[PATCH 12/12] gdi32: Allow the embedded bitmap loading in the subpixel rendering mode.

[Byeongsik Jeon]

https://docs.microsoft.com/en-us/windows/desktop/api/wingdi/ns-wingdi-taglogfonta#remarks

The following situations do not support ClearType antialiasing:

The font has tuned embedded bitmaps, for any font sizes that contain the
embedded bitmaps. For example, this occurs commonly in East Asian fonts.

Wine-bug: https://bugs.winehq.org/show_bug.cgi?id=28009
Signed-off-by: Byeongsik Jeon <bsjeon at hanmail.net>
---
[1]
This patch affects the WineTahoma rendering. This is a normal operation.
Instead of loading the embedded bitmap, the metrics returns to normal.

[2]
This is a different topic from the use of get_gasp_flags in freetype_SelectFont.
This determines whether to load the embedded bitmap.

This issue has been an issue for a long time in the Windows CJK legacy builtin
fonts. For some wrong programs, these fonts are programmed under the assumption
that they are rendered as bitmap. Ex. Space Funeral.

[3]
If the font with embedded bitmap has gasp DO_GRAY bits set,
does not use the bitmap. Ex. Calibri.


 dlls/gdi32/freetype.c | 34 +++++++++++++++++++++++++++++++++-
 1 file changed, 33 insertions(+), 1 deletion(-)

diff --git a/dlls/gdi32/freetype.c b/dlls/gdi32/freetype.c
index d3d9e391f7..45709a0a92 100644
--- a/dlls/gdi32/freetype.c
+++ b/dlls/gdi32/freetype.c
@@ -7608,6 +7608,38 @@ static DWORD get_ggo_glyph_from_bitmap( FT_GlyphSlot glyph, UINT format, FT_BBox
     return needed;
 }
 
+static FT_Int get_embedded_bitmap_load_flags( UINT format, GdiFont *font, BOOL needsTransform )
+{
+    FT_Int load_flags = 0;
+    WORD gasp_flags;
+
+    if ( needsTransform )
+        return FT_LOAD_NO_BITMAP;
+
+    switch (format)
+    {
+    case GGO_BITMAP:
+        break;
+    case GGO_GRAY2_BITMAP:
+    case GGO_GRAY4_BITMAP:
+    case GGO_GRAY8_BITMAP:
+    case GGO_NATIVE:
+    case GGO_BEZIER:
+        load_flags = FT_LOAD_NO_BITMAP;
+        break;
+    case WINE_GGO_GRAY16_BITMAP:
+    case WINE_GGO_HRGB_BITMAP:
+    case WINE_GGO_HBGR_BITMAP:
+    case WINE_GGO_VRGB_BITMAP:
+    case WINE_GGO_VBGR_BITMAP:
+        if (get_gasp_flags( font, &gasp_flags ) && (gasp_flags & GASP_DOGRAY))
+            load_flags = FT_LOAD_NO_BITMAP;
+        break;
+    }
+
+    return load_flags;
+}
+
 static FT_Int get_load_flags( UINT format, BOOL ggo_unhinted, BOOL natural_width )
 {
     FT_Int load_flags = FT_LOAD_IGNORE_GLOBAL_ADVANCE_WIDTH;
@@ -7700,7 +7732,7 @@ static DWORD get_glyph_outline(GdiFont *incoming_font, UINT glyph, UINT format,
         vertical_metrics = FALSE;
 
     load_flags = get_load_flags( format, ggo_unhinted, natural_width );
-    if (needsTransform || format != GGO_BITMAP) load_flags |= FT_LOAD_NO_BITMAP;
+    load_flags |= get_embedded_bitmap_load_flags( format, font, needsTransform );
     if (vertical_metrics) load_flags |= FT_LOAD_VERTICAL_LAYOUT;
 
     err = pFT_Load_Glyph(ft_face, glyph_index, load_flags);
-- 
2.20.1