67716 - X font should recognize font subsetted (plane'd) groups

Status: RESOLVED INVALID

(Core :: Layout, defect)

Description

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cns11643-1
cns11643-2
cns11643-3
cns11643-4
cns11643-5
...
nsFontMetricsGTK::FindGenericFont
3016 nsFontGTK*
3017 nsFontMetricsGTK::FindGenericFont(PRUnichar aChar)
3018 {
3019   if (mTriedAllGenerics) {
3020     return nsnull;
3021   }
3022   nsCAutoString prefix("font.name.");
3023   prefix.Append(*mGeneric);
3024   if (mLangGroup) {
3025     nsCAutoString pref = prefix;
3026     pref.Append(char('.'));
3027     const PRUnichar* langGroup = nsnull;
3028     mLangGroup->GetUnicode(&langGroup);
3029     pref.AppendWithConversion(langGroup);
3030     char* value = nsnull;
3031     gPref->CopyCharPref(pref.GetBuffer(), &value);
3032     nsCAutoString str;
3033     nsFontGTK* font;
3034     if (value) {
3035       str = value;
3036       nsMemory::Free(value);
3037       value = nsnull;
3038       font = TryNode(&str, aChar);
3039       if (font && font->SupportsChar(aChar)) {
3040         return font;
3041       }
not in primary plane so try all the other planes
3042     }
3043     value = nsnull;

Comment 1

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font vendors are subsetting or plane'ing the fonts; eg: cns11643-1, cns11643-2, 
...

The font display code needs to recognize and collect these subsets so characters 
in the other planes are displayed with the subset from this font instead of just 
a fallback from the total list of fonts.

For example: if a user specifies "sun-ming-cns11643-1" as the font for 
traditional Chinese and the document has chars that are in plane 2 they should 
use "sun-ming-cns11643-2" before looking for a fallback.

we probably want to have a list of the planes in a font that each nsFontNode can 
point to so chars in other planes can find the related font quickly.

Comment 2

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duplicate of
http://bugzilla.mozilla.org/show_bug.cgi?id=67732