Method Step

libs/imgui/imgui.cpp:1782–1817

}

bool ImGuiListClipper::Step()
{
    if (ItemsCount == 0 || ImGui::GetCurrentWindowRead()->SkipItems)
    {
        ItemsCount = -1; 
        return false; 
    }
    if (StepNo == 0) // Step 0: the clipper let you process the first element, regardless of it being visible or not, so we can measure the element height.
    {
        DisplayStart = 0;
        DisplayEnd = 1;
        StartPosY = ImGui::GetCursorPosY();
        StepNo = 1;
        return true;
    }
    if (StepNo == 1) // Step 1: the clipper infer height from first element, calculate the actual range of elements to display, and position the cursor before the first element.
    {
        if (ItemsCount == 1) { ItemsCount = -1; return false; }
        float items_height = ImGui::GetCursorPosY() - StartPosY;
        IM_ASSERT(items_height > 0.0f);   // If this triggers, it means Item 0 hasn't moved the cursor vertically
        Begin(ItemsCount-1, items_height);
        DisplayStart++;
        DisplayEnd++;
        StepNo = 3;
        return true;
    }
    if (StepNo == 2) // Step 2: dummy step only required if an explicit items_height was passed to constructor or Begin() and user still call Step(). Does nothing and switch to Step 3.
    {
        IM_ASSERT(DisplayStart >= 0 && DisplayEnd >= 0);
        StepNo = 3;
        return true;
    }
    if (StepNo == 3) // Step 3: the clipper validate that we have reached the expected Y position (corresponding to element DisplayEnd), advance the cursor to the end of the list and then returns 'false' to end the loop.
        End();
    return false;
}

//-----------------------------------------------------------------------------
// ImGuiWindow