TextAutosizer.h   [plain text]

/*
 * Copyright (C) 2012 Google 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.
 *
 * 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;
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 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef TextAutosizer_h
#define TextAutosizer_h

#if ENABLE(TEXT_AUTOSIZING)

#include "HTMLNames.h"
#include "WritingMode.h"
#include <wtf/Noncopyable.h>

namespace WebCore {

class Document;
class RenderBlock;
class RenderObject;
class RenderText;
struct TextAutosizingWindowInfo;
struct TextAutosizingClusterInfo;

class TextAutosizer final {
    WTF_MAKE_NONCOPYABLE(TextAutosizer); WTF_MAKE_FAST_ALLOCATED;

public:
    explicit TextAutosizer(Document*);
    ~TextAutosizer();

    bool processSubtree(RenderObject* layoutRoot);
    void recalculateMultipliers();

    static float computeAutosizedFontSize(float specifiedSize, float multiplier);

private:
    enum TraversalDirection {
        FirstToLast,
        LastToFirst
    };

    float clusterMultiplier(WritingMode, const TextAutosizingWindowInfo&, float textWidth) const;

    void processClusterInternal(TextAutosizingClusterInfo&, RenderBlock* container, RenderObject* subtreeRoot, const TextAutosizingWindowInfo&, float multiplier);
    void processCluster(TextAutosizingClusterInfo&, RenderBlock* container, RenderObject* subtreeRoot, const TextAutosizingWindowInfo&);
    void processCompositeCluster(Vector<TextAutosizingClusterInfo>&, const TextAutosizingWindowInfo&);
    void processContainer(float multiplier, RenderBlock* container, TextAutosizingClusterInfo&, RenderObject* subtreeRoot, const TextAutosizingWindowInfo&);

    void setMultiplier(RenderObject*, float);

    static bool isAutosizingContainer(const RenderObject*);
    static bool isNarrowDescendant(const RenderBlock*, TextAutosizingClusterInfo& parentClusterInfo);
    static bool isWiderDescendant(const RenderBlock*, const TextAutosizingClusterInfo& parentClusterInfo);
    static bool isIndependentDescendant(const RenderBlock*);
    static bool isAutosizingCluster(const RenderBlock*, TextAutosizingClusterInfo& parentClusterInfo);

    static bool containerShouldBeAutosized(const RenderBlock* container);
    static bool containerContainsOneOfTags(const RenderBlock* cluster, const Vector<QualifiedName>& tags);
    static bool containerIsRowOfLinks(const RenderObject* container);
    static bool contentHeightIsConstrained(const RenderBlock* container);
    static bool clusterShouldBeAutosized(TextAutosizingClusterInfo&, float blockWidth);
    static bool compositeClusterShouldBeAutosized(Vector<TextAutosizingClusterInfo>&, float blockWidth);
    static void measureDescendantTextWidth(const RenderBlock* container, TextAutosizingClusterInfo&, float minTextWidth, float& textWidth);

    // Use to traverse the tree of descendants, excluding descendants of containers (but returning the containers themselves).
    static RenderObject* nextInPreOrderSkippingDescendantsOfContainers(const RenderObject*, const RenderObject* stayWithin);

    static const RenderBlock* findDeepestBlockContainingAllText(const RenderBlock* cluster);

    // Depending on the traversal direction specified, finds the first or the last leaf text node child that doesn't
    // belong to any cluster.
    static const RenderObject* findFirstTextLeafNotInCluster(const RenderObject*, size_t& depth, TraversalDirection);

    // Returns groups of narrow descendants of a given autosizing cluster. The groups are combined
    // by the difference between the width of the descendant and the width of the parent cluster's
    // |blockContainingAllText|.
    static void getNarrowDescendantsGroupedByWidth(const TextAutosizingClusterInfo& parentClusterInfo, Vector<Vector<TextAutosizingClusterInfo> >&);

    Document* m_document;
};

} // namespace WebCore

#endif // ENABLE(TEXT_AUTOSIZING)

#endif // TextAutosizer_h