Added power saving mode (docking branch)

backends/imgui_impl_allegro5.cpp

@@ -35,6 +35,7 @@
 
 #include <stdint.h>     // uint64_t
 #include <cstring>      // memcpy
+#include <math.h>       // isinf
 #include "imgui.h"
 #include "imgui_impl_allegro5.h"
 
@@ -320,6 +321,24 @@ void ImGui_ImplAllegro5_Shutdown()
     g_ClipboardTextData = NULL;
 }
 
+void ImGui_ImplAllegro5_WaitForEvent(ALLEGRO_EVENT_QUEUE* queue)
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    int display_flags = al_get_display_flags(g_Display);
+    bool window_is_hidden = display_flags & ALLEGRO_MINIMIZED;
+    double waiting_time = window_is_hidden ? INFINITY : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        if (isinf(waiting_time))
+            al_wait_for_event(queue, NULL);
+        else
+            al_wait_for_event_timed(queue, NULL, waiting_time);
+    }
+}
+
+
 // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
 // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
 // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
@@ -328,6 +347,8 @@ bool ImGui_ImplAllegro5_ProcessEvent(ALLEGRO_EVENT* ev)
 {
     ImGuiIO& io = ImGui::GetIO();
 
+    io.FrameCountSinceLastInput = 0;
+
     switch (ev->type)
     {
     case ALLEGRO_EVENT_MOUSE_AXES:

backends/imgui_impl_allegro5.h

@@ -17,12 +17,14 @@
 #include "imgui.h"      // IMGUI_IMPL_API
 
 struct ALLEGRO_DISPLAY;
+struct ALLEGRO_EVENT_QUEUE;
 union ALLEGRO_EVENT;
 
 IMGUI_IMPL_API bool     ImGui_ImplAllegro5_Init(ALLEGRO_DISPLAY* display);
 IMGUI_IMPL_API void     ImGui_ImplAllegro5_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplAllegro5_NewFrame();
 IMGUI_IMPL_API void     ImGui_ImplAllegro5_RenderDrawData(ImDrawData* draw_data);
+IMGUI_IMPL_API void     ImGui_ImplAllegro5_WaitForEvent(ALLEGRO_EVENT_QUEUE* queue);
 IMGUI_IMPL_API bool     ImGui_ImplAllegro5_ProcessEvent(ALLEGRO_EVENT* event);
 
 // Use if you want to reset your rendering device without losing Dear ImGui state.

backends/imgui_impl_glfw.cpp

@@ -45,6 +45,8 @@
 #include "imgui.h"
 #include "imgui_impl_glfw.h"
 
+#include <math.h> // isinf
+
 // GLFW
 #include <GLFW/glfw3.h>
 #ifdef _WIN32
@@ -91,6 +93,7 @@ static bool                 g_WantUpdateMonitors = true;
 // Chain GLFW callbacks for main viewport: our callbacks will call the user's previously installed callbacks, if any.
 static GLFWmousebuttonfun   g_PrevUserCallbackMousebutton = NULL;
 static GLFWscrollfun        g_PrevUserCallbackScroll = NULL;
+static GLFWcursorposfun     g_PrevUserCallbackCursorPos = NULL;
 static GLFWkeyfun           g_PrevUserCallbackKey = NULL;
 static GLFWcharfun          g_PrevUserCallbackChar = NULL;
 static GLFWmonitorfun       g_PrevUserCallbackMonitor = NULL;
@@ -115,6 +118,9 @@ void ImGui_ImplGlfw_MouseButtonCallback(GLFWwindow* window, int button, int acti
     if (g_PrevUserCallbackMousebutton != NULL && window == g_Window)
         g_PrevUserCallbackMousebutton(window, button, action, mods);
 
+    ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
     if (action == GLFW_PRESS && button >= 0 && button < IM_ARRAYSIZE(g_MouseJustPressed))
         g_MouseJustPressed[button] = true;
 }
@@ -125,16 +131,31 @@ void ImGui_ImplGlfw_ScrollCallback(GLFWwindow* window, double xoffset, double yo
         g_PrevUserCallbackScroll(window, xoffset, yoffset);
 
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
     io.MouseWheelH += (float)xoffset;
     io.MouseWheel += (float)yoffset;
 }
 
+void ImGui_ImplGlfw_CursorPosCallback(GLFWwindow* window, double xpos, double ypos)
+{
+    if (g_PrevUserCallbackCursorPos != NULL)
+        g_PrevUserCallbackCursorPos(window, xpos, ypos);
+
+    ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
+    // Here, we just take note of the event without actually processing the cursor position.
+    // This is done in ImGui_ImplGlfw_NewFrame() / ImGui_ImplGlfw_UpdateMousePosAndButtons().
+}
+
 void ImGui_ImplGlfw_KeyCallback(GLFWwindow* window, int key, int scancode, int action, int mods)
 {
     if (g_PrevUserCallbackKey != NULL && window == g_Window)
         g_PrevUserCallbackKey(window, key, scancode, action, mods);
 
