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Bug 370313

Summary: [Canvas] Tweak canvas performance in IE7/8
Product: [RT] RAP Reporter: Tim Buschtoens <tbuschto>
Component: RWTAssignee: Project Inbox <rap-inbox>
Status: CLOSED WONTFIX QA Contact:
Severity: enhancement    
Priority: P3    
Version: 1.5   
Target Milestone: ---   
Hardware: All   
OS: All   
Whiteboard:
Bug Depends on:    
Bug Blocks: 361615    

Description Tim Buschtoens CLA 2012-02-01 05:56:14 EST 
Canvas in IE7/8 is using VML to draw, which gets very slow when the number of shapes increases. To improve performance, the follwing could be done:

* Remove shapes that are completely obscured. To keep this simple, only do this when the entire canvas is painted over with a rectangle. More complex versions are probably not worth the effort.

* Try merging shapes that have same properties. Doable at least with shapes that arent filled and could decrease the number of shapes considerably in some cases.

* Pool a limited number of shape objects outside of DOM. This might or might not work.

Fixing this would also be useful for client-scripted painting.
Comment 1 Tim Buschtoens CLA 2012-02-01 08:33:06 EST 
An additional or alternative solution would be to support flashcanvas http://flashcanvas.net. It has a MIT license.

Also, the text-layer of canvas should not be created unless its needed. For most browser its also not really necessary anymore.
Comment 2 Ivan Furnadjiev CLA 2014-08-07 04:57:51 EDT 
The IE7/8 support is discontinued in RAP 3.0. Close as WONTFIX.