map-widget: move the widget and its resources to 'map-widget'

Move all the map widget platform agnostic files to the
<subsurface-root>/map-widget folder.

This avoids the confusion about the desktop version of subsurface
using mobile components. The map widget is planned as a shared
component between the mobile and desktop versions.

desktop-widgets/mapwidget[.h/.cpp] still remain as those are specific
to the desktop version.

Signed-off-by: Lubomir I. Ivanov <neolit123@gmail.com>

13 files changed, 809 insertions, 0 deletions

diff --git a/map-widget/qml/MapWidget.qml b/map-widget/qml/MapWidget.qml
new file mode 100644
index 000000000..2a3283482
--- /dev/null
+++ b/map-widget/qml/MapWidget.qml
@@ -0,0 +1,355 @@
+// SPDX-License-Identifier: GPL-2.0
+import QtQuick 2.0
+import QtLocation 5.3
+import QtPositioning 5.3
+import org.subsurfacedivelog.mobile 1.0
+
+Item {
+	id: rootItem
+	property int nSelectedDives: 0
+
+	MapWidgetHelper {
+		id: mapHelper
+		map: map
+		editMode: false
+		onSelectedDivesChanged: nSelectedDives = list.length
+		onEditModeChanged: editMessage.isVisible = editMode === true ? 1 : 0
+		onCoordinatesChanged: {}
+		Component.onCompleted: {
+			map.plugin = Qt.createQmlObject(pluginObject, rootItem)
+			map.mapType = { "STREET": map.supportedMapTypes[0], "SATELLITE": map.supportedMapTypes[1] }
+			map.activeMapType = map.mapType.SATELLITE
+		}
+	}
+
+	Map {
+		id: map
+		anchors.fill: parent
+		zoomLevel: defaultZoomIn
+
+		property var mapType
+		readonly property var defaultCenter: QtPositioning.coordinate(0, 0)
+		readonly property real defaultZoomIn: 12.0
+		readonly property real defaultZoomOut: 1.0
+		readonly property real textVisibleZoom: 11.0
+		readonly property real zoomStep: 2.0
+		property var newCenter: defaultCenter
+		property real newZoom: 1.0
+		property real newZoomOut: 1.0
+		property var clickCoord: QtPositioning.coordinate(0, 0)
+		property bool isReady: false
+
+		Component.onCompleted: isReady = true
+		onZoomLevelChanged: {
+			if (isReady)
+				mapHelper.calculateSmallCircleRadius(map.center)
+		}
+
+		MapItemView {
+			id: mapItemView
+			model: mapHelper.model
+			delegate: MapQuickItem {
+				id: mapItem
+				anchorPoint.x: 0
+				anchorPoint.y: mapItemImage.height
+				coordinate:  model.coordinate
+				z: mapHelper.model.selectedUuid === model.uuid ? mapHelper.model.count - 1 : 0
+				sourceItem: Image {
+					id: mapItemImage
+					source: "qrc:///mapwidget-marker" + (mapHelper.model.selectedUuid === model.uuid ? "-selected" : (mapHelper.editMode ? "-gray" : ""))
+					SequentialAnimation {
+						id: mapItemImageAnimation
+						PropertyAnimation { target: mapItemImage; property: "scale"; from: 1.0; to: 0.7; duration: 120 }
+						PropertyAnimation { target: mapItemImage; property: "scale"; from: 0.7; to: 1.0; duration: 80 }
+					}
+					MouseArea {
+						drag.target: (mapHelper.editMode && mapHelper.model.selectedUuid === model.uuid) ? mapItem : undefined
+						anchors.fill: parent
+						onClicked: {
+							if (!mapHelper.editMode)
+								mapHelper.model.setSelectedUuid(model.uuid, true)
+						}
+						onDoubleClicked: map.doubleClickHandler(mapItem.coordinate)
+						onReleased: {
+							if (mapHelper.editMode && mapHelper.model.selectedUuid === model.uuid) {
+								mapHelper.updateCurrentDiveSiteCoordinates(mapHelper.model.selectedUuid, mapItem.coordinate)
+							}
+						}
+					}
+					Item {
+						// Text with a duplicate for shadow. DropShadow as layer effect is kind of slow here.
