Adding upstream version 4:7.4.7.upstream/4%7.4.7upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 861 insertions, 0 deletions

diff --git a/vcl/source/gdi/CommonSalLayout.cxx b/vcl/source/gdi/CommonSalLayout.cxx
new file mode 100644
index 000000000..7e2bcd629
--- /dev/null
+++ b/vcl/source/gdi/CommonSalLayout.cxx
@@ -0,0 +1,861 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#include <sal/config.h>
+
+#include <sal/log.hxx>
+#include <unotools/configmgr.hxx>
+#include <o3tl/temporary.hxx>
+
+#include <vcl/unohelp.hxx>
+#include <vcl/font/Feature.hxx>
+#include <vcl/font/FeatureParser.hxx>
+
+#include <ImplLayoutArgs.hxx>
+#include <TextLayoutCache.hxx>
+#include <font/FontSelectPattern.hxx>
+#include <salgdi.hxx>
+#include <sallayout.hxx>
+
+#include <com/sun/star/i18n/CharacterIteratorMode.hpp>
+
+#include <unicode/uchar.h>
+#include <hb-ot.h>
+#include <hb-graphite2.h>
+
+#include <memory>
+
+#if !HB_VERSION_ATLEAST(1, 1, 0)
+// Disabled Unicode compatibility decomposition, see fdo#66715
+static unsigned int unicodeDecomposeCompatibility(hb_unicode_funcs_t* /*ufuncs*/,
+                                                  hb_codepoint_t      /*u*/,
+                                                  hb_codepoint_t*     /*decomposed*/,
+                                                  void*               /*user_data*/)
+{
+    return 0;
+}
+
+static hb_unicode_funcs_t* getUnicodeFuncs()
+{
+    static hb_unicode_funcs_t* ufuncs = hb_unicode_funcs_create(hb_icu_get_unicode_funcs());
+    hb_unicode_funcs_set_decompose_compatibility_func(ufuncs, unicodeDecomposeCompatibility, nullptr, nullptr);
+    return ufuncs;
+}
+#endif
+
+GenericSalLayout::GenericSalLayout(LogicalFontInstance &rFont)
+    : m_GlyphItems(rFont)
+    , mpVertGlyphs(nullptr)
+    , mbFuzzing(utl::ConfigManager::IsFuzzing())
+{
+}
+
+GenericSalLayout::~GenericSalLayout()
+{
+}
+
+void GenericSalLayout::ParseFeatures(std::u16string_view aName)
+{
+    vcl::font::FeatureParser aParser(aName);
+    const OUString& sLanguage = aParser.getLanguage();
+    if (!sLanguage.isEmpty())
+        msLanguage = OUStringToOString(sLanguage, RTL_TEXTENCODING_ASCII_US);
+
+    for (auto const &rFeat : aParser.getFeatures())
+    {
+        hb_feature_t aFeature { rFeat.m_nTag, rFeat.m_nValue, rFeat.m_nStart, rFeat.m_nEnd };
+        maFeatures.push_back(aFeature);
+    }
+}
+
+namespace {
+
+struct SubRun
+{
+    int32_t mnMin;
+    int32_t mnEnd;
+    hb_script_t maScript;
+    hb_direction_t maDirection;
+};
+
+}
+
+namespace {
+#if U_ICU_VERSION_MAJOR_NUM >= 63
+    enum class VerticalOrientation {
+        Upright            = U_VO_UPRIGHT,
+        Rotated            = U_VO_ROTATED,
+        TransformedUpright = U_VO_TRANSFORMED_UPRIGHT,
+        TransformedRotated = U_VO_TRANSFORMED_ROTATED
+    };
+#else
+    #include "VerticalOrientationData.cxx"
+
+    // These must match the values in the file included above.
+    enum class VerticalOrientation {
+        Upright            = 0,
+        Rotated            = 1,
+        TransformedUpright = 2,
+        TransformedRotated = 3
+    };
+#endif
+
+    VerticalOrientation GetVerticalOrientation(sal_UCS4 cCh, const LanguageTag& rTag)
+    {
+        // Override orientation of fullwidth colon , semi-colon,
+        // and Bopomofo tonal marks.
