Internal: Nav,MultiSelect: import ImGuiSelectionUserData, SetNextItemSelectionUserData() from MultiSelect. Track NavLastValidSelectionUserData as a convenience.

docs/CHANGELOG.txt

@@ -55,7 +55,7 @@ Other changes:
 
 - Tooltips: made using SetItemTooltip()/IsItemHovered(ImGuiHoveredFlags_ForTooltip) defaults to
   activate tooltips on disabled items. This is done by adding ImGuiHoveredFlags_AllowWhenDisabled
-  to the default value of style.HoverFlagsForTooltipMouse/HoverFlagsForTooltipNav. (##1485)
+  to the default value of style.HoverFlagsForTooltipMouse/HoverFlagsForTooltipNav. (#1485)
 - Nav: Tabbing always enable nav highlight when ImGuiConfigFlags_NavEnableKeyboard is set.
   Previously was inconsistent and only enabled when stepping through a non-input item.
   (#6802, #3092, #5759, #787)

imgui.cpp

@@ -7065,6 +7065,7 @@ void ImGui::FocusWindow(ImGuiWindow* window, ImGuiFocusRequestFlags flags)
         g.NavLayer = ImGuiNavLayer_Main;
         g.NavFocusScopeId = window ? window->NavRootFocusScopeId : 0;
         g.NavIdIsAlive = false;
+        g.NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
 
         // Close popups if any
         ClosePopupsOverWindow(window, false);
@@ -9489,6 +9490,7 @@ bool ImGui::ItemAdd(const ImRect& bb, ImGuiID id, const ImRect* nav_bb_arg, ImGu
     g.LastItemData.NavRect = nav_bb_arg ? *nav_bb_arg : bb;
     g.LastItemData.InFlags = g.CurrentItemFlags | g.NextItemData.ItemFlags | extra_flags;
     g.LastItemData.StatusFlags = ImGuiItemStatusFlags_None;
+    // Note: we don't copy 'g.NextItemData.SelectionUserData' to an hypothetical g.LastItemData.SelectionUserData: since the former is not cleared.
 
     // Directional navigation processing
     if (id != 0)
@@ -10800,6 +10802,7 @@ void ImGui::SetNavWindow(ImGuiWindow* window)
     {
         IMGUI_DEBUG_LOG_FOCUS("[focus] SetNavWindow(\"%s\")\n", window ? window->Name : "<NULL>");
         g.NavWindow = window;
+        g.NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
     }
     g.NavInitRequest = g.NavMoveSubmitted = g.NavMoveScoringItems = false;
     NavUpdateAnyRequestFlag();
@@ -11019,6 +11022,11 @@ static void ImGui::NavApplyItemToResult(ImGuiNavItemData* result)
     result->FocusScopeId = g.CurrentFocusScopeId;
     result->InFlags = g.LastItemData.InFlags;
     result->RectRel = WindowRectAbsToRel(window, g.LastItemData.NavRect);
+    if (result->InFlags & ImGuiItemFlags_HasSelectionUserData)
+    {
+        IM_ASSERT(g.NextItemData.SelectionUserData != ImGuiSelectionUserData_Invalid);
+        result->SelectionUserData = g.NextItemData.SelectionUserData; // INTENTIONAL: At this point this field is not cleared in NextItemData. Avoid unnecessary copy to LastItemData.
+    }
 }
 
 // True when current work location may be scrolled horizontally when moving left / right.
@@ -11031,7 +11039,7 @@ void ImGui::NavUpdateCurrentWindowIsScrollPushableX()
 }
 
