Source/WebCore/dom/ScriptedAnimationController.cpp

/*
 * Copyright (C) 2011 Google Inc. All Rights Reserved.
 * Copyright (C) 2020 Apple Inc.  All rights reserved.
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 *    notice, this list of conditions and the following disclaimer in the
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 *  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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#include "config.h"
#include "ScriptedAnimationController.h"

#include "InspectorInstrumentation.h"
#include "Page.h"
#include "Quirks.h"
#include "RequestAnimationFrameCallback.h"
#include "Settings.h"
#include <wtf/Ref.h>
#include <wtf/SystemTracing.h>

namespace WebCore {

ScriptedAnimationController::ScriptedAnimationController(Document& document)
    : m_document(makeWeakPtr(document))
{
}

ScriptedAnimationController::~ScriptedAnimationController() = default;

bool ScriptedAnimationController::requestAnimationFrameEnabled() const
{
    return m_document && m_document->settings().requestAnimationFrameEnabled();
}

void ScriptedAnimationController::suspend()
{
    ++m_suspendCount;
}

void ScriptedAnimationController::resume()
{
    // It would be nice to put an ASSERT(m_suspendCount > 0) here, but in WK1 resume() can be called
    // even when suspend hasn't (if a tab was created in the background).
    if (m_suspendCount > 0)
        --m_suspendCount;

    if (!m_suspendCount && m_callbacks.size())
        scheduleAnimation();
}

Page* ScriptedAnimationController::page() const
{
    return m_document ? m_document->page() : nullptr;
}

Seconds ScriptedAnimationController::interval() const
{
    if (auto* page = this->page())
        return std::max(preferredScriptedAnimationInterval(), page->preferredRenderingUpdateInterval());
    return FullSpeedAnimationInterval;
}

Seconds ScriptedAnimationController::preferredScriptedAnimationInterval() const
{
    return preferredFrameInterval(m_throttlingReasons);
}

OptionSet<ThrottlingReason> ScriptedAnimationController::throttlingReasons() const
{
    if (auto* page = this->page())
        return page->throttlingReasons() | m_throttlingReasons;
    return { };
}

bool ScriptedAnimationController::isThrottledRelativeToPage() const
{
    if (auto* page = this->page())
        return preferredScriptedAnimationInterval() > page->preferredRenderingUpdateInterval();
    return false;
}

bool ScriptedAnimationController::shouldRescheduleRequestAnimationFrame(ReducedResolutionSeconds timestamp) const
{
    return isThrottledRelativeToPage() && (timestamp - m_lastAnimationFrameTimestamp < preferredScriptedAnimationInterval());
}

ScriptedAnimationController::CallbackId ScriptedAnimationController::registerCallback(Ref<RequestAnimationFrameCallback>&& callback)
{
    CallbackId callbackId = ++m_nextCallbackId;
    callback->m_firedOrCancelled = false;
    callback->m_id = callbackId;
    m_callbacks.append(WTFMove(callback));

    if (m_document)
        InspectorInstrumentation::didRequestAnimationFrame(*m_document, callbackId);

    if (!m_suspendCount)
        scheduleAnimation();
    return callbackId;
}

void ScriptedAnimationController::cancelCallback(CallbackId callbackId)
{
    bool cancelled = m_callbacks.removeFirstMatching([callbackId](auto& callback) {
        if (callback->m_id != callbackId)
            return false;
        callback->m_firedOrCancelled = true;
        return true;
    });

    if (cancelled && m_document)
        InspectorInstrumentation::didCancelAnimationFrame(*m_document, callbackId);
}

void ScriptedAnimationController::serviceRequestAnimationFrameCallbacks(ReducedResolutionSeconds timestamp)
{
    if (!m_callbacks.size() || m_suspendCount || !requestAnimationFrameEnabled())
        return;

    if (shouldRescheduleRequestAnimationFrame(timestamp)) {
        scheduleAnimation();
        return;
    }
    
    TraceScope tracingScope(RAFCallbackStart, RAFCallbackEnd);

    auto highResNowMs = std::round(1000 * timestamp.seconds());
    if (m_document && m_document->quirks().needsMillisecondResolutionForHighResTimeStamp())
        highResNowMs += 0.1;

    // First, generate a list of callbacks to consider.  Callbacks registered from this point
    // on are considered only for the "next" frame, not this one.
    CallbackList callbacks(m_callbacks);

    // Invoking callbacks may detach elements from our document, which clears the document's
    // reference to us, so take a defensive reference.
    Ref<ScriptedAnimationController> protectedThis(*this);
    Ref<Document> protectedDocument(*m_document);

    for (auto& callback : callbacks) {
        if (callback->m_firedOrCancelled)
            continue;
        callback->m_firedOrCancelled = true;

        InspectorInstrumentation::willFireAnimationFrame(protectedDocument, callback->m_id);
        callback->handleEvent(highResNowMs);
        InspectorInstrumentation::didFireAnimationFrame(protectedDocument);
    }

    // Remove any callbacks we fired from the list of pending callbacks.
    m_callbacks.removeAllMatching([](auto& callback) {
        return callback->m_firedOrCancelled;
    });

    m_lastAnimationFrameTimestamp = timestamp;

    if (m_callbacks.size())
        scheduleAnimation();
}

void ScriptedAnimationController::scheduleAnimation()
{
    if (!requestAnimationFrameEnabled())
        return;

    if (auto* page = this->page())
        page->renderingUpdateScheduler().scheduleTimedRenderingUpdate();
}

}