+        if ((cCh == 0xff1a || cCh == 0xff1b
+           || cCh == 0x2ca || cCh == 0x2cb || cCh == 0x2c7 || cCh == 0x2d9)
+                && rTag.getLanguage() == "zh")
+            return VerticalOrientation::TransformedUpright;
+
+#if U_ICU_VERSION_MAJOR_NUM >= 63
+        int32_t nRet = u_getIntPropertyValue(cCh, UCHAR_VERTICAL_ORIENTATION);
+#else
+        uint8_t nRet = 1;
+
+        if (cCh < 0x10000)
+        {
+            nRet = sVerticalOrientationValues[sVerticalOrientationPages[0][cCh >> kVerticalOrientationCharBits]]
+                                  [cCh & ((1 << kVerticalOrientationCharBits) - 1)];
+        }
+        else if (cCh < (kVerticalOrientationMaxPlane + 1) * 0x10000)
+        {
+            nRet = sVerticalOrientationValues[sVerticalOrientationPages[sVerticalOrientationPlanes[(cCh >> 16) - 1]]
+                                                   [(cCh & 0xffff) >> kVerticalOrientationCharBits]]
+                                   [cCh & ((1 << kVerticalOrientationCharBits) - 1)];
+        }
+        else
+        {
+            // Default value for unassigned
+            SAL_WARN("vcl.gdi", "Getting VerticalOrientation for codepoint outside Unicode range");
+        }
+#endif
+
+        return VerticalOrientation(nRet);
+    }
+
+} // namespace
+
+SalLayoutGlyphs GenericSalLayout::GetGlyphs() const
+{
+    SalLayoutGlyphs glyphs;
+    glyphs.AppendImpl(m_GlyphItems.clone());
+    return glyphs;
+}
+
+void GenericSalLayout::SetNeedFallback(vcl::text::ImplLayoutArgs& rArgs, sal_Int32 nCharPos, bool bRightToLeft)
+{
+    if (nCharPos < 0 || mbFuzzing)
+        return;
+
+    using namespace ::com::sun::star;
+
+    if (!mxBreak.is())
+        mxBreak = vcl::unohelper::CreateBreakIterator();
+
+    lang::Locale aLocale(rArgs.maLanguageTag.getLocale());
+
+    //if position nCharPos is missing in the font, grab the entire grapheme and
+    //mark all glyphs as missing so the whole thing is rendered with the same
+    //font
+    sal_Int32 nDone;
+    int nGraphemeEndPos =
+        mxBreak->nextCharacters(rArgs.mrStr, nCharPos, aLocale,
+            i18n::CharacterIteratorMode::SKIPCELL, 1, nDone);
+    // Safely advance nCharPos in case it is a non-BMP character.
+    rArgs.mrStr.iterateCodePoints(&nCharPos);
+    int nGraphemeStartPos =
+        mxBreak->previousCharacters(rArgs.mrStr, nCharPos, aLocale,
+            i18n::CharacterIteratorMode::SKIPCELL, 1, nDone);
+
+    //stay inside the Layout range (e.g. with tdf124116-1.odt)
+    nGraphemeStartPos = std::max(rArgs.mnMinCharPos, nGraphemeStartPos);
+    nGraphemeEndPos = std::min(rArgs.mnEndCharPos, nGraphemeEndPos);
+
+    rArgs.AddFallbackRun(nGraphemeStartPos, nGraphemeEndPos, bRightToLeft);
+}
+
+void GenericSalLayout::AdjustLayout(vcl::text::ImplLayoutArgs& rArgs)
+{
+    SalLayout::AdjustLayout(rArgs);
+
+    if (rArgs.mpAltNaturalDXArray) // Used when "TextRenderModeForResolutionIndependentLayout" is set
+        ApplyDXArray(rArgs.mpAltNaturalDXArray, rArgs.mnFlags);
+    else if (rArgs.mpDXArray)   // Normal case
+        ApplyDXArray(rArgs.mpDXArray, rArgs.mnFlags);
+    else if (rArgs.mnLayoutWidth)
+        Justify(rArgs.mnLayoutWidth);
+    // apply asian kerning if the glyphs are not already formatted
+    else if ((rArgs.mnFlags & SalLayoutFlags::KerningAsian)
+         && !(rArgs.mnFlags & SalLayoutFlags::Vertical))
+        ApplyAsianKerning(rArgs.mrStr);
+}
+
+void GenericSalLayout::DrawText(SalGraphics& rSalGraphics) const
+{
+    //call platform dependent DrawText functions
+    rSalGraphics.DrawTextLayout( *this );
+}
+
+// Find if the nominal glyph of the character is an input to “vert” feature.
+// We don’t check for a specific script or language as it shouldn’t matter
+// here; if the glyph would be the result from applying “vert” for any
+// script/language then we want to always treat it as upright glyph.
+bool GenericSalLayout::HasVerticalAlternate(sal_UCS4 aChar, sal_UCS4 aVariationSelector)
+{
+    hb_codepoint_t nGlyphIndex = 0;
+    hb_font_t *pHbFont = GetFont().GetHbFont();
+    if (!hb_font_get_glyph(pHbFont, aChar, aVariationSelector, &nGlyphIndex))
+        return false;
+
+    if (!mpVertGlyphs)
+    {
+        hb_face_t* pHbFace = hb_font_get_face(pHbFont);
+        mpVertGlyphs = hb_set_create();
+
+        // Find all GSUB lookups for “vert” feature.
