Method NewFrame

ImGUI GLFW Tutorial/imgui/imgui.cpp:3896–4096

}

void ImGui::NewFrame()
{
    IM_ASSERT(GImGui != NULL && "No current context. Did you call ImGui::CreateContext() and ImGui::SetCurrentContext() ?");
    ImGuiContext& g = *GImGui;

    // Remove pending delete hooks before frame start.
    // This deferred removal avoid issues of removal while iterating the hook vector
    for (int n = g.Hooks.Size - 1; n >= 0; n--)
        if (g.Hooks[n].Type == ImGuiContextHookType_PendingRemoval_)
            g.Hooks.erase(&g.Hooks[n]);

    CallContextHooks(&g, ImGuiContextHookType_NewFramePre);

    // Check and assert for various common IO and Configuration mistakes
    ErrorCheckNewFrameSanityChecks();

    // Load settings on first frame, save settings when modified (after a delay)
    UpdateSettings();

    g.Time += g.IO.DeltaTime;
    g.WithinFrameScope = true;
    g.FrameCount += 1;
    g.TooltipOverrideCount = 0;
    g.WindowsActiveCount = 0;
    g.MenusIdSubmittedThisFrame.resize(0);

    // Calculate frame-rate for the user, as a purely luxurious feature
    g.FramerateSecPerFrameAccum += g.IO.DeltaTime - g.FramerateSecPerFrame[g.FramerateSecPerFrameIdx];
    g.FramerateSecPerFrame[g.FramerateSecPerFrameIdx] = g.IO.DeltaTime;
    g.FramerateSecPerFrameIdx = (g.FramerateSecPerFrameIdx + 1) % IM_ARRAYSIZE(g.FramerateSecPerFrame);
    g.FramerateSecPerFrameCount = ImMin(g.FramerateSecPerFrameCount + 1, IM_ARRAYSIZE(g.FramerateSecPerFrame));
    g.IO.Framerate = (g.FramerateSecPerFrameAccum > 0.0f) ? (1.0f / (g.FramerateSecPerFrameAccum / (float)g.FramerateSecPerFrameCount)) : FLT_MAX;

    UpdateViewportsNewFrame();

    // Setup current font and draw list shared data
    g.IO.Fonts->Locked = true;
    SetCurrentFont(GetDefaultFont());
    IM_ASSERT(g.Font->IsLoaded());
    ImRect virtual_space(FLT_MAX, FLT_MAX, -FLT_MAX, -FLT_MAX);
    for (int n = 0; n < g.Viewports.Size; n++)
        virtual_space.Add(g.Viewports[n]->GetMainRect());
    g.DrawListSharedData.ClipRectFullscreen = virtual_space.ToVec4();
    g.DrawListSharedData.CurveTessellationTol = g.Style.CurveTessellationTol;
    g.DrawListSharedData.SetCircleTessellationMaxError(g.Style.CircleTessellationMaxError);
    g.DrawListSharedData.InitialFlags = ImDrawListFlags_None;
    if (g.Style.AntiAliasedLines)
        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLines;
    if (g.Style.AntiAliasedLinesUseTex && !(g.Font->ContainerAtlas->Flags & ImFontAtlasFlags_NoBakedLines))
        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedLinesUseTex;
    if (g.Style.AntiAliasedFill)
        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AntiAliasedFill;
    if (g.IO.BackendFlags & ImGuiBackendFlags_RendererHasVtxOffset)
        g.DrawListSharedData.InitialFlags |= ImDrawListFlags_AllowVtxOffset;

    // Mark rendering data as invalid to prevent user who may have a handle on it to use it.
    for (int n = 0; n < g.Viewports.Size; n++)
    {