using ImGuiNET; using SDL3; namespace ResoniteImGuiLib.SDL3; ///

/// Implementation of SDL3 platform backend for ImGui. /// https://github.com/ocornut/imgui/blob/master/backends/imgui_impl_sdl3.h ///

public class ImGuiSDL3 : IDisposable { public readonly IntPtr Window; public readonly IntPtr Renderer; public readonly uint WindowId; private uint _mouseWindowId; private int _mousePendingLeaveFrame; private IntPtr[] _mouseCursors = new IntPtr[(int)ImGuiMouseCursor.COUNT]; private IntPtr _mouseLastCursor = -1; private int _mouseButtonsDown; // I don't think we actually need these since it works just fine without them // // [UnmanagedFunctionPointer(CallingConvention.Cdecl)] // public delegate IntPtr Platform_GetClipboardTextFn(IntPtr ctx); // // [UnmanagedFunctionPointer(CallingConvention.Cdecl)] // public delegate void Platform_SetClipboardTextFn(IntPtr ctx, IntPtr text); // // private static Platform_GetClipboardTextFn getClipboardDelegate = GetClipboardText; // private static Platform_SetClipboardTextFn setClipboardDelegate = SetClipboardText; // // private static IntPtr getClipboardPtr; // private static IntPtr setClipboardPtr; // // private static IntPtr clipboardTextPtr = IntPtr.Zero; public ImGuiSDL3(IntPtr window, IntPtr renderer) { ImGuiIOPtr io = ImGui.GetIO(); io.BackendFlags |= ImGuiBackendFlags.HasMouseCursors; io.BackendFlags |= ImGuiBackendFlags.HasSetMousePos; Window = window; WindowId = SDL.GetWindowID(Window); Renderer = renderer; // I don't think we actually need these since it works just fine without them // // ImGuiPlatformIOPtr platformIo = ImGui.GetPlatformIO(); // platformIo.Platform_SetClipboardTextFn = Marshal.GetFunctionPointerForDelegate(setClipboardDelegate); // platformIo.Platform_GetClipboardTextFn = Marshal.GetFunctionPointerForDelegate(getClipboardDelegate); // getClipboardPtr = platformIo.Platform_GetClipboardTextFn; // setClipboardPtr = platformIo.Platform_SetClipboardTextFn; _mouseCursors[(int)ImGuiMouseCursor.Arrow] = SDL.CreateSystemCursor(SDL.SystemCursor.Default); _mouseCursors[(int)ImGuiMouseCursor.TextInput] = SDL.CreateSystemCursor(SDL.SystemCursor.Text); _mouseCursors[(int)ImGuiMouseCursor.ResizeAll] = SDL.CreateSystemCursor(SDL.SystemCursor.Move); _mouseCursors[(int)ImGuiMouseCursor.ResizeNS] = SDL.CreateSystemCursor(SDL.SystemCursor.NSResize); _mouseCursors[(int)ImGuiMouseCursor.ResizeEW] = SDL.CreateSystemCursor(SDL.SystemCursor.EWResize); _mouseCursors[(int)ImGuiMouseCursor.ResizeNESW] = SDL.CreateSystemCursor(SDL.SystemCursor.NESWResize); _mouseCursors[(int)ImGuiMouseCursor.ResizeNWSE] = SDL.CreateSystemCursor(SDL.SystemCursor.NWSEResize); _mouseCursors[(int)ImGuiMouseCursor.Hand] = SDL.CreateSystemCursor(SDL.SystemCursor.Pointer); _mouseCursors[(int)ImGuiMouseCursor.NotAllowed] = SDL.CreateSystemCursor(SDL.SystemCursor.NotAllowed); ImGuiViewportPtr viewport = ImGui.GetMainViewport(); SetupPlatformHandles(viewport, window); } public void Dispose() { foreach (IntPtr cursor