Added SDL_messagebox wrapper

src/LPUtf8StrMarshaler.cs

@@ -38,7 +38,7 @@ namespace SDL2
 			_leaveAllocatedInstance = new LPUtf8StrMarshaler(true),
 			_defaultInstance = new LPUtf8StrMarshaler(false);
 
-		private static ICustomMarshaler GetInstance(string cookie)
+		public static ICustomMarshaler GetInstance(string cookie)
 		{
 			switch (cookie)
 			{

src/SDL2.cs

@@ -4390,7 +4390,148 @@ namespace SDL2
 		
 		#endregion
 
+		#region SDL_messagebox.h
 
+		[Flags]
+		public enum SDL_MessageBoxFlags
+		{
+			SDL_MESSAGEBOX_ERROR        = 0x00000010,
+			SDL_MESSAGEBOX_WARNING      = 0x00000020,
+			SDL_MESSAGEBOX_INFORMATION  = 0x00000040
+		}
+
+		[Flags]
+		public enum SDL_MessageBoxButtonFlags
+		{
+			SDL_MESSAGEBOX_BUTTON_RETURNKEY_DEFAULT = 0x00000001,
+			SDL_MESSAGEBOX_BUTTON_ESCAPEKEY_DEFAULT = 0x00000002
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		internal struct INTERNAL_SDL_MessageBoxButtonData
+		{
+			public SDL_MessageBoxButtonFlags flags;
+			public int buttonid;
+			public IntPtr text; /* The UTF-8 button text */
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		public struct SDL_MessageBoxButtonData
+		{
+			public SDL_MessageBoxButtonFlags flags;
+			public int buttonid;
+			public string text; /* The UTF-8 button text */
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		public struct SDL_MessageBoxColor
+		{
+			public byte r, g, b;
+		}
+
+		public enum SDL_MessageBoxColorType
+		{
+			SDL_MESSAGEBOX_COLOR_BACKGROUND,
+			SDL_MESSAGEBOX_COLOR_TEXT,
+			SDL_MESSAGEBOX_COLOR_BUTTON_BORDER,
+			SDL_MESSAGEBOX_COLOR_BUTTON_BACKGROUND,
+			SDL_MESSAGEBOX_COLOR_BUTTON_SELECTED,
+			SDL_MESSAGEBOX_COLOR_MAX
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		public struct SDL_MessageBoxColorScheme
+		{
+			[MarshalAs(UnmanagedType.ByValArray, ArraySubType = UnmanagedType.Struct, SizeConst = (int)SDL_MessageBoxColorType.SDL_MESSAGEBOX_COLOR_MAX)]
+				public SDL_MessageBoxColor[] colors;
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		internal struct INTERNAL_SDL_MessageBoxData
+		{
+			public SDL_MessageBoxFlags flags;
+			public IntPtr window;                 /* Parent window, can be NULL */
+			public IntPtr title;              /* UTF-8 title */
+			public IntPtr message;            /* UTF-8 message text */
+			public int numbuttons;
+			public IntPtr buttons;
+			public IntPtr colorScheme;   /* Can be NULL to use system settings */
+		}
+
+		[StructLayout(LayoutKind.Sequential)]
+		public struct SDL_MessageBoxData
+		{
+			public SDL_MessageBoxFlags flags;
+			public IntPtr window;                 /* Parent window, can be NULL */
+			public string title;              /* UTF-8 title */
+			public string message;            /* UTF-8 message text */
+			public int numbuttons;
+			public SDL_MessageBoxButtonData[] buttons;
+			public SDL_MessageBoxColorScheme? colorScheme;   /* Can be NULL to use system settings */
+		}
+
+		[DllImport(nativeLibName, EntryPoint = "SDL_ShowMessageBox", CallingConvention = CallingConvention.Cdecl)]
+		internal static extern int INTERNAL_SDL_ShowMessageBox([In()] ref INTERNAL_SDL_MessageBoxData messageboxdata, out int buttonid);
+
+		public static unsafe int SDL_ShowMessageBox([In()] ref SDL_MessageBoxData messageboxdata, out int buttonid)
+		{
+			var utf8 = LPUtf8StrMarshaler.GetInstance(null);
+
+			var data = new INTERNAL_SDL_MessageBoxData()
+			{
+				flags = messageboxdata.flags,
+				window = messageboxdata.window,
+				title = utf8.MarshalManagedToNative(messageboxdata.title),
+				message = utf8.MarshalManagedToNative(messageboxdata.message),
+				numbuttons = messageboxdata.numbuttons,
+			};
+
+			var buttons = new INTERNAL_SDL_MessageBoxButtonData[messageboxdata.numbuttons];
+			for (int i = 0; i < messageboxdata.numbuttons; i++)
+			{
+				buttons[i] = new INTERNAL_SDL_MessageBoxButtonData()
+				{
+					flags = messageboxdata.buttons[i].flags,
+					buttonid = messageboxdata.buttons[i].buttonid,
+					text = utf8.MarshalManagedToNative(messageboxdata.buttons[i].text),
+				};
+			}
+
+			if (messageboxdata.colorScheme != null)
+			{
+				data.colorScheme = Marshal.AllocHGlobal(Marshal.SizeOf(typeof(SDL_MessageBoxColorScheme)));
+				Marshal.StructureToPtr(messageboxdata.colorScheme.Value, data.colorScheme, false);
+			}
+
+			int result;
+			fixed (INTERNAL_SDL_MessageBoxButtonData* buttonsPtr = &buttons[0])
+			{
+				data.buttons = (IntPtr)buttonsPtr;
+				result = INTERNAL_SDL_ShowMessageBox(ref data, out buttonid);
+			}
+
+			Marshal.FreeHGlobal(data.colorScheme);
+			for (int i = 0; i < messageboxdata.numbuttons; i++)
+			{
+				utf8.CleanUpNativeData(buttons[i].text);
+			}
+			utf8.CleanUpNativeData(data.message);
+			utf8.CleanUpNativeData(data.title);
+
+			return result;
+		}
+
+		[DllImport(nativeLibName, CallingConvention = CallingConvention.Cdecl)]
+		public static extern int SDL_ShowSimpleMessageBox(
+			SDL_MessageBoxFlags flags,
+			[In()] [MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(LPUtf8StrMarshaler))]
+				string title,
+			[In()] [MarshalAs(UnmanagedType.CustomMarshaler, MarshalTypeRef = typeof(LPUtf8StrMarshaler))]
+				string message,
+			IntPtr window
+		);
+
+		#endregion
 	}
 }