Method RenderDimmedBackgrounds

Dependencies/ImGui/src/imgui.cpp:6160–6217

Important: AddWindowToDrawData() has not been called yet, meaning DockNodeHost windows needs a DrawList->ChannelsMerge() before usage. We call ChannelsMerge() lazily here at it is faster that doing a full iteration of g.Windows[] prior to calling RenderDimmedBackgrounds().

// Important: AddWindowToDrawData() has not been called yet, meaning DockNodeHost windows needs a DrawList->ChannelsMerge() before usage.
// We call ChannelsMerge() lazily here at it is faster that doing a full iteration of g.Windows[] prior to calling RenderDimmedBackgrounds().
static void ImGui::RenderDimmedBackgrounds()
{
    ImGuiContext& g = *GImGui;
    ImGuiWindow* modal_window = GetTopMostAndVisiblePopupModal();
    if (g.DimBgRatio <= 0.0f && g.NavWindowingHighlightAlpha <= 0.0f)
        return;
    const bool dim_bg_for_modal = (modal_window != NULL);
    const bool dim_bg_for_window_list = (g.NavWindowingTargetAnim != NULL && g.NavWindowingTargetAnim->Active);
    if (!dim_bg_for_modal && !dim_bg_for_window_list)
        return;

    ImGuiViewport* viewports_already_dimmed[2] = { NULL, NULL };
    if (dim_bg_for_modal)
    {
        // Draw dimming behind modal or a begin stack child, whichever comes first in draw order.
        ImGuiWindow* dim_behind_window = FindBottomMostVisibleWindowWithinBeginStack(modal_window);
        RenderDimmedBackgroundBehindWindow(dim_behind_window, GetColorU32(modal_window->DC.ModalDimBgColor, g.DimBgRatio));
        viewports_already_dimmed[0] = modal_window->Viewport;
    }
    else if (dim_bg_for_window_list)
    {
        // Draw dimming behind Ctrl+Tab target window and behind Ctrl+Tab UI window
        RenderDimmedBackgroundBehindWindow(g.NavWindowingTargetAnim, GetColorU32(ImGuiCol_NavWindowingDimBg, g.DimBgRatio));
        viewports_already_dimmed[0] = g.NavWindowingTargetAnim->Viewport;
        if (g.NavWindowingListWindow != NULL && g.NavWindowingListWindow->Active && g.NavWindowingListWindow->Viewport && g.NavWindowingListWindow->Viewport != g.NavWindowingTargetAnim->Viewport)
        {
            RenderDimmedBackgroundBehindWindow(g.NavWindowingListWindow, GetColorU32(ImGuiCol_NavWindowingDimBg, g.DimBgRatio));
            viewports_already_dimmed[1] = g.NavWindowingListWindow->Viewport;
        }

        // Draw border around Ctrl+Tab target window
        ImGuiWindow* window = g.NavWindowingTargetAnim;
        ImGuiViewport* viewport = window->Viewport;
        float distance = g.FontSize;
        ImRect bb = window->Rect();
        bb.Expand(distance);
        if (bb.GetWidth() >= viewport->Size.x && bb.GetHeight() >= viewport->Size.y)
            bb.Expand(-distance - 1.0f); // If a window fits the entire viewport, adjust its highlight inward
        window->DrawList->ChannelsMerge();
        if (window->DrawList->CmdBuffer.Size == 0)
            window->DrawList->AddDrawCmd();
        window->DrawList->PushClipRect(viewport->Pos, viewport->Pos + viewport->Size);
        window->DrawList->AddRect(bb.Min, bb.Max, GetColorU32(ImGuiCol_NavWindowingHighlight, g.NavWindowingHighlightAlpha), window->WindowRounding, 0, 3.0f); // FIXME-DPI
        window->DrawList->PopClipRect();
    }

    // Draw dimming background on _other_ viewports than the ones our windows are in
    for (ImGuiViewportP* viewport : g.Viewports)
    {
        if (viewport == viewports_already_dimmed[0] || viewport == viewports_already_dimmed[1])
            continue;
        if (modal_window && viewport->Window && IsWindowAbove(viewport->Window, modal_window))
            continue;
        ImDrawList* draw_list = GetForegroundDrawList(viewport);
        const ImU32 dim_bg_col = GetColorU32(dim_bg_for_modal ? ImGuiCol_ModalWindowDimBg : ImGuiCol_NavWindowingDimBg, g.DimBgRatio);
        draw_list->AddRectFilled(viewport->Pos, viewport->Pos + viewport->Size, dim_bg_col);
    }
}