Docking: Added SetNextWindowUserType() + user type filtering in dockspace and window merging. Added DockSpace() flag ImGuiDockFlags_NoSplit. Renaming. Reworked the DockNodeUpdateFindOnlyNodeWithWindows code so DockNodeUpdate can access the first window.

imgui.cpp

@@ -2371,6 +2371,7 @@ ImGuiWindow::ImGuiWindow(ImGuiContext* context, const char* name)
     HiddenFramesRegular = HiddenFramesForResize = 0;
     SetWindowPosAllowFlags = SetWindowSizeAllowFlags = SetWindowCollapsedAllowFlags = SetWindowDockAllowFlags = ImGuiCond_Always | ImGuiCond_Once | ImGuiCond_FirstUseEver | ImGuiCond_Appearing;
     SetWindowPosVal = SetWindowPosPivot = ImVec2(FLT_MAX, FLT_MAX);
+    UserTypeId = 0;
 
     LastFrameActive = -1;
     ItemWidthDefault = 0.0f;
@@ -3350,7 +3351,7 @@ void ImGui::NewFrame()
 
     // Undocking
     // (needs to be before UpdateMovingWindow so the window is already offset and following the mouse on the detaching frame)
-    DockContextUpdateUndocking(g.DockContext);
+    DockContextNewFrameUpdateUndocking(g.DockContext);
 
     // Find hovered window
     // (needs to be before UpdateMovingWindow so we fill HoveredWindowUnderMovingWindow on the mouse release frame)
@@ -3404,7 +3405,7 @@ void ImGui::NewFrame()
     ClosePopupsOverWindow(g.NavWindow);
 
     // Docking
-    DockContextUpdateDocking(g.DockContext);
+    DockContextNewFrameUpdateDocking(g.DockContext);
 
     // Create implicit window - we will only render it if the user has added something to it.
     // We don't use "Debug" to avoid colliding with user trying to create a "Debug" window with custom flags.
@@ -4954,6 +4955,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
     {
         window->SizeContentsExplicit = ImVec2(0.0f, 0.0f);
     }
+    window->UserTypeId = g.NextWindowData.UserTypeId;
     if (g.NextWindowData.CollapsedCond)
         SetWindowCollapsed(window, g.NextWindowData.CollapsedVal, g.NextWindowData.CollapsedCond);
     if (g.NextWindowData.FocusCond)
@@ -6320,6 +6322,12 @@ void ImGui::SetNextWindowDock(ImGuiID id, ImGuiCond cond)
     g.NextWindowData.DockId = id;
 }
 
+void ImGui::SetNextWindowUserType(ImGuiID user_type)
+{
+    ImGuiContext& g = *GImGui;
+    g.NextWindowData.UserTypeId = user_type;
+}
+
 // In window space (not screen space!)
 ImVec2 ImGui::GetContentRegionMax()
 {
@@ -9580,7 +9588,6 @@ namespace ImGui
     static void             DockNodeRemoveWindow(ImGuiDockNode* node, ImGuiWindow* window, ImGuiID save_dock_id);
     static void             DockNodeHideHostWindow(ImGuiDockNode* node);
     static void             DockNodeUpdate(ImGuiDockNode* node);
-    static ImGuiDockNode*   DockNodeUpdateFindOnlyNodeWithWindows(ImGuiDockNode* node);
     static void             DockNodeUpdateVisibleFlagAndInactiveChilds(ImGuiDockNode* node);
     static void             DockNodeUpdateTabBar(ImGuiDockNode* node, ImGuiWindow* host_window);
     static void             DockNodeUpdateVisibleFlag(ImGuiDockNode* node);
@@ -9656,7 +9663,7 @@ void ImGui::DockContextRebuild(ImGuiDockContext* ctx)
     DockContextBuildAddWindowsToNodes(ctx);
 }
 
-void ImGui::DockContextUpdateUndocking(ImGuiDockContext* ctx)
+void ImGui::DockContextNewFrameUpdateUndocking(ImGuiDockContext* ctx)
 {
     ImGuiContext& g = *GImGui;
     if (!(g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable))
@@ -9682,7 +9689,7 @@ void ImGui::DockContextUpdateUndocking(ImGuiDockContext* ctx)
             DockContextProcessUndock(ctx, ctx->Requests[n].WindowUndock);
 }
 
