Implement relative mouse mode and mouse warping

Source/Ultraviolet.SDL2/Shared/Input/SDL2MouseDevice.cs

@@ -110,12 +110,51 @@ public override void Update(UltravioletTime time)
 
         }
 
-        /// <summary>
-        /// Gets the mouse cursor's position within the specified window.
-        /// </summary>
-        /// <param name="window">The window to evaluate.</param>
-        /// <returns>The cursor's compositor-space position within the specified 
-        /// window, or <see langword="null"/> if the cursor is outside of the window.</returns>
+        /// <inheritdoc/>
+        public override void WarpToWindow(IUltravioletWindow window, Int32 x, Int32 y)
+        {
+            Contract.EnsureNotDisposed(this, Disposed);
+            Contract.Require(window, nameof(window));
+
+            window.WarpMouseWithinWindow(x, y);
+        }
+
+        /// <inheritdoc/>
+        public override void WarpToWindowCenter(IUltravioletWindow window)
+        {
+            Contract.EnsureNotDisposed(this, Disposed);
+            Contract.Require(window, nameof(window));
+
+            var size = window.ClientSize;
+            window.WarpMouseWithinWindow(size.Width / 2, size.Height / 2);
+        }
+
+        /// <inheritdoc/>
+        public override void WarpToPrimaryWindow(Int32 x, Int32 y)
+        {
+            Contract.EnsureNotDisposed(this, Disposed);
+
+            var primary = Ultraviolet.GetPlatform().Windows.GetPrimary();
+            if (primary == null)
+                throw new InvalidOperationException(UltravioletStrings.NoPrimaryWindow);
+
+            primary.WarpMouseWithinWindow(x, y);
+        }
+
+        /// <inheritdoc/>
+        public override void WarpToPrimaryWindowCenter()
+        {
+            Contract.EnsureNotDisposed(this, Disposed);
+
+            var primary = Ultraviolet.GetPlatform().Windows.GetPrimary();
+            if (primary == null)
+                throw new InvalidOperationException(UltravioletStrings.NoPrimaryWindow);
+
+            var size = primary.ClientSize;
+            primary.WarpMouseWithinWindow(size.Width / 2, size.Height / 2);
+        }
+
+        /// <inheritdoc/>
         public override Point2? GetPositionInWindow(IUltravioletWindow window)
         {
             Contract.Require(window, nameof(window));
@@ -177,6 +216,30 @@ public override Boolean IsButtonDoubleClicked(MouseButton button)
             return (buttonStateDoubleClicks & SDL_BUTTON(button)) != 0;
         }
 
+        /// <inheritdoc/>
+        public override Boolean GetIsRelativeModeEnabled()
+        {
+            Contract.EnsureNotDisposed(this, Disposed);
+
+            return SDL_GetRelativeMouseMode();
+        }
+
+        /// <inheritdoc/>
+        public override Boolean SetIsRelativeModeEnabled(Boolean enabled)
+        {
+            Contract.EnsureNotDisposed(this, Disposed);
+
+            var result = SDL_SetRelativeMouseMode(enabled);
+            if (result == -1)
+                return false;
+
+            if (result < 0)
+                throw new SDL2Exception();
+
+            relativeMode = enabled;
+            return true;
+        }
+
         /// <inheritdoc/>
         public override IUltravioletWindow Window => window;
 
@@ -284,8 +347,16 @@ private void OnMouseMotion(ref SDL_MouseMotionEvent evt)
             if (!Ultraviolet.GetInput().EmulateMouseWithTouchInput && evt.which == SDL_TOUCH_MOUSEID)
                 return;
 
-            SetMousePosition(evt.windowID, evt.x, evt.y);
-            OnMoved(window, evt.x, evt.y, evt.xrel, evt.yrel);
+            if (relativeMode)
+            {
+                SetMousePosition(evt.windowID, evt.x, evt.y);
+                OnMoved(window, evt.x, evt.y, evt.xrel, evt.yrel);
+            }
+            else
+            {
+                SetMousePosition(evt.windowID, evt.x, evt.y);
+                OnMoved(window, evt.x, evt.y, evt.xrel, evt.yrel);
+            }
         }
 
