path: root/vcl/source/gdi/impglyphitem.cxx

/* -*- 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 <impglyphitem.hxx>
#include <vcl/glyphitemcache.hxx>
#include <vcl/vcllayout.hxx>
#include <vcl/lazydelete.hxx>
#include <tools/stream.hxx>
#include <TextLayoutCache.hxx>
#include <config_fuzzers.h>

// These need being explicit because of SalLayoutGlyphsImpl being private in vcl.
SalLayoutGlyphs::SalLayoutGlyphs() {}

SalLayoutGlyphs::~SalLayoutGlyphs() {}

SalLayoutGlyphs::SalLayoutGlyphs(SalLayoutGlyphs&& rOther) noexcept
{
    std::swap(m_pImpl, rOther.m_pImpl);
    std::swap(m_pExtraImpls, rOther.m_pExtraImpls);
}

SalLayoutGlyphs& SalLayoutGlyphs::operator=(SalLayoutGlyphs&& rOther) noexcept
{
    if (this != &rOther)
    {
        std::swap(m_pImpl, rOther.m_pImpl);
        std::swap(m_pExtraImpls, rOther.m_pExtraImpls);
    }
    return *this;
}

bool SalLayoutGlyphs::IsValid() const
{
    if (m_pImpl == nullptr)
        return false;
    if (!m_pImpl->IsValid())
        return false;
    if (m_pExtraImpls)
        for (std::unique_ptr<SalLayoutGlyphsImpl> const& impl : *m_pExtraImpls)
            if (!impl->IsValid())
                return false;
    return true;
}

void SalLayoutGlyphs::Invalidate()
{
    // Invalidating is in fact simply clearing.
    m_pImpl.reset();
    m_pExtraImpls.reset();
}

SalLayoutGlyphsImpl* SalLayoutGlyphs::Impl(unsigned int nLevel) const
{
    if (nLevel == 0)
        return m_pImpl.get();
    if (m_pExtraImpls != nullptr && nLevel - 1 < m_pExtraImpls->size())
        return (*m_pExtraImpls)[nLevel - 1].get();
    return nullptr;
}

void SalLayoutGlyphs::AppendImpl(SalLayoutGlyphsImpl* pImpl)
{
    if (!m_pImpl)
        m_pImpl.reset(pImpl);
    else
    {
        if (!m_pExtraImpls)
            m_pExtraImpls.reset(new std::vector<std::unique_ptr<SalLayoutGlyphsImpl>>);
        m_pExtraImpls->emplace_back(pImpl);
    }
}

SalLayoutGlyphsImpl* SalLayoutGlyphsImpl::clone() const { return new SalLayoutGlyphsImpl(*this); }

// Clone, but only glyphs in the given range in the original text string.
// It is possible the given range may not be cloned, in which case this returns nullptr.
SalLayoutGlyphsImpl* SalLayoutGlyphsImpl::cloneCharRange(sal_Int32 index, sal_Int32 length) const
{
    std::unique_ptr<SalLayoutGlyphsImpl> copy(new SalLayoutGlyphsImpl(*GetFont()));
    copy->SetFlags(GetFlags());
    copy->reserve(std::min<size_t>(size(), length));
    // Skip glyphs that are in the string before the given index (glyphs are sorted by charPos()).
    const_iterator pos = std::partition_point(
        begin(), end(), [index](const GlyphItem& it) { return it.charPos() < index; });
    if (pos == end())
        return nullptr;
    // Require a start at the exact position given, otherwise bail out.
    // TODO: This bails out also for RTL text.
    if (pos->charPos() != index)
        return nullptr;
    // Don't create a subset if it's not safe to break at the beginning or end of the sequence
    // (https://harfbuzz.github.io/harfbuzz-hb-buffer.html#hb-glyph-flags-t).
    if (pos->IsUnsafeToBreak() || (pos->IsInCluster() && !pos->IsClusterStart()))
        return nullptr;
    // LinearPos needs adjusting to start at xOffset/yOffset for the first item,
    // that's how it's computed in GenericSalLayout::LayoutText().
    DevicePoint zeroPoint = pos->linearPos() - DevicePoint(pos->xOffset(), pos->yOffset());
    // Add and adjust all glyphs until the given length.
    while (pos != end() && pos->charPos() < index + length)
    {
        if (pos->IsRTLGlyph())
            return nullptr; // Don't mix RTL and non-RTL runs.
        copy->push_back(*pos);
        copy->back().setLinearPos(copy->back().linearPos() - zeroPoint);
        ++pos;
    }
    if (pos != end())
    {
        if (pos->charPos() != index + length)
            return nullptr;
        if (pos->IsUnsafeToBreak() || (pos->IsInCluster() && !pos->IsClusterStart()))
            return nullptr;
    }
    return copy.release();
}

