:	Gerrit Change Git Commit 571954

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Description Lars Vogel

2021-02-26 06:37:30 EST

Always true, so we can remove USE_DOUBLE_BUFFER=true in BufferedCanvas

Comment 1 Eclipse Genie

2021-02-26 06:39:56 EST

New Gerrit change created: https://git.eclipse.org/r/c/platform/eclipse.platform.team/+/176933

Comment 2 Lars Vogel

2021-02-26 06:40:16 EST

Nikita, the whole class org.eclipse.compare.internal.BufferedCanvas is really old. Do you know if this double-buffering is still useful for modern SWT applications or can we simply replace it with a regular Canvas?

Comment 3 Nikita Nemkin

2021-02-26 07:18:22 EST

(In reply to Lars Vogel from comment #2)
> Nikita, the whole class org.eclipse.compare.internal.BufferedCanvas is
> really old. Do you know if this double-buffering is still useful for modern
> SWT applications or can we simply replace it with a regular Canvas?

macOS and GTK will double-buffer automatically, Windows needs SWT.DOUBLE_BUFFERED widget style to be specified explicitly.

So, BufferedCanvas should be replaced with Canvas(parent, SWT.DOUBLE_BUFFERED | ...)

Comment 4 Lars Vogel

2021-02-26 07:20:35 EST

Thanks Nikita.

Would it be possible to activate double buffering in Windows by default?

Comment 5 Nikita Nemkin

2021-02-26 07:37:05 EST

(In reply to Lars Vogel from comment #4)
> Thanks Nikita.
> 
> Would it be possible to activate double buffering in Windows by default?

This will reduce painting performance for widgets that don't need it, for example, if all a widget does is paint an image, it doesn't need buffering.

Also, advanced graphics on Windows (GDI+) are implicitly buffered. Forcing SWT.DOUBLE_BUFFERED will be even more wasteful in this case.

Comment 6 Lars Vogel

2021-02-26 08:45:26 EST

Thanks for the clarification, Nikita. Sounds like we should not change the win default.

Comment 7 Eclipse Genie

2021-03-10 10:35:38 EST

Gerrit change https://git.eclipse.org/r/c/platform/eclipse.platform.team/+/176933 was merged to [master].
Commit: http://git.eclipse.org/c/platform/eclipse.platform.team.git/commit/?id=cee65979a07f1df261572ed31930e458a4140372

Comment 8 Lars Vogel

2021-03-15 08:24:35 EDT

Thanks Nikita, I opened Bug 571954 for the complete replacement.