Make settings window only save data that changes

Currently, if a user presses 'OK' or 'Apply' on the settings window, it
will save all data from all controls on a settings pane, regardless of
whether of not they were changed.  The major issue with this is that
setting the data will overwrite all default values, making it impossible
for default values to be used if a user didn't actually change a value.
(Thanks to palana for pointing this fact out)

So instead, mark a control as 'changed' using QObject::property() and
QObject::sender(), and add a few helper functions to controls to ensure
that they are checked to see whether they were actually changed directly
by the user before saving the value to the config.

obs/window-basic-settings.cpp

@@ -72,6 +72,11 @@ static bool ConvertResText(const char *res, uint32_t &cx, uint32_t &cy)
 	return true;
 }
 
+static inline bool WidgetChanged(QWidget *widget)
+{
+	return widget->property("changed").toBool();
+}
+
 static inline void SetComboByName(QComboBox *combo, const char *name)
 {
 	int idx = combo->findText(QT_UTF8(name));
@@ -86,10 +91,20 @@ static inline void SetComboByValue(QComboBox *combo, const char *name)
 		combo->setCurrentIndex(idx);
 }
 
+static inline QString GetComboData(QComboBox *combo)
+{
+	int idx = combo->currentIndex();
+	if (idx == -1)
+		return QString();
+
+	return combo->itemData(idx).toString();
+}
+
 void OBSBasicSettings::HookWidget(QWidget *widget, const char *signal,
 		const char *slot)
 {
 	QObject::connect(widget, signal, this, slot);
+	widget->setProperty("changed", QVariant(false));
 }
 
 #define COMBO_CHANGED   SIGNAL(currentIndexChanged(int))
@@ -158,6 +173,39 @@ OBSBasicSettings::OBSBasicSettings(QWidget *parent)
 	LoadSettings(false);
 }
 
+void OBSBasicSettings::SaveCombo(QComboBox *widget, const char *section,
+		const char *value)
+{
+	if (WidgetChanged(widget))
+		config_set_string(main->Config(), section, value,
+				QT_TO_UTF8(widget->currentText()));
+}
+
+void OBSBasicSettings::SaveComboData(QComboBox *widget, const char *section,
+		const char *value)
+{
+	if (WidgetChanged(widget)) {
+		QString str = GetComboData(widget);
+		config_set_string(main->Config(), section, value,
+				QT_TO_UTF8(str));
+	}
+}
+
+void OBSBasicSettings::SaveEdit(QLineEdit *widget, const char *section,
+		const char *value)
+{
+	if (WidgetChanged(widget))
+		config_set_string(main->Config(), section, value,
+				QT_TO_UTF8(widget->text()));
+}
+
+void OBSBasicSettings::SaveSpinBox(QSpinBox *widget, const char *section,
+		const char *value)
+{
+	if (WidgetChanged(widget))
+		config_set_int(main->Config(), section, value, widget->value());
+}
+
 void OBSBasicSettings::LoadServiceTypes()
 {
 	const char    *type;
@@ -505,43 +553,41 @@ void OBSBasicSettings::SaveGeneralSettings()
 	QVariant langData = ui->language->itemData(languageIndex);
 	string language = langData.toString().toStdString();
 
-	config_set_string(GetGlobalConfig(), "General", "Language",
-			language.c_str());
+	if (WidgetChanged(ui->language))
+		config_set_string(GetGlobalConfig(), "General", "Language",
+				language.c_str());
 }
 
 void OBSBasicSettings::SaveVideoSettings()
 {
-	QString renderer         = ui->renderer->currentText();
 	QString baseResolution   = ui->baseResolution->currentText();
 	QString outputResolution = ui->outputResolution->currentText();
 	int     fpsType          = ui->fpsType->currentIndex();
-	QString fpsCommon        = ui->fpsCommon->currentText();
-	int     fpsInteger       = ui->fpsInteger->value();
-	int     fpsNumerator     = ui->fpsNumerator->value();
-	int     fpsDenominator   = ui->fpsDenominator->value();
 	uint32_t cx, cy;
 
 	/* ------------------- */
 
-	config_set_string(GetGlobalConfig(), "Video", "Renderer",
-			QT_TO_UTF8(renderer));
+	SaveCombo(ui->renderer, "Video", "Renderer");
 
