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

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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>
This commit is contained in:
Caolán McNamara
2019-09-04 10:57:06 +01:00
parent 4b3a648a2f
commit df4a6f9778
3 changed files with 47 additions and 0 deletions
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7
vcl/inc/unx/glyphcache.hxx
View File

@@ -117,6 +117,13 @@ public:
FreetypeFontInstance* GetFontInstance() const { return mpFontInstance.get(); }
void SetFontVariationsOnHBFont(hb_font_t* pHbFace) const;
// tdf#127189 FreeType <= 2.8 will fail to render stretched horizontal brace glyphs
// in starmath at a fairly low stretch ratio. 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"
static bool AlmostHorizontalDrainsRenderingPool();
private:
friend class GlyphCache;
friend class FreetypeFontInstance;

20
vcl/unx/generic/gdi/cairotextrender.cxx
View File

@@ -204,6 +204,22 @@ void CairoTextRender::DrawTextLayout(const GenericSalLayout& rLayout, const SalG
if (nWidth == 0 || nHeight == 0)
return;
int nRatio = nWidth * 10 / nHeight;
if (nRatio > 100 && rFSD.maTargetName == "OpenSymbol" && FreetypeFont::AlmostHorizontalDrainsRenderingPool())
{
// 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 >= freetype 2.9
// Restrict this bodge to a stretch ratio > ~10 of the OpenSymbol font
// where it has been seen in practice.
SAL_WARN("vcl", "rendering text would fail with stretch ratio of: " << nRatio << ", with FreeType <= 2.8");
return;
}
/*
* It might be ideal to cache surface and cairo context between calls and
* only destroy it when the drawable changes, but to do that we need to at
@@ -330,6 +346,10 @@ void CairoTextRender::DrawTextLayout(const GenericSalLayout& rLayout, const SalG
cairo_set_font_matrix(cr, &m);
cairo_show_glyphs(cr, &cairo_glyphs[nStartIndex], nLen);
if (cairo_status(cr) != CAIRO_STATUS_SUCCESS)
{
SAL_WARN("vcl", "rendering text failed with stretch ratio of: " << nRatio << ", " << cairo_status_to_string(cairo_status(cr)));
}
#if OSL_DEBUG_LEVEL > 2
//draw origin

20
vcl/unx/generic/glyphs/freetype_glyphcache.cxx
View File

@@ -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 );