flutter_flutter/sky/engine/platform/fonts/GlyphPageTreeNode.cpp

/*
 * Copyright (C) 2006, 2007, 2008 Apple Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
 *     its contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "flutter/sky/engine/platform/fonts/GlyphPageTreeNode.h"

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