tdf#163215: Enable kashida justification for AAT fonts

Currently, we use HarfBuzz-provided kashida insertion position
information to decide on positions to insert kashida. This data is used
both while ranking kashida insertion positions, and to avoid inserting
kashida in positions that would break shaping on a per-font basis.

Unfortunately, HarfBuzz cannot validate kashida insertion positions for
AAT fonts. As a result, kashida were previously not inserted for text
using AAT fonts.

This change updates kashida justification to skip validation against
HarfBuzz when AAT fonts are used.

Change-Id: If0d31512b1db0f1f8155963f9b1031eb01bacc45
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/175165
Tested-by: Jenkins
Reviewed-by: Jonathan Clark <jonathan@libreoffice.org>

1 files changed, 51 insertions, 0 deletions

diff --git a/vcl/qa/cppunit/complextext.cxx b/vcl/qa/cppunit/complextext.cxx
index 62b8ac2777dc..a3d033e7adba 100644
--- a/vcl/qa/cppunit/complextext.cxx
+++ b/vcl/qa/cppunit/complextext.cxx
@@ -697,4 +697,55 @@ CPPUNIT_TEST_FIXTURE(VclComplexTextTest, testPartialArabicComposition)
     CPPUNIT_ASSERT_DOUBLES_EQUAL(nCompleteWidth, nPartialWidth, /*delta*/ 0.01);
 }
 
+CPPUNIT_TEST_FIXTURE(VclComplexTextTest, testTdf163215)
+{
+    OUString aStr = u"ببببب"_ustr;
+    vcl::Font aFont(u"DejaVu Sans"_ustr, u"Book"_ustr, Size(0, 2048));
+
+    ScopedVclPtrInstance<VirtualDevice> pOutDev;
+    pOutDev->SetFont(aFont);
+
+    // Characteristic case with kashida position validation
+    auto pLayout1 = pOutDev->ImplLayout(aStr, 0, aStr.getLength(), Point(), 0, {}, {},
+                                        SalLayoutFlags::GlyphItemsOnly);
+    CPPUNIT_ASSERT(pLayout1->HasFontKashidaPositions());
+
+    SalLayoutGlyphs aGlyphs1 = pLayout1->GetGlyphs();
+
+    std::vector<bool> aFoundPositions1;
+    for (const auto& stGlyph : *aGlyphs1.Impl(0))
+    {
+        aFoundPositions1.push_back(stGlyph.IsSafeToInsertKashida());
+    }
+
+    CPPUNIT_ASSERT_EQUAL(size_t(5), aFoundPositions1.size());
+    CPPUNIT_ASSERT(aFoundPositions1.at(0));
+    CPPUNIT_ASSERT(aFoundPositions1.at(1));
+    CPPUNIT_ASSERT(aFoundPositions1.at(2));
+    CPPUNIT_ASSERT(aFoundPositions1.at(3));
+    CPPUNIT_ASSERT(!aFoundPositions1.at(4));
+
+    // Case with kashida position validation disabled
+    auto pLayout2 = pOutDev->ImplLayout(aStr, 0, aStr.getLength(), Point(), 0, {}, {},
+                                        SalLayoutFlags::GlyphItemsOnly
+                                            | SalLayoutFlags::DisableKashidaValidation);
+    CPPUNIT_ASSERT(!pLayout2->HasFontKashidaPositions());
+
+    SalLayoutGlyphs aGlyphs2 = pLayout2->GetGlyphs();
+
+    std::vector<bool> aFoundPositions2;
+    for (const auto& stGlyph : *aGlyphs2.Impl(0))
+    {
+        aFoundPositions2.push_back(stGlyph.IsSafeToInsertKashida());
+    }
+
+    // With position validation disabled, all positions must be marked as valid
+    CPPUNIT_ASSERT_EQUAL(size_t(5), aFoundPositions2.size());
+    CPPUNIT_ASSERT(aFoundPositions2.at(0));
+    CPPUNIT_ASSERT(aFoundPositions2.at(1));
+    CPPUNIT_ASSERT(aFoundPositions2.at(2));
+    CPPUNIT_ASSERT(aFoundPositions2.at(3));
+    CPPUNIT_ASSERT(aFoundPositions2.at(4));
+}
+
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