TreeNode: fixed non-opened clipped child node not moving Y2 marker. (#2920)

Author: ocornut

imgui.cpp

@@ -7649,7 +7649,7 @@ bool ImGui::Begin(const char* name, bool* p_open, ImGuiWindowFlags flags)
         window->DC.MenuBarAppending = false;
         window->DC.MenuColumns.Update(style.ItemSpacing.x, window_just_activated_by_user);
         window->DC.TreeDepth = 0;
-        window->DC.TreeHasStackDataDepthMask = 0x00;
+        window->DC.TreeHasStackDataDepthMask = window->DC.TreeRecordsClippedNodesY2Mask = 0x00;
         window->DC.ChildWindows.resize(0);
         window->DC.StateStorage = &window->StateStorage;
         window->DC.CurrentColumns = NULL;

imgui_internal.h

@@ -2474,7 +2474,8 @@ struct IMGUI_API ImGuiWindowTempData
     ImVec2                  MenuBarOffset;          // MenuBarOffset.x is sort of equivalent of a per-layer CursorPos.x, saved/restored as we switch to the menu bar. The only situation when MenuBarOffset.y is > 0 if when (SafeAreaPadding.y > FramePadding.y), often used on TVs.
     ImGuiMenuColumns        MenuColumns;            // Simplified columns storage for menu items measurement
     int                     TreeDepth;              // Current tree depth.
-    ImU32                   TreeHasStackDataDepthMask; // Store whether given depth has ImGuiTreeNodeStackData data. Could be turned into a ImU64 if necessary.
+    ImU32                   TreeHasStackDataDepthMask;      // Store whether given depth has ImGuiTreeNodeStackData data. Could be turned into a ImU64 if necessary.
+    ImU32                   TreeRecordsClippedNodesY2Mask;  // Store whether we should keep recording Y2. Cleared when passing clip max. Equivalent TreeHasStackDataDepthMask value should always be set.
     ImVector<ImGuiWindow*>  ChildWindows;
     ImGuiStorage*           StateStorage;           // Current persistent per-window storage (store e.g. tree node open/close state)
     ImGuiOldColumns*        CurrentColumns;         // Current columns set

imgui_widgets.cpp

@@ -6564,9 +6564,11 @@ static void TreeNodeStoreStackData(ImGuiTreeNodeFlags flags, float x1)
     // Initially I tried to latch value for GetColorU32(ImGuiCol_TreeLines) but it's not a good trade-off for very large trees.
     const bool draw_lines = (flags & (ImGuiTreeNodeFlags_DrawLinesFull | ImGuiTreeNodeFlags_DrawLinesToNodes)) != 0;
     tree_node_data->DrawLinesX1 = draw_lines ? (x1 + g.FontSize * 0.5f + g.Style.FramePadding.x) : +FLT_MAX;
-    tree_node_data->DrawLinesTableColumn = draw_lines && g.CurrentTable ? (ImGuiTableColumnIdx)g.CurrentTable->CurrentColumn : -1;
+    tree_node_data->DrawLinesTableColumn = (draw_lines && g.CurrentTable) ? (ImGuiTableColumnIdx)g.CurrentTable->CurrentColumn : -1;
     tree_node_data->DrawLinesToNodesY2 = -FLT_MAX;
     window->DC.TreeHasStackDataDepthMask |= (1 << window->DC.TreeDepth);
+    if (flags & ImGuiTreeNodeFlags_DrawLinesToNodes)
+        window->DC.TreeRecordsClippedNodesY2Mask |= (1 << window->DC.TreeDepth);
 }
 
 // When using public API, currently 'id == storage_id' is always true, but we separate the values to facilitate advanced user code doing storage queries outside of UI loop.
@@ -6656,10 +6658,12 @@ bool ImGui::TreeNodeBehavior(ImGuiID id, ImGuiTreeNodeFlags flags, const char* l
     const bool is_leaf = (flags & ImGuiTreeNodeFlags_Leaf) != 0;
     if (!is_visible)
     {
-        if (draw_tree_lines && (flags & ImGuiTreeNodeFlags_DrawLinesToNodes) && (window->DC.TreeHasStackDataDepthMask & (1 << window->DC.TreeDepth)))
+        if ((flags & ImGuiTreeNodeFlags_DrawLinesToNodes) && (window->DC.TreeRecordsClippedNodesY2Mask & (1 << (window->DC.TreeDepth - 1))))
         {
             ImGuiTreeNodeStackData* parent_data = &g.TreeNodeStack.Data[g.TreeNodeStack.Size - 1];
             parent_data->DrawLinesToNodesY2 = ImMax(parent_data->DrawLinesToNodesY2, window->DC.CursorPos.y); // Don't need to aim to mid Y position as we are clipped anyway.
+            if (frame_bb.Min.y >= window->ClipRect.Max.y)
+                window->DC.TreeRecordsClippedNodesY2Mask &= ~(1 << (window->DC.TreeDepth - 1)); // Done
         }
         if (is_open && store_tree_node_stack_data)
             TreeNodeStoreStackData(flags, text_pos.x - text_offset_x); // Call before TreePushOverrideID()