flutter_flutter/engine/platform/fonts/GlyphPageTreeNode.cpp

/*
 * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
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 * are met:
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 *     notice, this list of conditions and the following disclaimer.
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 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
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#include "sky/engine/config.h"
#include "sky/engine/platform/fonts/GlyphPageTreeNode.h"

#include <stdio.h>
#include "sky/engine/platform/fonts/SegmentedFontData.h"
#include "sky/engine/platform/fonts/SimpleFontData.h"
#include "sky/engine/platform/fonts/opentype/OpenTypeVerticalData.h"
#include "sky/engine/wtf/text/CString.h"
#include "sky/engine/wtf/text/WTFString.h"
#include "sky/engine/wtf/unicode/CharacterNames.h"

namespace blink {

using std::max;
using std::min;

HashMap<int, GlyphPageTreeNode*>* GlyphPageTreeNode::roots = 0;
GlyphPageTreeNode* GlyphPageTreeNode::pageZeroRoot = 0;

GlyphPageTreeNode* GlyphPageTreeNode::getRoot(unsigned pageNumber)
{
    static bool initialized;
    if (!initialized) {
        initialized = true;
        roots = new HashMap<int, GlyphPageTreeNode*>;
        pageZeroRoot = new GlyphPageTreeNode;
    }

    if (!pageNumber)
        return pageZeroRoot;

    if (GlyphPageTreeNode* foundNode = roots->get(pageNumber))
        return foundNode;

    GlyphPageTreeNode* node = new GlyphPageTreeNode;
#if ENABLE(ASSERT)
    node->m_pageNumber = pageNumber;
#endif
    roots->set(pageNumber, node);
    return node;
}

size_t GlyphPageTreeNode::treeGlyphPageCount()
{
    size_t count = 0;
    if (roots) {
        HashMap<int, GlyphPageTreeNode*>::iterator end = roots->end();
        for (HashMap<int, GlyphPageTreeNode*>::iterator it = roots->begin(); it != end; ++it)
            count += it->value->pageCount();
    }

    if (pageZeroRoot)
        count += pageZeroRoot->pageCount();

    return count;
}

size_t GlyphPageTreeNode::pageCount() const
{
    size_t count = m_page && m_page->owner() == this ? 1 : 0;
    GlyphPageTreeNodeMap::const_iterator end = m_children.end();
    for (GlyphPageTreeNodeMap::const_iterator it = m_children.begin(); it != end; ++it)
        count += it->value->pageCount();

    return count;
}

void GlyphPageTreeNode::pruneTreeCustomFontData(const FontData* fontData)
{
    // Enumerate all the roots and prune any tree that contains our custom font data.
    if (roots) {
        HashMap<int, GlyphPageTreeNode*>::iterator end = roots->end();
        for (HashMap<int, GlyphPageTreeNode*>::iterator it = roots->begin(); it != end; ++it)
            it->value->pruneCustomFontData(fontData);
    }

    if (pageZeroRoot)
        pageZeroRoot->pruneCustomFontData(fontData);
}

void GlyphPageTreeNode::pruneTreeFontData(const SimpleFontData* fontData)
{
    if (roots) {
        HashMap<int, GlyphPageTreeNode*>::iterator end = roots->end();
        for (HashMap<int, GlyphPageTreeNode*>::iterator it = roots->begin(); it != end; ++it)
            it->value->pruneFontData(fontData);
    }

    if (pageZeroRoot)
        pageZeroRoot->pruneFontData(fontData);
}

static bool fill(GlyphPage* pageToFill, unsigned offset, unsigned length, UChar* buffer, unsigned bufferLength, const SimpleFontData* fontData)
{
    bool hasGlyphs = fontData->fillGlyphPage(pageToFill, offset, length, buffer, bufferLength);
#if ENABLE(OPENTYPE_VERTICAL)
    if (hasGlyphs && fontData->verticalData())
        fontData->verticalData()->substituteWithVerticalGlyphs(fontData, pageToFill, offset, length);
#endif
    return hasGlyphs;
}

void GlyphPageTreeNode::initializePage(const FontData* fontData, unsigned pageNumber)
{
    ASSERT(!m_page);

