feat: add platform base to reuse code

Source/Platform/PlatformBase.cs

@@ -0,0 +1,109 @@
+using ImGuiNET;
+using NumericsConverter;
+using System;
+using UImGui.Assets;
+using UnityEngine;
+using UnityEngine.Assertions;
+
+namespace UImGui.Platform
+{
+	/// <summary>
+	/// TODO: Write all methods a this base class usage.
+	/// </summary>
+	internal class PlatformBase : IPlatform
+	{
+		protected readonly IniSettingsAsset _iniSettings;
+		protected readonly CursorShapesAsset _cursorShapes;
+
+		protected readonly PlatformCallbacks _callbacks = new PlatformCallbacks();
+
+		protected ImGuiMouseCursor _lastCursor = ImGuiMouseCursor.COUNT;
+
+		internal PlatformBase(CursorShapesAsset cursorShapes, IniSettingsAsset iniSettings)
+		{
+			_cursorShapes = cursorShapes;
+			_iniSettings = iniSettings;
+		}
+
+		public virtual bool Initialize(ImGuiIOPtr io, UIOConfig config, string platformName)
+		{
+			io.SetBackendPlatformName("Unity Input System");
+			io.BackendFlags |= ImGuiBackendFlags.HasMouseCursors;
+
+			// TODO: Check if this works
+			if ((config.ImGuiConfig & ImGuiConfigFlags.NavEnableSetMousePos) != 0)
+			{
+				io.BackendFlags |= ImGuiBackendFlags.HasSetMousePos;
+				io.WantSetMousePos = true;
+			}
+			else
+			{
+				io.BackendFlags &= ~ImGuiBackendFlags.HasSetMousePos;
+				io.WantSetMousePos = false;
+			}
+
+			unsafe
+			{
+				// TODO: IMGUI_FEATURE_CUSTOM_ASSERT.
+#if IMGUI_FEATURE_CUSTOM_ASSERT
+				//PlatformCallbacks.SetClipboardFunctions(
+				//	GetClipboardTextCallback, SetClipboardTextCallback,
+				//	ImeSetInputScreenPosCallback, LogAssertCallback, DebugBreakCallback);
+#else
+				PlatformCallbacks.SetClipboardFunctions(PlatformCallbacks.GetClipboardTextCallback, PlatformCallbacks.SetClipboardTextCallback);
+#endif
+			}
+
+			_callbacks.Assign(io);
+			io.ClipboardUserData = IntPtr.Zero;
+
+			if (_iniSettings != null)
+			{
+				io.SetIniFilename(null);
+				ImGui.LoadIniSettingsFromMemory(_iniSettings.Load());
+			}
+
+			return true;
+		}
+
+		public virtual void PrepareFrame(ImGuiIOPtr io, Rect displayRect)
+		{
+			Assert.IsTrue(io.Fonts.IsBuilt(), "Font atlas not built! Generally built by the renderer. Missing call to renderer NewFrame() function?");
+
+			io.DisplaySize = displayRect.size.ToSystem(); // TODO: dpi aware, scale, etc.
+
+			io.DeltaTime = Time.unscaledDeltaTime;
+
+			if (_iniSettings != null && io.WantSaveIniSettings)
+			{
+				_iniSettings.Save(ImGui.SaveIniSettingsToMemory());
+				io.WantSaveIniSettings = false;
+			}
+		}
+
+		public virtual void Shutdown(ImGuiIOPtr io)
+		{
+			io.SetBackendPlatformName(null);
+
+			_callbacks.Unset(io);
+		}
+
+		protected void UpdateCursor(ImGuiIOPtr io, ImGuiMouseCursor cursor)
+		{
+			if (io.MouseDrawCursor)
+			{
+				cursor = ImGuiMouseCursor.None;
+			}
+
+			if (_lastCursor == cursor) return;
+			if ((io.ConfigFlags & ImGuiConfigFlags.NoMouseCursorChange) != 0) return;
+
+			_lastCursor = cursor;
+			Cursor.visible = cursor != ImGuiMouseCursor.None; // Hide cursor if ImGui is drawing it or if it wants no cursor.
+			if (_cursorShapes != null)
+			{
+				Cursor.SetCursor(_cursorShapes[cursor].Texture, _cursorShapes[cursor].Hotspot, CursorMode.Auto);
+			}
+		}
+	}
+}