Source/WebCore/html/track/VTTRegion.h

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
 * Copyright (C) 2014 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:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * 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.
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 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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 */

#pragma once

#if ENABLE(VIDEO_TRACK)

#include "ContextDestructionObserver.h"
#include "FloatPoint.h"
#include "TextTrack.h"

namespace WebCore {

class HTMLDivElement;
class VTTCueBox;
class VTTScanner;

class VTTRegion final : public RefCounted<VTTRegion>, public ContextDestructionObserver {
public:
    static Ref<VTTRegion> create(ScriptExecutionContext& context)
    {
        return adoptRef(*new VTTRegion(context));
    }

    virtual ~VTTRegion();

    TextTrack* track() const { return m_track; }
    void setTrack(TextTrack*);

    const String& id() const { return m_id; }
    void setId(const String&);

    double width() const { return m_width; }
    ExceptionOr<void> setWidth(double);

    int height() const { return m_heightInLines; }
    ExceptionOr<void> setHeight(int);

    double regionAnchorX() const { return m_regionAnchor.x(); }
    ExceptionOr<void> setRegionAnchorX(double);

    double regionAnchorY() const { return m_regionAnchor.y(); }
    ExceptionOr<void> setRegionAnchorY(double);

    double viewportAnchorX() const { return m_viewportAnchor.x(); }
    ExceptionOr<void> setViewportAnchorX(double);

    double viewportAnchorY() const { return m_viewportAnchor.y(); }
    ExceptionOr<void> setViewportAnchorY(double);

    const AtomicString& scroll() const;
    ExceptionOr<void> setScroll(const AtomicString&);

    void updateParametersFromRegion(const VTTRegion&);

    const String& regionSettings() const { return m_settings; }
    void setRegionSettings(const String&);

    bool isScrollingRegion() { return m_scroll; }

    HTMLDivElement& getDisplayTree();
    
    void appendTextTrackCueBox(Ref<VTTCueBox>&&);
    void displayLastTextTrackCueBox();
    void willRemoveTextTrackCueBox(VTTCueBox*);

private:
    VTTRegion(ScriptExecutionContext&);

    void prepareRegionDisplayTree();

    // The timer is needed to continue processing when cue scrolling ended.
    void startTimer();
    void stopTimer();
    void scrollTimerFired();

    enum RegionSetting {
        None,
        Id,
        Width,
        Height,
        RegionAnchor,
        ViewportAnchor,
        Scroll
    };

    RegionSetting scanSettingName(VTTScanner&);

    void parseSettingValue(RegionSetting, VTTScanner&);

    static const AtomicString& textTrackCueContainerShadowPseudoId();
    static const AtomicString& textTrackCueContainerScrollingClass();
    static const AtomicString& textTrackRegionShadowPseudoId();

    String m_id;
    String m_settings;

    double m_width { 100 };
    unsigned m_heightInLines { 3 };

    FloatPoint m_regionAnchor { 0, 100 };
    FloatPoint m_viewportAnchor { 0, 100 };

    bool m_scroll { false };

    // The cue container is the container that is scrolled up to obtain the
    // effect of scrolling cues when this is enabled for the regions.
    RefPtr<HTMLDivElement> m_cueContainer;
    RefPtr<HTMLDivElement> m_regionDisplayTree;

    // The member variable track can be a raw pointer as it will never
    // reference a destroyed TextTrack, as this member variable
    // is cleared in the TextTrack destructor and it is generally
    // set/reset within the addRegion and removeRegion methods.
    TextTrack* m_track { nullptr };

    // Keep track of the current numeric value of the css "top" property.
    double m_currentTop { 0 };

    // The timer is used to display the next cue line after the current one has
    // been displayed. It's main use is for scrolling regions and it triggers as
    // soon as the animation for rolling out one line has finished, but
    // currently it is used also for non-scrolling regions to use a single
    // code path.
    Timer m_scrollTimer;
};

} // namespace WebCore

#endif