ImGui Events

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引言

上一节我们讨论了 ImGUI 并运行了官方示例，今天我们来为我们的引擎编写 ImGUI 事件。

事件声明

在头文件 ImGuiLayer.h 声明 ImGUI 的交互事件：

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#pragma once

#include "../Layer.h"

#include "../Events/KeyEvent.h"
#include "../Events/MouseEvent.h"
#include "../Events/ApplicationEvent.h"

namespace Infinite {

	class INFINITE_API ImGuiLayer : public Layer
	{
	public:
		ImGuiLayer();
		~ImGuiLayer();

		void OnAttach();
		void OnDetach();
		void OnUpdate();
		void OnEvent(Event& event);
	private:
+		bool OnMouseButtonPressedEvent(MouseButtonPressedEvent& e);
+		bool OnMouseButtonReleasedEvent(MouseButtonReleasedEvent& e);
+		bool OnMouseMovedEvent(MouseMovedEvent& e);
+		bool OnMouseScrolledEvent(MouseScrolledEvent& e);
+		bool OnKeyPressedEvent(KeyPressedEvent& e);
+		bool OnKeyReleasedEvent(KeyReleasedEvent& e);
+		bool OnKeyTypedEvent(KeyTypedEvent& e);
+		bool OnWindowResizeEvent(WindowResizeEvent& e);

	private:
		float m_Time = 0.0f;

	};
}

事件实现

在 ImGuiLayer.cpp 中添加头文件和事件的模板：

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#include "ifnpch.h"
#include "ImGuiLayer.h"

#include "../imgui.h"
#include "Platform/OpenGL/ImGuiOpenGLRenderer.h"

// TEMPORARY
+#include <GLFW/glfw3.h>
+#include <glad/glad.h>

#include "../Application.h"

namespace Infinite {

	ImGuiLayer::ImGuiLayer()
		: Layer("ImGuiLayer")
	{

	}

	ImGuiLayer::~ImGuiLayer()
	{

	}

	void ImGuiLayer::OnAttach()
	{
		ImGui::CreateContext();
		ImGui::StyleColorsDark();

		ImGuiIO& io = ImGui::GetIO();
		io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;
		io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;

		// TEMPORARY: should eventually use Infinite key codes
		io.KeyMap[ImGuiKey_Tab] = GLFW_KEY_TAB;
		io.KeyMap[ImGuiKey_LeftArrow] = GLFW_KEY_LEFT;
		io.KeyMap[ImGuiKey_RightArrow] = GLFW_KEY_RIGHT;
		io.KeyMap[ImGuiKey_UpArrow] = GLFW_KEY_UP;
		io.KeyMap[ImGuiKey_DownArrow] = GLFW_KEY_DOWN;
		io.KeyMap[ImGuiKey_PageUp] = GLFW_KEY_PAGE_UP;
		io.KeyMap[ImGuiKey_PageDown] = GLFW_KEY_PAGE_DOWN;
		io.KeyMap[ImGuiKey_Home] = GLFW_KEY_HOME;
		io.KeyMap[ImGuiKey_End] = GLFW_KEY_END;
		io.KeyMap[ImGuiKey_Insert] = GLFW_KEY_INSERT;
		io.KeyMap[ImGuiKey_Delete] = GLFW_KEY_DELETE;
		io.KeyMap[ImGuiKey_Backspace] = GLFW_KEY_BACKSPACE;
		io.KeyMap[ImGuiKey_Space] = GLFW_KEY_SPACE;
		io.KeyMap[ImGuiKey_Enter] = GLFW_KEY_ENTER;
		io.KeyMap[ImGuiKey_Escape] = GLFW_KEY_ESCAPE;
		io.KeyMap[ImGuiKey_A] = GLFW_KEY_A;
		io.KeyMap[ImGuiKey_C] = GLFW_KEY_C;
		io.KeyMap[ImGuiKey_V] = GLFW_KEY_V;
		io.KeyMap[ImGuiKey_X] = GLFW_KEY_X;
		io.KeyMap[ImGuiKey_Y] = GLFW_KEY_Y;
		io.KeyMap[ImGuiKey_Z] = GLFW_KEY_Z;

		ImGui_ImplOpenGL3_Init("#version 410");
	}

	void ImGuiLayer::OnDetach()
	{

	}

	void ImGuiLayer::OnUpdate()
	{
		ImGuiIO& io = ImGui::GetIO();
		Application& app = Application::Get();
		io.DisplaySize = ImVec2(app.GetWindow().GetWidth(), app.GetWindow().GetHeight());

		float time = (float)glfwGetTime();
		io.DeltaTime = m_Time > 0.0f ? (time - m_Time) : (1.0f / 60.0f);
		m_Time = time;

