TreeNode: Added IsItemToggledOpen() to explicitly query if item was just open/closed, facilitating interactions with custom multi-selections patterns. (#1896, #1861)

docs/CHANGELOG.txt

@@ -67,7 +67,9 @@ Other Changes:
 - TreeNode: Fixed combination of ImGuiTreeNodeFlags_SpanFullWidth and ImGuiTreeNodeFlags_OpenOnArrow
   incorrectly locating the arrow hit position to the left of the frame. (#2451, #2438, #1897)
 - TreeNode: The collapsing arrow accepts click even if modifier keys are being held, facilitating
-  interactions with multi-select patterns. (#2886, #1896, #1861)
+  interactions with custom multi-selections patterns. (#2886, #1896, #1861)
+- TreeNode: Added IsItemToggledOpen() to explicitly query if item was just open/closed, facilitating
+  interactions with custom multi-selections patterns. (#1896, #1861)
 - DragScalar, SliderScalar, InputScalar: Added p_ prefix to parameter that are pointers to the data
   to clarify how they are used, and more comments redirecting to the demo code. (#2844)
 - Misc: Optimized storage of window settings data (reducing allocation count).

imgui.cpp

@@ -4458,6 +4458,12 @@ bool ImGui::IsItemClicked(int mouse_button)
     return IsMouseClicked(mouse_button) && IsItemHovered(ImGuiHoveredFlags_None);
 }
 
+bool ImGui::IsItemToggledOpen()
+{
+    ImGuiContext& g = *GImGui;
+    return (g.CurrentWindow->DC.LastItemStatusFlags & ImGuiItemStatusFlags_ToggledOpen) ? true : false;
+}
+
 bool ImGui::IsItemToggledSelection()
 {
     ImGuiContext& g = *GImGui;

imgui.h

@@ -636,6 +636,7 @@ namespace ImGui
     IMGUI_API bool          IsItemActivated();                                                  // was the last item just made active (item was previously inactive).
     IMGUI_API bool          IsItemDeactivated();                                                // was the last item just made inactive (item was previously active). Useful for Undo/Redo patterns with widgets that requires continuous editing.
     IMGUI_API bool          IsItemDeactivatedAfterEdit();                                       // was the last item just made inactive and made a value change when it was active? (e.g. Slider/Drag moved). Useful for Undo/Redo patterns with widgets that requires continuous editing. Note that you may get false positives (some widgets such as Combo()/ListBox()/Selectable() will return true even when clicking an already selected item).
+    IMGUI_API bool          IsItemToggledOpen();                                                // was the last item open state toggled? set by TreeNode().
     IMGUI_API bool          IsAnyItemHovered();                                                 // is any item hovered?
     IMGUI_API bool          IsAnyItemActive();                                                  // is any item active?
     IMGUI_API bool          IsAnyItemFocused();                                                 // is any item focused?

imgui_demo.cpp

@@ -1613,7 +1613,7 @@ static void ShowDemoWindowWidgets()
     {
         // Submit an item (various types available) so we can query their status in the following block.
         static int item_type = 1;
-        ImGui::Combo("Item Type", &item_type, "Text\0Button\0Button (w/ repeat)\0Checkbox\0SliderFloat\0InputText\0InputFloat\0InputFloat3\0ColorEdit4\0MenuItem\0TreeNode (w/ double-click)\0ListBox\0");
+        ImGui::Combo("Item Type", &item_type, "Text\0Button\0Button (w/ repeat)\0Checkbox\0SliderFloat\0InputText\0InputFloat\0InputFloat3\0ColorEdit4\0MenuItem\0TreeNode\0TreeNode (w/ double-click)\0ListBox\0", 20);
         ImGui::SameLine();
         HelpMarker("Testing how various types of items are interacting with the IsItemXXX functions.");
         bool ret = false;
@@ -1630,8 +1630,9 @@ static void ShowDemoWindowWidgets()
         if (item_type == 7) { ret = ImGui::InputFloat3("ITEM: InputFloat3", col4f); }                   // Testing multi-component items (IsItemXXX flags are reported merged)
         if (item_type == 8) { ret = ImGui::ColorEdit4("ITEM: ColorEdit4", col4f); }                     // Testing multi-component items (IsItemXXX flags are reported merged)
         if (item_type == 9) { ret = ImGui::MenuItem("ITEM: MenuItem"); }                                // Testing menu item (they use ImGuiButtonFlags_PressedOnRelease button policy)
-        if (item_type == 10){ ret = ImGui::TreeNodeEx("ITEM: TreeNode w/ ImGuiTreeNodeFlags_OpenOnDoubleClick", ImGuiTreeNodeFlags_OpenOnDoubleClick | ImGuiTreeNodeFlags_NoTreePushOnOpen); } // Testing tree node with ImGuiButtonFlags_PressedOnDoubleClick button policy.
-        if (item_type == 11){ const char* items[] = { "Apple", "Banana", "Cherry", "Kiwi" }; static int current = 1; ret = ImGui::ListBox("ITEM: ListBox", &current, items, IM_ARRAYSIZE(items), IM_ARRAYSIZE(items)); }
+        if (item_type == 10){ ret = ImGui::TreeNode("ITEM: TreeNode"); if (ret) ImGui::TreePop(); }     // Testing tree node
+        if (item_type == 11){ ret = ImGui::TreeNodeEx("ITEM: TreeNode w/ ImGuiTreeNodeFlags_OpenOnDoubleClick", ImGuiTreeNodeFlags_OpenOnDoubleClick | ImGuiTreeNodeFlags_NoTreePushOnOpen); } // Testing tree node with ImGuiButtonFlags_PressedOnDoubleClick button policy.
+        if (item_type == 12){ const char* items[] = { "Apple", "Banana", "Cherry", "Kiwi" }; static int current = 1; ret = ImGui::ListBox("ITEM: ListBox", &current, items, IM_ARRAYSIZE(items), IM_ARRAYSIZE(items)); }
 