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
     if (action == GLFW_PRESS)
     {
         io.KeysDown[key] = true;
@@ -163,6 +184,7 @@ void ImGui_ImplGlfw_CharCallback(GLFWwindow* window, unsigned int c)
         g_PrevUserCallbackChar(window, c);
 
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
     io.AddInputCharacter(c);
 }
 
@@ -248,6 +270,7 @@ static bool ImGui_ImplGlfw_Init(GLFWwindow* window, bool install_callbacks, Glfw
         g_InstalledCallbacks = true;
         g_PrevUserCallbackMousebutton = glfwSetMouseButtonCallback(window, ImGui_ImplGlfw_MouseButtonCallback);
         g_PrevUserCallbackScroll = glfwSetScrollCallback(window, ImGui_ImplGlfw_ScrollCallback);
+        g_PrevUserCallbackCursorPos = glfwSetCursorPosCallback(window, ImGui_ImplGlfw_CursorPosCallback);
         g_PrevUserCallbackKey = glfwSetKeyCallback(window, ImGui_ImplGlfw_KeyCallback);
         g_PrevUserCallbackChar = glfwSetCharCallback(window, ImGui_ImplGlfw_CharCallback);
         g_PrevUserCallbackMonitor = glfwSetMonitorCallback(ImGui_ImplGlfw_MonitorCallback);
@@ -306,6 +329,22 @@ void ImGui_ImplGlfw_Shutdown()
     g_ClientApi = GlfwClientApi_Unknown;
 }
 
+void ImGui_ImplGlfw_WaitForEvent()
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    bool window_is_hidden = !glfwGetWindowAttrib(g_Window, GLFW_VISIBLE) || glfwGetWindowAttrib(g_Window, GLFW_ICONIFIED);
+    double waiting_time = window_is_hidden ? INFINITY : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        if (isinf(waiting_time))
+            glfwWaitEvents();
+        else
+            glfwWaitEventsTimeout(waiting_time);
+    }
+}
+
 static void ImGui_ImplGlfw_UpdateMousePosAndButtons()
 {
     // Update buttons

backends/imgui_impl_glfw.h

@@ -31,6 +31,7 @@ IMGUI_IMPL_API bool     ImGui_ImplGlfw_InitForVulkan(GLFWwindow* window, bool in
 IMGUI_IMPL_API bool     ImGui_ImplGlfw_InitForOther(GLFWwindow* window, bool install_callbacks);
 IMGUI_IMPL_API void     ImGui_ImplGlfw_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplGlfw_NewFrame();
+IMGUI_IMPL_API void     ImGui_ImplGlfw_WaitForEvent();
 
 // GLFW callbacks
 // - When calling Init with 'install_callbacks=true': GLFW callbacks will be installed for you. They will call user's previously installed callbacks, if any.

backends/imgui_impl_sdl.cpp

@@ -59,6 +59,8 @@
 #include "TargetConditionals.h"
 #endif
 
+#include <math.h> // isinf
+
 #define SDL_HAS_CAPTURE_AND_GLOBAL_MOUSE    SDL_VERSION_ATLEAST(2,0,4)
 #define SDL_HAS_WINDOW_ALPHA                SDL_VERSION_ATLEAST(2,0,5)
 #define SDL_HAS_ALWAYS_ON_TOP               SDL_VERSION_ATLEAST(2,0,5)
@@ -97,6 +99,26 @@ static void ImGui_ImplSDL2_SetClipboardText(void*, const char* text)
     SDL_SetClipboardText(text);
 }
 
+void ImGui_ImplSDL2_WaitForEvent()
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    Uint32 window_flags = SDL_GetWindowFlags(g_Window);
+    bool window_is_hidden = window_flags & (SDL_WINDOW_HIDDEN | SDL_WINDOW_MINIMIZED);
+    double waiting_time = window_is_hidden ? INFINITY : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        if (isinf(waiting_time))
+            SDL_WaitEvent(NULL);
+        else
+        {
+            const int waiting_time_ms = (int)(1000.0 * ImGui::GetEventWaitingTime());
+            SDL_WaitEventTimeout(NULL, waiting_time_ms);
+        }
+    }
+}
+
 // You can read the io.WantCaptureMouse, io.WantCaptureKeyboard flags to tell if dear imgui wants to use your inputs.
 // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
 // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
@@ -105,6 +127,8 @@ static void ImGui_ImplSDL2_SetClipboardText(void*, const char* text)
 bool ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event)
 {
     ImGuiIO& io = ImGui::GetIO();
+    io.FrameCountSinceLastInput = 0;
+
     switch (event->type)
     {
     case SDL_MOUSEWHEEL:

backends/imgui_impl_sdl.h

@@ -28,4 +28,5 @@ IMGUI_IMPL_API bool     ImGui_ImplSDL2_InitForD3D(SDL_Window* window);
 IMGUI_IMPL_API bool     ImGui_ImplSDL2_InitForMetal(SDL_Window* window);
 IMGUI_IMPL_API void     ImGui_ImplSDL2_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplSDL2_NewFrame(SDL_Window* window);
+IMGUI_IMPL_API void     ImGui_ImplSDL2_WaitForEvent();
 IMGUI_IMPL_API bool     ImGui_ImplSDL2_ProcessEvent(const SDL_Event* event);

backends/imgui_impl_win32.cpp

@@ -18,6 +18,7 @@
 #define WIN32_LEAN_AND_MEAN
 #endif
 #include <windows.h>
+#include <math.h> // isinf
 #include <tchar.h>
 #include <dwmapi.h>
 
@@ -384,6 +385,20 @@ void    ImGui_ImplWin32_NewFrame()
     ImGui_ImplWin32_UpdateGamepads();
 }
 
+void ImGui_ImplWin32_WaitForEvent()
+{
+    if (!(ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode))
+        return;
+
+    BOOL window_is_hidden = !IsWindowVisible(g_hWnd) || IsIconic(g_hWnd);
+    double waiting_time = window_is_hidden ? INFINITE : ImGui::GetEventWaitingTime();
+    if (waiting_time > 0.0)
+    {
+        DWORD waiting_time_ms = isinf(waiting_time) ? INFINITE : (DWORD)(1000.0 * waiting_time);
+        ::MsgWaitForMultipleObjectsEx(0, NULL, waiting_time_ms, QS_ALLINPUT, MWMO_INPUTAVAILABLE|MWMO_ALERTABLE);
+    }
+}
+
 // Allow compilation with old Windows SDK. MinGW doesn't have default _WIN32_WINNT/WINVER versions.
 #ifndef WM_MOUSEHWHEEL
 #define WM_MOUSEHWHEEL 0x020E
@@ -410,6 +425,9 @@ IMGUI_IMPL_API LRESULT ImGui_ImplWin32_WndProcHandler(HWND hwnd, UINT msg, WPARA
         return 0;
 
     ImGuiIO& io = ImGui::GetIO();
+
+    io.FrameCountSinceLastInput = 0;
+
     switch (msg)
     {
     case WM_LBUTTONDOWN: case WM_LBUTTONDBLCLK:

backends/imgui_impl_win32.h

@@ -18,6 +18,7 @@
 IMGUI_IMPL_API bool     ImGui_ImplWin32_Init(void* hwnd);
 IMGUI_IMPL_API void     ImGui_ImplWin32_Shutdown();
 IMGUI_IMPL_API void     ImGui_ImplWin32_NewFrame();
+IMGUI_IMPL_API void     ImGui_ImplWin32_WaitForEvent();
 
 // Win32 message handler your application need to call.
 // - Intentionally commented out in a '#if 0' block to avoid dragging dependencies on <windows.h> from this helper.

docs/TODO.txt

@@ -403,7 +403,6 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - inputs/io: clarify/standardize/expose repeat rate and repeat delays (#1808)
  - inputs/scrolling: support for smooth scrolling (#2462, #2569)
 
- - misc: idle: expose "woken up" boolean (set by inputs) and/or animation time (for cursor blink) for backend to be able stop refreshing easily.
  - misc: idle: if cursor blink if the _only_ visible animation, core imgui could rewrite vertex alpha to avoid CPU pass on ImGui:: calls.
  - misc: idle: if cursor blink if the _only_ visible animation, could even expose a dirty rectangle that optionally can be leverage by some app to render in a smaller viewport, getting rid of much pixel shading cost.
  - misc: no way to run a root-most GetID() with ImGui:: api since there's always a Debug window in the stack. (mentioned in #2960)
@@ -423,12 +422,10 @@ It's mostly a bunch of personal notes, probably incomplete. Feel free to query i
  - demo: window size constraint: square demo is broken when resizing from edges (#1975), would need to rework the callback system to solve this
 
