--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/webengine/osswebengine/WebCore/platform/GlyphPageTreeNode.h Mon Mar 30 12:54:55 2009 +0300
@@ -0,0 +1,156 @@
+/*
+ * Copyright (C) 2006 Apple Computer, 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
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef GlyphPageTreeNode_h
+#define GlyphPageTreeNode_h
+
+#include <wtf/unicode/Unicode.h>
+#include <wtf/Noncopyable.h>
+#include <wtf/HashMap.h>
+
+namespace WebCore {
+
+class FontData;
+class GlyphPageTreeNode;
+
+typedef unsigned short Glyph;
+
+// Holds the glyph index and the corresponding FontData information for a given
+// character.
+struct GlyphData {
+ Glyph glyph;
+ const FontData* fontData;
+};
+
+// A GlyphPage contains a fixed-size set of GlyphData mappings for a contiguous
+// range of characters in the Unicode code space. GlyphPages are indexed
+// starting from 0 and incrementing for each 256 glyphs.
+//
+// One page may actually include glyphs from other fonts if the characters are
+// missing in the parimary font. It is owned by exactly one GlyphPageTreeNode,
+// although multiple nodes may reference it as their "page" if they are supposed
+// to be overriding the parent's node, but provide no additional information.
+struct GlyphPage {
+ GlyphPage()
+ : m_owner(0)
+ {
+ }
+
+ GlyphPage(GlyphPageTreeNode* owner)
+ : m_owner(owner)
+ {
+ }
+
+ static const size_t size = 256; // Covers Latin-1 in a single page.
+ GlyphData m_glyphs[size];
+ GlyphPageTreeNode* m_owner;
+
+ const GlyphData& glyphDataForCharacter(UChar32 c) const { return m_glyphs[c % size]; }
+ void setGlyphDataForCharacter(UChar32 c, Glyph g, const FontData* f)
+ {
+ setGlyphDataForIndex(c % size, g, f);
+ }
+ void setGlyphDataForIndex(unsigned index, Glyph g, const FontData* f)
+ {
+ m_glyphs[index].glyph = g;
+ m_glyphs[index].fontData = f;
+ }
+ GlyphPageTreeNode* owner() const { return m_owner; }
+ // Implemented by the platform.
+ bool fill(UChar* characterBuffer, unsigned bufferLength, const FontData* fontData);
+};
+
+// The glyph page tree is a data structure that maps (FontData, glyph page number)
+// to a GlyphPage. Level 0 (the "root") is special. There is one root
+// GlyphPageTreeNode for each glyph page number. The roots do not have a
+// GlyphPage associated with them, and their initializePage() function is never
+// called to fill the glyphs.
+//
+// Each root node maps a FontData pointer to another GlyphPageTreeNode at
+// level 1 (the "root child") that stores the actual glyphs for a specific font data.
+// These nodes will only have a GlyphPage if they have glyphs for that range.
+//
+// Levels greater than one correspond to subsequent levels of the fallback list
+// for that font. These levels override their parent's page of glyphs by
+// filling in holes with the new font (thus making a more complete page).
+//
+// A NULL FontData pointer corresponds to the system fallback
+// font. It is tracked separately from the regular pages and overrides so that
+// the glyph pages do not get polluted with these last-resort glyphs. The
+// system fallback page is not populated at construction like the other pages,
+// but on demand for each glyph, because the system may need to use different
+// fallback fonts for each. This lazy population is done by the Font.
+class GlyphPageTreeNode {
+public:
+ GlyphPageTreeNode()
+ : m_parent(0)
+ , m_page(0)
+ , m_level(0)
+ , m_isSystemFallback(false)
+ , m_systemFallbackChild(0)
+#ifndef NDEBUG
+ , m_pageNumber(0)
+#endif
+ {
+ }
+
+ static GlyphPageTreeNode* getRootChild(const FontData* fontData, unsigned pageNumber)
+ {
+ return getRoot(pageNumber)->getChild(fontData, pageNumber);
+ }
+
+ GlyphPageTreeNode* parent() const { return m_parent; }
+ GlyphPageTreeNode* getChild(const FontData*, unsigned pageNumber);
+
+ // Returns a page of glyphs (or NULL if there are no glyphs in this page's character range).
+ GlyphPage* page() const { return m_page; }
+
+ // Returns the level of this node. See class-level comment.
+ unsigned level() const { return m_level; }
+
+ // The system fallback font has special rules (see above).
+ bool isSystemFallback() const { return m_isSystemFallback; }
+
+private:
+ static GlyphPageTreeNode* getRoot(unsigned pageNumber);
+ void initializePage(const FontData*, unsigned pageNumber);
+
+ GlyphPageTreeNode* m_parent;
+ GlyphPage* m_page;
+ unsigned m_level;
+ bool m_isSystemFallback;
+ HashMap<const FontData*, GlyphPageTreeNode*> m_children;
+ GlyphPageTreeNode* m_systemFallbackChild;
+#ifndef NDEBUG
+ unsigned m_pageNumber;
+#endif
+};
+
+} // namespace WebCore
+
+#endif // GlyphPageTreeNode_h