    // This function must not be called for the root of the tree, because that
    // level does not contain any glyphs.
    ASSERT(m_level > 0 && m_parent);

    // The parent's page will be 0 if we are level one or the parent's font data
    // did not contain any glyphs for that page.
    GlyphPage* parentPage = m_parent->page();

    // NULL FontData means we're being asked for the system fallback font.
    if (fontData) {
        if (m_level == 1) {
            // Children of the root hold pure pages. These will cover only one
            // font data's glyphs, and will have glyph index 0 if the font data does not
            // contain the glyph.
            unsigned start = pageNumber * GlyphPage::size;
            UChar buffer[GlyphPage::size * 2 + 2];
            unsigned bufferLength;
            unsigned i;

            // Fill in a buffer with the entire "page" of characters that we want to look up glyphs for.
            if (start < 0x10000) {
                bufferLength = GlyphPage::size;
                for (i = 0; i < GlyphPage::size; i++)
                    buffer[i] = start + i;

                if (start == 0) {
                    // Control characters must not render at all.
                    for (i = 0; i < 0x20; ++i)
                        buffer[i] = zeroWidthSpace;
                    for (i = 0x7F; i < 0xA0; i++)
                        buffer[i] = zeroWidthSpace;
                    buffer[softHyphen] = zeroWidthSpace;

                    // \n, \t, and nonbreaking space must render as a space.
                    buffer[newlineCharacter] = space;
                    buffer[characterTabulation] = space;
                    buffer[noBreakSpace] = space;
                } else if (start == (leftToRightMark & ~(GlyphPage::size - 1))) {
                    // LRM, RLM, LRE, RLE, ZWNJ, ZWJ, and PDF must not render at all.
                    buffer[leftToRightMark - start] = zeroWidthSpace;
                    buffer[rightToLeftMark - start] = zeroWidthSpace;
                    buffer[leftToRightEmbed - start] = zeroWidthSpace;
                    buffer[rightToLeftEmbed - start] = zeroWidthSpace;
                    buffer[leftToRightOverride - start] = zeroWidthSpace;
                    buffer[rightToLeftOverride - start] = zeroWidthSpace;
                    buffer[zeroWidthNonJoiner - start] = zeroWidthSpace;
                    buffer[zeroWidthJoiner - start] = zeroWidthSpace;
                    buffer[popDirectionalFormatting - start] = zeroWidthSpace;
                } else if (start == (objectReplacementCharacter & ~(GlyphPage::size - 1))) {
                    // Object replacement character must not render at all.
                    buffer[objectReplacementCharacter - start] = zeroWidthSpace;
                } else if (start == (zeroWidthNoBreakSpace & ~(GlyphPage::size - 1))) {
                    // ZWNBS/BOM must not render at all.
                    buffer[zeroWidthNoBreakSpace - start] = zeroWidthSpace;
                }
            } else {
                bufferLength = GlyphPage::size * 2;
                for (i = 0; i < GlyphPage::size; i++) {
                    int c = i + start;
                    buffer[i * 2] = U16_LEAD(c);
                    buffer[i * 2 + 1] = U16_TRAIL(c);
                }
            }

            // Now that we have a buffer full of characters, we want to get back an array
            // of glyph indices.  This part involves calling into the platform-specific
            // routine of our glyph map for actually filling in the page with the glyphs.
            // Success is not guaranteed. For example, Times fails to fill page 260, giving glyph data
            // for only 128 out of 256 characters.
            bool haveGlyphs;
            if (!fontData->isSegmented()) {
                m_page = GlyphPage::createForSingleFontData(this, toSimpleFontData(fontData));
                haveGlyphs = fill(m_page.get(), 0, GlyphPage::size, buffer, bufferLength, toSimpleFontData(fontData));
            } else {
                m_page = GlyphPage::createForMixedFontData(this);
                haveGlyphs = false;

                const SegmentedFontData* segmentedFontData = toSegmentedFontData(fontData);
                for (int i = segmentedFontData->numRanges() - 1; i >= 0; i--) {
                    const FontDataRange& range = segmentedFontData->rangeAt(i);
                    // all this casting is to ensure all the parameters to min and max have the same type,
                    // to avoid ambiguous template parameter errors on Windows
                    int from = max(0, static_cast<int>(range.from()) - static_cast<int>(start));
                    int to = 1 + min(static_cast<int>(range.to()) - static_cast<int>(start), static_cast<int>(GlyphPage::size) - 1);
                    if (from >= static_cast<int>(GlyphPage::size) || to <= 0)
                        continue;