+        hb_set_t* pLookups = hb_set_create();
+        hb_tag_t const pFeatures[] = { HB_TAG('v','e','r','t'), HB_TAG_NONE };
+        hb_ot_layout_collect_lookups(pHbFace, HB_OT_TAG_GSUB, nullptr, nullptr, pFeatures, pLookups);
+        if (!hb_set_is_empty(pLookups))
+        {
+            // Find the output glyphs in each lookup (i.e. the glyphs that
+            // would result from applying this lookup).
+            hb_codepoint_t nIdx = HB_SET_VALUE_INVALID;
+            while (hb_set_next(pLookups, &nIdx))
+            {
+                hb_set_t* pGlyphs = hb_set_create();
+                hb_ot_layout_lookup_collect_glyphs(pHbFace, HB_OT_TAG_GSUB, nIdx,
+                        nullptr,  // glyphs before
+                        pGlyphs,  // glyphs input
+                        nullptr,  // glyphs after
+                        nullptr); // glyphs out
+                hb_set_union(mpVertGlyphs, pGlyphs);
+            }
+        }
+    }
+
+    return hb_set_has(mpVertGlyphs, nGlyphIndex) != 0;
+}
+
+bool GenericSalLayout::LayoutText(vcl::text::ImplLayoutArgs& rArgs, const SalLayoutGlyphsImpl* pGlyphs)
+{
+    // No need to touch m_GlyphItems at all for an empty string.
+    if (rArgs.mnEndCharPos - rArgs.mnMinCharPos <= 0)
+        return true;
+
+    if (pGlyphs)
+    {
+        // Work with pre-computed glyph items.
+        m_GlyphItems = *pGlyphs;
+        for(const GlyphItem& item : m_GlyphItems)
+            if(!item.glyphId())
+                SetNeedFallback(rArgs, item.charPos(), item.IsRTLGlyph());
+        // Some flags are set as a side effect of text layout, restore them here.
+        rArgs.mnFlags |= pGlyphs->GetFlags();
+        return true;
+    }
+
+    hb_font_t *pHbFont = GetFont().GetHbFont();
+    bool isGraphite = GetFont().IsGraphiteFont();
+
+    int nGlyphCapacity = 2 * (rArgs.mnEndCharPos - rArgs.mnMinCharPos);
+    m_GlyphItems.reserve(nGlyphCapacity);
+
+    const int nLength = rArgs.mrStr.getLength();
+    const sal_Unicode *pStr = rArgs.mrStr.getStr();
+
+    std::optional<vcl::text::TextLayoutCache> oNewScriptRun;
+    vcl::text::TextLayoutCache const* pTextLayout;
+    if (rArgs.m_pTextLayoutCache)
+    {
+        pTextLayout = rArgs.m_pTextLayoutCache; // use cache!
+    }
+    else
+    {
+        oNewScriptRun.emplace(pStr, rArgs.mnEndCharPos);
+        pTextLayout = &*oNewScriptRun;
+    }
+
+    // nBaseOffset is used to align vertical text to the center of rotated
+    // horizontal text. That is the offset from original baseline to
+    // the center of EM box. Maybe we can use OpenType base table to improve this
+    // in the future.
+    DeviceCoordinate nBaseOffset = 0;
+    if (rArgs.mnFlags & SalLayoutFlags::Vertical)
+    {
+        hb_font_extents_t extents;
+        if (hb_font_get_h_extents(pHbFont, &extents))
+            nBaseOffset = ( extents.ascender + extents.descender ) / 2;
+    }
+
+    hb_buffer_t* pHbBuffer = hb_buffer_create();
+    hb_buffer_pre_allocate(pHbBuffer, nGlyphCapacity);
+#if !HB_VERSION_ATLEAST(1, 1, 0)
+    static hb_unicode_funcs_t* pHbUnicodeFuncs = getUnicodeFuncs();
+    hb_buffer_set_unicode_funcs(pHbBuffer, pHbUnicodeFuncs);
+#endif
+
+    const vcl::font::FontSelectPattern& rFontSelData = GetFont().GetFontSelectPattern();
+    if (rArgs.mnFlags & SalLayoutFlags::DisableKerning)
+    {
+        SAL_INFO("vcl.harfbuzz", "Disabling kerning for font: " << rFontSelData.maTargetName);
+        maFeatures.push_back({ HB_TAG('k','e','r','n'), 0, 0, static_cast<unsigned int>(-1) });
+    }
+
+    if (rFontSelData.GetPitch() == PITCH_FIXED)
+    {
+        SAL_INFO("vcl.harfbuzz", "Disabling ligatures for font: " << rFontSelData.maTargetName);
+        maFeatures.push_back({ HB_TAG('l','i','g','a'), 0, 0, static_cast<unsigned int>(-1) });
+    }
+
+    ParseFeatures(rFontSelData.maTargetName);
+
+    double nXScale = 0;
+    double nYScale = 0;
+    GetFont().GetScale(&nXScale, &nYScale);
+
+    DevicePoint aCurrPos(0, 0);
+    while (true)
+    {
+        int nBidiMinRunPos, nBidiEndRunPos;
+        bool bRightToLeft;
+        if (!rArgs.GetNextRun(&nBidiMinRunPos, &nBidiEndRunPos, &bRightToLeft))
+            break;
+
+        // Find script subruns.
