585163 - [d2d] TEST-UNEXPECTED-FAIL | svg/text-scale-01.svg

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Jeff Muizelaar [:jrmuizel]]

Looks like the geometry we send to d2d is different in the cases where we get different pixels. I'm not yet sure why.

Comment 1

[Jeff Muizelaar [:jrmuizel]]

The values that get passed into D2D are different:

font_matrix	{xx=100.00000149011612 ...}
ctm	{xx=1.0000000474974513 ...}	

vs.

font_matrix	{xx=100.00000000000000  ...}
ctm	{xx=1.0000000000000000 ...}

Not exactly sure why.

Comment 2

[Jeff Muizelaar [:jrmuizel]]

The inaccurate values for font_matrix come from converting 6/60 into a float and then treating it as a double. I see two possible fixes: we could add a AppUnitsToDoubleCSSPixels or AppUnitsToFloat64CSSPixels that would do the division at higher precision or we could switch the test to use sizes that have an exact representation in floating point instead of using .1 which does not.

Comment 3

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

Or we could do something like gfxContext::NudgeCurrentMatrixToIntegers

Comment 4

[Jeff Muizelaar [:jrmuizel]]

Attachment: Fix the test case to use numbers that are exactly representable in floating point

Comment 5

[Ali Juma [:ajuma]]

This landed in August 2010:

http://hg.mozilla.org/mozilla-central/rev/237c0f3abaf6