375909 - Incorrect coordinate computation in Canvas

Status: RESOLVED FIXED

(Core :: Graphics: Canvas2D, defect)

Description

[Jeremy Lea]

User-Agent:       Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a4pre) Gecko/20070329 Minefield/3.0a4pre
Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9a4pre) Gecko/20070329 Minefield/3.0a4pre

In nsCanvasRenderingContext2d there's an incorrect calculation of some coordinates (has appunits * appunits, not appunits/appunits).  It might be responsible for a few canvas bugs, but I've not tested...  I'll attach a patch now.

Reproducible: Always

Comment 1

[Jeremy Lea]

Attachment: Simple fix.

This should be right.  Uses coordinate transform functions rather than a simple one...

Comment 2

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Comment on attachment 260074 [details] [diff] [review]
Simple fix.

p2a should be renamed. A2B typically means "a factor which you multiply by A to get B". I would just call it appUnitsPerDevPixel :-).

Comment 3

[Robert O'Callahan (:roc) (email my personal email if necessary)]

If you attach a final patch, someone can check it in. Me if necessary.

Comment 4

[Jeremy Lea]

Attachment: With requested changes

OK, as requested p2a changed to appUnitsPerDevPixel.  Also split onto two lines since the line was getting long...

Comment 5

[Sylvain Pasche]

roc: the whiteboard flag should rather be [checkin needed] instead of [needs checkin], if I refer to http://wiki.mozilla.org/Bugzilla:MozillaFlagsAndSuch and what is done for the other bugs.

Comment 6

[Nickolay_Ponomarev]

Checked in:
mozilla/content/canvas/src/nsCanvasRenderingContext2D.cpp  1.83

Comment 7

[Jeremy Lea]

Thanks for the commit.  I don't know how to test this bug, since I found it the old fashioned way - by looking at the source code ;-).  It's possible that bug 326591 is a symptom, but that bug has no testcase either...