         /// <summary>
@@ -404,5 +475,6 @@ private void SetMousePositionFromDevicePosition(UInt32 windowID)
         private UInt32 buttonStateClicks;
         private UInt32 buttonStateDoubleClicks;
         private Boolean ignoredFirstMouseMotionEvent;
+        private Boolean relativeMode;
     }
 }

Source/Ultraviolet.SDL2/Shared/Native/SDLNative.cs

@@ -1322,6 +1322,39 @@ public unsafe static partial class SDLNative
         private static readonly SDL_freeDelegate pSDL_free = lib.LoadFunction<SDL_freeDelegate>("SDL_free");
         public static void SDL_free(IntPtr mem) => pSDL_free(mem);
 #endif
+
+#if ANDROID || IOS
+        [DllImport(LIBRARY, EntryPoint="SDL_GetRelativeMouseMode", CallingConvention = CallingConvention.Cdecl)]
+        public static extern Boolean SDL_GetRelativeMouseMode();
+#else
+        [MonoNativeFunctionWrapper]
+        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+        private delegate Boolean SDL_GetRelativeMouseModeDelegate();
+        private static readonly SDL_GetRelativeMouseModeDelegate pSDL_GetRelativeMouseMode = lib.LoadFunction<SDL_GetRelativeMouseModeDelegate>("SDL_GetRelativeMouseMode");
+        public static Boolean SDL_GetRelativeMouseMode() => pSDL_GetRelativeMouseMode();
+#endif
+
+#if ANDROID || IOS
+        [DllImport(LIBRARY, EntryPoint="SDL_SetRelativeMouseMode", CallingConvention = CallingConvention.Cdecl)]
+        public static extern Int32 SDL_SetRelativeMouseMode(Boolean enabled);
+#else
+        [MonoNativeFunctionWrapper]
+        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+        private delegate Int32 SDL_SetRelativeMouseModeDelegate(Boolean enabled);
+        private static readonly SDL_SetRelativeMouseModeDelegate pSDL_SetRelativeMouseMode = lib.LoadFunction<SDL_SetRelativeMouseModeDelegate>("SDL_SetRelativeMouseMode");
+        public static Int32 SDL_SetRelativeMouseMode(Boolean enabled) => pSDL_SetRelativeMouseMode(enabled);
+#endif
+
+#if ANDROID || IOS
+        [DllImport(LIBRARY, EntryPoint="SDL_WarpMouseInWindow", CallingConvention = CallingConvention.Cdecl)]
+        public static extern void SDL_WarpMouseInWindow(IntPtr window, Int32 x, Int32 y);
+#else
+        [MonoNativeFunctionWrapper]
+        [UnmanagedFunctionPointer(CallingConvention.Cdecl)]
+        private delegate void SDL_WarpMouseInWindowDelegate(IntPtr window, Int32 x, Int32 y);
+        private static readonly SDL_WarpMouseInWindowDelegate pSDL_WarpMouseInWindow = lib.LoadFunction<SDL_WarpMouseInWindowDelegate>("SDL_WarpMouseInWindow");
+        public static void SDL_WarpMouseInWindow(IntPtr window, Int32 x, Int32 y) => pSDL_WarpMouseInWindow(window, x, y);
+#endif
     }
 #pragma warning restore 1591
 }

Source/Ultraviolet.SDL2/Shared/Platform/SDL2UltravioletWindow.cs

@@ -129,6 +129,14 @@ void IMessageSubscriber<UltravioletMessageID>.ReceiveMessage(UltravioletMessageI
             }
         }
 
+        /// <inheritdoc/>
+        public void WarpMouseWithinWindow(Int32 x, Int32 y)
+        {
+            Contract.EnsureNotDisposed(this, Disposed);
+
+            SDL_WarpMouseInWindow(ptr, x, y);
+        }
+
         /// <inheritdoc/>
         public void SetFullscreenDisplayMode(DisplayMode displayMode)
         {