in _mouseCursors) SDL.DestroyCursor(cursor); } public void NewFrame() { ImGuiIOPtr io = ImGui.GetIO(); SDL.GetWindowSize(Window, out int w, out int h); if (SDL.GetWindowFlags(Window).HasFlag(SDL.WindowFlags.Minimized)) { w = h = 0; } SDL.GetWindowSizeInPixels(Window, out int displayW, out int displayH); io.DisplaySize = new System.Numerics.Vector2(w, h); if (w > 0 && h > 0) io.DisplayFramebufferScale = new System.Numerics.Vector2((float)displayW / w, (float)displayH / h); if (_mousePendingLeaveFrame > 0 && _mousePendingLeaveFrame >= ImGui.GetFrameCount()) { _mouseWindowId = 0; _mousePendingLeaveFrame = 0; io.AddMousePosEvent(-float.MaxValue, -float.MaxValue); } UpdateMouseData(); UpdateMouseCursor(); } public unsafe bool ProcessEvent(SDL.Event e) { ImGuiIOPtr io = ImGui.GetIO(); switch ((SDL.EventType)e.Type) { case SDL.EventType.MouseMotion: if (GetViewportForWindowId(e.Motion.WindowID) == null) return false; io.AddMouseSourceEvent(e.Motion.Which == SDL.TouchMouseID ? ImGuiMouseSource.TouchScreen : ImGuiMouseSource.Mouse); io.AddMousePosEvent(e.Motion.X, e.Motion.Y); return true; case SDL.EventType.MouseWheel: if (GetViewportForWindowId(e.Wheel.WindowID) == null) return false; float wheelX = -e.Wheel.X; float wheelY = e.Wheel.Y; io.AddMouseSourceEvent(e.Wheel.Which == SDL.TouchMouseID ? ImGuiMouseSource.TouchScreen : ImGuiMouseSource.Mouse); io.AddMouseWheelEvent(wheelX, wheelY); return true; case SDL.EventType.MouseButtonDown: case SDL.EventType.MouseButtonUp: if (GetViewportForWindowId(e.Button.WindowID) == null) return false; int mouseButton = e.Button.Button switch { SDL.ButtonLeft => 0, SDL.ButtonRight => 1, SDL.ButtonMiddle => 2, SDL.ButtonX1 => 3, SDL.ButtonX2 => 4, _ => -1 }; if (mouseButton == -1) break; io.AddMouseSourceEvent(e.Button.Which == SDL.TouchMouseID ? ImGuiMouseSource.TouchScreen : ImGuiMouseSource.Mouse); io.AddMouseButtonEvent(mouseButton, (SDL.EventType)e.Type == SDL.EventType.MouseButtonDown); _mouseButtonsDown = (SDL.EventType)e.Type == SDL.EventType.MouseButtonDown ? _mouseButtonsDown | 1 << mouseButton : _mouseButtonsDown & ~(1 << mouseButton); return true; case SDL.EventType.TextInput: if (GetViewportForWindowId(e.Text.WindowID) == null) return false; ImGuiNative.ImGuiIO_AddInputCharactersUTF8(io, (byte*)e.Text.Text); return true; case SDL.EventType.KeyDown: case SDL.EventType.KeyUp: if (GetViewportForWindowId(e.Key.WindowID) == null) return false; UpdateKeyModifiers(e.Key.Mod); ImGuiKey imguiKey = KeyEventToImGui(e.Key.Key, e.Key.Scancode); bool pressed = (SDL.EventType)e.Type == SDL.EventType.KeyDown; io.AddKeyEvent(imguiKey, pressed); io.SetKeyEventNativeData(imguiKey, (int)e.Key.Key, (int)e.Key.Scancode, (int)e.Key.Scancode); return true; case SDL.EventType.WindowMouseEnter: if (GetViewportForWindowId(e.Window.WindowID) == null) return false; _mouseWindowId = e.Window.WindowID; _mousePendingLeaveFrame = 0; return true; case SDL.EventType.WindowMouseLeave: if (GetViewportForWindowId(e.Window.WindowID) == null) return