Fix regression for dragging multiple events

include/editor.h

@@ -95,8 +95,7 @@ public:
     Tileset *getCurrentMapPrimaryTileset();
 
     DraggablePixmapItem *addMapEvent(Event *event);
-    void selectMapEvent(DraggablePixmapItem *object);
-    void selectMapEvent(DraggablePixmapItem *object, bool toggle);
+    void selectMapEvent(DraggablePixmapItem *object, bool toggle = false);
     DraggablePixmapItem *addNewEvent(Event::Type type);
     void updateSelectedEvents();
     void duplicateSelectedEvents();

include/ui/draggablepixmapitem.h

@@ -24,13 +24,7 @@ public:
         updatePosition();
     }
 
-    Editor *editor = nullptr;
     Event *event = nullptr;
-    QGraphicsItemAnimation *pos_anim = nullptr;
-
-    bool active;
-    int last_x;
-    int last_y;
 
     void updatePosition();
     void move(int dx, int dy);
@@ -38,6 +32,12 @@ public:
     void emitPositionChanged();
     void updatePixmap();
 
+private:
+    Editor *editor = nullptr;
+    QPoint lastPos;
+    bool active = false;
+    bool releaseSelectionQueued = false;
+
 signals:
     void positionChanged(Event *event);
     void xChanged(int);

src/core/editcommands.cpp

@@ -331,7 +331,7 @@ void EventCreate::redo() {
 
     // select this event
     editor->selected_events->clear();
-    editor->selectMapEvent(event->getPixmapItem(), false);
+    editor->selectMapEvent(event->getPixmapItem());
 }
 
 void EventCreate::undo() {

src/editor.cpp

@@ -1358,7 +1358,7 @@ void Editor::mouseEvent_map(QGraphicsSceneMouseEvent *event, MapPixmapItem *item
                     if (newEvent) {
                         newEvent->move(pos.x(), pos.y());
                         emit objectsChanged();
-                        selectMapEvent(newEvent, false);
+                        selectMapEvent(newEvent);
                     }
                 }
             }
@@ -1994,10 +1994,6 @@ void Editor::updateSelectedEvents() {
     emit objectsChanged();
 }
 
-void Editor::selectMapEvent(DraggablePixmapItem *object) {
-    selectMapEvent(object, false);
-}
-
 void Editor::selectMapEvent(DraggablePixmapItem *object, bool toggle) {
     if (!selected_events || !object)
         return;
@@ -2228,10 +2224,8 @@ void Editor::objectsView_onMousePress(QMouseEvent *event) {
 
     bool multiSelect = event->modifiers() & Qt::ControlModifier;
     if (!selectingEvent && !multiSelect && selected_events->length() > 1) {
-        DraggablePixmapItem *first = selected_events->first();
-        selected_events->clear();
-        selected_events->append(first);
-        updateSelectedEvents();
+        // User is clearing group selection by clicking on the background
+        this->selectMapEvent(selected_events->first());
     }
     selectingEvent = false;
 }

src/mainwindow.cpp

@@ -2014,7 +2014,7 @@ void MainWindow::addNewEvent(Event::Type type) {
             auto centerPos = ui->graphicsView_Map->mapToScene(halfSize.width(), halfSize.height());
             object->moveTo(Metatile::coordFromPixmapCoord(centerPos));
             updateObjects();
-            editor->selectMapEvent(object, false);
+            editor->selectMapEvent(object);
         } else {
             QMessageBox msgBox(this);
             msgBox.setText("Failed to add new event");

src/ui/draggablepixmapitem.cpp

@@ -34,11 +34,26 @@ void DraggablePixmapItem::updatePixmap() {
 }
 
 void DraggablePixmapItem::mousePressEvent(QGraphicsSceneMouseEvent *mouse) {
-    active = true;
-    QPoint pos = Metatile::coordFromPixmapCoord(mouse->scenePos());
-    last_x = pos.x();
-    last_y = pos.y();
-    this->editor->selectMapEvent(this, mouse->modifiers() & Qt::ControlModifier);
+    if (this->active)
+        return;
+    this->active = true;
+    this->lastPos = Metatile::coordFromPixmapCoord(mouse->scenePos());
+
+    bool selectionToggle = mouse->modifiers() & Qt::ControlModifier;
+    if (selectionToggle || !editor->selected_events->contains(this)) {
+        // User is either toggling this selection on/off as part of a group selection,
+        // or they're newly selecting just this item.
+        this->editor->selectMapEvent(this, selectionToggle);
+    } else {
+        // This item is already selected and the user isn't toggling the selection, so there are 4 possibilities:
+        // 1. This is the only selected event, and the selection is pointless.
+        // 2. This is the only selected event, and they want to drag the item around.
+        // 3. There's a group selection, and they want to start a new selection with just this item.
+        // 4. There's a group selection, and they want to drag the group around.
+        // 'selectMapEvent' will immediately clear the rest of the selection, which supports #1-3 but prevents #4.
+        // To support #4 we set the flag below, and we only call 'selectMapEvent' on mouse release if no move occurred.
+        this->releaseSelectionQueued = true;
+    }
     this->editor->selectingEvent = true;
 }
 
@@ -57,10 +72,17 @@ void DraggablePixmapItem::moveTo(const QPoint &pos) {
 }
 
 void DraggablePixmapItem::mouseMoveEvent(QGraphicsSceneMouseEvent *mouse) {
-    if (active) {
+    if (!this->active)
+        return;
+
     QPoint pos = Metatile::coordFromPixmapCoord(mouse->scenePos());
-        if (pos.x() != last_x || pos.y() != last_y) {
+    if (pos == this->lastPos)
+        return;
+
+    QPoint moveDistance = pos - this->lastPos;
+    this->lastPos = pos;
     emit this->editor->map_item->hoveredMapMetatileChanged(pos);
+
     QList <Event *> selectedEvents;
     if (editor->selected_events->contains(this)) {
         for (DraggablePixmapItem *item : *editor->selected_events) {
@@ -69,16 +91,20 @@ void DraggablePixmapItem::mouseMoveEvent(QGraphicsSceneMouseEvent *mouse) {
     } else {
         selectedEvents.append(this->event);
     }
-            editor->map->editHistory.push(new EventMove(selectedEvents, pos.x() - last_x, pos.y() - last_y, currentActionId));
-            last_x = pos.x();
-            last_y = pos.y();
-        }
-    }
+    editor->map->editHistory.push(new EventMove(selectedEvents, moveDistance.x(), moveDistance.y(), currentActionId));
+    this->releaseSelectionQueued = false;
 }
 
-void DraggablePixmapItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *) {
-    active = false;
+void DraggablePixmapItem::mouseReleaseEvent(QGraphicsSceneMouseEvent *mouse) {
+    if (!this->active)
+        return;
+    this->active = false;
     currentActionId++;
+    if (this->releaseSelectionQueued) {
+        this->releaseSelectionQueued = false;
+        if (Metatile::coordFromPixmapCoord(mouse->scenePos()) == this->lastPos)
+            this->editor->selectMapEvent(this);
+    }
 }
 
 void DraggablePixmapItem::mouseDoubleClickEvent(QGraphicsSceneMouseEvent *) {