Source/Ultraviolet.SDL2/Shared/SDL2UltravioletContext.cs

@@ -96,7 +96,10 @@ protected Boolean InitSDL(UltravioletConfiguration configuration)
                 SDL_INIT_TIMER | SDL_INIT_VIDEO | SDL_INIT_JOYSTICK | SDL_INIT_GAMECONTROLLER | SDL_INIT_EVENTS;
 
             if (Platform == UltravioletPlatform.Windows)
-                SDL_SetHint(SDL_HINT_WINDOWS_DISABLE_THREAD_NAMING, "1");
+            {
+                if (!SDL_SetHint(SDL_HINT_WINDOWS_DISABLE_THREAD_NAMING, "1"))
+                    throw new SDL2Exception();
+            }
 
             return SDL_Init(sdlFlags) == 0;
         }

Source/Ultraviolet/Shared/Input/MouseDevice.cs

@@ -48,6 +48,32 @@ public MouseDevice(UltravioletContext uv)
 
         }
 
+        /// <summary>
+        /// Sets the mouse cursor's position to the specified point within the specified window.
+        /// </summary>
+        /// <param name="window">The window within which to place the mouse cursor.</param>
+        /// <param name="x">The x-coordinate within <paramref name="window"/> at which to position the cursor.</param>
+        /// <param name="y">The y-coordinate within <paramref name="window"/> at which to position the cursor.</param>
+        public abstract void WarpToWindow(IUltravioletWindow window, Int32 x, Int32 y);
+
+        /// <summary>
+        /// Sets the mouse cursor's position to the center of the specified window.
+        /// </summary>
+        /// <param name="window">The window within which to place the mouse cursor.</param>
+        public abstract void WarpToWindowCenter(IUltravioletWindow window);
+
+        /// <summary>
+        /// Sets the mouse cursor's position to the specified point within the application's primary window.
+        /// </summary>
+        /// <param name="x">The x-coordinate within the primary window at which to position the cursor.</param>
+        /// <param name="y">The y-coordinate within the primary window at which to position the cursor.</param>
+        public abstract void WarpToPrimaryWindow(Int32 x, Int32 y);
+
+        /// <summary>
+        /// Sets the mouse cursor's position to the center of the application's primary window.
+        /// </summary>
+        public abstract void WarpToPrimaryWindowCenter();
+
         /// <summary>
         /// Gets the mouse cursor's position within the specified window.
         /// </summary>
@@ -70,6 +96,21 @@ public MouseDevice(UltravioletContext uv)
         /// <returns><see langword="true"/> if the button was double clicked this frame; otherwise, <see langword="false"/>.</returns>
         public abstract Boolean IsButtonDoubleClicked(MouseButton button);
 
+        /// <summary>
+        /// Gets a value indicating whether relative mouse mode is currently enabled.
+        /// </summary>
+        /// <returns><see langword="true"/> if relative mouse mode is currently enabled; otherwise, <see langword="false"/>.</returns>
+        public abstract Boolean GetIsRelativeModeEnabled();
+
+        /// <summary>
+        /// Enables or disables relative mouse mode. In relative mode, the cursor is hidden, and the driver will try
+        /// to report continuous motion in the current window. Only relative motion events will be delivered, and
+        /// the mouse position will not change.
+        /// </summary>
+        /// <param name="enabled"><see langword="true"/> to enable relative mode; otherwise, <see langword="false"/>.</param>
+        /// <returns><see langword="true"/> if relative mode was enabled or disabled; <see langword="false"/> if relative mode is not supported.</returns>
+        public abstract Boolean SetIsRelativeModeEnabled(Boolean enabled);
+
         /// <summary>
         /// Gets the window that currently contains the mouse cursor.
         /// </summary>

Source/Ultraviolet/Shared/Platform/IUltravioletWindow.cs

@@ -21,6 +21,13 @@ namespace Ultraviolet.Platform
     /// </summary>
     public interface IUltravioletWindow
     {
+        /// <summary>
+        /// Warps the cursor to the specified position within this window.
+        /// </summary>
+        /// <param name="x">The x-coordinate within the window to which the mouse will be warped.</param>
+        /// <param name="y">The y-coordinate within the window to which the mouse will be warped.</param>
+        void WarpMouseWithinWindow(Int32 x, Int32 y);
+
         /// <summary>
         /// Sets the window's fullscreen display mode.
         /// </summary>