397288 - Missing text without fallback from U+0000-00FF fast path when first font-family doesn't have necessary glyphs

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Karl Tomlinson (:karlt)]

If the first specified font available on the system does not support a character then gfxPangoFontGroup::CreateGlyphRunsFast draws nothing for that glyph.
It should instead fallback to CreateGlyphRunsItemizing.

Comment 1

[Karl Tomlinson (:karlt)]

Attachment: testcase

This should show two y characters and one psi.

Increase the font-size and CreateGlyphRunsItemizing is used and so all characters will be visible.  Decrease the font-size and CreateGlyphRunsFast is used and only the psi is visible.

(If Standard Symbols L is not available, and monotype's truetype Symbol is used rather than adobe's type1 Symbol, then the y's will be shown as psi's.  This seems to be a problem with monotype's font.  According to ftdump the first charmap has platform_id is TT_PLATFORM_MACINTOSH and encoding is TT_MAC_ID_ROMAN, but the font appears to have substituted Greek characters for Latin.  The second charmap has platform TT_PLATFORM_MICROSOFT and encoding TT_MS_ID_SYMBOL_CS, which may work much better or at least just not find any matches.)

Comment 2

[Karl Tomlinson (:karlt)]

Attachment: use CreateGlyphRunsItemizing when CreateGlyphRunsFast fails

This applies on top of the patch in bug 362682.

Comment 3

[Karl Tomlinson (:karlt)]

Attachment: reftest

Comment 4

[Karl Tomlinson (:karlt)]

Attachment: corrected indentation

(The scaled font assertion is fires once when creation fails rather than each time it is used.)

Comment 5

[Karl Tomlinson (:karlt)]

Comment on attachment 284235 [details] [diff] [review]
reftest

This reftest is not the best, as it already uses the itemizing path.

Comment 6

[Karl Tomlinson (:karlt)]

Attachment: reftest v2

This version changes font-family to force separate textruns.

Comment 7

[Stuart Parmenter]

Comment on attachment 284244 [details] [diff] [review]
reftest v2

does this test pass on all platforms?

Comment 8

[Karl Tomlinson (:karlt)]

The testcase renders appropriately on Mac.

However, on Windows the body text is treated as characters in the TT_MS_ID_SYMBOL_CS charset, including the numeric character references, which should be treated as ISO 10646.  (http://www.w3.org/TR/html4/charset.html#h-5.3.1).

Even the treatment of the y as mapping to TT_MS_ID_SYMBOL_CS, seems inconsistent with the resolution of bug 33127, or the effort to distinguish quirks mode in bug 195038.

Comment 9

[Karl Tomlinson (:karlt)]

Attachment: gentler reftest

To avoid debate over how a utf-8 y should be interpreted in text with Symbol font-family, I've changed the test to only use numeric character references.  This fails on Windows (as marked) but at least there is no debate over the ideal behavior.

Comment 10

[Stuart Parmenter]

this has nothing to do with the Symbol font family.  The 'Symbol' font on Windows only contains a symbol character map and thus is not a Unicode font.  Our handling of symbol fonts (symbol, wingdings, etc) is correct on Windows.

Comment 11

[Karl Tomlinson (:karlt)]

(In reply to comment #8)
> However, on Windows the body text is treated as characters in the
> TT_MS_ID_SYMBOL_CS charset, including the numeric character references, which
> should be treated as ISO 10646. 

Correction:
on Windows, the TT_MAC_ID_ROMAN charmap is used not TT_MS_ID_SYMBOL_CS.

Comment 12

[Karl Tomlinson (:karlt)]

Comment on attachment 284400 [details] [diff] [review]
gentler reftest

The test is no good on Windows because Windows has Monotype's Symbol font and uses the encoding corresponding to TT_PLATFORM_MACINTOSH, which is broken.

Even if numeric character references are converted from Unicode to TT_MAC_ID_ROMAN, then that (encoding for) Symbol will show a psi for the &#x79.

Comment 13

[Karl Tomlinson (:karlt)]

checked in:
1.56        mozilla/gfx/thebes/public/gfxPangoFonts.h
1.109       mozilla/gfx/thebes/src/gfxPangoFonts.cpp

Don't know what fonts (if there are any that) can be used in the test case on Windows and Mac.