tdf#127189 FreeType <= 2.8 will fail to render stretched horizontal brace...

glyphs in starmath at a fairly low stretch ratio. The failure will set
CAIRO_STATUS_FREETYPE_ERROR on the surface which cannot be cleared, so all
further painting to the surface fails.

This appears fixed in 2.9 with
https://git.savannah.gnu.org/cgit/freetype/freetype2.git/commit/?id=91015cb41d8f56777f93394f5a60914bc0c0f330
"Improve complex rendering at high ppem"

Change-Id: I8cbf8347ccd29beda4057b14f2e68678f6030bf4
Reviewed-on: https://gerrit.libreoffice.org/78587
Tested-by: Jenkins
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

1 files changed, 20 insertions, 0 deletions

diff --git a/vcl/unx/generic/glyphs/freetype_glyphcache.cxx b/vcl/unx/generic/glyphs/freetype_glyphcache.cxx
index 1b3532ceee1b..525da6e52b43 100644
--- a/vcl/unx/generic/glyphs/freetype_glyphcache.cxx
+++ b/vcl/unx/generic/glyphs/freetype_glyphcache.cxx
@@ -324,6 +324,26 @@ void GlyphCache::InitFreetype()
     (void)vclFontFileList::get();
 }
 
+namespace
+{
+    bool DoesAlmostHorizontalDrainRenderingPool()
+    {
+        FT_Int nMajor, nMinor, nPatch;
+        FT_Library_Version(aLibFT, &nMajor, &nMinor, &nPatch);
+        if (nMajor > 2)
+            return false;
+        if (nMajor == 2 && nMinor <= 8)
+            return true;
+        return false;
+    }
+}
+
+bool FreetypeFont::AlmostHorizontalDrainsRenderingPool()
+{
+    static bool bAlmostHorizontalDrainsRenderingPool = DoesAlmostHorizontalDrainRenderingPool();
+    return bAlmostHorizontalDrainsRenderingPool;
+}
+
 FT_Face FreetypeFont::GetFtFace() const
 {
     FT_Activate_Size( maSizeFT );