statistics: add a model that describes a list of charts

Qt's comboboxes are controlled by models, there's no way around
that. To customize the chart-selection widget this must therefore
be abstracted into a model. On the upside, this hopefully can
be used for desktop and mobile.

The model provides icons and paints a warning-symbol on it
if the statistics core code deems the chart to be not recommended.
Notably, when plotting a categorical bar chart against a
numerical value (in such a case histograms are preferred).

Includes a fix for a silly oversight in CMakelist.txt: add the
statstranslations.h header.

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

3 files changed, 176 insertions, 0 deletions

diff --git a/stats/CMakeLists.txt b/stats/CMakeLists.txt
index 31e809270..e0e2dc303 100644
--- a/stats/CMakeLists.txt
+++ b/stats/CMakeLists.txt
@@ -9,6 +9,8 @@ set(SUBSURFACE_STATS_SRCS
 	barseries.cpp
 	boxseries.h
 	boxseries.cpp
+	chartlistmodel.h
+	chartlistmodel.cpp
 	informationbox.h
 	informationbox.cpp
 	legend.h
@@ -25,6 +27,7 @@ set(SUBSURFACE_STATS_SRCS
 	statsseries.cpp
 	statsstate.h
 	statsstate.cpp
+	statstranslations.h
 	statsvariables.h
 	statsvariables.cpp
 	statsview.h
diff --git a/stats/chartlistmodel.cpp b/stats/chartlistmodel.cpp
new file mode 100644
index 000000000..9ae3dae6e
--- /dev/null
+++ b/stats/chartlistmodel.cpp
@@ -0,0 +1,119 @@
+// SPDX-License-Identifier: GPL-2.0
+#include "chartlistmodel.h"
+#include "core/metrics.h"
+#include "core/qthelper.h"
+#include <QIcon>
+#include <QFontMetrics>
+#include <QPainter>
+
+ChartListModel::ChartListModel() :
+	itemFont(defaultModelFont()), 
+	headerFont(itemFont.family(), itemFont.pointSize(), itemFont.weight(), true)
+{
+	QFontMetrics fm(itemFont);
+	int fontHeight = fm.height();
+
+	int iconSize = fontHeight * 3;
+	warningPixmap = QPixmap::fromImage(renderSVGIcon(":chart-warning-icon", fontHeight, true));
+	initIcon(ChartSubType::Vertical, ":chart-bar-vertical-icon", iconSize);
+	initIcon(ChartSubType::VerticalGrouped, ":chart-bar-grouped-vertical-icon", iconSize);
+	initIcon(ChartSubType::VerticalStacked, ":chart-bar-stacked-vertical-icon", iconSize);
+	initIcon(ChartSubType::Horizontal, ":chart-bar-horizontal-icon", iconSize);
+	initIcon(ChartSubType::HorizontalGrouped, ":chart-bar-grouped-horizontal-icon", iconSize);
+	initIcon(ChartSubType::HorizontalStacked, ":chart-bar-stacked-horizontal-icon", iconSize);
+	initIcon(ChartSubType::Dots, ":chart-points-icon", iconSize);
+	initIcon(ChartSubType::Box, ":chart-box-icon", iconSize);
+	initIcon(ChartSubType::Pie, ":chart-pie-icon", iconSize);
+}
+
+ChartListModel::~ChartListModel()
+{
+}
+
+void ChartListModel::initIcon(ChartSubType type, const char *name, int iconSize)
+{
+	QPixmap icon = QPixmap::fromImage(renderSVGIcon(name, iconSize, true));
+	QPixmap iconWarning = icon.copy();
+	QPainter painter(&iconWarning);
+	painter.drawPixmap(0, 0, warningPixmap);
+	subTypeIcons[(size_t)type].normal = icon;
+	subTypeIcons[(size_t)type].warning = iconWarning;
+}
+
+const QPixmap &ChartListModel::getIcon(ChartSubType type, bool warning) const
+{
+	int idx = std::clamp((int)type, 0, (int)ChartSubType::Count);
+	return warning ? subTypeIcons[idx].warning : subTypeIcons[idx].normal;
+}
+
+int ChartListModel::rowCount(const QModelIndex &parent) const
+{
+	return parent.isValid() ? 0 : (int)items.size();
+}
+
+Qt::ItemFlags ChartListModel::flags(const QModelIndex &index) const
+{
+	int row = index.row();
+	if (index.parent().isValid() || row < 0 || row >= (int)items.size())
+		return Qt::NoItemFlags;
+	return items[row].isHeader ? Qt::ItemIsEnabled