-void ImGui::DockContextUpdateDocking(ImGuiDockContext* ctx)
+void ImGui::DockContextNewFrameUpdateDocking(ImGuiDockContext* ctx)
 {
     ImGuiContext& g = *GImGui;
     if (!(g.IO.ConfigFlags & ImGuiConfigFlags_DockingEnable))
@@ -10000,6 +10007,8 @@ void ImGui::DockContextProcessUndock(ImGuiDockContext* ctx, ImGuiWindow* window)
 ImGuiDockNode::ImGuiDockNode(ImGuiID id)
 {
     ID = id;
+    UserTypeIdFilter = 0;
+    Flags = 0;
     ParentNode = ChildNodes[0] = ChildNodes[1] = NULL;
     TabBar = NULL;
     SplitAxis = ImGuiAxis_None;
@@ -10197,28 +10206,20 @@ static void ImGui::DockNodeHideHostWindow(ImGuiDockNode* node)
     }
 }
 
-static void DockNodeUpdateFindOnlyNodeWithWindowsRec(ImGuiDockNode* node, int* p_count, ImGuiDockNode** p_only_node_with_windows)
+static void DockNodeUpdateFindOnlyNodeWithWindowsRec(ImGuiDockNode* node, int* p_count, ImGuiDockNode** p_first_node_with_windows)
 {
     if (node->Windows.Size > 0)
     {
-        if (*p_only_node_with_windows == NULL)
+        if (*p_first_node_with_windows == NULL)
-            *p_only_node_with_windows = node;
+            *p_first_node_with_windows = node;
         (*p_count)++;
     }
     if (*p_count > 1)
         return;
     if (node->ChildNodes[0])
-        DockNodeUpdateFindOnlyNodeWithWindowsRec(node->ChildNodes[0], p_count, p_only_node_with_windows);
+        DockNodeUpdateFindOnlyNodeWithWindowsRec(node->ChildNodes[0], p_count, p_first_node_with_windows);
     if (node->ChildNodes[1])
-        DockNodeUpdateFindOnlyNodeWithWindowsRec(node->ChildNodes[1], p_count, p_only_node_with_windows);
+        DockNodeUpdateFindOnlyNodeWithWindowsRec(node->ChildNodes[1], p_count, p_first_node_with_windows);
-}
-
-static ImGuiDockNode* ImGui::DockNodeUpdateFindOnlyNodeWithWindows(ImGuiDockNode* node)
-{
-    int count = 0;
-    ImGuiDockNode* only_node_with_windows = NULL;
-    DockNodeUpdateFindOnlyNodeWithWindowsRec(node, &count, &only_node_with_windows);
-    return (count == 1 ? only_node_with_windows : NULL);
 }
 
 static void ImGui::DockNodeUpdateVisibleFlagAndInactiveChilds(ImGuiDockNode* node)
@@ -10280,8 +10281,19 @@ static void ImGui::DockNodeUpdate(ImGuiDockNode* node)
     if (node->IsRootNode())
     {
         DockNodeUpdateVisibleFlagAndInactiveChilds(node);
-        ImGuiDockNode* only_node_with_windows = node->IsExplicitRoot ? NULL : DockNodeUpdateFindOnlyNodeWithWindows(node);
+
-        node->OnlyNodeWithWindows = only_node_with_windows;
+        // Find if there's only a single visible window in the hierarchy (in which case we need to display a regular title bar, FIXME-DOCK: Not done yet!)
+        if (!node->IsExplicitRoot)
+        {
+            int count = 0;
+            ImGuiDockNode* first_node_with_windows = NULL;
+            DockNodeUpdateFindOnlyNodeWithWindowsRec(node, &count, &first_node_with_windows);
+            node->OnlyNodeWithWindows = (count == 1 ? first_node_with_windows : NULL);
+
+            // Copy the user type from _any_ of our window so it can be used for proper dock filtering.
+            if (first_node_with_windows)
+                node->UserTypeIdFilter = first_node_with_windows->Windows[0]->UserTypeId;
+        }
     }
 