  - examples: window minimize, maximize (#583)
- - examples: provide a zero frame-rate/idle example.
  - examples: dx11/dx12: try to use new swapchain blit models (#2970)
  - backends: move to backends/ folder?
  - backends: report it better when not able to create texture?
  - backends: apple: example_apple should be using modern GL3.
- - backends: glfw: could go idle when minimized? if (glfwGetWindowAttrib(window, GLFW_ICONIFIED)) { glfwWaitEvents(); continue; } // issue: DeltaTime will be super high on resume, perhaps provide a way to let impl know (#440)
  - backends: opengl: rename imgui_impl_opengl2 to impl_opengl_legacy and imgui_impl_opengl3 to imgui_impl_opengl? (#1900)
  - backends: opengl: could use a single vertex buffer and glBufferSubData for uploads?
  - backends: opengl: explicitly disable GL_STENCIL_TEST in bindings.

examples/example_allegro5/main.cpp

@@ -65,6 +65,7 @@ int main(int, char**)
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+        ImGui_ImplAllegro5_WaitForEvent(queue);
         ALLEGRO_EVENT ev;
         while (al_get_next_event(queue, &ev))
         {
@@ -107,6 +108,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

examples/example_glfw_opengl3/main.cpp

@@ -167,6 +167,7 @@ int main(int, char**)
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+        ImGui_ImplGlfw_WaitForEvent();
         glfwPollEvents();
 
         // Start the Dear ImGui frame
@@ -198,6 +199,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

examples/example_sdl_opengl3/main.cpp

@@ -164,6 +164,7 @@ int main(int, char**)
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
+        ImGui_ImplSDL2_WaitForEvent();
         SDL_Event event;
         while (SDL_PollEvent(&event))
         {
@@ -203,6 +204,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

examples/example_win32_directx11/main.cpp

@@ -95,6 +95,8 @@ int main(int, char**)
     ImVec4 clear_color = ImVec4(0.45f, 0.55f, 0.60f, 1.00f);
 
     // Main loop
+    MSG msg;
+    ZeroMemory(&msg, sizeof(msg));
     bool done = false;
     while (!done)
     {
@@ -103,7 +105,7 @@ int main(int, char**)
         // - When io.WantCaptureMouse is true, do not dispatch mouse input data to your main application.
         // - When io.WantCaptureKeyboard is true, do not dispatch keyboard input data to your main application.
         // Generally you may always pass all inputs to dear imgui, and hide them from your application based on those two flags.
-        MSG msg;
+        ImGui_ImplWin32_WaitForEvent();
         while (::PeekMessage(&msg, NULL, 0U, 0U, PM_REMOVE))
         {
             ::TranslateMessage(&msg);
@@ -143,6 +145,7 @@ int main(int, char**)
             ImGui::Text("counter = %d", counter);
 
             ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
+            ImGui::Text("Frames since last input: %d", ImGui::GetIO().FrameCountSinceLastInput);
             ImGui::End();
         }
 

imgui.cpp

@@ -4012,6 +4012,23 @@ ImGuiKeyModFlags ImGui::GetMergedKeyModFlags()
     return key_mod_flags;
 }
 
+double ImGui::GetEventWaitingTime()
+{
+    ImGuiContext& g = *GImGui;
+
+    if ((g.IO.ConfigFlags & ImGuiConfigFlags_EnablePowerSavingMode) && g.IO.FrameCountSinceLastInput > 2)
+        return ImMax(0.0, g.MaxWaitBeforeNextFrame);
+
+    return 0.0;
+}
+
+void ImGui::SetMaxWaitBeforeNextFrame(double time)
+{
+    ImGuiContext& g = *GImGui;
+
+    g.MaxWaitBeforeNextFrame = ImMin(g.MaxWaitBeforeNextFrame, time);
+}
+
 void ImGui::NewFrame()
 {
     IM_ASSERT(GImGui != NULL && "No current context. Did you call ImGui::CreateContext() and ImGui::SetCurrentContext() ?");
@@ -4039,6 +4056,7 @@ void ImGui::NewFrame()
     g.TooltipOverrideCount = 0;
     g.WindowsActiveCount = 0;
     g.MenusIdSubmittedThisFrame.resize(0);
+    g.MaxWaitBeforeNextFrame = INFINITY;
 
     // Calculate frame-rate for the user, as a purely luxurious feature
     g.FramerateSecPerFrameAccum += g.IO.DeltaTime - g.FramerateSecPerFrame[g.FramerateSecPerFrameIdx];
@@ -4647,6 +4665,7 @@ void ImGui::EndFrame()
     // End frame
     g.WithinFrameScope = false;
     g.FrameCountEnded = g.FrameCount;
+    g.IO.FrameCountSinceLastInput++;
 
     // Initiate moving window + handle left-click and right-click focus
     UpdateMouseMovingWindowEndFrame();