 // We get there when either NavId == id, or when g.NavAnyRequest is set (which is updated by NavUpdateAnyRequestFlag above)
-// This is called after LastItemData is set.
+// This is called after LastItemData is set, but NextItemData is also still valid.
 static void ImGui::NavProcessItem()
 {
     ImGuiContext& g = *GImGui;
@@ -11095,6 +11103,11 @@ static void ImGui::NavProcessItem()
         g.NavLayer = window->DC.NavLayerCurrent;
         g.NavFocusScopeId = g.CurrentFocusScopeId;
         g.NavIdIsAlive = true;
+        if (g.LastItemData.InFlags & ImGuiItemFlags_HasSelectionUserData)
+        {
+            IM_ASSERT(g.NextItemData.SelectionUserData != ImGuiSelectionUserData_Invalid);
+            g.NavLastValidSelectionUserData = g.NextItemData.SelectionUserData; // INTENTIONAL: At this point this field is not cleared in NextItemData. Avoid unnecessary copy to LastItemData.
+        }
         window->NavRectRel[window->DC.NavLayerCurrent] = WindowRectAbsToRel(window, nav_bb); // Store item bounding box (relative to window position)
     }
 }
@@ -11206,7 +11219,7 @@ void ImGui::NavMoveRequestResolveWithPastTreeNode(ImGuiNavItemData* result, ImGu
     ImGuiContext& g = *GImGui;
     g.NavMoveScoringItems = false;
     g.LastItemData.ID = tree_node_data->ID;
-    g.LastItemData.InFlags = tree_node_data->InFlags;
+    g.LastItemData.InFlags = tree_node_data->InFlags & ~ImGuiItemFlags_HasSelectionUserData; // Losing SelectionUserData, recovered next-frame (cheaper).
     g.LastItemData.NavRect = tree_node_data->NavRect;
     NavApplyItemToResult(result); // Result this instead of implementing a NavApplyPastTreeNodeToResult()
     NavClearPreferredPosForAxis(ImGuiAxis_Y);
@@ -11273,6 +11286,7 @@ void ImGui::NavRestoreLayer(ImGuiNavLayer layer)
     {
         ImGuiWindow* prev_nav_window = g.NavWindow;
         g.NavWindow = NavRestoreLastChildNavWindow(g.NavWindow);    // FIXME-NAV: Should clear ongoing nav requests?
+        g.NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
         if (prev_nav_window)
             IMGUI_DEBUG_LOG_FOCUS("[focus] NavRestoreLayer: from \"%s\" to SetNavWindow(\"%s\")\n", prev_nav_window->Name, g.NavWindow->Name);
     }
@@ -11568,6 +11582,8 @@ void ImGui::NavInitRequestApplyResult()
     IMGUI_DEBUG_LOG_NAV("[nav] NavInitRequest: ApplyResult: NavID 0x%08X in Layer %d Window \"%s\"\n", result->ID, g.NavLayer, g.NavWindow->Name);
     SetNavID(result->ID, g.NavLayer, result->FocusScopeId, result->RectRel);
     g.NavIdIsAlive = true; // Mark as alive from previous frame as we got a result
+    if (result->SelectionUserData != ImGuiSelectionUserData_Invalid)
+        g.NavLastValidSelectionUserData = result->SelectionUserData;
     if (g.NavInitRequestFromMove)
         NavRestoreHighlightAfterMove();
 }
@@ -11799,6 +11815,7 @@ void ImGui::NavMoveRequestApplyResult()
     {
         IMGUI_DEBUG_LOG_FOCUS("[focus] NavMoveRequest: SetNavWindow(\"%s\")\n", result->Window->Name);
         g.NavWindow = result->Window;
+        g.NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
     }
     if (g.ActiveId != result->ID)
         ClearActiveID();
@@ -11816,6 +11833,8 @@ void ImGui::NavMoveRequestApplyResult()
     IMGUI_DEBUG_LOG_NAV("[nav] NavMoveRequest: result NavID 0x%08X in Layer %d Window \"%s\"\n", result->ID, g.NavLayer, g.NavWindow->Name);
     ImVec2 preferred_scoring_pos_rel = g.NavWindow->RootWindowForNav->NavPreferredScoringPosRel[g.NavLayer];
     SetNavID(result->ID, g.NavLayer, result->FocusScopeId, result->RectRel);
+    if (result->SelectionUserData != ImGuiSelectionUserData_Invalid)
+        g.NavLastValidSelectionUserData = result->SelectionUserData;
 
     // Restore last preferred position for current axis
     // (storing in RootWindowForNav-> as the info is desirable at the beginning of a Move Request. In theory all storage should use RootWindowForNav..)
@@ -14113,6 +14132,7 @@ void ImGui::ShowMetricsWindow(bool* p_open)
         Text("NavId: 0x%08X, NavLayer: %d", g.NavId, g.NavLayer);
         DebugLocateItemOnHover(g.NavId);
         Text("NavInputSource: %s", GetInputSourceName(g.NavInputSource));
+        Text("NavLastValidSelectionUserData = %" IM_PRId64 " (0x%" IM_PRIX64 ")", g.NavLastValidSelectionUserData, g.NavLastValidSelectionUserData);
         Text("NavActive: %d, NavVisible: %d", g.IO.NavActive, g.IO.NavVisible);
         Text("NavActivateId/DownId/PressedId: %08X/%08X/%08X", g.NavActivateId, g.NavActivateDownId, g.NavActivatePressedId);
         Text("NavActivateFlags: %04X", g.NavActivateFlags);