     // Early out for standalone floating window that are holding on a DockId (with an invisible dock node)
@@ -10640,6 +10652,11 @@ static bool ImGui::DockNodeIsDropAllowed(ImGuiWindow* host_window, ImGuiWindow*
         ImGuiWindow* payload = root_payload->DockNodeAsHost ? root_payload->DockNodeAsHost->Windows[payload_n] : root_payload;
         if ((host_window->Flags & ImGuiWindowFlags_DockNodeHost) && payload->BeginOrderWithinContext < host_window->BeginOrderWithinContext)
             continue;
+
+        ImGuiID host_user_type_id = host_window->DockNodeAsHost ? host_window->DockNodeAsHost->UserTypeIdFilter : host_window->UserTypeId;
+        if (payload->UserTypeId != host_user_type_id)
+            return false;
+
         return true;
     }
     return false;
@@ -10756,6 +10773,8 @@ static bool ImGui::DockNodePreviewDockCalc(ImGuiWindow* host_window, ImGuiDockNo
         data->IsCenterAvailable = false;
 
     data->IsSidesAvailable = true;
+    if (host_node && (host_node->Flags & ImGuiDockFlags_NoSplit))
+        data->IsSidesAvailable = false;
     if (!is_outer_docking && host_node && host_node->ParentNode == NULL && host_node->IsDocumentRoot)
         data->IsSidesAvailable = false;
 
@@ -10871,6 +10890,9 @@ static void ImGui::DockNodePreviewDockRender(ImGuiWindow* host_window, ImGuiDock
         }
     }
 
+    if (host_node && (host_node->Flags & ImGuiDockFlags_NoSplit))
+        return;
+
     // Display drop boxes
     const float overlay_rounding = ImMax(3.0f, g.Style.FrameRounding);
     for (int dir = ImGuiDir_None; dir < ImGuiDir_COUNT; dir++)
@@ -11189,7 +11211,7 @@ void ImGui::SetWindowDock(ImGuiWindow* window, ImGuiID dock_id, ImGuiCond cond)
     window->DockId = dock_id;
 }
 
-void ImGui::DockSpace(const char* str_id, const ImVec2& size_arg)
+void ImGui::DockSpace(const char* str_id, const ImVec2& size_arg, ImGuiDockFlags dock_flags, ImGuiID user_type_filter)
 {
     ImGuiContext& g = *GImGui;
     ImGuiDockContext* ctx = g.DockContext;
@@ -11204,6 +11226,8 @@ void ImGui::DockSpace(const char* str_id, const ImVec2& size_arg)
         node = DockContextAddNode(ctx, id);
         node->IsDocumentRoot = true;
     }
+    node->Flags = dock_flags;
+    node->UserTypeIdFilter = user_type_filter;
     node->IsExplicitRoot = true;
 
     const ImVec2 content_avail = GetContentRegionAvail();
@@ -11235,6 +11259,7 @@ void ImGui::DockSpace(const char* str_id, const ImVec2& size_arg)
     host_window->DockNodeAsHost = node;
     host_window->ChildId = window->GetID(title);
     node->HostWindow = host_window;
+    node->OnlyNodeWithWindows = NULL;
 
     IM_ASSERT(node->IsRootNode());
     DockNodeUpdate(node);

imgui.h

@@ -111,6 +111,7 @@ typedef int ImGuiColorEditFlags;    // -> enum ImGuiColorEditFlags_  // Flags: f
 typedef int ImGuiColumnsFlags;      // -> enum ImGuiColumnsFlags_    // Flags: for Columns(), BeginColumns()
 typedef int ImGuiConfigFlags;       // -> enum ImGuiConfigFlags_     // Flags: for io.ConfigFlags
 typedef int ImGuiComboFlags;        // -> enum ImGuiComboFlags_      // Flags: for BeginCombo()
+typedef int ImGuiDockFlags;         // -> enum ImGuiDockFlags_       // Flags: for DockSpace()                   
 typedef int ImGuiDragDropFlags;     // -> enum ImGuiDragDropFlags_   // Flags: for *DragDrop*()
 typedef int ImGuiFocusedFlags;      // -> enum ImGuiFocusedFlags_    // Flags: for IsWindowFocused()
 typedef int ImGuiHoveredFlags;      // -> enum ImGuiHoveredFlags_    // Flags: for IsItemHovered(), IsWindowHovered() etc.
@@ -519,7 +520,8 @@ namespace ImGui
     // Docking 
     // [BETA API] Enable with io.ConfigFlags |= ImGuiConfigFlags_DockingEnable.
     // Note: you DO NOT need to call DockSpace() to use most Docking facilities! You can hold SHIFT anywhere while moving windows. Use DockSpace() if you need to create an explicit docking space _within_ an existing window. See Docking demo for details)
-    IMGUI_API void          DockSpace(const char* str_id, const ImVec2& size = ImVec2(0, 0));
+    IMGUI_API void          DockSpace(const char* str_id, const ImVec2& size = ImVec2(0, 0), ImGuiDockFlags flags = 0, ImGuiID user_type_filter = 0);
+    IMGUI_API void          SetNextWindowUserType(ImGuiID user_type);                           // FIXME-DOCK: set next window user type (docking filters by same user_type)
 