#ifdef DBG_UTIL
bool SalLayoutGlyphsImpl::isEqual(const SalLayoutGlyphsImpl* other) const
{
    if (GetFont()->mxFontMetric != other->GetFont()->mxFontMetric)
        return false;
    if (GetFlags() != other->GetFlags())
        return false;
    if (empty() || other->empty())
        return empty() == other->empty();
    if (size() != other->size())
        return false;
    for (size_t pos = 0; pos < size(); ++pos)
    {
        if ((*this)[pos] != (*other)[pos])
            return false;
    }
    return true;
}
#endif

bool SalLayoutGlyphsImpl::IsValid() const
{
    if (!m_rFontInstance.is())
        return false;
    return true;
}

SalLayoutGlyphsCache* SalLayoutGlyphsCache::self()
{
    static vcl::DeleteOnDeinit<SalLayoutGlyphsCache> cache(1000);
    return cache.get();
}

static SalLayoutGlyphs makeGlyphsSubset(const SalLayoutGlyphs& source,
                                        const OutputDevice* outputDevice, std::u16string_view text,
                                        sal_Int32 index, sal_Int32 len)
{
    SalLayoutGlyphs ret;
    for (int level = 0;; ++level)
    {
        const SalLayoutGlyphsImpl* sourceLevel = source.Impl(level);
        if (sourceLevel == nullptr)
            break;
        SalLayoutGlyphsImpl* cloned = sourceLevel->cloneCharRange(index, len);
        // If the glyphs range cannot be cloned, bail out.
        if (cloned == nullptr)
            return SalLayoutGlyphs();
        // If the entire string is mixed LTR/RTL but the subset is only LTR,
        // then make sure the flags match that, otherwise checkGlyphsEqual()
        // would assert on flags being different.
        cloned->SetFlags(cloned->GetFlags()
                         | outputDevice->GetBiDiLayoutFlags(text, index, index + len));
        // SalLayoutFlags::KashidaJustification is set only if any glyph
        // in the range has GlyphItemFlags::ALLOW_KASHIDA (otherwise unset it).
        bool hasKashida = false;
        for (const GlyphItem& item : *cloned)
        {
            if (item.AllowKashida())
            {
                assert(cloned->GetFlags() & SalLayoutFlags::KashidaJustification);
                hasKashida = true;
                break;
            }
        }
        if (!hasKashida)
            cloned->SetFlags(cloned->GetFlags() & ~SalLayoutFlags::KashidaJustification);
        ret.AppendImpl(cloned);
    }
    return ret;
}

#ifdef DBG_UTIL
static void checkGlyphsEqual(const SalLayoutGlyphs& g1, const SalLayoutGlyphs& g2)
{
    for (int level = 0;; ++level)
    {
        const SalLayoutGlyphsImpl* l1 = g1.Impl(level);
        const SalLayoutGlyphsImpl* l2 = g2.Impl(level);
        if (l1 == nullptr || l2 == nullptr)
        {
            assert(l1 == l2);
            break;
        }
        assert(l1->isEqual(l2));
    }
}
#endif