                    // If this is a custom font needs to be loaded, do not fill
                    // the page so that font fallback is used while loading.
                    RefPtr<CustomFontData> customData = range.fontData()->customFontData();
                    if (customData && customData->isLoadingFallback()) {
                        for (int j = from; j < to; j++) {
                            m_page->setCustomFontToLoad(j, customData.get());
                            haveGlyphs = true;
                        }
                        continue;
                    }

                    haveGlyphs |= fill(m_page.get(), from, to - from, buffer + from * (start < 0x10000 ? 1 : 2), (to - from) * (start < 0x10000 ? 1 : 2), range.fontData().get());
                }
            }

            if (!haveGlyphs)
                m_page = nullptr;
        } else if (parentPage && parentPage->owner() != m_parent) {
            // The page we're overriding may not be owned by our parent node.
            // This happens when our parent node provides no useful overrides
            // and just copies the pointer to an already-existing page (see
            // below).
            //
            // We want our override to be shared by all nodes that reference
            // that page to avoid duplication, and so standardize on having the
            // page's owner collect all the overrides.  Call getChild on the
            // page owner with the desired font data (this will populate
            // the page) and then reference it.
            m_page = parentPage->owner()->getChild(fontData, pageNumber)->page();
        } else {
            // Get the pure page for the fallback font (at level 1 with no
            // overrides). getRootChild will always create a page if one
            // doesn't exist, but the page doesn't necessarily have glyphs
            // (this pointer may be 0).
            GlyphPage* fallbackPage = getRootChild(fontData, pageNumber)->page();
            if (!parentPage) {
                // When the parent has no glyphs for this page, we can easily
                // override it just by supplying the glyphs from our font.
                m_page = fallbackPage;
            } else if (!fallbackPage) {
                // When our font has no glyphs for this page, we can just reference the
                // parent page.
                m_page = parentPage;
            } else {
                // Combine the parent's glyphs and ours to form a new more complete page.
                m_page = GlyphPage::createForMixedFontData(this);

                // Overlay the parent page on the fallback page. Check if the fallback font
                // has added anything.
                bool newGlyphs = false;
                for (unsigned i = 0; i < GlyphPage::size; i++) {
                    if (parentPage->glyphAt(i)) {
                        m_page->setGlyphDataForIndex(i, parentPage->glyphDataForIndex(i));
                    } else if (fallbackPage->glyphAt(i)) {
                        m_page->setGlyphDataForIndex(i, fallbackPage->glyphDataForIndex(i));
                        newGlyphs = true;
                    }

                    if (parentPage->customFontToLoadAt(i)) {
                        m_page->setCustomFontToLoad(i, parentPage->customFontToLoadAt(i));
                    } else if (fallbackPage->customFontToLoadAt(i) && !parentPage->glyphAt(i)) {
                        m_page->setCustomFontToLoad(i, fallbackPage->customFontToLoadAt(i));
                        newGlyphs = true;
                    }
                }

                if (!newGlyphs)
                    // We didn't override anything, so our override is just the parent page.
                    m_page = parentPage;
            }
        }
    } else {
        // System fallback. Initialized with the parent's page here, as individual
        // entries may use different fonts depending on character. If the Font
        // ever finds it needs a glyph out of the system fallback page, it will
        // ask the system for the best font to use and fill that glyph in for us.
        if (parentPage)
            m_page = parentPage->createCopiedSystemFallbackPage(this);
        else
            m_page = GlyphPage::createForMixedFontData(this);
    }
}

GlyphPageTreeNode* GlyphPageTreeNode::getChild(const FontData* fontData, unsigned pageNumber)
{
    ASSERT(fontData || !m_isSystemFallback);
    ASSERT(pageNumber == m_pageNumber);

    if (GlyphPageTreeNode* foundChild = fontData ? m_children.get(fontData) : m_systemFallbackChild.get())
        return foundChild;