+						y: mapItemImage.y + mapItemImage.height
+						visible: map.zoomLevel >= map.textVisibleZoom
+						Text {
+							id: mapItemTextShadow
+							x: mapItemText.x + 2; y: mapItemText.y + 2
+							text: mapItemText.text
+							font.pointSize: mapItemText.font.pointSize
+							color: "black"
+						}
+						Text {
+							id: mapItemText
+							text: model.name
+							font.pointSize: 11.0
+							color: mapHelper.model.selectedUuid === model.uuid ? "white" : "lightgrey"
+						}
+					}
+				}
+			}
+		}
+
+		SequentialAnimation {
+			id: mapAnimationZoomIn
+			NumberAnimation {
+				target: map; property: "zoomLevel"; to: map.newZoomOut; duration: Math.abs(map.newZoomOut - map.zoomLevel) * 200
+			}
+			ParallelAnimation {
+				CoordinateAnimation { target: map; property: "center"; to: map.newCenter; duration: 1000 }
+				NumberAnimation {
+					target: map; property: "zoomLevel"; to: map.newZoom ; duration: 2000; easing.type: Easing.InCubic
+				}
+			}
+		}
+
+		ParallelAnimation {
+			id: mapAnimationZoomOut
+			NumberAnimation { target: map; property: "zoomLevel"; from: map.zoomLevel; to: map.newZoom; duration: 3000 }
+			SequentialAnimation {
+				PauseAnimation { duration: 2000 }
+				CoordinateAnimation { target: map; property: "center"; to: map.newCenter; duration: 2000 }
+			}
+		}
+
+		ParallelAnimation {
+			id: mapAnimationClick
+			CoordinateAnimation { target: map; property: "center"; to: map.newCenter; duration: 500	}
+			NumberAnimation { target: map; property: "zoomLevel"; to: map.newZoom; duration: 500 }
+		}
+
+		MouseArea {
+			anchors.fill: parent
+			onDoubleClicked: map.doubleClickHandler(map.toCoordinate(Qt.point(mouseX, mouseY)))
+		}
+
+		function doubleClickHandler(coord) {
+			newCenter = coord
+			newZoom = zoomLevel + zoomStep
+			if (newZoom > maximumZoomLevel)
+				newZoom = maximumZoomLevel
+			mapAnimationClick.restart()
+		}
+
+		function animateMapZoomOut() {
+			newCenter = defaultCenter
+			newZoom = defaultZoomOut
+			mapAnimationZoomIn.stop()
+			mapAnimationZoomOut.restart()
+		}
+
+		function pointIsVisible(pt) {
+			return !isNaN(pt.x)
+		}
+
+		function stopZoomAnimations() {
+			mapAnimationZoomIn.stop()
+			mapAnimationZoomOut.stop()
+		}
+
+		function centerOnCoordinate(coord) {
+			stopZoomAnimations()
+			if (coord.latitude === 0.0 && coord.longitude === 0.0) {
+				// Do nothing
+			} else {
+				var newZoomOutFound = false
+				var zoomStored = zoomLevel
+				newZoomOut = zoomLevel
+				newCenter = coord
+				while (zoomLevel > minimumZoomLevel) {
+					var pt = fromCoordinate(coord)
+					if (pointIsVisible(pt)) {
+						newZoomOut = zoomLevel
+						newZoomOutFound = true
+						break
+					}
+					zoomLevel--
+				}
+				if (!newZoomOutFound)
+					newZoomOut = defaultZoomOut
+				zoomLevel = zoomStored
+				newZoom = zoomStored
+				mapAnimationZoomIn.restart()
+				mapAnimationZoomOut.stop()
+			}
+		}
+
+		function centerOnRectangle(topLeft, bottomRight, centerRect) {
+			stopZoomAnimations()
+			if (newCenter.latitude === 0.0 && newCenter.longitude === 0.0) {
+				// Do nothing
+			} else {
+				var centerStored = QtPositioning.coordinate(center.latitude, center.longitude)
+				var zoomStored = zoomLevel
+				var newZoomOutFound = false
+				newCenter = centerRect
+				// calculate zoom out
+				newZoomOut = zoomLevel
+				while (zoomLevel > minimumZoomLevel) {
+					var ptCenter = fromCoordinate(centerStored)
+					var ptCenterRect = fromCoordinate(centerRect)
+					if (pointIsVisible(ptCenter) && pointIsVisible(ptCenterRect)) {
+						newZoomOut = zoomLevel
+						newZoomOutFound = true
+						break
+					}
+					zoomLevel--
+				}
+				if (!newZoomOutFound)
+					newZoomOut = defaultZoomOut
+				// calculate zoom in
+				center = newCenter
+				zoomLevel = maximumZoomLevel
+				var diagonalRect = topLeft.distanceTo(bottomRight)
+				while (zoomLevel > minimumZoomLevel) {