+        std::vector<SubRun> aSubRuns;
+        int nCurrentPos = nBidiMinRunPos;
+        size_t k = 0;
+        for (; k < pTextLayout->runs.size(); ++k)
+        {
+            vcl::text::Run const& rRun(pTextLayout->runs[k]);
+            if (rRun.nStart <= nCurrentPos && nCurrentPos < rRun.nEnd)
+            {
+                break;
+            }
+        }
+
+        if (isGraphite)
+        {
+            hb_script_t aScript = hb_icu_script_to_script(pTextLayout->runs[k].nCode);
+            aSubRuns.push_back({ nBidiMinRunPos, nBidiEndRunPos, aScript, bRightToLeft ? HB_DIRECTION_RTL : HB_DIRECTION_LTR });
+        }
+        else
+        {
+            while (nCurrentPos < nBidiEndRunPos && k < pTextLayout->runs.size())
+            {
+                int32_t nMinRunPos = nCurrentPos;
+                int32_t nEndRunPos = std::min(pTextLayout->runs[k].nEnd, nBidiEndRunPos);
+                hb_direction_t aDirection = bRightToLeft ? HB_DIRECTION_RTL : HB_DIRECTION_LTR;
+                hb_script_t aScript = hb_icu_script_to_script(pTextLayout->runs[k].nCode);
+                // For vertical text, further divide the runs based on character
+                // orientation.
+                if (rArgs.mnFlags & SalLayoutFlags::Vertical)
+                {
+                    sal_Int32 nIdx = nMinRunPos;
+                    while (nIdx < nEndRunPos)
+                    {
+                        sal_Int32 nPrevIdx = nIdx;
+                        sal_UCS4 aChar = rArgs.mrStr.iterateCodePoints(&nIdx);
+                        VerticalOrientation aVo = GetVerticalOrientation(aChar, rArgs.maLanguageTag);
+
+                        sal_UCS4 aVariationSelector = 0;
+                        if (nIdx < nEndRunPos)
+                        {
+                            sal_Int32 nNextIdx = nIdx;
+                            sal_UCS4 aNextChar = rArgs.mrStr.iterateCodePoints(&nNextIdx);
+                            if (u_hasBinaryProperty(aNextChar, UCHAR_VARIATION_SELECTOR))
+                            {
+                                nIdx = nNextIdx;
+                                aVariationSelector = aNextChar;
+                            }
+                        }
+
+                        // Characters with U and Tu vertical orientation should
+                        // be shaped in vertical direction. But characters
+                        // with Tr should be shaped in vertical direction
+                        // only if they have vertical alternates, otherwise
+                        // they should be shaped in horizontal direction
+                        // and then rotated.
+                        // See http://unicode.org/reports/tr50/#vo
+                        if (aVo == VerticalOrientation::Upright ||
+                            aVo == VerticalOrientation::TransformedUpright ||
+                            (aVo == VerticalOrientation::TransformedRotated &&
+                             HasVerticalAlternate(aChar, aVariationSelector)))
+                        {
+                            aDirection = HB_DIRECTION_TTB;
+                        }
+                        else
+                        {
+                            aDirection = bRightToLeft ? HB_DIRECTION_RTL : HB_DIRECTION_LTR;
+                        }
+
+                        if (aSubRuns.empty() || aSubRuns.back().maDirection != aDirection)
+                            aSubRuns.push_back({ nPrevIdx, nIdx, aScript, aDirection });
+                        else
+                            aSubRuns.back().mnEnd = nIdx;
+                    }
+                }
+                else
+                {
+                    aSubRuns.push_back({ nMinRunPos, nEndRunPos, aScript, aDirection });
+                }
+
+                nCurrentPos = nEndRunPos;
+                ++k;
+            }
+        }
+
+        // RTL subruns should be reversed to ensure that final glyph order is
+        // correct.
