QMediaPlayer: emit errorChanged signal whenever the error has changed

There was a problem that error/errorString properties were not properly
notified when reseted on start playing. So now we use private setError()
method whenever 'error' should be changed.

Also as a drive-by there are several improvements:
- errorChanged signal will be emitted now only when the property's
value was actually changed.
- errorOccured signal is now emitted only when there is a real error,
i.e. it will never be emitted with NoError.

Fixes: QTBUG-113386
Change-Id: I16e26710941ed6b8429f39c201572092f2714c74
Reviewed-by: Lars Knoll <lars@knoll.priv.no>
(cherry picked from commit 9830f6593868be875465b8ed9b3796685600adb0)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 12 insertions, 9 deletions

diff --git a/src/multimedia/platform/qplatformmediaplayer.cpp b/src/multimedia/platform/qplatformmediaplayer.cpp
index 5fb82b523..76de92cff 100644
--- a/src/multimedia/platform/qplatformmediaplayer.cpp
+++ b/src/multimedia/platform/qplatformmediaplayer.cpp
@@ -29,7 +29,7 @@ void QPlatformMediaPlayer::mediaStatusChanged(QMediaPlayer::MediaStatus status)
 
 void QPlatformMediaPlayer::error(int error, const QString &errorString)
 {
-    player->d_func()->setError(error, errorString);
+    player->d_func()->setError(QMediaPlayer::Error(error), errorString);
 }
 
 QT_END_NAMESPACE
diff --git a/src/multimedia/playback/qmediaplayer.cpp b/src/multimedia/playback/qmediaplayer.cpp
index e17063652..36d8618ac 100644
--- a/src/multimedia/playback/qmediaplayer.cpp
+++ b/src/multimedia/playback/qmediaplayer.cpp
@@ -116,14 +116,18 @@ void QMediaPlayerPrivate::setStatus(QMediaPlayer::MediaStatus s)
     emit q->mediaStatusChanged(s);
 }
 
-void QMediaPlayerPrivate::setError(int error, const QString &errorString)
+void QMediaPlayerPrivate::setError(QMediaPlayer::Error error, const QString &errorString)
 {
     Q_Q(QMediaPlayer);
 
-    this->error = QMediaPlayer::Error(error);
-    this->errorString = errorString;
-    emit q->errorChanged();
-    emit q->errorOccurred(this->error, errorString);
+    auto prevError = std::exchange(this->error, error);
+    auto prevErrorString = std::exchange(this->errorString, errorString);
+
+    if (prevError != error || prevErrorString != errorString)
+        emit q->errorChanged();
+
+    if (error != QMediaPlayer::NoError)
+        emit q->errorOccurred(error, errorString);
 }
 
 void QMediaPlayerPrivate::setMedia(const QUrl &media, QIODevice *stream)
@@ -507,8 +511,7 @@ void QMediaPlayer::play()
         return;
 
     // Reset error conditions
-    d->error = NoError;
-    d->errorString = QString();
+    d->setError(NoError, QString());
 
     d->control->play();
 }
diff --git a/src/multimedia/playback/qmediaplayer_p.h b/src/multimedia/playback/qmediaplayer_p.h
index ce9bf091e..04f35e884 100644
--- a/src/multimedia/playback/qmediaplayer_p.h
+++ b/src/multimedia/playback/qmediaplayer_p.h
@@ -60,7 +60,7 @@ public:
 
     void setState(QMediaPlayer::PlaybackState state);
     void setStatus(QMediaPlayer::MediaStatus status);
-    void setError(int error, const QString &errorString);
+    void setError(QMediaPlayer::Error error, const QString &errorString);
 
     void setVideoSink(QVideoSink *sink)
     {