         // Display the value of IsItemHovered() and other common item state functions.
         // Note that the ImGuiHoveredFlags_XXX flags can be combined.
@@ -1652,6 +1653,7 @@ static void ShowDemoWindowWidgets()
             "IsItemDeactivatedAfterEdit() = %d\n"
             "IsItemVisible() = %d\n"
             "IsItemClicked() = %d\n"
+            "IsItemToggledOpen() = %d\n"
             "GetItemRectMin() = (%.1f, %.1f)\n"
             "GetItemRectMax() = (%.1f, %.1f)\n"
             "GetItemRectSize() = (%.1f, %.1f)",
@@ -1669,6 +1671,7 @@ static void ShowDemoWindowWidgets()
             ImGui::IsItemDeactivatedAfterEdit(),
             ImGui::IsItemVisible(),
             ImGui::IsItemClicked(),
+            ImGui::IsItemToggledOpen(),
             ImGui::GetItemRectMin().x, ImGui::GetItemRectMin().y,
             ImGui::GetItemRectMax().x, ImGui::GetItemRectMax().y,
             ImGui::GetItemRectSize().x, ImGui::GetItemRectSize().y

imgui_internal.h

@@ -444,8 +444,9 @@ enum ImGuiItemStatusFlags_
     ImGuiItemStatusFlags_HasDisplayRect     = 1 << 1,
     ImGuiItemStatusFlags_Edited             = 1 << 2,   // Value exposed by item was edited in the current frame (should match the bool return value of most widgets)
     ImGuiItemStatusFlags_ToggledSelection   = 1 << 3,   // Set when Selectable(), TreeNode() reports toggling a selection. We can't report "Selected" because reporting the change allows us to handle clipping with less issues.
-    ImGuiItemStatusFlags_HasDeactivated     = 1 << 4,   // Set if the widget/group is able to provide data for the ImGuiItemStatusFlags_Deactivated flag.
-    ImGuiItemStatusFlags_Deactivated        = 1 << 5    // Only valid if ImGuiItemStatusFlags_HasDeactivated is set.
+    ImGuiItemStatusFlags_ToggledOpen        = 1 << 4,   // Set when TreeNode() reports toggling their open state. 
+    ImGuiItemStatusFlags_HasDeactivated     = 1 << 5,   // Set if the widget/group is able to provide data for the ImGuiItemStatusFlags_Deactivated flag.
+    ImGuiItemStatusFlags_Deactivated        = 1 << 6    // Only valid if ImGuiItemStatusFlags_HasDeactivated is set.
 
 #ifdef IMGUI_ENABLE_TEST_ENGINE
     , // [imgui_tests only]

imgui_widgets.cpp

@@ -5291,9 +5291,9 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
 
     bool hovered, held;
     bool pressed = ButtonBehavior(interact_bb, id, &hovered, &held, button_flags);
-    bool toggled = false;
     if (!is_leaf)
     {
+        bool toggled = false;
         if (pressed)
         {
             if ((flags & (ImGuiTreeNodeFlags_OpenOnArrow | ImGuiTreeNodeFlags_OpenOnDoubleClick)) == 0 || (g.NavActivateId == id))
@@ -5321,6 +5321,7 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
         {
             is_open = !is_open;
             window->DC.StateStorage->SetInt(id, is_open);
+            window->DC.LastItemStatusFlags |= ImGuiItemStatusFlags_ToggledOpen;
         }
     }
     if (flags & ImGuiTreeNodeFlags_AllowItemOverlap)