bugGNUstep - Bugs: bug #47109, Cairo/Windows: Unexpected DPI may...

 
 

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bug #47109: Cairo/Windows: Unexpected DPI may cause font rendering issues

Submitted by:  Ivan Vučica <ivucica>
Submitted on:  Wed Feb 10 15:49:39 2016  
 
Category: BackendSeverity: 2 - Minor
Item Group: BugStatus: None
Privacy: PublicAssigned to: None
Open/Closed: Open

Wed Feb 10 16:40:43 2016, comment #1:

If someone wants to continue looking into fixing this, I've spent a few minutes trying to track this down completely blindly (i.e. I didn't actually run any code).

The number 16 in '16 characters until whitespace appears' seems to come from:
http://svn.gna.org/svn/gnustep/libs/gui/trunk/Source/NSLayoutManager.m
method -drawGlyphsForGlyphRange:atPoint: line "#define GBUF_SIZE 16 /* TODO: tweak */".

Combined with Riccardo's mention that this may be related to DPI, and following the call to C function GSShowGlyphsWithAdvances() from
http://svn.gna.org/svn/gnustep/libs/gui/trunk/Source/NSGraphicsContext.m
I'd say the fixer will want to look at
http://svn.gna.org/svn/gnustep/libs/back/trunk/Source/cairo/CairoGState.m
method -GSShowGlyphsWithAdvances:::, and
http://svn.gna.org/svn/gnustep/libs/back/trunk/Source/cairo/CairoFontInfo.m
method -drawGlyphs:length:on:.

Ivan Vučica <ivucica>
Project Member
Wed Feb 10 15:49:39 2016, original submission:

From James Carthew:
"Attached is a picture showing the rendering error. This was generated using the pre-built windows files from the GNUstep website. "

Commentary from Riccardo:
"Hi,

I am pretty sure you have a resolution problem, I have seen this several times on windows (and also on X11 on one FreeBSD workstation).

Please set your Windows to "100%" and do not enlarge text and icons.

For some reason, we enlarge the controls, but then use a small font to draw the text. It would be best of course to "scale" up also the the font, or, at least to ignore the resize and keep everything pixels-sized to GNUstep, but currently it is hybrid.

Riccardo"

Commentary from me:
"Odd whitespace in the middle of a word is also a bug. It seems to happen after exactly 16 glyphs."

Ivan Vučica <ivucica>
Project Member

 

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Items that depend on this one: None found

 

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    Follows 1 latest change.

    Date Changed By Updated Field Previous Value => Replaced By
    Wed Feb 10 15:49:39 2016ivucicaAttached File-=>Added 47c19cd2-0e50-400c-982f-a8a52df8c17b.png, #36298

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