     // Logging/Capture: all text output from interface is captured to tty/file/clipboard. By default, tree nodes are automatically opened during logging.
     IMGUI_API void          LogToTTY(int max_depth = -1);                                       // start logging to tty
@@ -779,6 +781,13 @@ enum ImGuiTabItemFlags_
     ImGuiTabItemFlags_NoPushId                      = 1 << 3    // Don't call PushID(tab->ID)/PopID() on BeginTabItem()/EndTabItem()
 };
 
+// Flags for ImGui::DockSpace()
+enum ImGuiDockFlags_
+{
+    ImGuiDockFlags_None                             = 0,
+    ImGuiDockFlags_NoSplit                          = 1 << 0
+};
+
 // Flags for ImGui::IsWindowFocused()
 enum ImGuiFocusedFlags_
 {

imgui_internal.h

@@ -704,6 +704,7 @@ struct ImGuiNextWindowData
     float                   BgAlphaVal;
     ImGuiID                 ViewportId;
     ImGuiID                 DockId;
+    ImGuiID                 UserTypeId;
     ImVec2                  MenuBarOffsetMinVal;                // This is not exposed publicly, so we don't clear it.
 
     ImGuiNextWindowData()
@@ -716,13 +717,14 @@ struct ImGuiNextWindowData
         SizeCallback = NULL;
         SizeCallbackUserData = NULL;
         BgAlphaVal = FLT_MAX;
-        ViewportId = DockId = 0;
+        ViewportId = DockId = UserTypeId = 0;
         MenuBarOffsetMinVal = ImVec2(0.0f, 0.0f);
     }
 
     void    Clear()
     {
         PosCond = SizeCond = ContentSizeCond = CollapsedCond = SizeConstraintCond = FocusCond = BgAlphaCond = ViewportCond = DockCond = 0;
+        UserTypeId = 0;
     }
 };
 
@@ -740,6 +742,8 @@ struct ImGuiTabBarSortItem
 struct ImGuiDockNode
 {
     ImGuiID                 ID;
+    ImGuiID                 UserTypeIdFilter;
+    ImGuiDockFlags          Flags;
     ImGuiDockNode*          ParentNode;
     ImGuiDockNode*          ChildNodes[2];
     ImVector<ImGuiWindow*>  Windows;                // Note: unordered list! Iterate TabBar->Tabs for user-order.
@@ -1200,6 +1204,7 @@ struct IMGUI_API ImGuiWindow
     ImGuiCond               SetWindowDockAllowFlags;            // store acceptable condition flags for SetNextWindowDock() use.
     ImVec2                  SetWindowPosVal;                    // store window position when using a non-zero Pivot (position set needs to be processed when we know the window size)
     ImVec2                  SetWindowPosPivot;                  // store window pivot for positioning. ImVec2(0,0) when positioning from top-left corner; ImVec2(0.5f,0.5f) for centering; ImVec2(1,1) for bottom right.
+    ImGuiID                 UserTypeId;                         // user value set with SetNextWindowUserType(const char*)
 
     ImGuiWindowTempData     DC;                                 // Temporary per-window data, reset at the beginning of the frame. This used to be called ImGuiDrawContext, hence the "DC" variable name.
     ImVector<ImGuiID>       IDStack;                            // ID stack. ID are hashes seeded with the value at the top of the stack
@@ -1457,8 +1462,8 @@ namespace ImGui
     IMGUI_API void          DockContextShutdown(ImGuiContext* imgui_context);
     IMGUI_API void          DockContextOnLoadSettings();
     IMGUI_API void          DockContextRebuild(ImGuiDockContext* ctx);
-    IMGUI_API void          DockContextUpdateUndocking(ImGuiDockContext* ctx);
+    IMGUI_API void          DockContextNewFrameUpdateUndocking(ImGuiDockContext* ctx);
-    IMGUI_API void          DockContextUpdateDocking(ImGuiDockContext* ctx);
+    IMGUI_API void          DockContextNewFrameUpdateDocking(ImGuiDockContext* ctx);
     IMGUI_API void          DockContextQueueUndock(ImGuiDockContext* ctx, ImGuiWindow* window);
     IMGUI_API void          BeginDocked(ImGuiWindow* window, bool* p_open);
     IMGUI_API void          BeginAsDockableDragDropSource(ImGuiWindow* window);