+        if (bRightToLeft)
+            std::reverse(aSubRuns.begin(), aSubRuns.end());
+
+        for (const auto& aSubRun : aSubRuns)
+        {
+            hb_buffer_clear_contents(pHbBuffer);
+
+            const int nMinRunPos = aSubRun.mnMin;
+            const int nEndRunPos = aSubRun.mnEnd;
+            const int nRunLen = nEndRunPos - nMinRunPos;
+
+            int nHbFlags = HB_BUFFER_FLAGS_DEFAULT;
+            if (nMinRunPos == 0)
+                nHbFlags |= HB_BUFFER_FLAG_BOT; /* Beginning-of-text */
+            if (nEndRunPos == nLength)
+                nHbFlags |= HB_BUFFER_FLAG_EOT; /* End-of-text */
+
+            hb_buffer_set_direction(pHbBuffer, aSubRun.maDirection);
+            hb_buffer_set_script(pHbBuffer, aSubRun.maScript);
+            if (!msLanguage.isEmpty())
+            {
+                hb_buffer_set_language(pHbBuffer, hb_language_from_string(msLanguage.getStr(), msLanguage.getLength()));
+            }
+            else
+            {
+                OString sLanguage = OUStringToOString(rArgs.maLanguageTag.getBcp47(), RTL_TEXTENCODING_ASCII_US);
+                hb_buffer_set_language(pHbBuffer, hb_language_from_string(sLanguage.getStr(), sLanguage.getLength()));
+            }
+            hb_buffer_set_flags(pHbBuffer, static_cast<hb_buffer_flags_t>(nHbFlags));
+            hb_buffer_add_utf16(
+                pHbBuffer, reinterpret_cast<uint16_t const *>(pStr), nLength,
+                nMinRunPos, nRunLen);
+            hb_buffer_set_cluster_level(pHbBuffer, HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS);
+
+            // The shapers that we want HarfBuzz to use, in the order of
+            // preference. The coretext_aat shaper is available only on macOS,
+            // but there is no harm in always including it, HarfBuzz will
+            // ignore unavailable shapers.
+            const char*const pHbShapers[] = { "graphite2", "coretext_aat", "ot", "fallback", nullptr };
+            bool ok = hb_shape_full(pHbFont, pHbBuffer, maFeatures.data(), maFeatures.size(), pHbShapers);
+            assert(ok);
+            (void) ok;
+
+            int nRunGlyphCount = hb_buffer_get_length(pHbBuffer);
+            hb_glyph_info_t *pHbGlyphInfos = hb_buffer_get_glyph_infos(pHbBuffer, nullptr);
+            hb_glyph_position_t *pHbPositions = hb_buffer_get_glyph_positions(pHbBuffer, nullptr);
+
+            for (int i = 0; i < nRunGlyphCount; ++i) {
+                int32_t nGlyphIndex = pHbGlyphInfos[i].codepoint;
+                int32_t nCharPos = pHbGlyphInfos[i].cluster;
+                int32_t nCharCount = 0;
+                bool bInCluster = false;
+                bool bClusterStart = false;
+
+                // Find the number of characters that make up this glyph.
+                if (!bRightToLeft)
+                {
+                    // If the cluster is the same as previous glyph, then this
+                    // already consumed, skip.
+                    if (i > 0 && pHbGlyphInfos[i].cluster == pHbGlyphInfos[i - 1].cluster)
+                    {
+                        nCharCount = 0;
+                        bInCluster = true;
+                    }
+                    else
+                    {
+                        // Find the next glyph with a different cluster, or the
+                        // end of text.
+                        int j = i;
+                        int32_t nNextCharPos = nCharPos;
+                        while (nNextCharPos == nCharPos && j < nRunGlyphCount)
+                            nNextCharPos = pHbGlyphInfos[j++].cluster;
+
+                        if (nNextCharPos == nCharPos)
+                            nNextCharPos = nEndRunPos;
+                        nCharCount = nNextCharPos - nCharPos;
+                        if ((i == 0 || pHbGlyphInfos[i].cluster != pHbGlyphInfos[i - 1].cluster) &&
+                            (i < nRunGlyphCount - 1 && pHbGlyphInfos[i].cluster == pHbGlyphInfos[i + 1].cluster))
+                            bClusterStart = true;
+                    }
+                }
+                else
+                {
+                    // If the cluster is the same as previous glyph, then this
+                    // will be consumed later, skip.
+                    if (i < nRunGlyphCount - 1 && pHbGlyphInfos[i].cluster == pHbGlyphInfos[i + 1].cluster)
+                    {
+                        nCharCount = 0;
+                        bInCluster = true;
+                    }
+                    else
+                    {
+                        // Find the previous glyph with a different cluster, or
+                        // the end of text.