-	if (ConvertResText(QT_TO_UTF8(baseResolution), cx, cy)) {
+	if (WidgetChanged(ui->baseResolution) &&
+	    ConvertResText(QT_TO_UTF8(baseResolution), cx, cy)) {
 		config_set_uint(main->Config(), "Video", "BaseCX", cx);
 		config_set_uint(main->Config(), "Video", "BaseCY", cy);
 	}
 
-	if (ConvertResText(QT_TO_UTF8(outputResolution), cx, cy)) {
+	if (WidgetChanged(ui->outputResolution) &&
+	    ConvertResText(QT_TO_UTF8(outputResolution), cx, cy)) {
 		config_set_uint(main->Config(), "Video", "OutputCX", cx);
 		config_set_uint(main->Config(), "Video", "OutputCY", cy);
 	}
 
-	config_set_uint(main->Config(), "Video", "FPSType", fpsType);
-	config_set_string(main->Config(), "Video", "FPSCommon",
-			QT_TO_UTF8(fpsCommon));
-	config_set_uint(main->Config(), "Video", "FPSInt", fpsInteger);
-	config_set_uint(main->Config(), "Video", "FPSNum", fpsNumerator);
-	config_set_uint(main->Config(), "Video", "FPSDen", fpsDenominator);
+	if (WidgetChanged(ui->fpsType))
+		config_set_uint(main->Config(), "Video", "FPSType", fpsType);
+
+	SaveCombo(ui->fpsCommon, "Video", "FPSCommon");
+	SaveSpinBox(ui->fpsInteger, "Video", "FPSInt");
+	SaveSpinBox(ui->fpsNumerator, "Video", "FPSNum");
+	SaveSpinBox(ui->fpsDenominator, "Video", "FPSDen");
 
 	main->ResetVideo();
 }
@@ -549,36 +595,15 @@ void OBSBasicSettings::SaveVideoSettings()
 /* TODO: Temporary! */
 void OBSBasicSettings::SaveOutputSettings()
 {
-	int videoBitrate     = ui->simpleOutputVBitrate->value();
-	QString audioBitrate = ui->simpleOutputABitrate->currentText();
-	QString path         = ui->simpleOutputPath->text();
-
-	config_set_uint(main->Config(), "SimpleOutput", "VBitrate",
-			videoBitrate);
-	config_set_string(main->Config(), "SimpleOutput", "ABitrate",
-			QT_TO_UTF8(audioBitrate));
-	config_set_string(main->Config(), "SimpleOutput", "FilePath",
-			QT_TO_UTF8(path));
-}
-
-static inline QString GetComboData(QComboBox *combo)
-{
-	int idx = combo->currentIndex();
-	if (idx == -1)
-		return QString();
-
-	return combo->itemData(idx).toString();
+	SaveSpinBox(ui->simpleOutputVBitrate, "SimpleOutput", "VBitrate");
+	SaveCombo(ui->simpleOutputABitrate, "SimpleOutput", "ABitrate");
+	SaveEdit(ui->simpleOutputPath, "SimpleOutput", "FilePath");
 }
 
 void OBSBasicSettings::SaveAudioSettings()
 {
 	QString sampleRateStr  = ui->sampleRate->currentText();
 	int channelSetupIdx    = ui->channelSetup->currentIndex();
-	QString desktopDevice1 = GetComboData(ui->desktopAudioDevice1);
-	QString desktopDevice2 = GetComboData(ui->desktopAudioDevice2);
-	QString auxDevice1     = GetComboData(ui->auxAudioDevice1);
-	QString auxDevice2     = GetComboData(ui->auxAudioDevice2);
-	QString auxDevice3     = GetComboData(ui->auxAudioDevice3);
 
 	const char *channelSetup = (channelSetupIdx == 0) ? "Mono" : "Stereo";
 
@@ -588,20 +613,19 @@ void OBSBasicSettings::SaveAudioSettings()
 	else if (sampleRateStr == "48khz")
 		sampleRate = 48000;
 
