DirectShow: fix media player's positionChanged() signal.

The signal was not emitted at the right time or with incorrect values
under certain circumstances.

Change-Id: Ib8b1d38381d908399752856db7b0a987c4422bb1
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>

src/plugins/directshow/player/directshowplayercontrol.cpp

@@ -64,7 +64,7 @@ DirectShowPlayerControl::DirectShowPlayerControl(DirectShowPlayerService *servic
     , m_streamTypes(0)
     , m_volume(100)
     , m_muted(false)
-    , m_position(0)
+    , m_emitPosition(-1)
     , m_pendingPosition(-1)
     , m_duration(0)
     , m_playbackRate(0)
@@ -98,7 +98,7 @@ qint64 DirectShowPlayerControl::position() const
     if (m_pendingPosition != -1)
         return m_pendingPosition;
 
-    return const_cast<qint64 &>(m_position) = m_service->position();
+    return m_service->position();
 }
 
 void DirectShowPlayerControl::setPosition(qint64 position)
@@ -215,6 +215,7 @@ const QIODevice *DirectShowPlayerControl::mediaStream() const
 void DirectShowPlayerControl::setMedia(const QMediaContent &media, QIODevice *stream)
 {
     m_pendingPosition = -1;
+    m_emitPosition = -1;
 
     m_media = media;
     m_stream = stream;
@@ -247,6 +248,7 @@ void DirectShowPlayerControl::playOrPause(QMediaPlayer::State state)
             return;
     }
 
+    m_emitPosition = -1;
     m_state = state;
 
     if (m_pendingPosition != -1)
@@ -262,6 +264,7 @@ void DirectShowPlayerControl::playOrPause(QMediaPlayer::State state)
 
 void DirectShowPlayerControl::stop()
 {
+    m_emitPosition = -1;
     m_service->stop();
     emit stateChanged(m_state = QMediaPlayer::StoppedState);
 }
@@ -293,8 +296,8 @@ void DirectShowPlayerControl::emitPropertyChanges()
         emit videoAvailableChanged(m_streamTypes & DirectShowPlayerService::VideoStream);
     }
 
-    if (properties & PositionProperty)
-        emit positionChanged(m_position);
+    if (properties & PositionProperty && m_emitPosition != -1)
+        emit positionChanged(m_emitPosition);
 
     if (properties & DurationProperty)
         emit durationChanged(m_duration);
@@ -389,8 +392,8 @@ void DirectShowPlayerControl::updateError(QMediaPlayer::Error error, const QStri
 
 void DirectShowPlayerControl::updatePosition(qint64 position)
 {
-    if (m_position != position) {
-        m_position = position;
+    if (m_emitPosition != position) {
+        m_emitPosition = position;
 
         scheduleUpdate(PositionProperty);
     }

src/plugins/directshow/player/directshowplayercontrol.h

@@ -130,7 +130,7 @@ private:
     int m_streamTypes;
     int m_volume;
     bool m_muted;
-    qint64 m_position;
+    qint64 m_emitPosition;
     qint64 m_pendingPosition;
     qint64 m_duration;
     qreal m_playbackRate;

src/plugins/directshow/player/directshowplayerservice.cpp

@@ -103,6 +103,7 @@ DirectShowPlayerService::DirectShowPlayerService(QObject *parent)
     , m_buffering(false)
     , m_seekable(false)
     , m_atEnd(false)
+    , m_dontCacheNextSeekResult(false)
 {
     m_playerControl = new DirectShowPlayerControl(this);
     m_metaDataControl = new DirectShowMetaDataControl(this);
@@ -229,6 +230,7 @@ void DirectShowPlayerService::load(const QMediaContent &media, QIODevice *stream
     m_buffering = false;
     m_seekable = false;
     m_atEnd = false;
+    m_dontCacheNextSeekResult = false;
     m_metaDataControl->updateGraph(0, 0);
 
     if (m_resources.isEmpty() && !stream) {
@@ -672,7 +674,9 @@ void DirectShowPlayerService::play()
         if (m_executedTasks & Stop) {
             m_atEnd = false;
             if (m_seekPosition == -1) {
+                m_dontCacheNextSeekResult = true;
                 m_seekPosition = 0;
+                m_position = 0;
                 m_pendingTasks |= Seek;
             }
             m_executedTasks ^= Stop;
@@ -718,7 +722,9 @@ void DirectShowPlayerService::pause()
         if (m_executedTasks & Stop) {
             m_atEnd = false;
             if (m_seekPosition == -1) {
+                m_dontCacheNextSeekResult = true;
                 m_seekPosition = 0;
+                m_position = 0;
                 m_pendingTasks |= Seek;
             }
             m_executedTasks ^= Stop;
@@ -791,6 +797,8 @@ void DirectShowPlayerService::doStop(QMutexLocker *locker)
         }
 
         m_seekPosition = 0;
+        m_position = 0;
+        m_dontCacheNextSeekResult = true;
         m_pendingTasks |= Seek;
 
         m_executedTasks &= ~(Play | Pause);
@@ -913,8 +921,10 @@ void DirectShowPlayerService::doSeek(QMutexLocker *locker)
         // Cache current values as we can't query IMediaSeeking during a seek due to the
         // possibility of a deadlock when flushing the VideoSurfaceFilter.
         LONGLONG currentPosition = 0;
-        seeking->GetCurrentPosition(&currentPosition);
-        m_position = currentPosition / qt_directShowTimeScale;
+        if (!m_dontCacheNextSeekResult) {
+            seeking->GetCurrentPosition(&currentPosition);
+            m_position = currentPosition / qt_directShowTimeScale;
+        }
 
         LONGLONG minimum = 0;
         LONGLONG maximum = 0;
@@ -928,8 +938,10 @@ void DirectShowPlayerService::doSeek(QMutexLocker *locker)
                 &seekPosition, AM_SEEKING_AbsolutePositioning, 0, AM_SEEKING_NoPositioning);
         locker->relock();
 
-        seeking->GetCurrentPosition(&currentPosition);
-        m_position = currentPosition / qt_directShowTimeScale;
+        if (!m_dontCacheNextSeekResult) {
+            seeking->GetCurrentPosition(&currentPosition);
+            m_position = currentPosition / qt_directShowTimeScale;
+        }
 
         seeking->Release();
 
@@ -937,6 +949,7 @@ void DirectShowPlayerService::doSeek(QMutexLocker *locker)
     }
 
     m_seekPosition = -1;
+    m_dontCacheNextSeekResult = false;
 }
 
 int DirectShowPlayerService::bufferStatus() const

src/plugins/directshow/player/directshowplayerservice.h

@@ -195,6 +195,7 @@ private:
     bool m_buffering;
     bool m_seekable;
     bool m_atEnd;
+    bool m_dontCacheNextSeekResult;
     QMediaTimeRange m_playbackRange;
     QUrl m_url;
     QMediaResourceList m_resources;