+                        int j = i;
+                        int32_t nNextCharPos = nCharPos;
+                        while (nNextCharPos == nCharPos && j >= 0)
+                            nNextCharPos = pHbGlyphInfos[j--].cluster;
+
+                        if (nNextCharPos == nCharPos)
+                            nNextCharPos = nEndRunPos;
+                        nCharCount = nNextCharPos - nCharPos;
+                        if ((i == nRunGlyphCount - 1 || pHbGlyphInfos[i].cluster != pHbGlyphInfos[i + 1].cluster) &&
+                            (i > 0 && pHbGlyphInfos[i].cluster == pHbGlyphInfos[i - 1].cluster))
+                            bClusterStart = true;
+                    }
+                }
+
+                // if needed request glyph fallback by updating LayoutArgs
+                if (!nGlyphIndex)
+                {
+                    SetNeedFallback(rArgs, nCharPos, bRightToLeft);
+                    if (SalLayoutFlags::ForFallback & rArgs.mnFlags)
+                        continue;
+                }
+
+                GlyphItemFlags nGlyphFlags = GlyphItemFlags::NONE;
+                if (bRightToLeft)
+                    nGlyphFlags |= GlyphItemFlags::IS_RTL_GLYPH;
+
+                if (bClusterStart)
+                    nGlyphFlags |= GlyphItemFlags::IS_CLUSTER_START;
+
+                if (bInCluster)
+                    nGlyphFlags |= GlyphItemFlags::IS_IN_CLUSTER;
+
+                sal_UCS4 aChar
+                    = rArgs.mrStr.iterateCodePoints(&o3tl::temporary(sal_Int32(nCharPos)), 0);
+
+                if (u_getIntPropertyValue(aChar, UCHAR_GENERAL_CATEGORY) == U_NON_SPACING_MARK)
+                    nGlyphFlags |= GlyphItemFlags::IS_DIACRITIC;
+
+                if (u_isUWhiteSpace(aChar))
+                    nGlyphFlags |= GlyphItemFlags::IS_SPACING;
+
+                if (aSubRun.maScript == HB_SCRIPT_ARABIC &&
+                    HB_DIRECTION_IS_BACKWARD(aSubRun.maDirection) &&
+                    !(nGlyphFlags & GlyphItemFlags::IS_SPACING))
+                {
+                    nGlyphFlags |= GlyphItemFlags::ALLOW_KASHIDA;
+                    rArgs.mnFlags |= SalLayoutFlags::KashidaJustification;
+                }
+
+#if HB_VERSION_ATLEAST(1, 5, 0)
+                if (hb_glyph_info_get_glyph_flags(&pHbGlyphInfos[i]) & HB_GLYPH_FLAG_UNSAFE_TO_BREAK)
+                    nGlyphFlags |= GlyphItemFlags::IS_UNSAFE_TO_BREAK;
+#else
+                // If support is not present, then always prevent breaking.
+                nGlyphFlags |= GlyphItemFlags::IS_UNSAFE_TO_BREAK;
+#endif
+
+                DeviceCoordinate nAdvance, nXOffset, nYOffset;
+                if (aSubRun.maDirection == HB_DIRECTION_TTB)
+                {
+                    nGlyphFlags |= GlyphItemFlags::IS_VERTICAL;
+
+                    nAdvance = -pHbPositions[i].y_advance;
+                    nXOffset = -pHbPositions[i].y_offset;
+                    nYOffset = -pHbPositions[i].x_offset - nBaseOffset;
+
+                    if (GetFont().NeedOffsetCorrection(pHbPositions[i].y_offset))
+                    {
+                        // We need glyph's advance, top bearing, and height to
+                        // correct y offset.
+                        tools::Rectangle aRect;
+                        // Get cached bound rect value for the font,
+                        GetFont().GetGlyphBoundRect(nGlyphIndex, aRect, true);
+
+                        nXOffset = -(aRect.Top() / nXScale  + ( pHbPositions[i].y_advance
+                                    + ( aRect.GetHeight() / nXScale ) ) / 2 );
+                    }
+
+                }
+                else
+                {
+                    nAdvance =  pHbPositions[i].x_advance;
+                    nXOffset =  pHbPositions[i].x_offset;
+                    nYOffset = -pHbPositions[i].y_offset;
+                }
+
+                nAdvance = std::lround(nAdvance * nXScale);
+                nXOffset = std::lround(nXOffset * nXScale);
+                nYOffset = std::lround(nYOffset * nYScale);
+
+                DevicePoint aNewPos(aCurrPos.getX() + nXOffset, aCurrPos.getY() + nYOffset);
+                const GlyphItem aGI(nCharPos, nCharCount, nGlyphIndex, aNewPos, nGlyphFlags,
+                                    nAdvance, nXOffset, nYOffset);
+                m_GlyphItems.push_back(aGI);
+
+                aCurrPos.adjustX(nAdvance);
+            }
+        }
+    }
+
+    hb_buffer_destroy(pHbBuffer);
+
+    // Some flags are set as a side effect of text layout, save them here.
