Problem in GlyphIndexList.Replace()

[samhocevar]

At line 114 in GlyphIndexList.cs, _tmpGlypIndexBackup may be empty if the whole string was replaced with a ligature, so the code crashes there when accessing _tmpGlypIndexBackup[0].

I might be able to fix this later, but I do not really understand GlyphIndexToUserChar yet. Maybe you know what’s going on and can fix it more quickly than me :-)

[prepare]

Thank you,
fixed, see => 0735269

---

Disable Ligature and Enable Ligature, Palatino Font

pic 1: f-i Disable Ligature, 2 glyph indices (f and i)

---

pic 2: f-i Enable Ligature, 2 glyph indices are replaced with 1 f-i glyph index

[prepare]

@samhocevar

when we do glyph substitution,
user input chars may not be mapped with output rendered glyph index 1:1. (see pic2 above)

so GlyphIndexToUserChar and related structures
are needed to store that mapping when developing a 'textbox' control.

[samhocevar]

It looks like there is still a problem; see:

1. List is emptied

        _tmpGlypIndexBackup.Clear();
   

2. removeLen elements are added starting from 0:

        int endAt = index + removeLen;
        for (int i = index; i < endAt; ++i)
        {
            _tmpGlypIndexBackup.Add(_mapGlyphIndexToUserChar[i]);
        }
   

3. removeLen elements are removed starting from index:

        _tmpGlypIndexBackup.RemoveRange(index, removeLen);
   

[prepare]

@samhocevar,

removeLen must >=1 right ?

if so then _tmpGlypIndexBackup.Count must > 0

since collection count > 0
we pick the 1st glyph index before call RemoveRange()

_tmpGlypIndexBackup[0] should not crash.

from 0735269

[prepare]

@samhocevar ,

I see !

:)

see=> 776257e

[prepare]

pic 1: Palatino Linotype font

[samhocevar]

OK! But then, is _tmpGlypIndexBackup really needed? We only take the first element, then it is emptied again 🤔

[prepare]

actually, not need.
I use it during debug.

see =>b981263

[prepare]

user_char-to-glyph_index , and glyph_index-to-user_char

more information

pic 1: Palatino Linotype, Script=Latin, red lines are abstract