		ImGui_ImplOpenGL3_NewFrame();
		ImGui::NewFrame();

		static bool show = true;
		ImGui::ShowDemoWindow(&show);

		ImGui::Render();
		ImGui_ImplOpenGL3_RenderDrawData(ImGui::GetDrawData());
	}

+	void ImGuiLayer::OnEvent(Event& event)
+	{
+		
+	}

+	bool ImGuiLayer::OnMouseButtonPressedEvent(MouseButtonPressedEvent& e)
+	{
+
+	}

+	bool ImGuiLayer::OnMouseButtonReleasedEvent(MouseButtonReleasedEvent& e)
+	{
+		
+	}

+	bool ImGuiLayer::OnMouseMovedEvent(MouseMovedEvent& e)
+	{
+		
+	}

+	bool ImGuiLayer::OnMouseScrolledEvent(MouseScrolledEvent& e)
+	{
+		
+	}

+	bool ImGuiLayer::OnKeyPressedEvent(KeyPressedEvent& e)
+	{
+		
+	}

+	bool ImGuiLayer::OnKeyReleasedEvent(KeyReleasedEvent& e)
+	{
+	
+	}

+	bool ImGuiLayer::OnKeyTypedEvent(KeyTypedEvent& e)
+	{
+		
+	}



+	bool ImGuiLayer::OnWindowResizeEvent(WindowResizeEvent& e)
+	{
+
+	}
}

下面我们依次实现这些事件：

Event

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void ImGuiLayer::OnEvent(Event& event)
{
    EventDispatcher dispatcher(event);
    dispatcher.Dispatch<MouseButtonPressedEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnMouseButtonPressedEvent));
    dispatcher.Dispatch<MouseButtonReleasedEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnMouseButtonReleasedEvent));
    dispatcher.Dispatch<MouseMovedEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnMouseMovedEvent));
    dispatcher.Dispatch<MouseScrolledEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnMouseScrolledEvent));
    dispatcher.Dispatch<KeyPressedEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnKeyPressedEvent));
    dispatcher.Dispatch<KeyTypedEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnKeyTypedEvent));
    dispatcher.Dispatch<KeyReleasedEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnKeyReleasedEvent));
    dispatcher.Dispatch<WindowResizeEvent>(IFN_BIND_EVENT_FN(ImGuiLayer::OnWindowResizeEvent));
}

这里的 IFN_BIND_EVENT_FN 则在 Core.h 中定义：

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#define IFN_BIND_EVENT_FN(fn) std::bind(&fn, this, std::placeholders::_1)

Mouse

MouseButtonPressed
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bool ImGuiLayer::OnMouseButtonPressedEvent(MouseButtonPressedEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    io.MouseDown[e.GetMouseButton()] = true;

    return false;
}
MouseButtonReleased
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bool ImGuiLayer::OnMouseButtonReleasedEvent(MouseButtonReleasedEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    io.MouseDown[e.GetMouseButton()] = false;

    return false;
}
MouseMoved
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bool ImGuiLayer::OnMouseMovedEvent(MouseMovedEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    io.MousePos = ImVec2(e.GetX(), e.GetY());

    return false;
}
MouseScrolled
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bool ImGuiLayer::OnMouseScrolledEvent(MouseScrolledEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    io.MouseWheelH += e.GetXOffset();
    io.MouseWheel += e.GetYOffset();

    return false;
}

Key

KeyPressed
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bool ImGuiLayer::OnKeyPressedEvent(KeyPressedEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    io.KeysDown[e.GetKeyCode()] = true;

    io.KeyCtrl = io.KeysDown[GLFW_KEY_LEFT_CONTROL] || io.KeysDown[GLFW_KEY_RIGHT_CONTROL];
    io.KeyShift = io.KeysDown[GLFW_KEY_LEFT_SHIFT] || io.KeysDown[GLFW_KEY_RIGHT_SHIFT];
    io.KeyAlt = io.KeysDown[GLFW_KEY_LEFT_ALT] || io.KeysDown[GLFW_KEY_RIGHT_ALT];
    io.KeySuper = io.KeysDown[GLFW_KEY_LEFT_SUPER] || io.KeysDown[GLFW_KEY_RIGHT_SUPER];
    return false;
}
KeyReleased
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bool ImGuiLayer::OnKeyReleasedEvent(KeyReleasedEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    io.KeysDown[e.GetKeyCode()] = false;

    return false;
}
KeyTyped

KeyTyped 的实现比较复杂，首先我们需要先在 Event.h 添加 KeyTyped 枚举类型：

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	enum class EventType
	{
		None = 0,
		WindowClose, WindowResize, WindowFocus, WindowLostFocus, WindowMoved,
		AppTick, AppUpdate, AppRender,
+		KeyPressed, KeyReleased, KeyTyped,
		MouseButtonPressed, MouseButtonReleased, MouseMoved, MouseScrolled
	};

