gecko/layout/base/nsRefreshDriver.cpp

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is nsRefreshDriver.
*
* The Initial Developer of the Original Code is the Mozilla Foundation.
* Portions created by the Initial Developer are Copyright (C) 2009
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
* L. David Baron <dbaron@dbaron.org>, Mozilla Corporation (original author)
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
/*
* Code to notify things that animate before a refresh, at an appropriate
* refresh rate. (Perhaps temporary, until replaced by compositor.)
*/
#include "nsRefreshDriver.h"
#include "nsPresContext.h"
#include "nsComponentManagerUtils.h"
#include "prlog.h"
#include "nsAutoPtr.h"
#include "nsCSSFrameConstructor.h"
#include "nsIDocument.h"
#include "nsGUIEvent.h"
#include "nsEventDispatcher.h"
#include "jsapi.h"
#include "nsContentUtils.h"
using mozilla::TimeStamp;
#define DEFAULT_FRAME_RATE 60
#define DEFAULT_THROTTLED_FRAME_RATE 1
static PRBool sPrecisePref;
/* static */ void
nsRefreshDriver::InitializeStatics()
{
nsContentUtils::AddBoolPrefVarCache("layout.frame_rate.precise",
&sPrecisePref,
PR_FALSE);
}
// Compute the interval to use for the refresh driver timer, in
// milliseconds
PRInt32
nsRefreshDriver::GetRefreshTimerInterval() const
{
const char* prefName =
mThrottled ? "layout.throttled_frame_rate" : "layout.frame_rate";
PRInt32 rate = nsContentUtils::GetIntPref(prefName, -1);
if (rate <= 0) {
// TODO: get the rate from the platform
rate = mThrottled ? DEFAULT_THROTTLED_FRAME_RATE : DEFAULT_FRAME_RATE;
}
NS_ASSERTION(rate > 0, "Must have positive rate here");
PRInt32 interval = NSToIntRound(1000.0/rate);
if (mThrottled) {
interval = NS_MAX(interval, mLastTimerInterval * 2);
}
mLastTimerInterval = interval;
return interval;
}
PRInt32
nsRefreshDriver::GetRefreshTimerType() const
{
if (mThrottled) {
return nsITimer::TYPE_ONE_SHOT;
}
if (HaveAnimationFrameListeners() || sPrecisePref) {
return nsITimer::TYPE_REPEATING_PRECISE;
}
return nsITimer::TYPE_REPEATING_SLACK;
}
nsRefreshDriver::nsRefreshDriver(nsPresContext *aPresContext)
: mPresContext(aPresContext),
mFrozen(false),
mThrottled(false),
mTimerIsPrecise(false),
mLastTimerInterval(0)
{
}
nsRefreshDriver::~nsRefreshDriver()
{
NS_ABORT_IF_FALSE(ObserverCount() == 0,
"observers should have unregistered");
NS_ABORT_IF_FALSE(!mTimer, "timer should be gone");
}
TimeStamp
nsRefreshDriver::MostRecentRefresh() const
{
const_cast<nsRefreshDriver*>(this)->EnsureTimerStarted();
return mMostRecentRefresh;
}
PRInt64
nsRefreshDriver::MostRecentRefreshEpochTime() const
{
const_cast<nsRefreshDriver*>(this)->EnsureTimerStarted();
return mMostRecentRefreshEpochTime;
}
PRBool
nsRefreshDriver::AddRefreshObserver(nsARefreshObserver *aObserver,
mozFlushType aFlushType)
{
ObserverArray& array = ArrayFor(aFlushType);
PRBool success = array.AppendElement(aObserver) != nsnull;
EnsureTimerStarted();
return success;
}
PRBool
nsRefreshDriver::RemoveRefreshObserver(nsARefreshObserver *aObserver,
mozFlushType aFlushType)
{
ObserverArray& array = ArrayFor(aFlushType);
return array.RemoveElement(aObserver);
}
void
nsRefreshDriver::EnsureTimerStarted()
{
if (mTimer || mFrozen || !mPresContext) {
// It's already been started, or we don't want to start it now or
// we've been disconnected.
return;
}
UpdateMostRecentRefresh();
mTimer = do_CreateInstance(NS_TIMER_CONTRACTID);
if (!mTimer) {
return;
}
PRInt32 timerType = GetRefreshTimerType();
mTimerIsPrecise = (timerType == nsITimer::TYPE_REPEATING_PRECISE);
nsresult rv = mTimer->InitWithCallback(this,
GetRefreshTimerInterval(),
timerType);
if (NS_FAILED(rv)) {
mTimer = nsnull;
}
}
void
nsRefreshDriver::StopTimer()
{
if (!mTimer) {
return;
}
mTimer->Cancel();
mTimer = nsnull;
}
PRUint32
nsRefreshDriver::ObserverCount() const
{
PRUint32 sum = 0;
for (PRUint32 i = 0; i < NS_ARRAY_LENGTH(mObservers); ++i) {
sum += mObservers[i].Length();
}
// Even while throttled, we need to process layout and style changes. Style
// changes can trigger transitions which fire events when they complete, and
// layout changes can affect media queries on child documents, triggering
// style changes, etc.