-	config_set_uint(main->Config(), "Audio", "SampleRate", sampleRate);
-	config_set_string(main->Config(), "Audio", "ChannelSetup",
-			channelSetup);
-
-	config_set_string(main->Config(), "Audio", "DesktopDevice1",
-			QT_TO_UTF8(desktopDevice1));
-	config_set_string(main->Config(), "Audio", "DesktopDevice2",
-			QT_TO_UTF8(desktopDevice2));
-	config_set_string(main->Config(), "Audio", "AuxDevice1",
-			QT_TO_UTF8(auxDevice1));
-	config_set_string(main->Config(), "Audio", "AuxDevice2",
-			QT_TO_UTF8(auxDevice2));
-	config_set_string(main->Config(), "Audio", "AuxDevice3",
-			QT_TO_UTF8(auxDevice3));
+	if (WidgetChanged(ui->sampleRate))
+		config_set_uint(main->Config(), "Audio", "SampleRate",
+				sampleRate);
+
+	if (WidgetChanged(ui->channelSetup))
+		config_set_string(main->Config(), "Audio", "ChannelSetup",
+				channelSetup);
+
+	SaveComboData(ui->desktopAudioDevice1, "Audio", "DesktopDevice1");
+	SaveComboData(ui->desktopAudioDevice2, "Audio", "DesktopDevice2");
+	SaveComboData(ui->auxAudioDevice1, "Audio", "AuxDevice1");
+	SaveComboData(ui->auxAudioDevice2, "Audio", "AuxDevice2");
+	SaveComboData(ui->auxAudioDevice3, "Audio", "AuxDevice3");
 
 	main->ResetAudioDevices();
 }
@@ -745,6 +769,7 @@ void OBSBasicSettings::GeneralChanged()
 {
 	if (!loading) {
 		generalChanged = true;
+		sender()->setProperty("changed", QVariant(true));
 		EnableApplyButton(true);
 	}
 }
@@ -753,6 +778,7 @@ void OBSBasicSettings::OutputsChanged()
 {
 	if (!loading) {
 		outputsChanged = true;
+		sender()->setProperty("changed", QVariant(true));
 		EnableApplyButton(true);
 	}
 }
@@ -761,6 +787,7 @@ void OBSBasicSettings::AudioChanged()
 {
 	if (!loading) {
 		audioChanged = true;
+		sender()->setProperty("changed", QVariant(true));
 		EnableApplyButton(true);
 	}
 }
@@ -770,6 +797,7 @@ void OBSBasicSettings::AudioChangedRestart()
 	if (!loading) {
 		audioChanged = true;
 		ui->audioMsg->setText(QTStr("Basic.Settings.ProgramRestart"));
+		sender()->setProperty("changed", QVariant(true));
 		EnableApplyButton(true);
 	}
 }
@@ -779,6 +807,7 @@ void OBSBasicSettings::VideoChangedRestart()
 	if (!loading) {
 		videoChanged = true;
 		ui->videoMsg->setText(QTStr("Basic.Settings.ProgramRestart"));
+		sender()->setProperty("changed", QVariant(true));
 		EnableApplyButton(true);
 	}
 }
@@ -787,6 +816,7 @@ void OBSBasicSettings::VideoChangedResolution()
 {
 	if (!loading && ValidResolutions(ui.get())) {
 		videoChanged = true;
+		sender()->setProperty("changed", QVariant(true));
 		EnableApplyButton(true);
 	}
 }
@@ -795,6 +825,7 @@ void OBSBasicSettings::VideoChanged()
 {
 	if (!loading) {
 		videoChanged = true;
+		sender()->setProperty("changed", QVariant(true));
 		EnableApplyButton(true);
 	}
 }

obs/window-basic-settings.hpp

@@ -47,6 +47,15 @@ private:
 
 	OBSPropertiesView *streamProperties;
 
+	void SaveCombo(QComboBox *widget, const char *section,
+			const char *value);
+	void SaveComboData(QComboBox *widget, const char *section,
+			const char *value);
+	void SaveEdit(QLineEdit *widget, const char *section,
+			const char *value);
+	void SaveSpinBox(QSpinBox *widget, const char *section,
+			const char *value);
+
 	inline bool Changed() const
 	{
 		return generalChanged || outputsChanged ||