ImGuiTableFlags_ScrollY cancels ImGuiChildFlags_NavFlattened

[Brambor]

Version/Branch of Dear ImGui:

Version 1.95.5, Branch: XXX (master/docking/etc.); using CleverRaven/Cataclysm-DDA#78144

Back-ends:

n/a

Compiler, OS:

Windows 10 + MSVC 2019

Full config/build information:

Dear ImGui 1.91.5 (19150)
--------------------------------
sizeof(size_t): 8, sizeof(ImDrawIdx): 2, sizeof(ImDrawVert): 20
define: __cplusplus=199711
define: _WIN32
define: _WIN64
define: _MSC_VER=1929
define: _MSVC_LANG=201703
--------------------------------
io.BackendPlatformName: imgui_impl_sdl2
io.BackendRendererName: imgui_impl_sdlrenderer2
io.ConfigFlags: 0x00000003
 NavEnableKeyboard
 NavEnableGamepad
io.ConfigNavCaptureKeyboard
io.ConfigInputTextCursorBlink
io.ConfigWindowsResizeFromEdges
io.ConfigMemoryCompactTimer = 60.0
io.BackendFlags: 0x0000000E
 HasMouseCursors
 HasSetMousePos
 RendererHasVtxOffset
--------------------------------
io.Fonts: 2 fonts, Flags: 0x00000000, TexSize: 512,128
io.DisplaySize: 1536.00,841.00
io.DisplayFramebufferScale: 1.00,1.00
--------------------------------
style.WindowPadding: 8.00,8.00
style.WindowBorderSize: 1.00
style.FramePadding: 4.00,3.00
style.FrameRounding: 0.00
style.FrameBorderSize: 0.00
style.ItemSpacing: 8.00,4.00
style.ItemInnerSpacing: 4.00,4.00

Details:

I want a menu with:

• buttons selectable with the mouse
• table with a TableSetupScrollFreeze( 0, /*rows*/1 ) and with ImGuiTableFlags_ScrollY
• entries of the table
• table fills the rest of the screen
• the user to (when they open the menu) use arrow keys to select entries of the menu, not the buttons, not the whole table

I tried making the buttons unselectable. When opening the menu, the user still has to first select the table and only then use up/down arrows to select entries:

Then I tried to put the table inside of BeginChild( "table", ImVec2( 0, 0 ), ImGuiChildFlags_NavFlattened ); to expose the entries allowing up/down arrows right away without the need to press enter to select the table first.

I worked out that this solution worked only as long, as BeginTable didn't have ImGuiTableFlags_ScrollY.

• when it doesn't have the flag, on opening the menu and pressing the down arrow, an entry is selected
• when it does have the flag, on opening the menu, the user has to select the table first - THIS FEELS LIKE A BUG

I need ImGuiTableFlags_ScrollY in order to have the header frozen. When I don't use it, the header can hide as the child window scrolls:

Important bits of my code I would expect to work (with ImGuiTableFlags_ScrollY), but it does not:

    ImGui::PushItemFlag( ImGuiItemFlags_NoNav, true );
    // draw buttons
    ImGui::PopItemFlag();  // ImGuiItemFlags_NoNav

    ImGui::BeginChild( "table", ImVec2( 0, 0 ), ImGuiChildFlags_NavFlattened );
    if( ! ImGui::BeginTable( "PATH_MANAGER", 6, ImGuiTableFlags_Resizable | ImGuiTableFlags_ScrollY ) ) {
        ImGui::EndChild();
        return;
    }
    ImGui::TableSetupScrollFreeze( 0, 1 );
    // draw table
    ImGui::EndTable();
    ImGui::EndChild();

Much more of my code

bool cataimgui::window::action_button( const std::string &action, const std::string &text )
{
    if( ImGui::Button( text.c_str() ) ) {
        button_action = action;
        return true;
    }
    return false;
}

void path_manager_ui::enabled_active_button( const std::string action, bool enabled )
{
    ImGui::BeginDisabled( !enabled );
    action_button( action, ctxt.get_button_text( action ) );
    ImGui::EndDisabled();
}

void path_manager_ui::draw_controls()
{
    // Put it all into a child window to use NavFlattened to select the first entry in the table
    // instead of the table itself.
    // make buttons unselectable with arrows
    ImGui::PushItemFlag( ImGuiItemFlags_NoNav, true );
    // walk buttons
    cataimgui::draw_colored_text( _( "Walk:" ) );
    ImGui::SameLine();
    enabled_active_button( "WALK_PATH", pimpl->avatar_at_what_start_or_end() != -1 );
    ImGui::SameLine();
    enabled_active_button( "WALK_PATH_FROM_MIDDLE", !pimpl->avatar_at_what_paths().empty() );

