Magic_Game/src/kiwano-imgui/ImGuiModule.cpp

// Copyright (C) 2019 Nomango

#include <kiwano/core/common.h>
#include <kiwano/core/event/KeyEvent.h>
#include <kiwano/core/event/MouseEvent.h>
#include <kiwano/platform/Window.h>
#include <kiwano/platform/Input.h>
#include <kiwano/renderer/Renderer.h>
#include <kiwano-imgui/ImGuiModule.h>
#include <kiwano-imgui/imgui_impl.h>

namespace kiwano
{
	namespace imgui
	{
		ImGuiModule::ImGuiModule()
			: target_window_(nullptr)
		{
		}

		void ImGuiModule::SetupComponent()
		{
			// Setup Dear ImGui context
			IMGUI_CHECKVERSION();
			ImGui::CreateContext();
			ImGuiIO& io = ImGui::GetIO(); (void)io;

			// Setup Dear ImGui style
			ImGui::StyleColorsDark();

			// Setup Platform/Renderer bindings
			target_window_ = Renderer::Instance().GetTargetWindow();

			io.BackendFlags |= ImGuiBackendFlags_HasMouseCursors;         // We can honor GetMouseCursor() values (optional)
			io.BackendFlags |= ImGuiBackendFlags_HasSetMousePos;          // We can honor io.WantSetMousePos requests (optional, rarely used)
			io.BackendPlatformName = "imgui_impl_win32";
			io.ImeWindowHandle = target_window_;

			// Keyboard mapping. ImGui will use those indices to peek into the io.KeysDown[] array that we will update during the application lifetime.
			io.KeyMap[ImGuiKey_Tab] = (int)KeyCode::Tab;
			io.KeyMap[ImGuiKey_LeftArrow] = (int)KeyCode::Left;
			io.KeyMap[ImGuiKey_RightArrow] = (int)KeyCode::Right;
			io.KeyMap[ImGuiKey_UpArrow] = (int)KeyCode::Up;
			io.KeyMap[ImGuiKey_DownArrow] = (int)KeyCode::Down;
			io.KeyMap[ImGuiKey_Delete] = (int)KeyCode::Delete;
			io.KeyMap[ImGuiKey_Backspace] = (int)KeyCode::Back;
			io.KeyMap[ImGuiKey_Space] = (int)KeyCode::Space;
			io.KeyMap[ImGuiKey_Enter] = (int)KeyCode::Enter;
			io.KeyMap[ImGuiKey_Escape] = (int)KeyCode::Esc;
			io.KeyMap[ImGuiKey_A] = (int)KeyCode::A;
			io.KeyMap[ImGuiKey_C] = (int)KeyCode::C;
			io.KeyMap[ImGuiKey_V] = (int)KeyCode::V;
			io.KeyMap[ImGuiKey_X] = (int)KeyCode::X;
			io.KeyMap[ImGuiKey_Y] = (int)KeyCode::Y;
			io.KeyMap[ImGuiKey_Z] = (int)KeyCode::Z;

			ImGui_Impl_Init(Renderer::Instance());
		}

		void ImGuiModule::DestroyComponent()
		{
			ImGui_Impl_Shutdown();
			ImGui::DestroyContext();
		}

		void ImGuiModule::OnUpdate(Duration dt)
		{
			ImGuiIO& io = ImGui::GetIO();

			// Setup time step
			io.DeltaTime = dt.Seconds();

			// Read keyboard modifiers inputs
			io.KeyCtrl = Input::Instance().IsDown(KeyCode::Ctrl);
			io.KeyShift = Input::Instance().IsDown(KeyCode::Shift);
			io.KeyAlt = Input::Instance().IsDown(KeyCode::Alt);
			io.KeySuper = Input::Instance().IsDown(KeyCode::Super);
			// io.KeysDown[], io.MousePos, io.MouseDown[], io.MouseWheel: filled by the HandleEvent function below.