+					var c0 = toCoordinate(Qt.point(0.0, 0.0))
+					var c1 = toCoordinate(Qt.point(width, height))
+					if (c0.distanceTo(c1) > diagonalRect) {
+						newZoom = zoomLevel - 2.0
+						break
+					}
+					zoomLevel--
+				}
+				if (newZoom > defaultZoomIn)
+					newZoom = defaultZoomIn
+				zoomLevel = zoomStored
+				center = centerStored
+				mapAnimationZoomIn.restart()
+				mapAnimationZoomOut.stop()
+			}
+		}
+
+		function deselectMapLocation() {
+			stopZoomAnimations()
+		}
+	}
+
+	Rectangle {
+		id: editMessage
+		radius: padding
+		color: "#b08000"
+		border.color: "white"
+		x: (map.width - width) * 0.5; y: padding
+		width: editMessageText.width + padding * 2.0
+		height: editMessageText.height + padding * 2.0
+		visible: false
+		opacity: 0.0
+		property int isVisible: -1
+		property real padding: 10.0
+		onOpacityChanged: visible = opacity != 0.0
+		states: [
+			State { when: editMessage.isVisible === 1; PropertyChanges { target: editMessage; opacity: 1.0 }},
+			State { when: editMessage.isVisible === 0; PropertyChanges { target: editMessage; opacity: 0.0 }}
+		]
+		transitions: Transition { NumberAnimation { properties: "opacity"; easing.type: Easing.InOutQuad }}
+		Text {
+			id: editMessageText
+			y: editMessage.padding; x: editMessage.padding
+			verticalAlignment: Text.AlignVCenter
+			color: "white"
+			font.pointSize: 11.0
+			text: qsTr("Drag the selected dive location")
+		}
+	}
+
+	Image {
+		id: toggleImage
+		x: 10; y: x
+		width: 40
+		height: 40
+		source: "qrc:///mapwidget-toggle-" + (map.activeMapType === map.mapType.SATELLITE ? "street" : "satellite")
+		SequentialAnimation {
+			id: toggleImageAnimation
+			PropertyAnimation { target: toggleImage; property: "scale"; from: 1.0; to: 0.8; duration: 120 }
+			PropertyAnimation { target: toggleImage; property: "scale"; from: 0.8; to: 1.0; duration: 80 }
+		}
+		MouseArea {
+			anchors.fill: parent
+			onClicked: {
+				map.activeMapType = map.activeMapType === map.mapType.SATELLITE ? map.mapType.STREET : map.mapType.SATELLITE
+				toggleImageAnimation.restart()
+			}
+		}
+	}
+
+	Image {
+		id: imageZoomIn
+		x: 10 + (toggleImage.width - imageZoomIn.width) * 0.5; y: toggleImage.y + toggleImage.height + 10
+		width: 20
+		height: 20
+		source: "qrc:///mapwidget-zoom-in"
+		SequentialAnimation {
+			id: imageZoomInAnimation
+			PropertyAnimation { target: imageZoomIn; property: "scale"; from: 1.0; to: 0.8; duration: 120 }
+			PropertyAnimation { target: imageZoomIn; property: "scale"; from: 0.8; to: 1.0; duration: 80 }
+		}
+		MouseArea {
+			anchors.fill: parent
+			onClicked: {
+				map.newCenter = map.center
+				map.newZoom = map.zoomLevel + map.zoomStep
+				if (map.newZoom > map.maximumZoomLevel)
+					map.newZoom = map.maximumZoomLevel
+				mapAnimationClick.restart()
+				imageZoomInAnimation.restart()
+			}
+		}
+	}
+
+	Image {
+		id: imageZoomOut
+		x: imageZoomIn.x; y: imageZoomIn.y + imageZoomIn.height + 10
+		source: "qrc:///mapwidget-zoom-out"
+		width: 20
+		height: 20
+		SequentialAnimation {
+			id: imageZoomOutAnimation
+			PropertyAnimation { target: imageZoomOut; property: "scale"; from: 1.0; to: 0.8; duration: 120 }
+			PropertyAnimation { target: imageZoomOut; property: "scale"; from: 0.8; to: 1.0; duration: 80 }
+		}
+		MouseArea {
+			anchors.fill: parent
+			onClicked: {
+				map.newCenter = map.center
+				map.newZoom = map.zoomLevel - map.zoomStep
+				mapAnimationClick.restart()
+				imageZoomOutAnimation.restart()
+			}
+		}
+	}
+
+	function openLocationInGoogleMaps(latitude, longitude) {
+		var loc = latitude + " " + longitude
+		var url = "https://www.google.com/maps/place/" + loc + "/@" + loc + ",5000m/data=!3m1!1e3!4m2!3m1!1s0x0:0x0"
+		Qt.openUrlExternally(url)
+	}
+
+	MapWidgetContextMenu {
+		id: contextMenu
+		y: 10; x: map.width - y
+		onActionSelected: {
+			switch (action) {
+			case contextMenu.actions.OPEN_LOCATION_IN_GOOGLE_MAPS:
+				openLocationInGoogleMaps(map.center.latitude, map.center.longitude)
+				break
+			case contextMenu.actions.COPY_LOCATION_DECIMAL:
+				mapHelper.copyToClipboardCoordinates(map.center, false)
+				break
+			case contextMenu.actions.COPY_LOCATION_SEXAGESIMAL:
+				mapHelper.copyToClipboardCoordinates(map.center, true)
+				break
+			case contextMenu.actions.SELECT_VISIBLE_LOCATIONS:
+				mapHelper.selectVisibleLocations()
+				break
+			}
+		}
+	}
+}
diff --git a/map-widget/qml/MapWidgetContextMenu.qml b/map-widget/qml/MapWidgetContextMenu.qml
new file mode 100644
index 000000000..17450a729
--- /dev/null
+++ b/map-widget/qml/MapWidgetContextMenu.qml
@@ -0,0 +1,124 @@
+// SPDX-License-Identifier: GPL-2.0
+import QtQuick 2.0
+
+Item {
+	id: container
+	signal actionSelected(int action)
+
+	readonly property var actions: {
+		"OPEN_LOCATION_IN_GOOGLE_MAPS": 0,
+		"COPY_LOCATION_DECIMAL":        1,
+		"COPY_LOCATION_SEXAGESIMAL":    2,
+		"SELECT_VISIBLE_LOCATIONS":     3
+	}
+	readonly property var menuItemData: [
+		{ idx: actions.OPEN_LOCATION_IN_GOOGLE_MAPS, itemText: qsTr("Open location in Google Maps") },
+		{ idx: actions.COPY_LOCATION_DECIMAL,        itemText: qsTr("Copy location to clipboard (decimal)") },
+		{ idx: actions.COPY_LOCATION_SEXAGESIMAL,    itemText: qsTr("Copy location to clipboard (sexagesimal)") },
+		{ idx: actions.SELECT_VISIBLE_LOCATIONS,     itemText: qsTr("Select visible dive locations") }
+	]
+	readonly property real itemTextPadding: 10.0
+	readonly property real itemHeight: 34.0
+	readonly property int itemAnimationDuration: 100
+	readonly property color colorItemBackground: "#dedede"
+	readonly property color colorItemBackgroundSelected: "grey"
+	readonly property color colorItemText: "black"
+	readonly property color colorItemTextSelected: "#dedede"
+	readonly property color colorItemBorder: "black"
+	property int listViewIsVisible: -1
+	property real maxItemWidth: 0.0
+
+	Image {
+		id: contextMenuImage
+		x: -width
+		source: "qrc:///mapwidget-context-menu"
+
+		SequentialAnimation {
+			id:contextMenuImageAnimation
+			PropertyAnimation { target: contextMenuImage; property: "scale"; from: 1.0; to: 0.8; duration: 80 }
+			PropertyAnimation { target: contextMenuImage; property: "scale"; from: 0.8; to: 1.0; duration: 60 }
+		}
+
+		MouseArea {
+			anchors.fill: parent
+			onClicked: {
+				contextMenuImageAnimation.restart()
+				listViewIsVisible = (listViewIsVisible !== 1) ? 1 : 0
+			}
+		}
+	}
+
+	ListModel {
+		id: listModel
+		property int selectedIdx: -1
+		Component.onCompleted: {
+			for (var i = 0; i < menuItemData.length; i++)
+				append(menuItemData[i]);
+		}
+	}
+
+	Component {
+		id: listItemDelegate
+		Rectangle {
+			color: model.idx === listModel.selectedIdx ? colorItemBackgroundSelected : colorItemBackground
+			width: maxItemWidth
+			height: itemHeight
+			border.color: colorItemBorder
+			Text {
+				x: itemTextPadding
+				height: itemHeight
+				verticalAlignment: Text.AlignVCenter
+				text: model.itemText
+				font.pointSize: 10.0
+				color: model.idx === listModel.selectedIdx ? colorItemTextSelected : colorItemText
+				onWidthChanged: {
+					if (width + itemTextPadding * 2.0 > maxItemWidth)
+						maxItemWidth = width + itemTextPadding * 2.0
+				}
+				Behavior on color { ColorAnimation { duration: itemAnimationDuration }}
+			}
+			Behavior on color { ColorAnimation { duration: itemAnimationDuration }}
+		}
+	}
+
+	ListView {
+		id: listView
+		y: contextMenuImage.y + contextMenuImage.height + 10;
+		width: maxItemWidth;
+		height: listModel.count * itemHeight
+		visible: false
+		opacity: 0.0
+		interactive: false
+		model: listModel
+		delegate: listItemDelegate
+
+		onCountChanged:	x = -maxItemWidth
+		onVisibleChanged: listModel.selectedIdx = -1
+		onOpacityChanged: visible = opacity != 0.0
+
+		Timer {
+			id: timerListViewVisible
+			running: false
+			repeat: false
+			interval: itemAnimationDuration + 50
