Method NewFrame

imgui_tiny_app/imgui/imgui.cpp:5683–5978

}

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
    g.ConfigFlagsLastFrame = g.ConfigFlagsCurrFrame;
    ErrorCheckNewFrameSanityChecks();
    g.ConfigFlagsCurrFrame = g.IO.ConfigFlags;

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

    g.Time += g.IO.DeltaTime;
    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_COUNTOF(g.FramerateSecPerFrame);
    g.FramerateSecPerFrameCount = ImMin(g.FramerateSecPerFrameCount + 1, IM_COUNTOF(g.FramerateSecPerFrame));
    g.IO.Framerate = (g.FramerateSecPerFrameAccum > 0.0f) ? (1.0f / (g.FramerateSecPerFrameAccum / (float)g.FramerateSecPerFrameCount)) : FLT_MAX;

    // Process input queue (trickle as many events as possible), turn events into writes to IO structure
    g.InputEventsTrail.resize(0);
    UpdateInputEvents(g.IO.ConfigInputTrickleEventQueue);

    // Update viewports (after processing input queue, so io.MouseHoveredViewport is set)
    UpdateViewportsNewFrame();

    // Update texture list (collect destroyed textures, etc.)
    UpdateTexturesNewFrame();

    // Setup current font and draw list shared data
    SetupDrawListSharedData();
    UpdateFontsNewFrame();

    g.WithinFrameScope = true;

    // Mark rendering data as invalid to prevent user who may have a handle on it to use it.
    for (ImGuiViewportP* viewport : g.Viewports)
    {
        viewport->DrawData = NULL;
        viewport->DrawDataP.Valid = false;
    }

    // Drag and drop keep the source ID alive so even if the source disappear our state is consistent