			// Update OS mouse position
			UpdateMousePos();

			// Update OS mouse cursor with the cursor requested by imgui
			UpdateMouseCursor();
		}

		void ImGuiModule::BeforeRender()
		{
			NewFrame();
		}

		void ImGuiModule::AfterRender()
		{
			Render();
		}

		void ImGuiModule::HandleEvent(Event* evt)
		{
			if (ImGui::GetCurrentContext() == NULL)
				return;

			ImGuiIO& io = ImGui::GetIO();
			if (evt->IsType<MouseEvent>())
			{
				if (evt->IsType<MouseDownEvent>())
				{
					MouseButton button = dynamic_cast<MouseDownEvent*>(evt)->button;
					int index = 0;
					if		(button == MouseButton::Left) index = 0;
					else if (button == MouseButton::Right) index = 1;
					else if (button == MouseButton::Middle) index = 2;
					io.MouseDown[index] = true;
				}
				else if (evt->IsType<MouseUpEvent>())
				{
					MouseButton button = dynamic_cast<MouseUpEvent*>(evt)->button;
					int index = 0;
					if		(button == MouseButton::Left) index = 0;
					else if (button == MouseButton::Right) index = 1;
					else if (button == MouseButton::Middle) index = 2;
					io.MouseDown[index] = false;
				}
				else if (evt->IsType<MouseWheelEvent>())
				{
					float wheel = dynamic_cast<MouseWheelEvent*>(evt)->wheel;
					io.MouseWheel += wheel;
				}
			}
			else if (evt->IsType<KeyEvent>())
			{
				if (evt->IsType<KeyDownEvent>())
				{
					KeyCode key = dynamic_cast<KeyDownEvent*>(evt)->code;
					io.KeysDown[(int)key] = true;
				}
				else if (evt->IsType<KeyUpEvent>())
				{
					KeyCode key = dynamic_cast<KeyUpEvent*>(evt)->code;
					io.KeysDown[(int)key] = false;
				}
				else if (evt->IsType<KeyCharEvent>())
				{
					// You can also use ToAscii()+GetKeyboardState() to retrieve characters.
					char ch = dynamic_cast<KeyCharEvent*>(evt)->value;
					io.AddInputCharacter(static_cast<ImWchar>(ch));
				}
			}
		}

		void ImGuiModule::NewFrame()
		{
			ImGui_Impl_NewFrame();

			ImGuiIO& io = ImGui::GetIO();
			KGE_ASSERT(io.Fonts->IsBuilt() && "Font atlas not built!");

			// Setup display size (every frame to accommodate for window resizing)
			Size display_size = Renderer::Instance().GetOutputSize();
			io.DisplaySize = ImVec2(display_size.x, display_size.y);

			ImGui::NewFrame();
		}

		void ImGuiModule::Render()
		{
			ImGui::Render();

			ImGui_Impl_RenderDrawData(ImGui::GetDrawData());
		}

		void ImGuiModule::UpdateMousePos()
		{
			ImGuiIO& io = ImGui::GetIO();

			// Set OS mouse position if requested (rarely used, only when ImGuiConfigFlags_NavEnableSetMousePos is enabled by user)
			if (io.WantSetMousePos)
			{
				POINT pos = { (int)io.MousePos.x, (int)io.MousePos.y };
				::ClientToScreen(target_window_, &pos);
				::SetCursorPos(pos.x, pos.y);
			}

			Point pos = Input::Instance().GetMousePos();
			io.MousePos = ImVec2(pos.x, pos.y);
		}

		void ImGuiModule::UpdateMouseCursor()
		{
			if (ImGui::GetIO().ConfigFlags & ImGuiConfigFlags_NoMouseCursorChange)
				return;

			CursorType cursor = CursorType::Arrow;
			switch (ImGui::GetMouseCursor())
			{
			case ImGuiMouseCursor_Arrow:        cursor = CursorType::Arrow; break;
			case ImGuiMouseCursor_TextInput:    cursor = CursorType::TextInput; break;
			case ImGuiMouseCursor_ResizeAll:    cursor = CursorType::SizeAll; break;
			case ImGuiMouseCursor_ResizeEW:     cursor = CursorType::SizeWE; break;
			case ImGuiMouseCursor_ResizeNS:     cursor = CursorType::SizeNS; break;
			case ImGuiMouseCursor_ResizeNESW:   cursor = CursorType::SizeNESW; break;
			case ImGuiMouseCursor_ResizeNWSE:   cursor = CursorType::SizeNWSE; break;
			case ImGuiMouseCursor_Hand:         cursor = CursorType::Hand; break;
			}

			Window::Instance().SetCursor(cursor);
		}

	}
}