+			onTriggered: listViewIsVisible = 0
+		}
+
+		MouseArea {
+			anchors.fill: parent
+			onClicked: {
+				if (opacity < 1.0)
+					return;
+				var idx = listView.indexAt(mouseX, mouseY)
+				listModel.selectedIdx = idx
+				container.actionSelected(idx)
+				timerListViewVisible.restart()
+			}
+		}
+		states: [
+			State { when: listViewIsVisible === 1; PropertyChanges { target: listView; opacity: 1.0 }},
+			State { when: listViewIsVisible === 0; PropertyChanges { target: listView; opacity: 0.0 }}
+		]
+		transitions: Transition { NumberAnimation { properties: "opacity"; easing.type: Easing.InOutQuad }}
+	}
+}
diff --git a/map-widget/qml/MapWidgetError.qml b/map-widget/qml/MapWidgetError.qml
new file mode 100644
index 000000000..346e95f07
--- /dev/null
+++ b/map-widget/qml/MapWidgetError.qml
@@ -0,0 +1,13 @@
+// SPDX-License-Identifier: GPL-2.0
+import QtQuick 2.0
+
+Item {
+	Text {
+		anchors.fill: parent
+		horizontalAlignment: Text.AlignHCenter
+		verticalAlignment: Text.AlignVCenter
+		color: "red"
+		text: qsTr("MapWidget.qml failed to load!
+The QML modules QtPositioning and QtLocation could be missing!")
+	}
+}
diff --git a/map-widget/qml/icons/mapwidget-context-menu.png b/map-widget/qml/icons/mapwidget-context-menu.png
new file mode 100644
index 000000000..6ab7cf77d
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-context-menu.png
diff --git a/map-widget/qml/icons/mapwidget-marker-gray.png b/map-widget/qml/icons/mapwidget-marker-gray.png
new file mode 100644
index 000000000..856db9f5b
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-marker-gray.png
diff --git a/map-widget/qml/icons/mapwidget-marker-selected.png b/map-widget/qml/icons/mapwidget-marker-selected.png
new file mode 100644
index 000000000..57f4efa27
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-marker-selected.png
diff --git a/map-widget/qml/icons/mapwidget-marker.png b/map-widget/qml/icons/mapwidget-marker.png
new file mode 100644
index 000000000..a1be73866
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-marker.png
diff --git a/map-widget/qml/icons/mapwidget-toggle-satellite.png b/map-widget/qml/icons/mapwidget-toggle-satellite.png
new file mode 100644
index 000000000..7ee536929
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-toggle-satellite.png
diff --git a/map-widget/qml/icons/mapwidget-toggle-street.png b/map-widget/qml/icons/mapwidget-toggle-street.png
new file mode 100644
index 000000000..04a668c3f
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-toggle-street.png
diff --git a/map-widget/qml/icons/mapwidget-zoom-in.png b/map-widget/qml/icons/mapwidget-zoom-in.png
new file mode 100644
index 000000000..8c2521c3e
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-zoom-in.png
diff --git a/map-widget/qml/icons/mapwidget-zoom-out.png b/map-widget/qml/icons/mapwidget-zoom-out.png
new file mode 100644
index 000000000..bd372f17d
--- /dev/null
+++ b/map-widget/qml/icons/mapwidget-zoom-out.png
diff --git a/map-widget/qmlmapwidgethelper.cpp b/map-widget/qmlmapwidgethelper.cpp
new file mode 100644
index 000000000..ba197f63f
--- /dev/null
+++ b/map-widget/qmlmapwidgethelper.cpp
@@ -0,0 +1,264 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <QApplication>
+#include <QClipboard>
+#include <QGeoCoordinate>
+#include <QDebug>
+#include <QVector>
+
+#include "qmlmapwidgethelper.h"
+#include "core/dive.h"
+#include "core/divesite.h"
+#include "core/helpers.h"
+#include "qt-models/maplocationmodel.h"
+
+#define MIN_DISTANCE_BETWEEN_DIVE_SITES_M 50.0
+#define SMALL_CIRCLE_RADIUS_PX            26.0
+
+MapWidgetHelper::MapWidgetHelper(QObject *parent) : QObject(parent)
+{
+	m_mapLocationModel = new MapLocationModel(this);
+	connect(m_mapLocationModel, SIGNAL(selectedLocationChanged(MapLocation *)),
+	        this, SLOT(selectedLocationChanged(MapLocation *)));
+}
+
+void MapWidgetHelper::centerOnDiveSite(struct dive_site *ds)
+{
+	int idx;
+	struct dive *dive;
+	QVector<struct dive_site *> selDS;
