Method UpdateTexturesNewFrame

imgui_tiny_app/imgui/imgui.cpp:9534–9555

//-----------------------------------------------------------------------------

static void ImGui::UpdateTexturesNewFrame()
{
    // Cannot update every atlases based on atlas's FrameCount < g.FrameCount, because an atlas may be shared by multiple contexts with different frame count.
    ImGuiContext& g = *GImGui;
    const bool has_textures = (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasTextures) != 0;
    for (ImFontAtlas* atlas : g.FontAtlases)
    {
        if (atlas->OwnerContext == &g)
        {
            ImFontAtlasUpdateNewFrame(atlas, g.FrameCount, has_textures);
        }
        else
        {
            // (1) If you manage font atlases yourself, e.g. create a ImFontAtlas yourself you need to call ImFontAtlasUpdateNewFrame() on it.
            // Otherwise, calling ImGui::CreateContext() without parameter will create an atlas owned by the context.
            // (2) If you have multiple font atlases, make sure the 'atlas->RendererHasTextures' as specified in the ImFontAtlasUpdateNewFrame() call matches for that.
            // (3) If you have multiple imgui contexts, they also need to have a matching value for ImGuiBackendFlags_RendererHasTextures.
            IM_ASSERT(atlas->Builder != NULL && atlas->Builder->FrameCount != -1);
            IM_ASSERT(atlas->RendererHasTextures == has_textures);
        }
    }
}

// Build a single texture list
static void ImGui::UpdateTexturesEndFrame()