feat: drag-and-drop support for explorer

.vscode/launch.json

@@ -0,0 +1,16 @@
+{
+    // Use IntelliSense to learn about possible attributes.
+    // Hover to view descriptions of existing attributes.
+    // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+    "version": "0.2.0",
+    "configurations": [
+        {
+            "type": "lldb",
+            "request": "launch",
+            "name": "Debug",
+            "program": "${workspaceFolder}/bin/editor",
+            "args": [],
+            "cwd": "${workspaceFolder}",
+        }
+    ]
+}

editor/panes/explorermodel.cpp

@@ -5,11 +5,14 @@
 #include "qimage.h"
 #include "qnamespace.h"
 #include "qobject.h"
+#include "qstringview.h"
 #include "qwidget.h"
+#include "qmimedata.h"
 #include "common.h"
 #include <algorithm>
 #include <cstdio>
 #include <optional>
+#include <vector>
 #include "objects/base/instance.h"
 
 // https://doc.qt.io/qt-6/qtwidgets-itemviews-simpletreemodel-example.html#testing-the-model
@@ -23,7 +26,7 @@ ExplorerModel::ExplorerModel(InstanceRef dataRoot, QWidget *parent)
     hierarchyPreUpdateHandler = [&](InstanceRef object, std::optional<InstanceRef> oldParent, std::optional<InstanceRef> newParent) {
         if (oldParent.has_value()) {
             auto children = oldParent.value()->GetChildren();
-            size_t idx = std::find(children.begin(), children.end(), object) - children.end();
+            size_t idx = std::find(children.begin(), children.end(), object) - children.begin();
             beginRemoveRows(toIndex(oldParent.value()), idx, idx);
         }
 
@@ -197,7 +200,50 @@ Qt::DropActions ExplorerModel::supportedDropActions() const {
 }
 
 
-InstanceRef ExplorerModel::fromIndex(const QModelIndex index) {
+InstanceRef ExplorerModel::fromIndex(const QModelIndex index) const {
     if (!index.isValid()) return workspace;
     return static_cast<Instance*>(index.internalPointer())->shared_from_this();
 }
+
+struct DragDropSlot {
+    std::vector<InstanceRef> instances;
+};
+
+bool ExplorerModel::dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) {
+//    if (action != Qt::InternalMove) return;
+    QByteArray byteData = data->data("application/x-openblocks-instance-pointers");
+    uintptr_t slotPtr = byteData.toULongLong();
+    DragDropSlot* slot = (DragDropSlot*)slotPtr;
+    
+    if (!parent.isValid()) {
+        delete slot;
+        return true;
+    }
+
+    InstanceRef parentInst = fromIndex(parent);
+    for (InstanceRef instance : slot->instances) {
+        instance->SetParent(parentInst);
+    }
+
+    delete slot;
+    return true;
+}
+
+QMimeData* ExplorerModel::mimeData(const QModelIndexList& indexes) const {
+    // application/x-openblocks-instance-pointers
+    DragDropSlot* slot = new DragDropSlot();
+
+    for (const QModelIndex& index : indexes) {
+        slot->instances.push_back(fromIndex(index));
+    }
+
+    // uintptr_t ptr = (uintptr_t)&slot;
+
+    QMimeData* mimeData = new QMimeData();
+    mimeData->setData("application/x-openblocks-instance-pointers", QByteArray::number((qulonglong)slot));
+    return mimeData;
+}
+
+QStringList ExplorerModel::mimeTypes() const {
+    return QStringList("application/x-openblocks-instance-pointers");
+}

editor/panes/explorermodel.h

@@ -35,9 +35,12 @@ public:
     bool moveRows(const QModelIndex &sourceParent, int sourceRow, int count, const QModelIndex &destinationParent, int destinationChild) override;
     bool removeRows(int row, int count, const QModelIndex & parent = QModelIndex()) override;
     bool insertRows(int row, int count, const QModelIndex & parent = QModelIndex()) override;
+    bool dropMimeData(const QMimeData *data, Qt::DropAction action, int row, int column, const QModelIndex &parent) override;
+    QMimeData* mimeData(const QModelIndexList& indexes) const override;
+    QStringList mimeTypes() const override;
     Qt::DropActions supportedDragActions() const override;
     Qt::DropActions supportedDropActions() const override;
-    InstanceRef fromIndex(const QModelIndex index);
+    InstanceRef fromIndex(const QModelIndex index) const;
 private:
     InstanceRef rootItem;
     QModelIndex toIndex(InstanceRef item);

editor/panes/explorerview.cpp

@@ -1,6 +1,7 @@
 #include "explorerview.h"
 #include "explorermodel.h"
 #include "common.h"
+#include "qabstractitemmodel.h"
 #include "qaction.h"
 #include "qnamespace.h"
 
@@ -9,7 +10,11 @@ ExplorerView::ExplorerView(QWidget* parent):
     model(ExplorerModel(std::dynamic_pointer_cast<Instance>(workspace))) {
 
     this->setModel(&model);
-    this->setRootIsDecorated(false);
+    // Disabling the root decoration will cause the expand/collapse chevrons to be hidden too, we don't want that
+    // https://stackoverflow.com/a/4687016/16255372
+    // this->setRootIsDecorated(false);
+    // The branches can be customized like this if you want:
+    // this->setStyleSheet(QString("QTreeView::branch { border: none; }"));
     this->setDragDropMode(QAbstractItemView::InternalMove);
     this->setSelectionMode(QAbstractItemView::ExtendedSelection);
     this->setDragEnabled(true);

editor/panes/explorerview.h

@@ -17,7 +17,9 @@ class ExplorerView : public QTreeView {
 public:
     ExplorerView(QWidget* parent = nullptr);
     ~ExplorerView() override;
-    void keyPressEvent(QKeyEvent* evt) override;
+
+    void keyPressEvent(QKeyEvent*) override;
+    // void dropEvent(QDropEvent*) override;
 private:
     ExplorerModel model;
     QMenu contextMenu;