sum += mStyleFlushObservers.Length();
sum += mLayoutFlushObservers.Length();
sum += mBeforePaintTargets.Length();
sum += mAnimationFrameListenerDocs.Length();
return sum;
}
void
nsRefreshDriver::UpdateMostRecentRefresh()
{
// Call JS_Now first, since that can have nonzero latency in some rare cases.
mMostRecentRefreshEpochTime = JS_Now();
mMostRecentRefresh = TimeStamp::Now();
}
nsRefreshDriver::ObserverArray&
nsRefreshDriver::ArrayFor(mozFlushType aFlushType)
{
switch (aFlushType) {
case Flush_Style:
return mObservers[0];
case Flush_Layout:
return mObservers[1];
case Flush_Display:
return mObservers[2];
default:
NS_ABORT_IF_FALSE(PR_FALSE, "bad flush type");
return *static_cast<ObserverArray*>(nsnull);
}
}
/*
* nsISupports implementation
*/
NS_IMPL_ISUPPORTS1(nsRefreshDriver, nsITimerCallback)
/*
* nsITimerCallback implementation
*/
NS_IMETHODIMP
nsRefreshDriver::Notify(nsITimer * /* unused */)
{
NS_PRECONDITION(!mFrozen, "Why are we notified while frozen?");
NS_PRECONDITION(mPresContext, "Why are we notified after disconnection?");
UpdateMostRecentRefresh();
nsCOMPtr<nsIPresShell> presShell = mPresContext->GetPresShell();
if (!presShell || ObserverCount() == 0) {
// Things are being destroyed, or we no longer have any observers.
// We don't want to stop the timer when observers are initially
// removed, because sometimes observers can be added and removed
// often depending on what other things are going on and in that
// situation we don't want to thrash our timer. So instead we
// wait until we get a Notify() call when we have no observers
// before stopping the timer.
StopTimer();
return NS_OK;
}
/*
* The timer holds a reference to |this| while calling |Notify|.
* However, implementations of |WillRefresh| are permitted to destroy
* the pres context, which will cause our |mPresContext| to become
* null. If this happens, we must stop notifying observers.
*/
for (PRUint32 i = 0; i < NS_ARRAY_LENGTH(mObservers); ++i) {
ObserverArray::EndLimitedIterator etor(mObservers[i]);
while (etor.HasMore()) {
nsRefPtr<nsARefreshObserver> obs = etor.GetNext();
obs->WillRefresh(mMostRecentRefresh);
if (!mPresContext || !mPresContext->GetPresShell()) {
StopTimer();
return NS_OK;
}
}
if (i == 0) {
// Don't just loop while we have things in mBeforePaintTargets,
// the whole point is that event handlers should readd the
// target as needed.
nsTArray< nsCOMPtr<nsIDocument> > targets;
targets.SwapElements(mBeforePaintTargets);
for (PRUint32 i = 0; i < targets.Length(); ++i) {
targets[i]->BeforePaintEventFiring();
}
// Also grab all of our animation frame listeners up front.
nsIDocument::AnimationListenerList animationListeners;
for (PRUint32 i = 0; i < mAnimationFrameListenerDocs.Length(); ++i) {
mAnimationFrameListenerDocs[i]->
TakeAnimationFrameListeners(animationListeners);
}
// OK, now reset mAnimationFrameListenerDocs so they can be
// readded as needed.
mAnimationFrameListenerDocs.Clear();
PRInt64 eventTime = mMostRecentRefreshEpochTime / PR_USEC_PER_MSEC;
for (PRUint32 i = 0; i < targets.Length(); ++i) {
nsEvent ev(PR_TRUE, NS_BEFOREPAINT);
ev.time = eventTime;
nsEventDispatcher::Dispatch(targets[i], nsnull, &ev);
}
for (PRUint32 i = 0; i < animationListeners.Length(); ++i) {
animationListeners[i]->OnBeforePaint(eventTime);
}
// This is the Flush_Style case.
if (mPresContext && mPresContext->GetPresShell()) {
nsAutoTArray<nsIPresShell*, 16> observers;
observers.AppendElements(mStyleFlushObservers);
for (PRUint32 j = observers.Length();
j && mPresContext && mPresContext->GetPresShell(); --j) {
// Make sure to not process observers which might have been removed
// during previous iterations.
