[PATCH v2 3/7] gdi32: Properly handle exact fits in GetTextExtentExPoint.

[Sven Baars]

On 12-11-2020 10:25, Huw Davies wrote:
> On Mon, Nov 09, 2020 at 03:07:15PM +0100, Sven Baars wrote:
>> Signed-off-by: Sven Baars <sbaars at codeweavers.com>
>> ---
>>  dlls/gdi32/font.c | 12 +++++++++++-
>>  1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/dlls/gdi32/font.c b/dlls/gdi32/font.c
>> index 6ad03df176b..4a6ca1916ac 100644
>> --- a/dlls/gdi32/font.c
>> +++ b/dlls/gdi32/font.c
>> @@ -4897,6 +4897,11 @@ BOOL WINAPI GetTextExtentExPointI( HDC hdc, const WORD *indices, INT count, INT
>>                  unsigned int dx = abs( INTERNAL_XDSTOWS( dc, pos[i] )) + (i + 1) * dc->charExtra;
>>                  if (nfit && dx > (unsigned int)max_ext) break;
>>                  if (dxs) dxs[i] = dx;
>> +                if (nfit && dx == (unsigned int)max_ext)
>> +                {
>> +                    i++;
>> +                    break;
>> +                }
>>              }
>>              if (nfit) *nfit = i;
>>          }
>> @@ -5033,7 +5038,12 @@ BOOL WINAPI GetTextExtentExPointW( HDC hdc, LPCWSTR str, INT count, INT max_ext,
>>              {
>>                  unsigned int dx = abs( INTERNAL_XDSTOWS( dc, pos[i] )) + (i + 1) * dc->charExtra;
>>                  if (nfit && dx > (unsigned int)max_ext) break;
>> -		if (dxs) dxs[i] = dx;
>> +                if (dxs) dxs[i] = dx;
>> +                if (nfit && dx == (unsigned int)max_ext)
>> +                {
>> +                    i++;
>> +                    break;
>> +                }
>>              }
>>              if (nfit) *nfit = i;
>>          }
> 
> These will need tests.  Also, combining the new if()s with the test
> two lines above would most likely make things simpler.
> 
> Huw.
> 
Hi Huw,

The tests are already present in

https://source.winehq.org/git/wine.git/blob/HEAD:/dlls/gdi32/tests/font.c#l1435

and I further extended these in patch 2. They currently wrongfully
succeed because the characters that are supposed to have width 0 do not
have width 0. They would start failing after patch 5 without this patch.
If this is not sufficient, are there any characters with width 0 that
are currently reported correctly to have width 0 by wine that can be
used for this test?

As for the if statement, it would look like this:

                 if (dxs) dxs[i] = dx;
                 if (nfit && dx >= (unsigned int)max_ext)
                 {
                     if (dx == (unsigned int)max_ext)
                         i++;
                     break;
                 }

however, that would mean that dx is also set in the > case, which is not
the case on Windows. I could add a test for this, but that will
currently fail on wine because of the earlier call to
get_char_positions(), so it will not detect a wrong implementation of
this if statement.

Cheers,
Sven