+	QVector<QGeoCoordinate> selGC;
+	QGeoCoordinate dsCoord;
+
+	for_each_dive (idx, dive) {
+		struct dive_site *dss = get_dive_site_for_dive(dive);
+		if (!dive_site_has_gps_location(dss) || !dive->selected)
+			continue;
+		// only store dive sites with GPS
+		selDS.append(dss);
+		selGC.append(QGeoCoordinate(dss->latitude.udeg * 0.000001,
+		                            dss->longitude.udeg * 0.000001));
+	}
+	if (!dive_site_has_gps_location(ds) && !selDS.size()) {
+		// only a single dive site with no GPS selected
+		m_mapLocationModel->setSelectedUuid(ds ? ds->uuid : 0, false);
+		QMetaObject::invokeMethod(m_map, "deselectMapLocation");
+
+	} else if (selDS.size() == 1) {
+		// a single dive site with GPS selected
+		ds = selDS.at(0);
+		m_mapLocationModel->setSelectedUuid(ds->uuid, false);
+		dsCoord.setLatitude(ds->latitude.udeg * 0.000001);
+		dsCoord.setLongitude(ds->longitude.udeg * 0.000001);
+		QMetaObject::invokeMethod(m_map, "centerOnCoordinate", Q_ARG(QVariant, QVariant::fromValue(dsCoord)));
+	} else if (selDS.size() > 1) {
+		/* more than one dive sites with GPS selected.
+		 * find the most top-left and bottom-right dive sites on the map coordinate system. */
+		ds = selDS.at(0);
+		m_mapLocationModel->setSelectedUuid(ds->uuid, false);
+		qreal minLat = 0.0, minLon = 0.0, maxLat = 0.0, maxLon = 0.0;
+		bool start = true;
+		foreach(QGeoCoordinate gc, selGC) {
+			qreal lat = gc.latitude();
+			qreal lon = gc.longitude();
+			if (start) {
+				minLat = maxLat = lat;
+				minLon = maxLon = lon;
+				start = false;
+				continue;
+			}
+			if (lat < minLat)
+				minLat = lat;
+			else if (lat > maxLat)
+				maxLat = lat;
+			if (lon < minLon)
+				minLon = lon;
+			else if (lon > maxLon)
+				maxLon = lon;
+		}
+		// pass rectangle coordinates to QML
+		QGeoCoordinate coordTopLeft(minLat, minLon);
+		QGeoCoordinate coordBottomRight(maxLat, maxLon);
+		QGeoCoordinate coordCenter(minLat + (maxLat - minLat) * 0.5, minLon + (maxLon - minLon) * 0.5);
+		QMetaObject::invokeMethod(m_map, "centerOnRectangle",
+		                          Q_ARG(QVariant, QVariant::fromValue(coordTopLeft)),
+		                          Q_ARG(QVariant, QVariant::fromValue(coordBottomRight)),
+		                          Q_ARG(QVariant, QVariant::fromValue(coordCenter)));
+	}
+}
+
+void MapWidgetHelper::reloadMapLocations()
+{
+	struct dive_site *ds;
+	int idx;
+	QMap<QString, MapLocation *> locationNameMap;
+	m_mapLocationModel->clear();
+	MapLocation *location;
+	QVector<MapLocation *> locationList;
+	qreal latitude, longitude;
+
+	if (displayed_dive_site.uuid && dive_site_has_gps_location(&displayed_dive_site)) {
+		latitude = displayed_dive_site.latitude.udeg * 0.000001;
+		longitude = displayed_dive_site.longitude.udeg * 0.000001;
+		location = new MapLocation(displayed_dive_site.uuid, QGeoCoordinate(latitude, longitude),
+		                           QString(displayed_dive_site.name));
+		locationList.append(location);
+		locationNameMap[QString(displayed_dive_site.name)] = location;
+	}
+	for_each_dive_site(idx, ds) {
+		if (!dive_site_has_gps_location(ds) || ds->uuid == displayed_dive_site.uuid)
+			continue;
+		latitude = ds->latitude.udeg * 0.000001;
+		longitude = ds->longitude.udeg * 0.000001;
+		QGeoCoordinate dsCoord(latitude, longitude);
+		QString name(ds->name);
+		// don't add dive locations with the same name, unless they are
+		// at least MIN_DISTANCE_BETWEEN_DIVE_SITES_M apart
+		if (locationNameMap.contains(name)) {
+			MapLocation *existingLocation = locationNameMap[name];
+			QGeoCoordinate coord = qvariant_cast<QGeoCoordinate>(existingLocation->getRole(MapLocation::Roles::RoleCoordinate));
+			if (dsCoord.distanceTo(coord) < MIN_DISTANCE_BETWEEN_DIVE_SITES_M)
+				continue;
+		}
+		location = new MapLocation(ds->uuid, dsCoord, name);
+		locationList.append(location);
+		locationNameMap[name] = location;
+	}
+	m_mapLocationModel->addList(locationList);