+				   : Qt::ItemIsSelectable | Qt::ItemIsEnabled;
+}
+
+QVariant ChartListModel::data(const QModelIndex &index, int role) const
+{
+	int row = index.row();
+	if (index.parent().isValid() || row < 0 || row >= (int)items.size())
+		return QVariant();
+
+	switch (role) {
+	case Qt::FontRole:
+		return items[row].isHeader ? headerFont : itemFont;
+	case Qt::DisplayRole:
+		return items[row].fullName;
+	case Qt::DecorationRole:
+		return items[row].warning ? QVariant::fromValue(QIcon(warningPixmap))
+					  : QVariant();
+	case IconRole:
+		return items[row].isHeader ? QVariant()
+					   : QVariant::fromValue(getIcon(items[row].subtype, items[row].warning));
+	case IconSizeRole:
+		return items[row].isHeader ? QVariant()
+					   : QVariant::fromValue(getIcon(items[row].subtype, items[row].warning).size());
+	case ChartNameRole:
+		return items[row].name;
+	case IsHeaderRole:
+		return items[row].isHeader;
+	case Qt::UserRole:
+		return items[row].id;
+	}
+	return QVariant();
+}
+
+int ChartListModel::update(const StatsState::ChartList &charts)
+{
+	// Sort non-recommended entries to the back
+	std::vector<StatsState::Chart> sorted;
+	sorted.reserve(charts.charts.size());
+	std::copy_if(charts.charts.begin(), charts.charts.end(), std::back_inserter(sorted),
+		     [] (const StatsState::Chart &chart) { return !chart.warning; });
+	std::copy_if(charts.charts.begin(), charts.charts.end(), std::back_inserter(sorted),
+		     [] (const StatsState::Chart &chart) { return chart.warning; });
+
+	beginResetModel();
+	items.clear();
+	QString act;
+	int res = -1;
+	for (const StatsState::Chart &chart: sorted) {
+		if (act != chart.name) {
+			items.push_back({ true, chart.name, QString(), (ChartSubType)-1, -1, false });
+			act = chart.name;
+		}
+		if (charts.selected == chart.id)
+			res = (int)items.size();
+		QString fullName = QString("%1 / %2").arg(chart.name, chart.subtypeName);
+		items.push_back({ false, chart.subtypeName, fullName, chart.subtype, chart.id, chart.warning });
+	}
+	endResetModel();
+	return res;
+}
diff --git a/stats/chartlistmodel.h b/stats/chartlistmodel.h
new file mode 100644
index 000000000..a33f6875a
--- /dev/null
+++ b/stats/chartlistmodel.h
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0
+// A model to feed to the chart-selection combobox
+#ifndef CHART_LIST_MODEL_H
+#define CHART_LIST_MODEL_H
+
+#include "statsstate.h"
+#include <vector>
+#include <QAbstractListModel>
+#include <QString>
+#include <QFont>
+#include <QIcon>
+#include <QPixmap>
+
+class ChartListModel : public QAbstractListModel {
+	Q_OBJECT
+public:
+	ChartListModel();
+	~ChartListModel();
+
+	// Returns index of selected item
+	int update(const StatsState::ChartList &charts);
+
+	static const constexpr int ChartNameRole = Qt::UserRole + 1;
+	static const constexpr int IsHeaderRole = Qt::UserRole + 2;
+	static const constexpr int IconRole = Qt::UserRole + 3;
+	static const constexpr int IconSizeRole = Qt::UserRole + 4;
+private:
+	struct Item {
+		bool isHeader;
+		QString name;
+		QString fullName;
+		ChartSubType subtype;
+		int id;
+		bool warning;
+	};
+
+	struct SubTypeIcons {
+		QPixmap normal;
+		QPixmap warning;
+	};
+	QPixmap warningPixmap;
+	SubTypeIcons subTypeIcons[(size_t)ChartSubType::Count];
+
+	QFont itemFont;
+	QFont headerFont;
+	std::vector<Item> items;
+	int rowCount(const QModelIndex &parent) const override;
+	QVariant data(const QModelIndex &index, int role) const override;
+	Qt::ItemFlags flags(const QModelIndex &index) const override;
+	void initIcon(ChartSubType type, const char *name, int iconSize);
+	const QPixmap &getIcon(ChartSubType type, bool warning) const;
+};
+
+#endif