const SalLayoutGlyphs*
SalLayoutGlyphsCache::GetLayoutGlyphs(VclPtr<const OutputDevice> outputDevice, const OUString& text,
                                      sal_Int32 nIndex, sal_Int32 nLen, tools::Long nLogicWidth,
                                      const vcl::text::TextLayoutCache* layoutCache)
{
    if (nLen == 0)
        return nullptr;
    const CachedGlyphsKey key(outputDevice, text, nIndex, nLen, nLogicWidth);
    GlyphsCache::const_iterator it = mCachedGlyphs.find(key);
    if (it != mCachedGlyphs.end())
    {
        if (it->second.IsValid())
            return &it->second;
        // Do not try to create the layout here. If a cache item exists, it's already
        // been attempted and the layout was invalid (this happens with MultiSalLayout).
        // So in that case this is a cached failure.
        return nullptr;
    }
#if !ENABLE_FUZZERS
    const SalLayoutFlags glyphItemsOnlyLayout = SalLayoutFlags::GlyphItemsOnly;
#else
    // ofz#39150 skip detecting bidi directions
    const SalLayoutFlags glyphItemsOnlyLayout
        = SalLayoutFlags::GlyphItemsOnly | SalLayoutFlags::BiDiStrong;
#endif
    if (nIndex != 0 || nLen != text.getLength())
    {
        // The glyphs functions are often called first for an entire string
        // and then with an increasing starting index until the end of the string.
        // Which means it's possible to get the glyphs faster by just copying
        // a subset of the full glyphs and adjusting as necessary.
        if (mLastTemporaryKey.has_value() && mLastTemporaryKey == key)
            return &mLastTemporaryGlyphs;
        const CachedGlyphsKey keyWhole(outputDevice, text, 0, text.getLength(), nLogicWidth);
        GlyphsCache::const_iterator itWhole = mCachedGlyphs.find(keyWhole);
        if (itWhole != mCachedGlyphs.end() && itWhole->second.IsValid())
        {
            mLastTemporaryGlyphs
                = makeGlyphsSubset(itWhole->second, outputDevice, text, nIndex, nLen);
            if (mLastTemporaryGlyphs.IsValid())
            {
                mLastTemporaryKey = std::move(key);
#ifdef DBG_UTIL
                // Check if the subset result really matches what we would get normally,
                // to make sure corner cases are handled well (see SalLayoutGlyphsImpl::cloneCharRange()).
                std::unique_ptr<SalLayout> layout
                    = outputDevice->ImplLayout(text, nIndex, nLen, Point(0, 0), nLogicWidth, {},
                                               glyphItemsOnlyLayout, layoutCache);
                assert(layout);
                checkGlyphsEqual(mLastTemporaryGlyphs, layout->GetGlyphs());
#endif
                return &mLastTemporaryGlyphs;
            }
        }
    }
    std::shared_ptr<const vcl::text::TextLayoutCache> tmpLayoutCache;
    if (layoutCache == nullptr)
    {
        tmpLayoutCache = vcl::text::TextLayoutCache::Create(text);
        layoutCache = tmpLayoutCache.get();
    }
    std::unique_ptr<SalLayout> layout = outputDevice->ImplLayout(
        text, nIndex, nLen, Point(0, 0), nLogicWidth, {}, glyphItemsOnlyLayout, layoutCache);
    if (layout)
    {
        SalLayoutGlyphs glyphs = layout->GetGlyphs();
        if (glyphs.IsValid())
        {
            // TODO: Fallbacks do not work reliably (fallback font not included in the key),
            // so do not cache (but still return once, using the temporary without a key set).
            if (glyphs.Impl(1) != nullptr)
            {
                mLastTemporaryGlyphs = std::move(glyphs);
                mLastTemporaryKey.reset();
                return &mLastTemporaryGlyphs;
            }
            mCachedGlyphs.insert(std::make_pair(key, layout->GetGlyphs()));
            assert(mCachedGlyphs.find(key)
                   == mCachedGlyphs.begin()); // newly inserted item is first
            return &mCachedGlyphs.begin()->second;
        }
    }
    // Failure, cache it too as invalid glyphs.
    mCachedGlyphs.insert(std::make_pair(key, SalLayoutGlyphs()));
    return nullptr;
}

SalLayoutGlyphsCache::CachedGlyphsKey::CachedGlyphsKey(const VclPtr<const OutputDevice>& d,
                                                       const OUString& t, sal_Int32 i, sal_Int32 l,
                                                       tools::Long w)
    : text(t)
    , index(i)
    , len(l)
    , logicWidth(w)
    , outputDevice(d)
    // we also need to save things used in OutputDevice::ImplPrepareLayoutArgs(), in case they
    // change in the output device
    // TODO there is still something missing, otherwise it wouldn't be necessary to compare
    // also the OutputDevice pointers
    , font(outputDevice->GetFont())
    // TODO It would be possible to get a better hit ratio if mapMode wasn't part of the key
    // and results that differ only in mapmode would have coordinates adjusted based on that.
    // That would occassionally lead to rounding errors (at least differences that would
    // make checkGlyphsEqual() fail).
    , mapMode(outputDevice->GetMapMode())
    , rtl(outputDevice->IsRTLEnabled())
    , layoutMode(outputDevice->GetLayoutMode())
    , digitLanguage(outputDevice->GetDigitLanguage())
{
    hashValue = 0;
    o3tl::hash_combine(hashValue, vcl::text::FirstCharsStringHash()(text));
    o3tl::hash_combine(hashValue, index);
    o3tl::hash_combine(hashValue, len);
    o3tl::hash_combine(hashValue, logicWidth);

    o3tl::hash_combine(hashValue, outputDevice.get());
    o3tl::hash_combine(hashValue, font.GetHashValueIgnoreColor());
    o3tl::hash_combine(hashValue, mapMode.GetHashValue());
    o3tl::hash_combine(hashValue, rtl);
    o3tl::hash_combine(hashValue, layoutMode);
    o3tl::hash_combine(hashValue, digitLanguage.get());
}

inline bool SalLayoutGlyphsCache::CachedGlyphsKey::operator==(const CachedGlyphsKey& other) const
{
    return hashValue == other.hashValue && index == other.index && len == other.len
           && logicWidth == other.logicWidth && outputDevice == other.outputDevice
           && mapMode == other.mapMode && rtl == other.rtl && layoutMode == other.layoutMode
           && digitLanguage == other.digitLanguage
           // Need to use EqualIgnoreColor, because sometimes the color changes, but it's irrelevant
           // for text layout (and also obsolete in vcl::Font).
           && font.EqualIgnoreColor(other.font)
           && vcl::text::FastStringCompareEqual()(text, other.text);
    // Slower things last in the comparison.
}

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