3 files changed, 108 insertions, 0 deletions
diff --git a/stats/CMakeLists.txt b/stats/CMakeLists.txt
index bf11d06fd..e8f49e35f 100644
--- a/stats/CMakeLists.txt
+++ b/stats/CMakeLists.txt
@@ -5,6 +5,8 @@ include_directories(.
 )
 
 set(SUBSURFACE_STATS_SRCS
+	informationbox.h
+	informationbox.cpp
 	legend.h
 	legend.cpp
 	statsaxis.h
diff --git a/stats/informationbox.cpp b/stats/informationbox.cpp
new file mode 100644
index 000000000..015f821be
--- /dev/null
+++ b/stats/informationbox.cpp
@@ -0,0 +1,75 @@
+#include "informationbox.h"
+#include "statscolors.h"
+#include "zvalues.h"
+
+#include <QChart>
+#include <QFontMetrics>
+
+static const QColor informationBorderColor(Qt::black);
+static const QColor informationColor(0xff, 0xff, 0x00, 192); // Note: fourth argument is opacity
+static const int informationBorder = 2;
+static const int distanceFromPointer = 10; // Distance to place box from mouse pointer or scatter item
+
+InformationBox::InformationBox(QtCharts::QChart *chart) : QGraphicsRectItem(chart), chart(chart)
+{
+	setPen(QPen(informationBorderColor, informationBorder));
+	setBrush(informationColor);
+	setZValue(ZValues::informationBox);
+}
+
+void InformationBox::setText(const std::vector<QString> &text, QPointF pos)
+{
+	width = height = 0.0;
+	textItems.clear();
+
+	for (const QString &s: text) {
+		if (!s.isEmpty())
+			addLine(s);
+	}
+
+	width += 4.0 * informationBorder;
+	height += 4.0 * informationBorder;
+
+	// Setting the position will also set the proper size
+	setPos(pos);
+}
+
+void InformationBox::setPos(QPointF pos)
+{
+	QRectF plotArea = chart->plotArea();
+
+	double x = pos.x() + distanceFromPointer;
+	if (x + width >= plotArea.right() && pos.x() - width >= plotArea.x())
+		x = pos.x() - width;
+	double y = pos.y() + distanceFromPointer;
+	if (y + height >= plotArea.bottom() && pos.y() - height >= plotArea.y())
+		y = pos.y() - height;
+
+	setRect(x, y, width, height);
+	double actY = y + 2.0 * informationBorder;
+	for (auto &item: textItems) {
+		item->setPos(QPointF(x + 2.0 * informationBorder, actY));
+		actY += item->boundingRect().height();
+	}
+}
+
+void InformationBox::addLine(const QString &s)
+{
+	textItems.emplace_back(new QGraphicsSimpleTextItem(s, this));
+	QGraphicsSimpleTextItem &item = *textItems.back();
+	item.setBrush(QBrush(darkLabelColor));
+	item.setPos(QPointF(0.0, height));
+	item.setFont(font);
+	item.setZValue(ZValues::informationBox);
+	QRectF rect = item.boundingRect();
+	width = std::max(width, rect.width());
+	height += rect.height();
+}
+
+// Try to stay within three-thirds of the chart height
+int InformationBox::recommendedMaxLines() const
+{
+	QFontMetrics fm(font);
+	int maxHeight = static_cast<int>(chart->plotArea().height());
+	return maxHeight * 2 / fm.height() / 3;
+}
diff --git a/stats/informationbox.h b/stats/informationbox.h
new file mode 100644
index 000000000..7e9253dc7
--- /dev/null
+++ b/stats/informationbox.h
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: GPL-2.0
+// A small box displaying statistics information, notably
+// for a scatter-plot item or a bar in a bar chart.
+#ifndef INFORMATION_BOX_H
+#define INFORMATION_BOX_H
+
+#include <vector>
+#include <memory>
+#include <QGraphicsRectItem>
+#include <QFont>
+
+namespace QtCharts {
+	class QChart;
+}
+struct dive;
+
+// Information window showing data of highlighted dive
+struct InformationBox : QGraphicsRectItem {
+	InformationBox(QtCharts::QChart *chart);
+	void setText(const std::vector<QString> &text, QPointF pos);
+	void setPos(QPointF pos);
+	int recommendedMaxLines() const;
+private:
+	QtCharts::QChart *chart;
+	QFont font; // For future specialization.
+	double width, height;
+	void addLine(const QString &s);
+	std::vector<std::unique_ptr<QGraphicsSimpleTextItem>> textItems;
+};
+
+#endif