MultiSelect: added GetMultiSelectState() + store LastSelectionSize as provided by user, convenient for quick debugging and testing.

imgui_internal.h

@@ -1758,7 +1758,6 @@ struct IMGUI_API ImGuiMultiSelectTempData
     bool                    IsEndIO;            // Set when switching IO from BeginMultiSelect() to EndMultiSelect() state.
     bool                    IsFocused;          // Set if currently focusing the selection scope (any item of the selection). May be used if you have custom shortcut associated to selection.
     bool                    IsKeyboardSetRange; // Set by BeginMultiSelect() when using Shift+Navigation. Because scrolling may be affected we can't afford a frame of lag with Shift+Navigation.
-    bool                    IsSelectionEmpty;   // Set by BeginMultiSelect() based on optional info provided by user. May be false positive, never false negative.
     bool                    NavIdPassedBy;
     bool                    RangeSrcPassedBy;   // Set by the item that matches RangeSrcItem.
     bool                    RangeDstPassedBy;   // Set by the item that matches NavJustMovedToId when IsSetRange is set.
@@ -1775,12 +1774,13 @@ struct IMGUI_API ImGuiMultiSelectState
     ImGuiWindow*            Window;
     ImGuiID                 ID;
     int                     LastFrameActive;    // Last used frame-count, for GC.
+    int                     LastSelectionSize;  // Set by BeginMultiSelect() based on optional info provided by user. May be -1 if unknown.
     ImS8                    RangeSelected;      // -1 (don't have) or true/false
     ImS8                    NavIdSelected;      // -1 (don't have) or true/false
     ImGuiSelectionUserData  RangeSrcItem;       //
     ImGuiSelectionUserData  NavIdItem;          // SetNextItemSelectionUserData() value for NavId (if part of submitted items)
 
-    ImGuiMultiSelectState() { Window = NULL; ID = 0; LastFrameActive = 0; RangeSelected = NavIdSelected = -1; RangeSrcItem = NavIdItem = ImGuiSelectionUserData_Invalid; }
+    ImGuiMultiSelectState() { Window = NULL; ID = 0; LastFrameActive = LastSelectionSize = 0; RangeSelected = NavIdSelected = -1; RangeSrcItem = NavIdItem = ImGuiSelectionUserData_Invalid; }
 };
 
 #endif // #ifdef IMGUI_HAS_MULTI_SELECT
@@ -3411,7 +3411,8 @@ namespace ImGui
     // Multi-Select API
     IMGUI_API void          MultiSelectItemHeader(ImGuiID id, bool* p_selected, ImGuiButtonFlags* p_button_flags);
     IMGUI_API void          MultiSelectItemFooter(ImGuiID id, bool* p_selected, bool* p_pressed);
-    inline ImGuiBoxSelectState* GetBoxSelectState(ImGuiID id) { ImGuiContext& g = *GImGui; return (id != 0 && g.BoxSelectState.ID == id && g.BoxSelectState.IsActive) ? &g.BoxSelectState : NULL; }
+    inline ImGuiBoxSelectState*     GetBoxSelectState(ImGuiID id)   { ImGuiContext& g = *GImGui; return (id != 0 && g.BoxSelectState.ID == id && g.BoxSelectState.IsActive) ? &g.BoxSelectState : NULL; }
+    inline ImGuiMultiSelectState*   GetMultiSelectState(ImGuiID id) { ImGuiContext& g = *GImGui; return g.MultiSelectStorage.GetByKey(id); }
 
     // Internal Columns API (this is not exposed because we will encourage transitioning to the Tables API)
     IMGUI_API void          SetWindowClipRectBeforeSetChannel(ImGuiWindow* window, const ImRect& clip_rect);

imgui_widgets.cpp

@@ -7330,7 +7330,6 @@ ImGuiMultiSelectIO* ImGui::BeginMultiSelect(ImGuiMultiSelectFlags flags, int cur
     ms->FocusScopeId = id;
     ms->Flags = flags;
     ms->IsFocused = (ms->FocusScopeId == g.NavFocusScopeId);
-    ms->IsSelectionEmpty = (current_selection_size == 0);
     ms->BackupCursorMaxPos = window->DC.CursorMaxPos;
     ms->ScopeRectMin = window->DC.CursorMaxPos = window->DC.CursorPos;
     PushFocusScope(ms->FocusScopeId);
@@ -7344,6 +7343,7 @@ ImGuiMultiSelectIO* ImGui::BeginMultiSelect(ImGuiMultiSelectFlags flags, int cur
     ImGuiMultiSelectState* storage = g.MultiSelectStorage.GetOrAddByKey(id);
     storage->ID = id;
     storage->LastFrameActive = g.FrameCount;
+    storage->LastSelectionSize = current_selection_size;
     storage->Window = window;
     ms->Storage = storage;
 
@@ -7400,7 +7400,7 @@ ImGuiMultiSelectIO* ImGui::BeginMultiSelect(ImGuiMultiSelectFlags flags, int cur
     {
         ImGuiSelectionRequest req = { ImGuiSelectionRequestType_SetAll, request_select_all, ImGuiSelectionUserData_Invalid, ImGuiSelectionUserData_Invalid };
         if (!request_select_all)
-            ms->IsSelectionEmpty = true;
+            storage->LastSelectionSize = 0;
         ms->IO.Requests.push_back(req);
     }
     ms->LoopRequestSetAll = request_select_all ? 1 : request_clear ? 0 : -1;
@@ -7658,13 +7658,13 @@ void ImGui::MultiSelectItemFooter(ImGuiID id, bool* p_selected, bool* p_pressed)
                 selected = !selected;
                 ImGuiSelectionRequest req = { ImGuiSelectionRequestType_SetRange, selected, item_data, item_data };
                 ImGuiSelectionRequest* prev_req = (ms->IO.Requests.Size > 0) ? &ms->IO.Requests.Data[ms->IO.Requests.Size - 1] : NULL;
-                if (ms->IsSelectionEmpty && bs->IsStartedFromVoid)
+                if (storage->LastSelectionSize == 0 && bs->IsStartedFromVoid)
                     pressed = true; // First item act as a pressed: code below will emit selection request and set NavId (whatever we emit here will be overriden anyway)
                 else if (prev_req && prev_req->Type == ImGuiSelectionRequestType_SetRange && prev_req->RangeLastItem == ms->BoxSelectLastitem && prev_req->Selected == selected)
                     prev_req->RangeLastItem = item_data; // Merge span into same request
                 else
                     ms->IO.Requests.push_back(req);
-                ms->IsSelectionEmpty = false;
+                storage->LastSelectionSize++;
             }
             ms->BoxSelectLastitem = item_data;
         }
@@ -7799,6 +7799,7 @@ void ImGui::DebugNodeMultiSelectState(ImGuiMultiSelectState* storage)
         return;
     Text("RangeSrcItem = %" IM_PRId64 " (0x%" IM_PRIX64 "), RangeSelected = %d", storage->RangeSrcItem, storage->RangeSrcItem, storage->RangeSelected);
     Text("NavIdItem = %" IM_PRId64 " (0x%" IM_PRIX64 "), NavIdSelected = %d", storage->NavIdItem, storage->NavIdItem, storage->NavIdSelected);
+    Text("LastSelectionSize = %d", storage->LastSelectionSize); // Provided by user
     TreePop();
 #else
     IM_UNUSED(storage);