statistics: switch themes on the mobile version

When changing the theme to a dark theme, also change the
statistics theme. The code is a mess, because it crashes
when setting the theme right at the beginning. Therefore,
there is a "theme has been set" flag. Also, this directly
accesses the ThemeInterface singleton object. I have no
time to fight QML, sorry.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

CHANGELOG.md

@@ -1,4 +1,5 @@
 - profile: include profile editing in undo system
+- mobile: Add a dark theme for statistics
 - core: avoid crash with corrupted cloud storage
 - mobile: fix profile scaling issue on high DPR devices
 - mobile: bring back profile icons

mobile-widgets/statsmanager.cpp

@@ -1,8 +1,9 @@
 // SPDX-License-Identifier: GPL-2.0
 #include "statsmanager.h"
+#include "themeinterface.h"
 #include "stats/chartlistmodel.h"
 
-StatsManager::StatsManager() : view(nullptr), charts(nullptr)
+StatsManager::StatsManager() : view(nullptr), charts(nullptr), themeInitialized(false)
 {
 	updateUi();
 }
@@ -19,6 +20,9 @@ void StatsManager::init(StatsView *v, ChartListModel *m)
 		fprintf(stderr, "StatsManager::init(): no ChartListModel - statistics will not work.\n");
 	view = v;
 	charts = m;
+
+	connect(ThemeInterface::instance(), &ThemeInterface::currentThemeChanged,
+		this, &StatsManager::themeChanged);
 }
 
 void StatsManager::doit()
@@ -64,6 +68,8 @@ void StatsManager::updateUi()
 	operation2IndexChanged();
 	sortMode1IndexChanged();
 
+	if (view && !std::exchange(themeInitialized, true))
+		themeChanged();
 	if (charts)
 		charts->update(uiState.charts);
 	if (view)
@@ -123,3 +129,14 @@ void StatsManager::setChart(int idx)
 	state.chartChanged(idx);
 	updateUi();
 }
+
+void StatsManager::themeChanged()
+{
+	if (!view)
+		return;
+
+	// We could just make currentTheme accessible instead of
+	// using Qt's inane propertySystem. Whatever.
+	QString theme = ThemeInterface::instance()->property("currentTheme").toString();
+	view->setTheme(theme == "Dark");
+}

mobile-widgets/statsmanager.h

@@ -49,6 +49,8 @@ signals:
 	void binner2IndexChanged();
 	void operation2IndexChanged();
 	void sortMode1IndexChanged();
+private slots:
+	void themeChanged();
 private:
 	StatsView *view;
 	ChartListModel *charts;
@@ -66,8 +68,8 @@ private:
 	int operation2Index;
 	int sortMode1Index;
 	StatsState::UIState uiState;	// Remember UI state so that we can interpret indexes
+	bool themeInitialized;		// setTheme() crashes if called in init()
 	void updateUi();
-
 };
 
 #endif