+    if (rArgs.mnFlags & SalLayoutFlags::GlyphItemsOnly)
+        m_GlyphItems.SetFlags(rArgs.mnFlags);
+
+    return true;
+}
+
+void GenericSalLayout::GetCharWidths(std::vector<DeviceCoordinate>& rCharWidths) const
+{
+    const int nCharCount = mnEndCharPos - mnMinCharPos;
+
+    rCharWidths.clear();
+    rCharWidths.resize(nCharCount, 0);
+
+    for (auto const& aGlyphItem : m_GlyphItems)
+    {
+        const int nIndex = aGlyphItem.charPos() - mnMinCharPos;
+        if (nIndex >= nCharCount)
+            continue;
+        rCharWidths[nIndex] += aGlyphItem.newWidth();
+    }
+}
+
+// A note on how Kashida justification is implemented (because it took me 5
+// years to figure it out):
+// The decision to insert Kashidas, where and how much is taken by Writer.
+// This decision is communicated to us in a very indirect way; by increasing
+// the width of the character after which Kashidas should be inserted by the
+// desired amount.
+//
+// Writer eventually calls IsKashidaPosValid() to check whether it can insert a
+// Kashida between two characters or not.
+//
+// Here we do:
+// - In LayoutText() set KashidaJustification flag based on text script.
+// - In ApplyDXArray():
+//   * Check the above flag to decide whether to insert Kashidas or not.
+//   * For any RTL glyph that has DX adjustment, insert enough Kashidas to
+//     fill in the added space.
+template<typename DC>
+void GenericSalLayout::ApplyDXArray(const DC* pDXArray, SalLayoutFlags nLayoutFlags)
+{
+    int nCharCount = mnEndCharPos - mnMinCharPos;
+    std::vector<DeviceCoordinate> aOldCharWidths;
+    std::unique_ptr<DC[]> const pNewCharWidths(new DC[nCharCount]);
+
+    // Get the natural character widths (i.e. before applying DX adjustments).
+    GetCharWidths(aOldCharWidths);
+
+    // Calculate the character widths after DX adjustments.
+    for (int i = 0; i < nCharCount; ++i)
+    {
+        if (i == 0)
+            pNewCharWidths[i] = pDXArray[i];
+        else
+            pNewCharWidths[i] = pDXArray[i] - pDXArray[i - 1];
+    }
+
+    bool bKashidaJustify = false;
+    DeviceCoordinate nKashidaWidth = 0;
+    hb_codepoint_t nKashidaIndex = 0;
+    if (nLayoutFlags & SalLayoutFlags::KashidaJustification)
+    {
+        hb_font_t *pHbFont = GetFont().GetHbFont();
+        // Find Kashida glyph width and index.
+        if (hb_font_get_glyph(pHbFont, 0x0640, 0, &nKashidaIndex))
+            nKashidaWidth = GetFont().GetKashidaWidth();
+        bKashidaJustify = nKashidaWidth != 0;
+    }
+
+    // Map of Kashida insertion points (in the glyph items vector) and the
+    // requested width.
+    std::map<size_t, DeviceCoordinate> pKashidas;
+
+    // The accumulated difference in X position.
+    DC nDelta = 0;
+
+    // Apply the DX adjustments to glyph positions and widths.
+    size_t i = 0;
+    while (i < m_GlyphItems.size())
+    {
+        // Accumulate the width difference for all characters corresponding to
+        // this glyph.
+        int nCharPos = m_GlyphItems[i].charPos() - mnMinCharPos;
+        DC nDiff = 0;
+        for (int j = 0; j < m_GlyphItems[i].charCount(); j++)
+            nDiff += pNewCharWidths[nCharPos + j] - aOldCharWidths[nCharPos + j];
+
+        if (!m_GlyphItems[i].IsRTLGlyph())
+        {
+            // Adjust the width and position of the first (leftmost) glyph in
+            // the cluster.
+            m_GlyphItems[i].addNewWidth(nDiff);
+            m_GlyphItems[i].adjustLinearPosX(nDelta);
+
+            // Adjust the position of the rest of the glyphs in the cluster.
+            while (++i < m_GlyphItems.size())
+            {
+                if (!m_GlyphItems[i].IsInCluster())
+                    break;
+                m_GlyphItems[i].adjustLinearPosX(nDelta);
+            }
+        }
+        else if (m_GlyphItems[i].IsInCluster())
+        {
+            // RTL glyph in the middle of the cluster, will be handled in the
+            // loop below.
+            i++;
+        }
+        else
+        {
+            // Adjust the width and position of the first (rightmost) glyph in
+            // the cluster.
+            // For RTL, we put all the adjustment to the left of the glyph.