    // recording buttons
    cataimgui::draw_colored_text( _( "Recording:" ) );
    ImGui::SameLine();
    enabled_active_button( "START_RECORDING", !pimpl->is_recording_path() );
    ImGui::SameLine();
    enabled_active_button( "CONTINUE_RECORDING", !pimpl->is_recording_path()
                           && pimpl->avatar_at_what_start_or_end() != -1 );
    ImGui::SameLine();
    enabled_active_button( "STOP_RECORDING", pimpl->is_recording_path() );

    // manage buttons
    cataimgui::draw_colored_text( _( "Manage:" ) );
    ImGui::SameLine();
    enabled_active_button( "DELETE_PATH", pimpl->selected_id != -1 );
    ImGui::SameLine();
    enabled_active_button( "MOVE_PATH_UP", pimpl->selected_id > 0 );
    ImGui::SameLine();
    enabled_active_button( "MOVE_PATH_DOWN", pimpl->selected_id != -1 &&
                           pimpl->selected_id + 1 < static_cast<int>( pimpl->paths.size() ) );

    // name buttons
    cataimgui::draw_colored_text( _( "Rename:" ) );
    ImGui::SameLine();
    enabled_active_button( "RENAME_START", pimpl->selected_id != -1 );
    ImGui::SameLine();
    enabled_active_button( "RENAME_END", pimpl->selected_id != -1 );
    ImGui::SameLine();
    enabled_active_button( "SWAP_START_END", pimpl->selected_id != -1 );
    ImGui::PopItemFlag();  // ImGuiItemFlags_NoNav

    ImGui::BeginChild( "table", ImVec2( 0, 0 ), ImGuiChildFlags_NavFlattened );
    if( ! ImGui::BeginTable( "PATH_MANAGER", 6, ImGuiTableFlags_Resizable | ImGuiTableFlags_ScrollY ) ) {
        ImGui::EndChild();
        return;
    }
    // TODO invlet
    ImGui::TableSetupScrollFreeze( 0, 1 );
    ImGui::TableSetupColumn( _( "start name" ) );
    ImGui::TableSetupColumn( _( "start distance" ) );
    ImGui::TableSetupColumn( _( "end name" ) );
    ImGui::TableSetupColumn( _( "end distance" ) );
    ImGui::TableSetupColumn( _( "closest tile" ) );
    ImGui::TableSetupColumn( _( "total length" ) );
    ImGui::PushItemFlag( ImGuiItemFlags_NoNav, true );
    ImGui::TableHeadersRow();
    ImGui::PopItemFlag();  // ImGuiItemFlags_NoNav

    ImGuiListClipper clipper;
    clipper.Begin( pimpl->paths.size() );
    while( clipper.Step() ) {
        for( int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++ ) {
            const path &curr_path = pimpl->paths[i];
            ImGui::TableNextColumn();
            if( ImGui::Selectable( ( "##" + std::to_string( i ) ).c_str(), pimpl->selected_id == i,
                                   ImGuiSelectableFlags_SpanAllColumns )
              ) {
                pimpl->selected_id = i;
            }
            ImGui::SameLine();
            cataimgui::draw_colored_text( curr_path.name_start );

            ImGui::TableNextColumn();
            cataimgui::draw_colored_text( avatar_distance_from_tile( curr_path.recorded_path.front() ) );

            ImGui::TableNextColumn();
            cataimgui::draw_colored_text( curr_path.name_end );

            ImGui::TableNextColumn();
            cataimgui::draw_colored_text( avatar_distance_from_tile( curr_path.recorded_path.back() ) );

            ImGui::TableNextColumn();
            cataimgui::draw_colored_text( avatar_distance_from_tile(
                                              curr_path.recorded_path[curr_path.avatar_closest_i_approximate()] ) );