+}
+
+void MapWidgetHelper::selectedLocationChanged(MapLocation *location)
+{
+	int idx;
+	struct dive *dive;
+	m_selectedDiveIds.clear();
+	QGeoCoordinate locationCoord = location->coordinate();
+	for_each_dive (idx, dive) {
+		struct dive_site *ds = get_dive_site_for_dive(dive);
+		if (!dive_site_has_gps_location(ds))
+			continue;
+		const qreal latitude = ds->latitude.udeg * 0.000001;
+		const qreal longitude = ds->longitude.udeg * 0.000001;
+		QGeoCoordinate dsCoord(latitude, longitude);
+		if (locationCoord.distanceTo(dsCoord) < m_smallCircleRadius)
+			m_selectedDiveIds.append(idx);
+	}
+	emit selectedDivesChanged(m_selectedDiveIds);
+}
+
+void MapWidgetHelper::selectVisibleLocations()
+{
+	int idx;
+	struct dive *dive;
+	bool selectedFirst = false;
+	m_selectedDiveIds.clear();
+	for_each_dive (idx, dive) {
+		struct dive_site *ds = get_dive_site_for_dive(dive);
+		if (!dive_site_has_gps_location(ds))
+			continue;
+		const qreal latitude = ds->latitude.udeg * 0.000001;
+		const qreal longitude = ds->longitude.udeg * 0.000001;
+		QGeoCoordinate dsCoord(latitude, longitude);
+		QPointF point;
+		QMetaObject::invokeMethod(m_map, "fromCoordinate", Q_RETURN_ARG(QPointF, point),
+		                          Q_ARG(QGeoCoordinate, dsCoord));
+		if (!qIsNaN(point.x())) {
+			if (!selectedFirst) {
+				m_mapLocationModel->setSelectedUuid(ds->uuid, false);
+				selectedFirst = true;
+			}
+			m_selectedDiveIds.append(idx);
+		}
+	}
+	emit selectedDivesChanged(m_selectedDiveIds);
+}
+
+/*
+ * Based on a 2D Map widget circle with center "coord" and radius SMALL_CIRCLE_RADIUS_PX,
+ * obtain a "small circle" with radius m_smallCircleRadius in meters:
+ *     https://en.wikipedia.org/wiki/Circle_of_a_sphere
+ *
+ * The idea behind this circle is to be able to select multiple nearby dives, when clicking on
+ * the map. This code can be in QML, but it is in C++ instead for performance reasons.
+ *
+ * This can be made faster with an exponential regression [a * exp(b * x)], with a pretty
+ * decent R-squared, but it becomes bound to map provider zoom level mappings and the
+ * SMALL_CIRCLE_RADIUS_PX value, which makes the code hard to maintain.
+ */
+void MapWidgetHelper::calculateSmallCircleRadius(QGeoCoordinate coord)
+{
+	QPointF point;
+	QMetaObject::invokeMethod(m_map, "fromCoordinate", Q_RETURN_ARG(QPointF, point),
+	                          Q_ARG(QGeoCoordinate, coord));
+	QPointF point2(point.x() + SMALL_CIRCLE_RADIUS_PX, point.y());
+	QGeoCoordinate coord2;
+	QMetaObject::invokeMethod(m_map, "toCoordinate", Q_RETURN_ARG(QGeoCoordinate, coord2),
+	                          Q_ARG(QPointF, point2));
+	m_smallCircleRadius = coord2.distanceTo(coord);
+}
+
+void MapWidgetHelper::copyToClipboardCoordinates(QGeoCoordinate coord, bool formatTraditional)
+{
+	bool savep = prefs.coordinates_traditional;
+	prefs.coordinates_traditional = formatTraditional;
+
+	const int lat = lrint(1000000.0 * coord.latitude());
+	const int lon = lrint(1000000.0 * coord.longitude());
+	const char *coordinates = printGPSCoords(lat, lon);
+	QApplication::clipboard()->setText(QString(coordinates), QClipboard::Clipboard);
+
+	free((void *)coordinates);
+	prefs.coordinates_traditional = savep;
+}
+
+void MapWidgetHelper::updateCurrentDiveSiteCoordinates(quint32 uuid, QGeoCoordinate coord)
+{
+	MapLocation *loc = m_mapLocationModel->getMapLocationForUuid(uuid);
+	if (loc)
+		loc->setCoordinate(coord);
+	displayed_dive_site.latitude.udeg = lrint(coord.latitude() * 1000000.0);
+	displayed_dive_site.longitude.udeg = lrint(coord.longitude() * 1000000.0);
+	emit coordinatesChanged();
+}
+
+bool MapWidgetHelper::editMode()
+{
+	return m_editMode;
+}
+
+void MapWidgetHelper::setEditMode(bool editMode)
+{
+	m_editMode = editMode;
+	MapLocation *exists = m_mapLocationModel->getMapLocationForUuid(displayed_dive_site.uuid);
+	// if divesite uuid doesn't exist in the model, add a new MapLocation.