false; _mousePendingLeaveFrame = ImGui.GetFrameCount() + 1; return true; case SDL.EventType.WindowFocusGained: case SDL.EventType.WindowFocusLost: if (GetViewportForWindowId(e.Window.WindowID) == null) return false; io.AddFocusEvent((SDL.EventType)e.Type == SDL.EventType.WindowFocusGained); return true; default: break; } return false; } private void UpdateMouseData() { ImGuiIOPtr io = ImGui.GetIO(); IntPtr focusedWindow = SDL.GetKeyboardFocus(); bool isAppFocused = focusedWindow == Window; if (isAppFocused) { if (io.WantSetMousePos) { SDL.WarpMouseInWindow(Window, (int)io.MousePos.X, (int)io.MousePos.Y); } } } private void UpdateMouseCursor() { ImGuiIOPtr io = ImGui.GetIO(); if ((io.ConfigFlags & ImGuiConfigFlags.NoMouseCursorChange) != 0) return; ImGuiMouseCursor imguiCursor = ImGui.GetMouseCursor(); if (io.MouseDrawCursor || imguiCursor == ImGuiMouseCursor.None) { SDL.HideCursor(); } else { IntPtr expectedCursor = _mouseCursors[(int)imguiCursor]; if (_mouseLastCursor != expectedCursor) { SDL.SetCursor(expectedCursor); _mouseLastCursor = expectedCursor; } SDL.ShowCursor(); } } private ImGuiKey KeyEventToImGui(SDL.Keycode keycoade, SDL.Scancode scancode) { switch (scancode) { case SDL.Scancode.Kp0: return ImGuiKey.Keypad0; case SDL.Scancode.Kp1: return ImGuiKey.Keypad1; case SDL.Scancode.Kp2: return ImGuiKey.Keypad2; case SDL.Scancode.Kp3: return ImGuiKey.Keypad3; case SDL.Scancode.Kp4: return ImGuiKey.Keypad4; case SDL.Scancode.Kp5: return ImGuiKey.Keypad5; case SDL.Scancode.Kp6: return ImGuiKey.Keypad6; case SDL.Scancode.Kp7: return ImGuiKey.Keypad7; case SDL.Scancode.Kp8: return ImGuiKey.Keypad8; case SDL.Scancode.Kp9: return ImGuiKey.Keypad9; case SDL.Scancode.KpPeriod: return ImGuiKey.KeypadDecimal; case SDL.Scancode.KpDivide: return ImGuiKey.KeypadDivide; case SDL.Scancode.KpMultiply: return ImGuiKey.KeypadMultiply; case SDL.Scancode.KpMinus: return ImGuiKey.KeypadSubtract; case SDL.Scancode.KpPlus: return ImGuiKey.KeypadAdd; case SDL.Scancode.KpEnter: return ImGuiKey.KeypadEnter; case SDL.Scancode.KpEquals: return ImGuiKey.KeypadEqual; default: break; } switch (keycoade) { case SDL.Keycode.Tab: return ImGuiKey.Tab; case SDL.Keycode.Left: return ImGuiKey.LeftArrow; case SDL.Keycode.Right: return ImGuiKey.RightArrow; case SDL.Keycode.Up: return ImGuiKey.UpArrow; case SDL.Keycode.Down: return ImGuiKey.DownArrow; case SDL.Keycode.Pageup: return ImGuiKey.PageUp; case SDL.Keycode.Pagedown: return ImGuiKey.PageDown; case SDL.Keycode.Home: return ImGuiKey.Home; case SDL.Keycode.End: return ImGuiKey.End; case SDL.Keycode.Insert: return ImGuiKey.Insert; case SDL.Keycode.Delete: return ImGuiKey.Delete; case SDL.Keycode.Backspace: return ImGuiKey.Backspace; case SDL.Keycode.Space: return ImGuiKey.Space; case SDL.Keycode.Return: return ImGuiKey.Enter; case SDL.Keycode.Escape: return ImGuiKey.Escape; case SDL.Keycode.Apostrophe: return ImGuiKey.Apostrophe; case SDL.Keycode.Comma: return ImGuiKey.Comma; case