    GlyphPageTreeNode* child = new GlyphPageTreeNode;
    child->m_parent = this;
    child->m_level = m_level + 1;
    if (fontData && fontData->isCustomFont()) {
        for (GlyphPageTreeNode* curr = this; curr; curr = curr->m_parent)
            curr->m_customFontCount++;
    }

#if ENABLE(ASSERT)
    child->m_pageNumber = m_pageNumber;
#endif
    if (fontData) {
        m_children.set(fontData, adoptPtr(child));
        fontData->setMaxGlyphPageTreeLevel(max(fontData->maxGlyphPageTreeLevel(), child->m_level));
    } else {
        m_systemFallbackChild = adoptPtr(child);
        child->m_isSystemFallback = true;
    }
    child->initializePage(fontData, pageNumber);
    return child;
}

void GlyphPageTreeNode::pruneCustomFontData(const FontData* fontData)
{
    if (!fontData || !m_customFontCount)
        return;

    // Prune any branch that contains this FontData.
    if (OwnPtr<GlyphPageTreeNode> node = m_children.take(fontData)) {
        if (unsigned customFontCount = node->m_customFontCount + 1) {
            for (GlyphPageTreeNode* curr = this; curr; curr = curr->m_parent)
                curr->m_customFontCount -= customFontCount;
        }
    }

    // Check any branches that remain that still have custom fonts underneath them.
    if (!m_customFontCount)
        return;

    GlyphPageTreeNodeMap::iterator end = m_children.end();
    for (GlyphPageTreeNodeMap::iterator it = m_children.begin(); it != end; ++it)
        it->value->pruneCustomFontData(fontData);
}

void GlyphPageTreeNode::pruneFontData(const SimpleFontData* fontData, unsigned level)
{
    ASSERT(fontData);

    // Prune fall back child (if any) of this font.
    if (m_systemFallbackChild && m_systemFallbackChild->m_page)
        m_systemFallbackChild->m_page->removeFontDataFromSystemFallbackPage(fontData);

    // Prune any branch that contains this FontData.
    if (OwnPtr<GlyphPageTreeNode> node = m_children.take(fontData)) {
        if (unsigned customFontCount = node->m_customFontCount) {
            for (GlyphPageTreeNode* curr = this; curr; curr = curr->m_parent)
                curr->m_customFontCount -= customFontCount;
        }
    }

    level++;
    if (level > fontData->maxGlyphPageTreeLevel())
        return;

    GlyphPageTreeNodeMap::iterator end = m_children.end();
    for (GlyphPageTreeNodeMap::iterator it = m_children.begin(); it != end; ++it)
        it->value->pruneFontData(fontData, level);
}

#ifndef NDEBUG
    void GlyphPageTreeNode::showSubtree()
    {
        Vector<char> indent(level());
        indent.fill('\t', level());
        indent.append(0);

        GlyphPageTreeNodeMap::iterator end = m_children.end();
        for (GlyphPageTreeNodeMap::iterator it = m_children.begin(); it != end; ++it) {
            printf("%s\t%p %s\n", indent.data(), it->key, it->key->description().utf8().data());
            it->value->showSubtree();
        }
        if (m_systemFallbackChild) {
            printf("%s\t* fallback\n", indent.data());
            m_systemFallbackChild->showSubtree();
        }
    }
#endif

} // namespace blink

#ifndef NDEBUG
void showGlyphPageTrees()
{
    printf("Page 0:\n");
    showGlyphPageTree(0);
    HashMap<int, blink::GlyphPageTreeNode*>::iterator end = blink::GlyphPageTreeNode::roots->end();
    for (HashMap<int, blink::GlyphPageTreeNode*>::iterator it = blink::GlyphPageTreeNode::roots->begin(); it != end; ++it) {
        printf("\nPage %d:\n", it->key);
        showGlyphPageTree(it->key);
    }
}

void showGlyphPageTree(unsigned pageNumber)
{
    blink::GlyphPageTreeNode::getRoot(pageNumber)->showSubtree();
}
#endif