Split message content into its own module

This is laying some groundwork for the rich text chatbar.

src/roominfo/CMakeLists.txt

@@ -14,4 +14,10 @@ ecm_add_qml_module(RoomInfo GENERATE_PLUGIN_SOURCE
         LocationsPage.qml
         RoomPinnedMessagesPage.qml
         RoomSearchPage.qml
+    SOURCES
+        locationhelper.cpp
+)
+
+target_link_libraries(RoomInfo PRIVATE
+    Qt::Core
 )

src/roominfo/locationhelper.cpp

@@ -0,0 +1,46 @@
+// SPDX-FileCopyrightText: 2023 Volker Krause <vkrause@kde.org>
+// SPDX-License-Identifier: LGPL-2.0-or-later
+
+#include "locationhelper.h"
+
+#include <cmath>
+
+QRectF LocationHelper::unite(const QRectF &r1, const QRectF &r2)
+{
+    // this looks weird but is actually intentional as we need to handle point-like "rects" as well
+    if ((!r1.isEmpty() || r1.isNull()) && (!r2.isEmpty() || r2.isNull())) {
+        return r1 | r2;
+    }
+    return (!r1.isEmpty() || r1.isNull()) ? r1 : r2;
+}
+
+QPointF LocationHelper::center(const QRectF &r)
+{
+    return r.center();
+}
+
+constexpr inline double degToRad(double deg)
+{
+    return deg / 180.0 * M_PI;
+}
+
+static QPointF mercatorProject(double lat, double lon, double zoom)
+{
+    const auto x = (256.0 / (2.0 * M_PI)) * std::pow(2.0, zoom) * (degToRad(lon) + M_PI);
+    const auto y = (256.0 / (2.0 * M_PI)) * std::pow(2.0, zoom) * (M_PI - std::log(std::tan(M_PI / 4.0 + degToRad(lat) / 2.0)));
+    return QPointF(x, y);
+}
+
+float LocationHelper::zoomToFit(const QRectF &r, float mapWidth, float mapHeight)
+{
+    const auto p1 = mercatorProject(r.bottomLeft().y(), r.bottomLeft().x(), 1.0);
+    const auto p2 = mercatorProject(r.topRight().y(), r.topRight().x(), 1.0);
+
+    const auto zx = std::log2((mapWidth / (p2.x() - p1.x())));
+    const auto zy = std::log2((mapHeight / (p2.y() - p1.y())));
+    const auto z = std::min(zx, zy);
+
+    return z;
+}
+
+#include "moc_locationhelper.cpp"

src/roominfo/locationhelper.h

@@ -0,0 +1,27 @@
+// SPDX-FileCopyrightText: 2023 Volker Krause <vkrause@kde.org>
+// SPDX-License-Identifier: LGPL-2.0-or-later
+#pragma once
+
+#include <QMetaType>
+#include <QObject>
+#include <QQmlEngine>
+#include <QRectF>
+
+/** Location related helper functions for QML. */
+class LocationHelper : public QObject
+{
+    Q_OBJECT
+    QML_ELEMENT
+    QML_SINGLETON
+
+public:
+    /** Unite two rectangles. */
+    Q_INVOKABLE static QRectF unite(const QRectF &r1, const QRectF &r2);
+    /** Returns the center of @p r. */
+    Q_INVOKABLE static QPointF center(const QRectF &r);
+
+    /** Returns the highest zoom level to fit @r into a map of size @p mapWidth x @p mapHeight. */
+    Q_INVOKABLE static float zoomToFit(const QRectF &r, float mapWidth, float mapHeight);
+};
+
+Q_DECLARE_METATYPE(LocationHelper)