New power saver mode

Author: Madman10K

Config/Core/Renderer.yaml

@@ -1,3 +1,6 @@
-vulkan: false                 # The Vulkan renderer is not yet implemented
-v-sync: false                 # To run or not to run in V-Sync mode
+vulkan: false                 # Enables Vulkan/WebGPU renderers
+v-sync: true                  # To run or not to run in V-Sync mode
 msaa-samples: 8               # Multisampling sample count
+power-saving:                 # The power saving mode limits the number of frames that are drawn when idling. Will not work for applications with live plots or animations
+  enabled: true
+  idle-frames: 9              # The number of frames to output while idling

Framework/C/Interfaces/CRendererInterface.h

@@ -20,6 +20,9 @@ extern "C"
     UIMGUI_PUBLIC_API UImGui_String UImGui_Renderer_getGPUName();
     // Event Safety - begin, post-begin
     UIMGUI_PUBLIC_API UImGui_String UImGui_Renderer_getDriverVersion();
+
+    // Event Safety - begin, post-begin
+    UIMGUI_PUBLIC_API void UImGui_Renderer_forceUpdate();
 #ifdef __cplusplus
 }
 #endif

Framework/C/Internal/RendererData.h

@@ -9,15 +9,19 @@ extern "C"
      * @brief Renderer data struct
      * @var bVulkan - Whether the application uses the vulkan renderer
      * @var bUsingVSync - Whether the application uses VSync(sync the application framerate with monitor refresh rate)
-     * @var msaaSamples - Number of samples for MSAA anti-aliasing
-     * @var bSampleRateShading - Apply anti-aliasing on shaders
-     * @var sampleRateShadingMult - Shader anti-aliasing multiplier
+     * @var msaaSamples - Number of samples for MSAA antialiasing
+     * @var bEnablePowerSavingMode - Whether to enable power saving(rendering with a reduce frame rate when the
+     * application sits idle). Note: do not use for highly dynamic applications with plots or animations
+     * @var idleFrameRate - The number of frames to render per second when idle
      */
     typedef struct UIMGUI_PUBLIC_API UImGui_RendererData
     {
         bool bVulkan;
         bool bUsingVSync;
         uint32_t msaaSamples;
+
+        bool bEnablePowerSavingMode;
+        float idleFrameRate;
     } UImGui_RendererData;
 #ifdef __cplusplus
 }

Framework/Core/Interfaces/RendererInterface.cpp

@@ -35,3 +35,8 @@ const UImGui::FString& UImGui::Renderer::getDriverVersion() noexcept
 {
     return get().driverVersion;
 }
+
+void UImGui::Renderer::forceUpdate() noexcept
+{
+    get().bIdling = false;
+}

Framework/Core/Interfaces/RendererInterface.hpp

@@ -20,6 +20,10 @@ namespace UImGui
         static const FString& getGPUName() noexcept;
         // Event Safety - begin, post-begin
         static const FString& getDriverVersion() noexcept;
+
+        // Forces an update even when idling in power saving mode
+        // Event Safety - begin, post-begin
+        static void forceUpdate() noexcept;
     private:
         friend class RendererInternal;
         friend class WindowInternal;

Framework/Renderer/Renderer.cpp

@@ -52,6 +52,27 @@ void UImGui::RendererInternal::tick(void* rendererInstance) noexcept
 {
     auto& inst = *(static_cast<RendererInternal*>(rendererInstance));
     static double deltaTime = 0.0f;
+
+#ifndef __EMSCRIPTEN__
+    inst.bIdling = false;
+    if (inst.data.idleFrameRate > 0.0f && inst.data.bEnablePowerSavingMode)
+    {
+        const double waitTimeout = 1.0 / inst.data.idleFrameRate;
+
+        Timer timer;
+        timer.start();
+
+        glfwWaitEventsTimeout(waitTimeout);
+
+        timer.stop();
+        const double elapsed = timer.get();
+        const double duration = elapsed - waitTimeout;
+        const double idleExpected = 1.0 / inst.data.idleFrameRate;
+
+        inst.bIdling = duration > (idleExpected * 0.9);
+    }
+#endif
+
     glfwPollEvents();
 
     const double now = glfwGetTime();
@@ -61,6 +82,48 @@ void UImGui::RendererInternal::tick(void* rendererInstance) noexcept
     // Updates the state of the keybindings
     Global::get().window.updateKeyState();
 
+#ifdef __EMSCRIPTEN__
+    if (inst.data.idleFrameRate > 0.0f && inst.data.bEnablePowerSavingMode)
+    {
+        ImGuiContext& g = *ImGui::GetCurrentContext();
+        bool bHasInputEvent = !g.InputEventsQueue.empty();
+
+        static double lastRefreshTime = 0.0f;
+        static double accumulatedTime = 0.0f;
+        accumulatedTime += deltaTime;
+
+        bool bShouldIdle = false;
+        if (bHasInputEvent)
+        {
+            inst.bIdling = false;
+            bShouldIdle = false;
+        }
+        else
+        {
+            inst.bIdling = true;
+            if ((accumulatedTime - lastRefreshTime) < 1.0 / inst.data.idleFrameRate)
+                bShouldIdle = true;
+            else
+                bShouldIdle = false;
+        }
+
+        if (!bShouldIdle)
+        {
+            lastRefreshTime = accumulatedTime;
+            accumulatedTime = 0.0f;
+        }
+        else
+        {
+            lastRefreshTime = 0.0f;
+            return;
+        }
+    }
+#endif
+
+    // Do not render if the window is minimised
+    if (Window::getWindowIconified())
+        glfwWaitEvents();
+
     inst.renderer->renderStart(deltaTime);
     GUIRenderer::beginUI(static_cast<float>(deltaTime), inst.renderer);
     inst.renderer->renderEnd(deltaTime);
@@ -90,6 +153,15 @@ void UImGui::RendererInternal::loadConfig() noexcept
         data.bUsingVSync = node["v-sync"].as<bool>();
     if (node["msaa-samples"])
         data.msaaSamples = node["msaa-samples"].as<uint32_t>();
+
+    const auto& powerSaving = node["power-saving"];
+    if (powerSaving)
+    {
+        if (powerSaving["enabled"])
+            data.bEnablePowerSavingMode = powerSaving["enabled"].as<bool>();
+        if (powerSaving["idle-frames"])
+            data.idleFrameRate = powerSaving["idle-frames"].as<float>();
+    }
 }
 
 void UImGui::RendererInternal::saveConfig() const noexcept
@@ -100,6 +172,10 @@ void UImGui::RendererInternal::saveConfig() const noexcept
     out << YAML::Key << "vulkan" << YAML::Value << data.bVulkan;
     out << YAML::Key << "v-sync" << YAML::Value << data.bUsingVSync;
     out << YAML::Key << "msaa-samples" << YAML::Value << data.msaaSamples;
+    out << YAML::Key << "power-saving" << YAML::Value << YAML::BeginMap;
+    out << YAML::Key << "enabled" << YAML::Value << data.bEnablePowerSavingMode;
+    out << YAML::Key << "idle-frames" << YAML::Value << data.idleFrameRate;
+    out << YAML::EndMap;
 
     std::ofstream fout((Instance::get()->initInfo.configDir + "Core/Renderer.yaml").c_str());
     fout << out.c_str();

Framework/Renderer/Renderer.hpp

@@ -53,7 +53,10 @@ namespace UImGui
             .bVulkan = false,
             .bUsingVSync = true,
             .msaaSamples = 1,
+            .bEnablePowerSavingMode = false,
+            .idleFrameRate = 9.0f
         };
+        bool bIdling = false;
     };
 
 }