imgui_internal.h

@@ -309,6 +309,18 @@ namespace ImStb
 #endif
 #endif // #ifndef IM_DEBUG_BREAK
 
+// Format specifiers, printing 64-bit hasn't been decently standardized...
+// In a real application you should be using PRId64 and PRIu64 from <inttypes.h> (non-windows) and on Windows define them yourself.
+#if defined(_MSC_VER) && !defined(__clang__)
+#define IM_PRId64   "I64d"
+#define IM_PRIu64   "I64u"
+#define IM_PRIX64   "I64X"
+#else
+#define IM_PRId64   "lld"
+#define IM_PRIu64   "llu"
+#define IM_PRIX64   "llX"
+#endif
+
 //-----------------------------------------------------------------------------
 // [SECTION] Generic helpers
 // Note that the ImXXX helpers functions are lower-level than ImGui functions.
@@ -810,6 +822,7 @@ enum ImGuiItemFlags_
 
     // Controlled by widget code
     ImGuiItemFlags_Inputable                = 1 << 10, // false     // [WIP] Auto-activate input mode when tab focused. Currently only used and supported by a few items before it becomes a generic feature.
+    ImGuiItemFlags_HasSelectionUserData     = 1 << 11, // false     // Set by SetNextItemSelectionUserData()
 };
 
 // Status flags for an already submitted item
@@ -1174,6 +1187,10 @@ struct ImGuiNextWindowData
     inline void ClearFlags()    { Flags = ImGuiNextWindowDataFlags_None; }
 };
 
+// Multi-Selection item index or identifier when using SetNextItemSelectionUserData()/BeginMultiSelect()
+// (Most users are likely to use this store an item INDEX but this may be used to store a POINTER as well.)
+typedef ImS64 ImGuiSelectionUserData;
+
 enum ImGuiNextItemDataFlags_
 {
     ImGuiNextItemDataFlags_None     = 0,
@@ -1184,13 +1201,14 @@ enum ImGuiNextItemDataFlags_
 struct ImGuiNextItemData
 {
     ImGuiNextItemDataFlags      Flags;
-    ImGuiItemFlags              ItemFlags;      // Currently only tested/used for ImGuiItemFlags_AllowOverlap.
-    float                       Width;          // Set by SetNextItemWidth()
-    ImGuiID                     FocusScopeId;   // Set by SetNextItemMultiSelectData() (!= 0 signify value has been set, so it's an alternate version of HasSelectionData, we don't use Flags for this because they are cleared too early. This is mostly used for debugging)
+    ImGuiItemFlags              ItemFlags;          // Currently only tested/used for ImGuiItemFlags_AllowOverlap.
+    // Non-flags members are NOT cleared by ItemAdd() meaning they are still valid during NavProcessItem()
+    float                       Width;              // Set by SetNextItemWidth()
+    ImGuiSelectionUserData      SelectionUserData;  // Set by SetNextItemSelectionUserData() (note that NULL/0 is a valid value, we use -1 == ImGuiSelectionUserData_Invalid to mark invalid values)
     ImGuiCond                   OpenCond;
-    bool                        OpenVal;        // Set by SetNextItemOpen()
+    bool                        OpenVal;            // Set by SetNextItemOpen()
 
-    ImGuiNextItemData()         { memset(this, 0, sizeof(*this)); }
+    ImGuiNextItemData()         { memset(this, 0, sizeof(*this)); SelectionUserData = -1; }
     inline void ClearFlags()    { Flags = ImGuiNextItemDataFlags_None; ItemFlags = ImGuiItemFlags_None; } // Also cleared manually by ItemAdd()!
 };
 
@@ -1528,12 +1546,13 @@ struct ImGuiNavItemData
     ImGuiID             FocusScopeId;   // Init,Move    // Best candidate focus scope ID
     ImRect              RectRel;        // Init,Move    // Best candidate bounding box in window relative space
     ImGuiItemFlags      InFlags;        // ????,Move    // Best candidate item flags
+    ImGuiSelectionUserData SelectionUserData;//I+Mov    // Best candidate SetNextItemSelectionData() value.
     float               DistBox;        //      Move    // Best candidate box distance to current NavId
     float               DistCenter;     //      Move    // Best candidate center distance to current NavId
     float               DistAxial;      //      Move    // Best candidate axial distance to current NavId
 
     ImGuiNavItemData()  { Clear(); }
-    void Clear()        { Window = NULL; ID = FocusScopeId = 0; InFlags = 0; DistBox = DistCenter = DistAxial = FLT_MAX; }
+    void Clear()        { Window = NULL; ID = FocusScopeId = 0; InFlags = 0; SelectionUserData = -1; DistBox = DistCenter = DistAxial = FLT_MAX; }
 };
 