+            m_GlyphItems[i].addNewWidth(nDiff);
+            m_GlyphItems[i].adjustLinearPosX(nDelta + nDiff);
+
+            // Adjust the X position of all glyphs in the cluster.
+            size_t j = i;
+            while (j > 0)
+            {
+                --j;
+                if (!m_GlyphItems[j].IsInCluster())
+                    break;
+                m_GlyphItems[j].adjustLinearPosX(nDelta + nDiff);
+            }
+
+            // If this glyph is Kashida-justifiable, then mark this as a
+            // Kashida position. Since this must be a RTL glyph, we mark the
+            // last glyph in the cluster not the first as this would be the
+            // base glyph.
+            if (bKashidaJustify && m_GlyphItems[i].AllowKashida() &&
+                nDiff > m_GlyphItems[i].charCount()) // Rounding errors, 1 pixel per character!
+            {
+                pKashidas[i] = nDiff;
+                // Move any non-spacing marks attached to this cluster as well.
+                // Looping backward because this is RTL glyph.
+                while (j > 0)
+                {
+                    if (!m_GlyphItems[j].IsDiacritic())
+                        break;
+                    m_GlyphItems[j--].adjustLinearPosX(nDiff);
+                }
+            }
+            i++;
+        }
+
+        // Increment the delta, the loop above makes sure we do so only once
+        // for every character (cluster) not for every glyph (otherwise we
+        // would apply it multiple times for each glyphs belonging to the same
+        // character which is wrong since DX adjustments are character based).
+        nDelta += nDiff;
+    }
+
+    // Insert Kashida glyphs.
+    if (!bKashidaJustify || pKashidas.empty())
+        return;
+
+    size_t nInserted = 0;
+    for (auto const& pKashida : pKashidas)
+    {
+        auto pGlyphIter = m_GlyphItems.begin() + nInserted + pKashida.first;
+
+        // The total Kashida width.
+        DeviceCoordinate nTotalWidth = pKashida.second;
+
+        // Number of times to repeat each Kashida.
+        int nCopies = 1;
+        if (nTotalWidth > nKashidaWidth)
+            nCopies = nTotalWidth / nKashidaWidth;
+
+        // See if we can improve the fit by adding an extra Kashidas and
+        // squeezing them together a bit.
+        DeviceCoordinate nOverlap = 0;
+        DeviceCoordinate nShortfall = nTotalWidth - nKashidaWidth * nCopies;
+        if (nShortfall > 0)
+        {
+            ++nCopies;
+            DeviceCoordinate nExcess = nCopies * nKashidaWidth - nTotalWidth;
+            if (nExcess > 0)
+                nOverlap = nExcess / (nCopies - 1);
+        }
+
+        DevicePoint aPos(pGlyphIter->linearPos().getX() - nTotalWidth, 0);
+        int nCharPos = pGlyphIter->charPos();
+        GlyphItemFlags const nFlags = GlyphItemFlags::IS_IN_CLUSTER | GlyphItemFlags::IS_RTL_GLYPH;
+        while (nCopies--)
+        {
+            GlyphItem aKashida(nCharPos, 0, nKashidaIndex, aPos, nFlags, nKashidaWidth, 0, 0);
+            pGlyphIter = m_GlyphItems.insert(pGlyphIter, aKashida);
+            aPos.adjustX(nKashidaWidth - nOverlap);
+            ++pGlyphIter;
+            ++nInserted;
+        }
+    }
+}
+
+bool GenericSalLayout::IsKashidaPosValid(int nCharPos) const
+{
+    for (auto pIter = m_GlyphItems.begin(); pIter != m_GlyphItems.end(); ++pIter)
+    {
+        if (pIter->charPos() == nCharPos)
+        {
+            // The position is the first glyph, this would happen if we
+            // changed the text styling in the middle of a word. Since we don’t
+            // do ligatures across layout engine instances, this can’t be a
+            // ligature so it should be fine.
+            if (pIter == m_GlyphItems.begin())
+                return true;
+
+            // If the character is not supported by this layout, return false
+            // so that fallback layouts would be checked for it.
+            if (pIter->glyphId() == 0)
+                break;
+
+            // Search backwards for previous glyph belonging to a different
+            // character. We are looking backwards because we are dealing with
+            // RTL glyphs, which will be in visual order.
+            for (auto pPrev = pIter - 1; pPrev != m_GlyphItems.begin(); --pPrev)
+            {
+                if (pPrev->charPos() != nCharPos)
+                {
+                    // Check if the found glyph belongs to the next character,
+                    // otherwise the current glyph will be a ligature which is
+                    // invalid kashida position.
+                    if (pPrev->charPos() == (nCharPos + 1))
+                        return true;
+                    break;
+                }
+            }
+        }
+    }
+
+    return false;
+}
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */