Method ScrollToRectEx

src/imgui/imgui.cpp:11624–11694

Scroll to keep newly navigated item fully into view

// Scroll to keep newly navigated item fully into view
ImVec2 ImGui::ScrollToRectEx(ImGuiWindow* window, const ImRect& item_rect, ImGuiScrollFlags flags)
{
    ImGuiContext& g = *GImGui;
    ImRect scroll_rect(window->InnerRect.Min - ImVec2(1, 1), window->InnerRect.Max + ImVec2(1, 1));
    scroll_rect.Min.x = ImMin(scroll_rect.Min.x + window->DecoInnerSizeX1, scroll_rect.Max.x);
    scroll_rect.Min.y = ImMin(scroll_rect.Min.y + window->DecoInnerSizeY1, scroll_rect.Max.y);
    //GetForegroundDrawList(window)->AddRect(item_rect.Min, item_rect.Max, IM_COL32(255,0,0,255), 0.0f, 0, 5.0f); // [DEBUG]
    //GetForegroundDrawList(window)->AddRect(scroll_rect.Min, scroll_rect.Max, IM_COL32_WHITE); // [DEBUG]

    // Check that only one behavior is selected per axis
    IM_ASSERT((flags & ImGuiScrollFlags_MaskX_) == 0 || ImIsPowerOfTwo(flags & ImGuiScrollFlags_MaskX_));
    IM_ASSERT((flags & ImGuiScrollFlags_MaskY_) == 0 || ImIsPowerOfTwo(flags & ImGuiScrollFlags_MaskY_));

    // Defaults
    ImGuiScrollFlags in_flags = flags;
    if ((flags & ImGuiScrollFlags_MaskX_) == 0 && window->ScrollbarX)
        flags |= ImGuiScrollFlags_KeepVisibleEdgeX;
    if ((flags & ImGuiScrollFlags_MaskY_) == 0)
        flags |= window->Appearing ? ImGuiScrollFlags_AlwaysCenterY : ImGuiScrollFlags_KeepVisibleEdgeY;

    const bool fully_visible_x = item_rect.Min.x >= scroll_rect.Min.x && item_rect.Max.x <= scroll_rect.Max.x;
    const bool fully_visible_y = item_rect.Min.y >= scroll_rect.Min.y && item_rect.Max.y <= scroll_rect.Max.y;
    const bool can_be_fully_visible_x = (item_rect.GetWidth() + g.Style.ItemSpacing.x * 2.0f) <= scroll_rect.GetWidth() || (window->AutoFitFramesX > 0) || (window->Flags & ImGuiWindowFlags_AlwaysAutoResize) != 0;
    const bool can_be_fully_visible_y = (item_rect.GetHeight() + g.Style.ItemSpacing.y * 2.0f) <= scroll_rect.GetHeight() || (window->AutoFitFramesY > 0) || (window->Flags & ImGuiWindowFlags_AlwaysAutoResize) != 0;

    if ((flags & ImGuiScrollFlags_KeepVisibleEdgeX) && !fully_visible_x)
    {
        if (item_rect.Min.x < scroll_rect.Min.x || !can_be_fully_visible_x)
            SetScrollFromPosX(window, item_rect.Min.x - g.Style.ItemSpacing.x - window->Pos.x, 0.0f);
        else if (item_rect.Max.x >= scroll_rect.Max.x)
            SetScrollFromPosX(window, item_rect.Max.x + g.Style.ItemSpacing.x - window->Pos.x, 1.0f);
    }
    else if (((flags & ImGuiScrollFlags_KeepVisibleCenterX) && !fully_visible_x) || (flags & ImGuiScrollFlags_AlwaysCenterX))
    {
        if (can_be_fully_visible_x)
            SetScrollFromPosX(window, ImTrunc((item_rect.Min.x + item_rect.Max.x) * 0.5f) - window->Pos.x, 0.5f);
        else
            SetScrollFromPosX(window, item_rect.Min.x - window->Pos.x, 0.0f);
    }

    if ((flags & ImGuiScrollFlags_KeepVisibleEdgeY) && !fully_visible_y)
    {
        if (item_rect.Min.y < scroll_rect.Min.y || !can_be_fully_visible_y)
            SetScrollFromPosY(window, item_rect.Min.y - g.Style.ItemSpacing.y - window->Pos.y, 0.0f);
        else if (item_rect.Max.y >= scroll_rect.Max.y)
            SetScrollFromPosY(window, item_rect.Max.y + g.Style.ItemSpacing.y - window->Pos.y, 1.0f);
    }
    else if (((flags & ImGuiScrollFlags_KeepVisibleCenterY) && !fully_visible_y) || (flags & ImGuiScrollFlags_AlwaysCenterY))
    {
        if (can_be_fully_visible_y)
            SetScrollFromPosY(window, ImTrunc((item_rect.Min.y + item_rect.Max.y) * 0.5f) - window->Pos.y, 0.5f);
        else
            SetScrollFromPosY(window, item_rect.Min.y - window->Pos.y, 0.0f);
    }

    ImVec2 next_scroll = CalcNextScrollFromScrollTargetAndClamp(window);
    ImVec2 delta_scroll = next_scroll - window->Scroll;