nsIPresShell* shell = observers[j - 1];
if (!mStyleFlushObservers.Contains(shell))
continue;
NS_ADDREF(shell);
mStyleFlushObservers.RemoveElement(shell);
shell->FrameConstructor()->mObservingRefreshDriver = PR_FALSE;
shell->FlushPendingNotifications(Flush_Style);
NS_RELEASE(shell);
}
}
} else if (i == 1) {
// This is the Flush_Layout case.
if (mPresContext && mPresContext->GetPresShell()) {
nsAutoTArray<nsIPresShell*, 16> observers;
observers.AppendElements(mLayoutFlushObservers);
for (PRUint32 j = observers.Length();
j && mPresContext && mPresContext->GetPresShell(); --j) {
// Make sure to not process observers which might have been removed
// during previous iterations.
nsIPresShell* shell = observers[j - 1];
if (!mLayoutFlushObservers.Contains(shell))
continue;
NS_ADDREF(shell);
mLayoutFlushObservers.RemoveElement(shell);
shell->mReflowScheduled = PR_FALSE;
shell->mSuppressInterruptibleReflows = PR_FALSE;
shell->FlushPendingNotifications(Flush_InterruptibleLayout);
NS_RELEASE(shell);
}
}
}
}
if (mThrottled ||
(mTimerIsPrecise !=
(GetRefreshTimerType() == nsITimer::TYPE_REPEATING_PRECISE))) {
// Stop the timer now and restart it here. Stopping is in the mThrottled
// case ok because either it's already one-shot, and it just fired, and all
// we need to do is null it out, or it's repeating and we need to reset it
// to be one-shot. Stopping and restarting in the case when we need to
// switch from precise to slack timers or vice versa is unfortunately
// required.
// Note that the EnsureTimerStarted() call here is ok because
// EnsureTimerStarted makes sure to not start the timer if it shouldn't be
// started.
StopTimer();
EnsureTimerStarted();
}
return NS_OK;
}
void
nsRefreshDriver::Freeze()
{
NS_ASSERTION(!mFrozen, "Freeze called on already-frozen refresh driver");
StopTimer();
mFrozen = true;
}
void
nsRefreshDriver::Thaw()
{
NS_ASSERTION(mFrozen, "Thaw called on an unfrozen refresh driver");
mFrozen = false;
if (ObserverCount()) {
NS_DispatchToCurrentThread(NS_NewRunnableMethod(this, &nsRefreshDriver::DoRefresh));
EnsureTimerStarted();
}
}
void
nsRefreshDriver::SetThrottled(bool aThrottled)
{
if (aThrottled != mThrottled) {
mThrottled = aThrottled;
if (mTimer) {
// We want to switch our timer type here, so just stop and
// restart the timer.
StopTimer();
EnsureTimerStarted();
}
}
}
void
nsRefreshDriver::DoRefresh()
{
// Don't do a refresh unless we're in a state where we should be refreshing.
if (!mFrozen && mPresContext && mTimer) {
Notify(nsnull);
}
}
#ifdef DEBUG
PRBool
nsRefreshDriver::IsRefreshObserver(nsARefreshObserver *aObserver,
mozFlushType aFlushType)
{
ObserverArray& array = ArrayFor(aFlushType);
return array.Contains(aObserver);
}
#endif
PRBool
nsRefreshDriver::ScheduleBeforePaintEvent(nsIDocument* aDocument)
{
NS_ASSERTION(mBeforePaintTargets.IndexOf(aDocument) ==
mBeforePaintTargets.NoIndex,
"Shouldn't have a paint event posted for this document");
PRBool appended = mBeforePaintTargets.AppendElement(aDocument) != nsnull;
EnsureTimerStarted();
return appended;
}
void
nsRefreshDriver::ScheduleAnimationFrameListeners(nsIDocument* aDocument)
{
NS_ASSERTION(mAnimationFrameListenerDocs.IndexOf(aDocument) ==
mAnimationFrameListenerDocs.NoIndex,
"Don't schedule the same document multiple times");
mAnimationFrameListenerDocs.AppendElement(aDocument);
// No need to worry about restarting our timer in precise mode if it's
// already running; that will happen automatically when it fires.
EnsureTimerStarted();
}
void
nsRefreshDriver::RevokeBeforePaintEvent(nsIDocument* aDocument)
{
mBeforePaintTargets.RemoveElement(aDocument);
}
void
nsRefreshDriver::RevokeAnimationFrameListeners(nsIDocument* aDocument)
{
mAnimationFrameListenerDocs.RemoveElement(aDocument);
// No need to worry about restarting our timer in slack mode if it's already
// running; that will happen automatically when it fires.
}