            ImGui::TableNextColumn();
            ImGui::Text( "%zu", curr_path.recorded_path.size() );
        }
    }
    ImGui::EndTable();
    ImGui::EndChild();
}

void cataimgui::window::draw()
{
    button_action.clear();
    if( !is_open ) {
        return;
    }
    bool handled_resize = false;
    if( is_bounds_changed() ) {
        cached_bounds = get_bounds();
        // we want to make sure is_resized is able to be handled for at least a full frame
        handled_resize = true;
    }
    if( cached_bounds.x == -1 || cached_bounds.y == -1 ) {
        ImVec2 center = ImGui::GetMainViewport()->GetCenter();
        if( cached_bounds.x != -1.f ) {
            center.x = cached_bounds.x;
        }
        if( cached_bounds.y != -1.f ) {
            center.y = cached_bounds.y;
        }
        ImGui::SetNextWindowPos( center, ImGuiCond_Always, { cached_bounds.x == -1.f ? 0.5f : 0.f,  cached_bounds.y == -1.f ? 0.5f : 0.f } );
    } else if( cached_bounds.x >= 0 && cached_bounds.y >= 0 ) {
        ImGui::SetNextWindowPos( { cached_bounds.x, cached_bounds.y } );
    }
    if( cached_bounds.h > 1.0 || cached_bounds.w > 1.0 ) {
        ImGui::SetNextWindowSize( { cached_bounds.w, cached_bounds.h } );
    } else if( cached_bounds.h > 0.0 && cached_bounds.w > 0.0 && cached_bounds.h <= 1.0 &&
               cached_bounds.w <= 1.0 ) {
        ImGui::SetNextWindowSize( ImGui::GetMainViewport()->Size * ImVec2 { cached_bounds.w, cached_bounds.h } );
    }
    if( ImGui::Begin( id.c_str(), &is_open, window_flags ) ) {
        draw_controls();
        if( p_impl->window_adaptor->is_on_top && !force_to_back ) {
            ImGui::BringWindowToDisplayFront( ImGui::GetCurrentWindow() );
        }
        if( handled_resize ) {
            point catapos;
            point catasize;
            ImVec2 impos = ImGui::GetWindowPos();
            ImVec2 imsize = ImGui::GetWindowSize();
            imvec2_to_point( &impos, &catapos );
            imvec2_to_point( &imsize, &catasize );
            p_impl->window_adaptor->position_absolute( catapos, catasize );
        }
    }
    ImGui::End();
    if( handled_resize ) {
        p_impl->is_resized = false;
    }
}

cataimgui::window::window( int window_flags )
{
    p_impl = nullptr;

    this->window_flags = window_flags | ImGuiWindowFlags_NoCollapse | ImGuiWindowFlags_NoResize |
                         ImGuiWindowFlags_NoSavedSettings | ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoNavFocus |
                         ImGuiWindowFlags_NoBringToFrontOnFocus;
}

path_manager_ui::path_manager_ui( path_manager_impl *pimpl_in )
    : cataimgui::window( _( "Path Manager" ) ), pimpl( pimpl_in ) {}

My question is: Why does ImGuiTableFlags_ScrollY cancel the effect of ImGuiChildFlags_NavFlattened?

Screenshots/Video:

No response

Minimal, Complete and Verifiable Example code:

I made it a part of imgui_demo.cpp.

#include <string>

void ShowExampleAppscrollYandflatnav(bool* p_open)
{
    ImGui::Begin( "scroll Y breaks nav", p_open );

    ImGui::BeginChild( "table", ImVec2( 100, 100 ), ImGuiChildFlags_NavFlattened );
    // Deleting ImGuiTableFlags_ScrollY makes ImGuiChildFlags_NavFlattened work
    ImGui::BeginTable( "PATH_MANAGER", 1, ImGuiTableFlags_ScrollY );
    for( int i = 0; i < 3; ++i ) {
        ImGui::TableNextColumn();
        ImGui::Button( std::to_string( i ).c_str() );
    }
    ImGui::EndTable();
    ImGui::EndChild();

    ImGui::End();
}

1. Compile, run, open the menu.
2. Press arrow down
3. Observe: you get
   • 
   • Note: whole table is selected.
4. change line ImGui::BeginTable( "PATH_MANAGER", 1, ImGuiTableFlags_ScrollY ); to ImGui::BeginTable( "PATH_MANAGER", 1 );
5. Compile, run, open the menu.
6. Press arrow down
7. Observe: you get
   • 
   • Note: Entry 2 is selected.

[Brambor]

I minimized the "Minimal, Complete and Verifiable Example" nicely and provided reproduction steps.

[Brambor]

It would be nice if I could do ImGuiChildFlags_NavFlattened for a table and didn't have to do it with the BeginChild.