+	if (editMode && !exists) {
+		QGeoCoordinate coord(0.0, 0.0);
+		m_mapLocationModel->add(new MapLocation(displayed_dive_site.uuid, coord,
+		                                        QString(displayed_dive_site.name)));
+		QMetaObject::invokeMethod(m_map, "centerOnCoordinate",
+		                          Q_ARG(QVariant, QVariant::fromValue(coord)));
+	}
+	emit editModeChanged();
+}
+
+QString MapWidgetHelper::pluginObject()
+{
+	QString str;
+	str += "import QtQuick 2.0;";
+	str += "import QtLocation 5.3;";
+	str += "Plugin {";
+	str += "    id: mapPlugin;";
+	str += "    name: 'googlemaps';";
+	str += "    PluginParameter { name: 'googlemaps.maps.language'; value: '%lang%' }";
+	str += "    PluginParameter { name: 'googlemaps.cachefolder'; value: '%cacheFolder%' }";
+	str += "    Component.onCompleted: {";
+	str += "        if (availableServiceProviders.indexOf(name) === -1) {";
+	str += "            console.warn('MapWidget.qml: cannot find a plugin named: ' + name);";
+	str += "        }";
+	str += "    }";
+	str += "}";
+	QString lang = uiLanguage(NULL).replace('_', '-');
+	str.replace("%lang%", lang);
+	QString cacheFolder = QString(system_default_directory()).append("/googlemaps");
+	str.replace("%cacheFolder%", cacheFolder.replace("\\", "/"));
+	return str;
+}
diff --git a/map-widget/qmlmapwidgethelper.h b/map-widget/qmlmapwidgethelper.h
new file mode 100644
index 000000000..36d25d178
--- /dev/null
+++ b/map-widget/qmlmapwidgethelper.h
@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef QMLMAPWIDGETHELPER_H
+#define QMLMAPWIDGETHELPER_H
+
+#include <QObject>
+
+class QGeoCoordinate;
+class MapLocationModel;
+class MapLocation;
+struct dive_site;
+
+class MapWidgetHelper : public QObject {
+
+	Q_OBJECT
+	Q_PROPERTY(QObject *map MEMBER m_map)
+	Q_PROPERTY(MapLocationModel *model MEMBER m_mapLocationModel NOTIFY modelChanged)
+	Q_PROPERTY(bool editMode READ editMode WRITE setEditMode NOTIFY editModeChanged)
+	Q_PROPERTY(QString pluginObject READ pluginObject NOTIFY pluginObjectChanged)
+
+public:
+	explicit MapWidgetHelper(QObject *parent = NULL);
+
+	void centerOnDiveSite(struct dive_site *);
+	void reloadMapLocations();
+	Q_INVOKABLE void copyToClipboardCoordinates(QGeoCoordinate coord, bool formatTraditional);
+	Q_INVOKABLE void calculateSmallCircleRadius(QGeoCoordinate coord);
+	Q_INVOKABLE void updateCurrentDiveSiteCoordinates(quint32 uuid, QGeoCoordinate coord);
+	Q_INVOKABLE void selectVisibleLocations();
+	bool editMode();
+	void setEditMode(bool editMode);
+	QString pluginObject();
+
+private:
+	QObject *m_map;
+	MapLocationModel *m_mapLocationModel;
+	qreal m_smallCircleRadius;
+	QList<int> m_selectedDiveIds;
+	bool m_editMode;
+
+private slots:
+	void selectedLocationChanged(MapLocation *);
+
+signals:
+	void modelChanged();
+	void editModeChanged();
+	void selectedDivesChanged(QList<int> list);
+	void coordinatesChanged();
+	void pluginObjectChanged();
+};
+
+extern "C" const char *printGPSCoords(int lat, int lon);
+
+#endif