Method DockNodeTreeMerge

imgui_tiny_app/imgui/imgui.cpp:20146–20189

}

void ImGui::DockNodeTreeMerge(ImGuiContext* ctx, ImGuiDockNode* parent_node, ImGuiDockNode* merge_lead_child)
{
    // When called from DockContextProcessUndockNode() it is possible that one of the child is NULL.
    ImGuiContext& g = *GImGui;
    ImGuiDockNode* child_0 = parent_node->ChildNodes[0];
    ImGuiDockNode* child_1 = parent_node->ChildNodes[1];
    IM_ASSERT(child_0 || child_1);
    IM_ASSERT(merge_lead_child == child_0 || merge_lead_child == child_1);
    if ((child_0 && child_0->Windows.Size > 0) || (child_1 && child_1->Windows.Size > 0))
    {
        IM_ASSERT(parent_node->TabBar == NULL);
        IM_ASSERT(parent_node->Windows.Size == 0);
    }
    IMGUI_DEBUG_LOG_DOCKING("[docking] DockNodeTreeMerge: 0x%08X + 0x%08X back into parent 0x%08X\n", child_0 ? child_0->ID : 0, child_1 ? child_1->ID : 0, parent_node->ID);

    ImVec2 backup_last_explicit_size = parent_node->SizeRef;
    DockNodeMoveChildNodes(parent_node, merge_lead_child);
    if (child_0)
    {
        DockNodeMoveWindows(parent_node, child_0); // Generally only 1 of the 2 child node will have windows
        DockSettingsRenameNodeReferences(child_0->ID, parent_node->ID);
    }
    if (child_1)
    {
        DockNodeMoveWindows(parent_node, child_1);
        DockSettingsRenameNodeReferences(child_1->ID, parent_node->ID);
    }
    DockNodeApplyPosSizeToWindows(parent_node);
    parent_node->AuthorityForPos = parent_node->AuthorityForSize = parent_node->AuthorityForViewport = ImGuiDataAuthority_Auto;
    parent_node->VisibleWindow = merge_lead_child->VisibleWindow;
    parent_node->SizeRef = backup_last_explicit_size;

    // Flags transfer
    parent_node->LocalFlags &= ~ImGuiDockNodeFlags_LocalFlagsTransferMask_; // Preserve Dockspace flag
    parent_node->LocalFlags |= (child_0 ? child_0->LocalFlags : 0) & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
    parent_node->LocalFlags |= (child_1 ? child_1->LocalFlags : 0) & ImGuiDockNodeFlags_LocalFlagsTransferMask_;
    parent_node->LocalFlagsInWindows = (child_0 ? child_0->LocalFlagsInWindows : 0) | (child_1 ? child_1->LocalFlagsInWindows : 0); // FIXME: Would be more consistent to update from actual windows
    parent_node->UpdateMergedFlags();

    if (child_0)
        DockContextDeleteNode(ctx, child_0);
    if (child_1)
        DockContextDeleteNode(ctx, child_1);
}

// Update Pos/Size for a node hierarchy (don't affect child Windows yet)
// (Depth-first, Pre-Order)