MultiSelect: added ImGuiSelectionBasicStorage::GetStorageIdFromIndex() indirection to be easier on the reader.

Tempting to make it a virtual.

imgui.h

@@ -2823,7 +2823,7 @@ struct ImGuiSelectionRequest
 
 // Optional helper to store multi-selection state + apply multi-selection requests.
 // - Used by our demos and provided as a convenience to easily implement basic multi-selection.
-// - USING THIS IS NOT MANDATORY. This is only a helper and not a required API. Advanced users are likely to implement their own.
+// - USING THIS IS NOT MANDATORY. This is only a helper and not a required API.
 // To store a multi-selection, in your application you could:
 // - A) Use this helper as a convenience. We use our simple key->value ImGuiStorage as a std::set<ImGuiID> replacement.
 // - B) Use your own external storage: e.g. std::set<MyObjectId>, std::vector<MyObjectId>, interval trees, etc.
@@ -2845,7 +2845,7 @@ struct ImGuiSelectionBasicStorage
     // Members
     ImGuiStorage    Storage;        // [Internal] Selection set. Think of this as similar to e.g. std::set<ImGuiID>
     int             Size;           // Number of selected items (== number of 1 in the Storage), maintained by this helper.
-    ImGuiID         (*AdapterIndexToStorageId)(ImGuiSelectionBasicStorage* self, int idx);  // e.g. selection.AdapterIndexToStorageId = [](ImGuiSelectionBasicStorage* self, int idx) { return ((MyItems**)self->AdapterData)[idx]->ID; };
+    ImGuiID         (*AdapterIndexToStorageId)(ImGuiSelectionBasicStorage* self, int idx);  // e.g. selection.AdapterIndexToStorageId = [](ImGuiSelectionBasicStorage* self, int idx) { return ((MyItems**)self->UserData)[idx]->ID; };
     void*           UserData;       // User data for use by adapter function                // e.g. selection.UserData = (void*)my_items;
 
     // Methods: apply selection requests coming from BeginMultiSelect() and EndMultiSelect() functions. Uses 'items_count' based to BeginMultiSelect()
@@ -2857,6 +2857,7 @@ struct ImGuiSelectionBasicStorage
     void    Swap(ImGuiSelectionBasicStorage& r) { Storage.Data.swap(r.Storage.Data); }
     bool    Contains(ImGuiID id) const          { return Storage.GetInt(id, 0) != 0; }
     void    SetItemSelected(ImGuiID id, bool v) { int* p_int = Storage.GetIntRef(id, 0); if (v && *p_int == 0) { *p_int = 1; Size++; } else if (!v && *p_int != 0) { *p_int = 0; Size--; } }
+    ImGuiID GetStorageIdFromIndex(int idx)      { return AdapterIndexToStorageId(this, idx); }
 };
 
 //-----------------------------------------------------------------------------

imgui_demo.cpp

@@ -2798,12 +2798,12 @@ struct ExampleSelectionWithDeletion : ImGuiSelectionBasicStorage
 
         // If focused item is selected: land on first unselected item after focused item.
         for (int idx = focused_idx + 1; idx < items_count; idx++)
-            if (!Contains(AdapterIndexToStorageId(this, idx)))
+            if (!Contains(GetStorageIdFromIndex(idx)))
                 return idx;
 
         // If focused item is selected: otherwise return last unselected item before focused item.
         for (int idx = IM_MIN(focused_idx, items_count) - 1; idx >= 0; idx--)
-            if (!Contains(AdapterIndexToStorageId(this, idx)))
+            if (!Contains(GetStorageIdFromIndex(idx)))
                 return idx;
 
         return -1;
@@ -2822,7 +2822,7 @@ struct ExampleSelectionWithDeletion : ImGuiSelectionBasicStorage
         int item_next_idx_to_select = -1;
         for (int idx = 0; idx < items.Size; idx++)
         {
-            if (!Contains(AdapterIndexToStorageId(this, idx)))
+            if (!Contains(GetStorageIdFromIndex(idx)))
                 new_items.push_back(items[idx]);
             if (item_curr_idx_to_select == idx)
                 item_next_idx_to_select = new_items.Size - 1;
@@ -2832,7 +2832,7 @@ struct ExampleSelectionWithDeletion : ImGuiSelectionBasicStorage
         // Update selection
         Clear();
         if (item_next_idx_to_select != -1 && ms_io->NavIdSelected)
-            SetItemSelected(AdapterIndexToStorageId(this, item_next_idx_to_select), true);
+            SetItemSelected(GetStorageIdFromIndex(item_next_idx_to_select), true);
     }
 };
 

imgui_widgets.cpp

@@ -7846,11 +7846,11 @@ void ImGuiSelectionBasicStorage::ApplyRequests(ImGuiMultiSelectIO* ms_io)
         {
             Storage.Data.reserve(ms_io->ItemsCount);
             for (int idx = 0; idx < ms_io->ItemsCount; idx++)
-                SetItemSelected(AdapterIndexToStorageId(this, idx), true);
+                SetItemSelected(GetStorageIdFromIndex(idx), true);
         }
         if (req.Type == ImGuiSelectionRequestType_SetRange)
             for (int idx = (int)req.RangeFirstItem; idx <= (int)req.RangeLastItem; idx++)
-                SetItemSelected(AdapterIndexToStorageId(this, idx), req.Selected);
+                SetItemSelected(GetStorageIdFromIndex(idx), req.Selected);
     }
 }