Add expand / collapse support to TreeView

cpp/open3d/visualization/gui/TreeView.cpp

@@ -11,6 +11,7 @@
 
 #include <cmath>
 #include <list>
+#include <optional>
 #include <sstream>
 #include <unordered_map>
 
@@ -212,6 +213,7 @@ struct TreeView::Impl {
         std::shared_ptr<Widget> cell;
         Item *parent = nullptr;
         std::list<Item> children;
+        std::optional<bool> expanded;
     };
     int id_;
     Item root_;
@@ -361,6 +363,21 @@ void TreeView::Layout(const LayoutContext &context) {
     // to defer layout to Draw().
 }
 
+void TreeView::Expand(ItemId id) {
+    auto it = impl_->id2item_.find(id);
+    if (it != impl_->id2item_.end()) {
+        it->second->expanded = true;
+    }
+    // Invalidate();
+}
+
+void TreeView::Collapse(ItemId id) {
+    auto it = impl_->id2item_.find(id);
+    if (it != impl_->id2item_.end()) {
+        it->second->expanded = false;
+    }
+}
+
 Widget::DrawResult TreeView::Draw(const DrawContext &context) {
     auto result = Widget::DrawResult::NONE;
     auto &frame = GetFrame();
@@ -417,8 +434,12 @@ Widget::DrawResult TreeView::Draw(const DrawContext &context) {
                     colorToImguiRGBA(context.theme.tree_selected_color));
         }
 
-        int flags = ImGuiTreeNodeFlags_DefaultOpen |
-                    ImGuiTreeNodeFlags_AllowItemOverlap;
+        int flags = ImGuiTreeNodeFlags_AllowItemOverlap;
+        bool expanded = item.expanded.value_or(true);
+
+        if (expanded) {
+            flags |= ImGuiTreeNodeFlags_DefaultOpen;
+        }
         if (impl_->can_select_parents_) {
             flags |= ImGuiTreeNodeFlags_OpenOnDoubleClick;
             flags |= ImGuiTreeNodeFlags_OpenOnArrow;
@@ -465,7 +486,10 @@ Widget::DrawResult TreeView::Draw(const DrawContext &context) {
             }
         };
 
-        if (ImGui::TreeNodeEx(item.id_string.c_str(), flags, "%s", "")) {
+        bool open = ImGui::TreeNodeEx(item.id_string.c_str(), flags, "%s", "");
+        item.expanded = open;
+
+        if (open) {
             DrawThis(item, height, is_selectable);
 
             for (auto &child : item.children) {

cpp/open3d/visualization/gui/TreeView.h

@@ -134,6 +134,9 @@ class TreeView : public Widget {
     void SetOnSelectionChanged(
             std::function<void(ItemId)> on_selection_changed);
 
+    void Expand(ItemId);
+    void Collapse(ItemId);
+
 private:
     struct Impl;
     std::unique_ptr<Impl> impl_;

cpp/pybind/t/geometry/pointcloud.cpp

@@ -261,9 +261,10 @@ void pybind_pointcloud_definitions(py::module& m) {
                    "non-negative number less than number of points in the "
                    "input pointcloud.",
                    "start_index"_a = 0);
-    pointcloud.def("remove_radius_outliers", &PointCloud::RemoveRadiusOutliers,
-                   "nb_points"_a, "search_radius"_a,
-                   R"(Remove points that have less than nb_points neighbors in a
+    pointcloud.def(
+            "remove_radius_outliers", &PointCloud::RemoveRadiusOutliers,
+            "nb_points"_a, "search_radius"_a,
+            R"(Remove points that have less than nb_points neighbors in a
 sphere of a given search radius.
 
 Args:

cpp/pybind/visualization/gui/gui.cpp

@@ -1665,9 +1665,13 @@ void pybind_gui_definitions(py::module &m) {
             .def("set_on_selection_changed", &TreeView::SetOnSelectionChanged,
                  "Sets f(new_item_id) which is called when the user "
                  "changes the selection.");
+    .def("expand", &TreeView::Expand, "Expand (open) the given TreeView item.")
 
-    // ---- TreeView cells ----
-    auto checkable_cell = static_cast<
+            .def("collapse", &TreeView::Collapse,
+                 "Collapse (close) the given TreeView item.")
+
+            // ---- TreeView cells ----
+            auto checkable_cell = static_cast<
             py::class_<CheckableTextTreeCell,
                        UnownedPointer<CheckableTextTreeCell>, Widget>>(
             m_gui.attr("CheckableTextTreeCell"));

cpp/tests/visualization/CMakeLists.txt

@@ -3,3 +3,17 @@ if (BUILD_GUI)
         rendering/MaterialModifier.cpp
     )
 endif()
+
+
+add_executable(TreeViewTest
+    TreeViewTest.cpp
+)
+
+target_link_libraries(TreeViewTest
+    PRIVATE
+        Open3D::Open3D
+)
+
+set_target_properties(TreeViewTest PROPERTIES
+    RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/bin
+)