SDL.Keycode.Minus: return ImGuiKey.Minus; case SDL.Keycode.Period: return ImGuiKey.Period; case SDL.Keycode.Slash: return ImGuiKey.Slash; case SDL.Keycode.Semicolon: return ImGuiKey.Semicolon; case SDL.Keycode.Equals: return ImGuiKey.Equal; case SDL.Keycode.LeftBracket: return ImGuiKey.LeftBracket; case SDL.Keycode.Backslash: return ImGuiKey.Backslash; case SDL.Keycode.RightBracket: return ImGuiKey.RightBracket; case SDL.Keycode.Grave: return ImGuiKey.GraveAccent; case SDL.Keycode.Capslock: return ImGuiKey.CapsLock; case SDL.Keycode.ScrollLock: return ImGuiKey.ScrollLock; case SDL.Keycode.NumLockClear: return ImGuiKey.NumLock; case SDL.Keycode.PrintScreen: return ImGuiKey.PrintScreen; case SDL.Keycode.Pause: return ImGuiKey.Pause; case SDL.Keycode.LCtrl: return ImGuiKey.LeftCtrl; case SDL.Keycode.LShift: return ImGuiKey.LeftShift; case SDL.Keycode.LAlt: return ImGuiKey.LeftAlt; case SDL.Keycode.LGui: return ImGuiKey.LeftSuper; case SDL.Keycode.RCtrl: return ImGuiKey.RightCtrl; case SDL.Keycode.RShift: return ImGuiKey.RightShift; case SDL.Keycode.RAlt: return ImGuiKey.RightAlt; case SDL.Keycode.RGUI: return ImGuiKey.RightSuper; case SDL.Keycode.Application: return ImGuiKey.Menu; case SDL.Keycode.Alpha0: return ImGuiKey._0; case SDL.Keycode.Alpha1: return ImGuiKey._1; case SDL.Keycode.Alpha2: return ImGuiKey._2; case SDL.Keycode.Alpha3: return ImGuiKey._3; case SDL.Keycode.Alpha4: return ImGuiKey._4; case SDL.Keycode.Alpha5: return ImGuiKey._5; case SDL.Keycode.Alpha6: return ImGuiKey._6; case SDL.Keycode.Alpha7: return ImGuiKey._7; case SDL.Keycode.Alpha8: return ImGuiKey._8; case SDL.Keycode.Alpha9: return ImGuiKey._9; case SDL.Keycode.A: return ImGuiKey.A; case SDL.Keycode.B: return ImGuiKey.B; case SDL.Keycode.C: return ImGuiKey.C; case SDL.Keycode.D: return ImGuiKey.D; case SDL.Keycode.E: return ImGuiKey.E; case SDL.Keycode.F: return ImGuiKey.F; case SDL.Keycode.G: return ImGuiKey.G; case SDL.Keycode.H: return ImGuiKey.H; case SDL.Keycode.I: return ImGuiKey.I; case SDL.Keycode.J: return ImGuiKey.J; case SDL.Keycode.K: return ImGuiKey.K; case SDL.Keycode.L: return ImGuiKey.L; case SDL.Keycode.M: return ImGuiKey.M; case SDL.Keycode.N: return ImGuiKey.N; case SDL.Keycode.O: return ImGuiKey.O; case SDL.Keycode.P: return ImGuiKey.P; case SDL.Keycode.Q: return ImGuiKey.Q; case SDL.Keycode.R: return ImGuiKey.R; case SDL.Keycode.S: return ImGuiKey.S; case SDL.Keycode.T: return ImGuiKey.T; case SDL.Keycode.U: return ImGuiKey.U; case SDL.Keycode.V: return ImGuiKey.V; case SDL.Keycode.W: return ImGuiKey.W; case SDL.Keycode.X: return ImGuiKey.X; case SDL.Keycode.Y: return ImGuiKey.Y; case SDL.Keycode.Z: return ImGuiKey.Z; case SDL.Keycode.F1: return ImGuiKey.F1; case SDL.Keycode.F2: return ImGuiKey.F2; case SDL.Keycode.F3: return ImGuiKey.F3; case SDL.Keycode.F4: return ImGuiKey.F4; case SDL.Keycode.F5: return ImGuiKey.F5; case SDL.Keycode.F6: return ImGuiKey.F6; case SDL.Keycode.F7: return ImGuiKey.F7; case SDL.Keycode.F8: return ImGuiKey.F8; case SDL.Keycode.F9: return ImGuiKey.F9; case SDL.Keycode.F10: return ImGuiKey.F10; case SDL.Keycode.F11: return ImGuiKey.F11; case SDL.Keycode.F12: return ImGuiKey.F12; case SDL.Keycode.F13: return ImGuiKey.F13; case SDL.Keycode.F14: return ImGuiKey.F14; case SDL.Keycode.F15: return ImGuiKey.F15; case SDL.Keycode.F16: return ImGuiKey.F16; case SDL.Keycode.F17: return ImGuiKey.F17; case SDL.Keycode.F18: return ImGuiKey.F18; case SDL.Keycode.F19: return ImGuiKey.F19; case SDL.Keycode.F20: return ImGuiKey.F20; case SDL.Keycode.F21: return ImGuiKey.F21; case SDL.Keycode.F22: return ImGuiKey.F22; case SDL.Keycode.F23: return ImGuiKey.F23; case SDL.Keycode.F24: return ImGuiKey.F24; case SDL.Keycode.AcBack: return ImGuiKey.AppBack; case SDL.Keycode.AcForward: return ImGuiKey.AppForward; default: break; } return ImGuiKey.None; } public static IntPtr Data() => ImGui.GetIO().BackendPlatformUserData; // I don't think we actually need these since it works just fine without them // // public static IntPtr GetClipboardText(IntPtr ctx) // { // if (clipboardTextPtr != IntPtr.Zero) // { // Marshal.FreeHGlobal(clipboardTextPtr); // clipboardTextPtr = IntPtr.Zero; // } // // string text = SDL.GetClipboardText(); // clipboardTextPtr = Marshal.StringToHGlobalAnsi(text ?? string.Empty); // return clipboardTextPtr; // } // // public static void SetClipboardText(IntPtr ctx, IntPtr text) // { // string managedText = Marshal.PtrToStringAnsi(text); // if (managedText != null) // { // SDL.SetClipboardText(managedText); // } // } // !! This is sorta fucked // public static void UpdateKeyModifiers(SDL.Keymod keymods) // { // ImGuiIOPtr io = ImGui.GetIO(); // io.KeyCtrl = keymods.HasFlag(SDL.Keymod.LCtrl) || keymods.HasFlag(SDL.Keymod.RCtrl); // io.KeyShift = keymods.HasFlag(SDL.Keymod.LShift) || keymods.HasFlag(SDL.Keymod.RShift); // io.KeyAlt = keymods.HasFlag(SDL.Keymod.LAlt) || keymods.HasFlag(SDL.Keymod.RAlt); // io.KeySuper = keymods.HasFlag(SDL.Keymod.LGUI) || keymods.HasFlag(SDL.Keymod.RGUI); // } private static void UpdateKeyModifiers(SDL.Keymod mod) { ImGuiIOPtr io = ImGui.GetIO(); io.AddKeyEvent(ImGuiKey.ModCtrl, (mod & SDL.Keymod.Ctrl) != 0); io.AddKeyEvent(ImGuiKey.ModShift, (mod & SDL.Keymod.Shift) != 0); io.AddKeyEvent(ImGuiKey.ModAlt, (mod & SDL.Keymod.Alt) != 0); io.AddKeyEvent(ImGuiKey.ModSuper, (mod & SDL.Keymod.GUI) != 0); } public static ImGuiViewportPtr? GetViewportForWindowId(uint id) { ImGuiViewportPtr viewport = ImGui.GetMainViewport(); return viewport.ID == id ? ImGui.GetMainViewport() : null; } private static void SetupPlatformHandles(ImGuiViewportPtr viewport, IntPtr window) { viewport.PlatformHandle = window; viewport.PlatformHandleRaw = 0; #if _WIN32 && !__WINTR__ SDL.GetPointerProperty(SDL.GetWindowProperties(window), SDL.Props.WindowWin32HWNDPointer, 0); #elif __APPLE__ && SDL_VIDEO_DRIVER_COCOA SDL.GetPointerProperty(SDL.GetWindowProperties(window), SDL.Props.WindowCocoaWindow, 0); #endif } }