 //-----------------------------------------------------------------------------
@@ -1631,6 +1650,9 @@ struct ImGuiOldColumns
 // [SECTION] Multi-select support
 //-----------------------------------------------------------------------------
 
+// We always assume that -1 is an invalid value (which works for indices and pointers)
+#define ImGuiSelectionUserData_Invalid        ((ImGuiSelectionUserData)-1)
+
 #ifdef IMGUI_HAS_MULTI_SELECT
 // <this is filled in 'range_select' branch>
 #endif // #ifdef IMGUI_HAS_MULTI_SELECT
@@ -1939,6 +1961,7 @@ struct ImGuiContext
     ImGuiActivateFlags      NavNextActivateFlags;
     ImGuiInputSource        NavInputSource;                     // Keyboard or Gamepad mode? THIS CAN ONLY BE ImGuiInputSource_Keyboard or ImGuiInputSource_Mouse
     ImGuiNavLayer           NavLayer;                           // Layer we are navigating on. For now the system is hard-coded for 0=main contents and 1=menu/title bar, may expose layers later.
+    ImGuiSelectionUserData  NavLastValidSelectionUserData;      // Last valid data passed to SetNextItemSelectionUser(), or -1. For current window. Not reset when focusing an item that doesn't have selection data.
     bool                    NavIdIsAlive;                       // Nav widget has been seen this frame ~~ NavRectRel is valid
     bool                    NavMousePosDirty;                   // When set we will update mouse position if (io.ConfigFlags & ImGuiConfigFlags_NavEnableSetMousePos) if set (NB: this not enabled by default)
     bool                    NavDisableHighlight;                // When user starts using mouse, we hide gamepad/keyboard highlight (NB: but they are still available, which is why NavDisableHighlight isn't always != NavDisableMouseHover)
@@ -2186,6 +2209,7 @@ struct ImGuiContext
         NavJustMovedToKeyMods = ImGuiMod_None;
         NavInputSource = ImGuiInputSource_Keyboard;
         NavLayer = ImGuiNavLayer_Main;
+        NavLastValidSelectionUserData = ImGuiSelectionUserData_Invalid;
         NavIdIsAlive = false;
         NavMousePosDirty = false;
         NavDisableHighlight = true;
@@ -3241,6 +3265,7 @@ namespace ImGui
     IMGUI_API void          TreePushOverrideID(ImGuiID id);
     IMGUI_API void          TreeNodeSetOpen(ImGuiID id, bool open);
     IMGUI_API bool          TreeNodeUpdateNextOpen(ImGuiID id, ImGuiTreeNodeFlags flags);   // Return open state. Consume previous SetNextItemOpen() data, if any. May return true when logging.
+    IMGUI_API void          SetNextItemSelectionUserData(ImGuiSelectionUserData selection_user_data);
 
     // Template functions are instantiated in imgui_widgets.cpp for a finite number of types.
     // To use them externally (for custom widget) you may need an "extern template" statement in your code in order to link to existing instances and silence Clang warnings (see #2036).

imgui_widgets.cpp

@@ -19,6 +19,7 @@ Index of this file:
 // [SECTION] Widgets: TreeNode, CollapsingHeader, etc.
 // [SECTION] Widgets: Selectable
 // [SECTION] Widgets: Typing-Select support
+// [SECTION] Widgets: Multi-Select support
 // [SECTION] Widgets: ListBox
 // [SECTION] Widgets: PlotLines, PlotHistogram
 // [SECTION] Widgets: Value helpers
@@ -6759,7 +6760,15 @@ int ImGui::TypingSelectFindResult(ImGuiTypingSelectRequest* req, int items_count
 // [SECTION] Widgets: Multi-Select support
 //-------------------------------------------------------------------------
 
-//
+void ImGui::SetNextItemSelectionUserData(ImGuiSelectionUserData selection_user_data)
+{
+    // Note that flags will be cleared by ItemAdd(), so it's only useful for Navigation code!
+    // This designed so widgets can also cheaply set this before calling ItemAdd(), so we are not tied to MultiSelect api.
+    ImGuiContext& g = *GImGui;
+    g.NextItemData.ItemFlags |= ImGuiItemFlags_HasSelectionUserData;
+    g.NextItemData.SelectionUserData = selection_user_data;
+}
+
 
 //-------------------------------------------------------------------------
 // [SECTION] Widgets: ListBox