[reactos] 01/01: [WIN32SS][NTGDI] usWinAscent and usWinDescent must be treated as signed (#1670)

[Katayama Hirofumi MZ]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=641a0ea99be50975e7949…

commit 641a0ea99be50975e79498e48ae73b2edfc5c616
Author:     Katayama Hirofumi MZ <katayama.hirofumi.mz(a)gmail.com>
AuthorDate: Thu Jun 20 18:58:45 2019 +0900
Commit:     GitHub <noreply(a)github.com>
CommitDate: Thu Jun 20 18:58:45 2019 +0900

    [WIN32SS][NTGDI] usWinAscent and usWinDescent must be treated as signed (#1670)
    
    TT_OS2.usWinAscent and TT_OS2.usWinDescent must be treated as FT_Short. These values
affect font metrics. This PR will fix CORE-14994.
---
 win32ss/gdi/ntgdi/freetype.c | 32 ++++++++++++++++++--------------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/win32ss/gdi/ntgdi/freetype.c b/win32ss/gdi/ntgdi/freetype.c
index 6a2fae1ed7..027ccdb66e 100644
--- a/win32ss/gdi/ntgdi/freetype.c
+++ b/win32ss/gdi/ntgdi/freetype.c
@@ -1868,21 +1868,17 @@ FillTMEx(TEXTMETRICW *TM, PFONTGDI FontGDI,
         return;
     }
 
-    if (pOS2->usWinAscent + pOS2->usWinDescent == 0)
+    if ((FT_Short)pOS2->usWinAscent + (FT_Short)pOS2->usWinDescent == 0)
     {
         Ascent = pHori->Ascender;
         Descent = -pHori->Descender;
     }
     else
     {
-        Ascent = pOS2->usWinAscent;
-        Descent = pOS2->usWinDescent;
+        Ascent = (FT_Short)pOS2->usWinAscent;
+        Descent = (FT_Short)pOS2->usWinDescent;
     }
 
-    if (FontGDI->Magic != FONTGDI_MAGIC)
-    {
-        IntRequestFontSize(NULL, FontGDI, 0, 0);
-    }
     TM->tmAscent = FontGDI->tmAscent;
     TM->tmDescent = FontGDI->tmDescent;
     TM->tmHeight = TM->tmAscent + TM->tmDescent;
@@ -2649,7 +2645,7 @@ FontFamilyFillInfo(PFONTFAMILYINFO Info, LPCWSTR FaceName,
     }
 
     Ntm->ntmSizeEM = Otm->otmEMSquare;
-    Ntm->ntmCellHeight = pOS2->usWinAscent + pOS2->usWinDescent;
+    Ntm->ntmCellHeight = (FT_Short)pOS2->usWinAscent +
(FT_Short)pOS2->usWinDescent;
     Ntm->ntmAvgWidth = 0;
 
     ExFreePoolWithTag(Otm, GDITAG_TEXT);
@@ -3273,12 +3269,20 @@ IntRequestFontSize(PDC dc, PFONTGDI FontGDI, LONG lfWidth, LONG
lfHeight)
         return FT_Request_Size(face, &req);
     }
 
-    /* See also:
https://docs.microsoft.com/en-us/typography/opentype/spec/os2#fsselection */
+    /*
+     * NOTE: We cast TT_OS2.usWinAscent and TT_OS2.usWinDescent to signed FT_Short.
+     * Why? See:
https://docs.microsoft.com/en-us/typography/opentype/spec/os2#uswindescent
+     *
+     * > usWinDescent is "usually" a positive value ...
+     *
+     * We can read it as "not always". See CORE-14994.
+     * See also:
https://docs.microsoft.com/en-us/typography/opentype/spec/os2#fsselection
+     */
 #define FM_SEL_USE_TYPO_METRICS 0x80
     if (lfHeight > 0)
     {
         /* case (A): lfHeight is positive */
-        Sum = pOS2->usWinAscent + pOS2->usWinDescent;
+        Sum = (FT_Short)pOS2->usWinAscent + (FT_Short)pOS2->usWinDescent;
         if (Sum == 0 || (pOS2->fsSelection & FM_SEL_USE_TYPO_METRICS))
         {
             Ascent = pHori->Ascender;
@@ -3287,8 +3291,8 @@ IntRequestFontSize(PDC dc, PFONTGDI FontGDI, LONG lfWidth, LONG
lfHeight)
         }
         else
         {
-            Ascent = pOS2->usWinAscent;
-            Descent = pOS2->usWinDescent;
+            Ascent = (FT_Short)pOS2->usWinAscent;
+            Descent = (FT_Short)pOS2->usWinDescent;
         }
 
         FontGDI->tmAscent = FT_MulDiv(lfHeight, Ascent, Sum);
@@ -3306,8 +3310,8 @@ IntRequestFontSize(PDC dc, PFONTGDI FontGDI, LONG lfWidth, LONG
lfHeight)
         }
         else
         {
-            FontGDI->tmAscent = FT_MulDiv(-lfHeight, pOS2->usWinAscent,
face->units_per_EM);
-            FontGDI->tmDescent = FT_MulDiv(-lfHeight, pOS2->usWinDescent,
face->units_per_EM);
+            FontGDI->tmAscent = FT_MulDiv(-lfHeight, (FT_Short)pOS2->usWinAscent,
face->units_per_EM);
+            FontGDI->tmDescent = FT_MulDiv(-lfHeight, (FT_Short)pOS2->usWinDescent,
face->units_per_EM);
         }
         FontGDI->tmHeight = FontGDI->tmAscent + FontGDI->tmDescent;
         FontGDI->tmInternalLeading = FontGDI->tmHeight + lfHeight;