接着在 KeyEvent.h 中添加事件：

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class INFINITE_API KeyTypedEvent : public KeyEvent
{
    public:
    KeyTypedEvent(int keycode)
        : KeyEvent(keycode) {}

    std::string ToString() const override
    {
        std::stringstream ss;
        ss << "KeyTypedEvent: " << m_KeyCode;
        return ss.str();
    }

    EVENT_CLASS_TYPE(KeyTyped)
};

最后回到 ImGuiLayer.cpp 实现事件：

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bool ImGuiLayer::OnKeyTypedEvent(KeyTypedEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    int keycode = e.GetKeyCode();
    if (keycode > 0 && keycode < 0x10000)
        io.AddInputCharacter((unsigned short)keycode);

    return false;
}

Windows

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bool ImGuiLayer::OnWindowResizeEvent(WindowResizeEvent& e)
{
    ImGuiIO& io = ImGui::GetIO();
    io.DisplaySize = ImVec2(e.GetWidth(), e.GetHeight());
    io.DisplayFramebufferScale = ImVec2(1.0f, 1.0f);
    glViewport(0, 0 , e.GetWidth(), e.GetHeight());

    return false;
}

预生成文件

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workspace "Infinite"
  architecture "x64"
  startproject "Sandbox"

  configurations
  {
    "Debug",
    "Release",
    "Dist"
  }

outputdir = "%{cfg.buildcfg}-%{cfg.system}-%{cfg.architecture}"

-- Include directories relative to root folder (solution directory)
IncludeDir = {}
IncludeDir["GLFW"] = "Infinite/vendor/GLFW/include"
IncludeDir["GLAD"] = "Infinite/vendor/GLAD/include"
IncludeDir["ImGui"] = "Infinite/vendor/imgui/include"

include "Infinite/vendor/GLFW"
include "Infinite/vendor/GLAD"
include "Infinite/vendor/imgui"

project "Infinite"
  location "Infinite"
  kind "SharedLib"
  language "C++"
+ staticruntime "off"

  targetdir ("bin/" .. outputdir .. "/%{prj.name}")
  objdir ("bin-int/" .. outputdir .. "/%{prj.name}")

  pchheader "ifnpch.h"
  pchsource "Infinite/src/ifnpch.cpp"

  files
  {
    "%{prj.name}/src/**.h",
    "%{prj.name}/src/**.cpp"
  }

  includedirs
  {
    "%{prj.name}/src",
    "%{prj.name}/vendor/spdlog/include",
    "%{IncludeDir.GLFW}",
    "%{IncludeDir.GLAD}",
    "%{IncludeDir.ImGui}"
  }

  links
  {
    "GLFW",
    "GLAD",
    "ImGui",
    "opengl32.lib"
  }

  filter "system:windows"
    cppdialect "C++17"
    systemversion "latest"

    defines
    {
      "IFN_PLATFORM_WINDOWS",
      "IFN_BUILD_DLL",
      "GLFW_INCLUDE_NONE"
    }

    postbuildcommands
    {
+     ("{COPY} %{cfg.buildtarget.relpath} \"../bin/" .. outputdir .. "/Sandbox/\"")
    }

  filter "configurations:Debug"
      defines "IFN_DEBUG"
+     runtime "Debug"
      symbols "On"

  filter "configurations:Release"
      defines "IFN_RELEASE"
+     runtime "Release"
      optimize "On"

  filter "configurations:Dist"
      defines "IFN_DIST"
+     runtime "Release"
      optimize "On"



project "Sandbox"
  location "Sandbox"
  kind "ConsoleApp"
+ staticruntime "off"

  language "C++"

  targetdir ("bin/" .. outputdir .. "/%{prj.name}")
  objdir ("bin-int/" .. outputdir .. "/%{prj.name}")

  files
  {
    "%{prj.name}/src/**.h",
    "%{prj.name}/src/**.cpp"
  }

  includedirs
  {
    "Infinite/vendor/spdlog/include",
    "Infinite/src/Infinite",
    "Infinite/src/Events",
    "Infinite/src/**.h",
    "Infinite/src/**.cpp"
  }

  links
  {
    "Infinite"
  }

  filter "system:windows"
    cppdialect "C++17"
    systemversion "latest"

    defines
    {
      "IFN_PLATFORM_WINDOWS"
    }

  filter "configurations:Debug"
      defines "IFN_DEBUG"
+     runtime "Debug"
      symbols "On"

  filter "configurations:Release"
      defines "IFN_RELEASE"
+     runtime "Release"
      optimize "On"

  filter "configurations:Dist"
      defines "IFN_DIST"
+     runtime "Release"
      optimize "On"

调试

在调试过程中由于没有给事件实现添加作用域，运行时报错外部符号无法解析，以后需要多加注意。

Mouse


Key