Re: Question about display engine

[Ergus <spacibba@aol.com>]

On Mon, Oct 14, 2019 at 12:01:46AM +0300, Eli Zaretskii wrote:
>> Date: Sun, 13 Oct 2019 21:38:36 +0200
>> From: Ergus <spacibba@aol.com>
>> Cc: rudalics@gmx.at, emacs-devel@gnu.org
>>
>> (gdb) p it->sp
>> $1 = 0
>> (gdb) p it->method
>> $2 = GET_FROM_C_STRING
>
>If we are producing glyphs from a C string, then faces should not be
>used at all, because C strings cannot have faces.
>
>So you should to condition the call to face_at_pos on something like
>
>  it->s == NULL
>
Hi:

This have fixed the issue, I understand now what was happening. Should I
merge into master now? maybe you should close the related issues then
right?.


>because there can not be any face on any position of a C string.
>
>> (gdb) pgrowx it->glyph_row
>> TEXT: 85 glyphs
>>   0    0: CHAR[-] str=0x4fab1a8f[0] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   1    1: CHAR[U] str=0x4fab18f0[1] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   2    2: CHAR[U] str=0x4fab18f0[1] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   3    3: CHAR[U] str=0x4fab18f0[1] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   4    4: CHAR[:] str=0xf2787f0[0] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   5    5: CHAR[%] str=0x4faaee54[1] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   6    6: CHAR[%] str=0x4faaede4[1] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   7    7: CHAR[-] str=0x4fab1721[1] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   8    8: CHAR[-] str=0x4fa9d9a8[0] blev=0,btyp=L w=1 a+d=0+0 face=1
>>   9    9: CHAR[F] str=0x4fa9d9a8[2] blev=0,btyp=L w=1 a+d=0+0 face=1
>>  10   10: CHAR[1] str=0x4fa9d9a8[2] blev=0,btyp=L w=1 a+d=0+0 face=1
>
>This is a mode line, so it figures out: extend_face_to_end_of_line was
>called when the iterator was processing the final blanks of the mode
>line, see display_mode_line.
>