gdi32: Add support for checking the font's gasp flags.

dlls/gdi32/font.c

@@ -32,11 +32,18 @@
 #include "windef.h"
 #include "winbase.h"
 #include "winnls.h"
+#include "winternl.h"
 #include "gdi_private.h"
 #include "wine/exception.h"
 #include "wine/unicode.h"
 #include "wine/debug.h"
 
+#ifdef WORDS_BIGENDIAN
+#define get_be_word(x) (x)
+#else
+#define get_be_word(x) RtlUshortByteSwap(x)
+#endif
+
 WINE_DEFAULT_DEBUG_CHANNEL(font);
 
   /* Device -> World size conversion */
@@ -258,10 +265,73 @@ static void FONT_NewTextMetricExWToA(const NEWTEXTMETRICEXW *ptmW, NEWTEXTMETRIC
     memcpy(&ptmA->ntmFontSig, &ptmW->ntmFontSig, sizeof(FONTSIGNATURE));
 }
 
+static DWORD get_font_ppem( HDC hdc )
+{
+    TEXTMETRICW tm;
+    DWORD ppem;
+    DC *dc = get_dc_ptr( hdc );
+
+    if (!dc) return GDI_ERROR;
+
+    GetTextMetricsW( hdc, &tm );
+    ppem = abs( INTERNAL_YWSTODS( dc, tm.tmAscent + tm.tmDescent - tm.tmInternalLeading ) );
+    release_dc_ptr( dc );
+    return ppem;
+}
+
+#define GASP_GRIDFIT 0x01
+#define GASP_DOGRAY  0x02
+
+static BOOL get_gasp_flags( HDC hdc, WORD *flags )
+{
+    DWORD size, gasp_tag = 0x70736167;
+    WORD buf[16]; /* Enough for seven ranges before we need to alloc */
+    WORD *alloced = NULL, *ptr = buf;
+    WORD num_recs, version;
+    DWORD ppem = get_font_ppem( hdc );
+    BOOL ret = FALSE;
+
+    *flags = 0;
+    if (ppem == GDI_ERROR) return FALSE;
+
+    size = GetFontData( hdc, gasp_tag,  0, NULL, 0 );
+    if (size == GDI_ERROR) return FALSE;
+    if (size < 4 * sizeof(WORD)) return FALSE;
+    if (size > sizeof(buf))
+    {
+        ptr = alloced = HeapAlloc( GetProcessHeap(), 0, size );
+        if (!ptr) return FALSE;
+    }
+
+    GetFontData( hdc, gasp_tag, 0, ptr, size );
+
+    version  = get_be_word( *ptr++ );
+    num_recs = get_be_word( *ptr++ );
+
+    if (version > 1 || size < (num_recs * 2 + 2) * sizeof(WORD))
+    {
+        FIXME( "Unsupported gasp table: ver %d size %d recs %d\n", version, size, num_recs );
+        goto done;
+    }
+
+    while (num_recs--)
+    {
+        *flags = get_be_word( *(ptr + 1) );
+        if (ppem <= get_be_word( *ptr )) break;
+        ptr += 2;
+    }
+    TRACE( "got flags %04x for ppem %d\n", *flags, ppem );
+    ret = TRUE;
+
+done:
+    HeapFree( GetProcessHeap(), 0, alloced );
+    return ret;
+}
 
 UINT get_font_aa_flags( HDC hdc )
 {
     LOGFONTW lf;
+    WORD gasp_flags;
 
     if (GetObjectType( hdc ) == OBJ_MEMDC)
     {
@@ -274,7 +344,10 @@ UINT get_font_aa_flags( HDC hdc )
     GetObjectW( GetCurrentObject( hdc, OBJ_FONT ), sizeof(lf), &lf );
     if (lf.lfQuality == NONANTIALIASED_QUALITY) return GGO_BITMAP;
 
-    /* FIXME, check gasp and user prefs */
+    if (get_gasp_flags( hdc, &gasp_flags ) && !(gasp_flags & GASP_DOGRAY))
+        return GGO_BITMAP;
+
+    /* FIXME, check user prefs */
     return GGO_GRAY4_BITMAP;
 }