Immediate Mode GUI for XNA

GUI.cs

    abstract class GUI
    {

        #region Enums

        public enum ElementState
        {
            None,
            Hovered,
            Clicked,
        }

        #endregion

        #region Framework

        protected static GUI Current { get; set; }

        protected Color DefaultTextColor = Color.LightGray;
        protected Color HoverTextColor = Color.White;
        protected Color SelectedTextColor = Color.DarkGray;


        protected MouseState mouseState;
        protected bool mousedown
        {
            get
            {
                return mouseState.LeftButton == ButtonState.Pressed;
            }
        }

        protected int hotitem;
        protected int activeitem;

        protected SpriteBatch spriteBatch;
        protected ContentManager Content;

        protected static Texture2D DimTexture;

        /// <summary>
        /// In an inherited class, draws the GUI
        /// </summary>
        /// <param name="gameTime">The current GameTime, for animated effects.</param>
        protected abstract void Draw(GameTime gameTime);

        public static void DrawGUI(GameTime gameTime)
        {
            Current.Prepare();
            Current.Draw(gameTime);
            Current.Finish();
        }

        protected GUI(ContentManager content, SpriteBatch sb)
        {
            if (DimTexture == null)
            {
                DimTexture = new Texture2D(sb.GraphicsDevice, 1, 1);
                DimTexture.SetData(new Color[] { new Color(255, 255, 255, 128) });
            }

            spriteBatch = sb;
            Content = content;
        }


        public void Prepare()
        {
            hotitem = 0;
            mouseState = Mouse.GetState();
            spriteBatch.Begin();
        }

        public void Finish()
        {
            if (mousedown == false)
            {
                activeitem = 0;
            }
            else if (activeitem == 0)
            {
                activeitem = -1;
            }
            spriteBatch.End();
        }

        #endregion

        #region TextButton

        /// <summary>
        /// Create a clickable text button
        /// </summary>
        /// <param name="font">The font to draw the text in</param>
        /// <param name="text">The string to draw</param>
        /// <param name="xpos">The x-coordinate on screen</param>
        /// <param name="ypos">The y-coordinate on screen</param>
        /// <param name="id">Magic</param>
        /// <returns>ElementState indicating if the text was hovered or clicked.</returns>
        protected ElementState TextButton(SpriteFont font, string text, int xpos, int ypos, int id)
        {
            return TextButton(font, text, xpos, ypos, DefaultTextColor, HoverTextColor, SelectedTextColor, id);
        }

        /// <summary>
        /// Create a clickable text button
        /// </summary>
        /// <param name="font">The font to draw the text in</param>
        /// <param name="text">The string to draw</param>
        /// <param name="xpos">The x-coordinate on screen</param>
        /// <param name="ypos">The y-coordinate on screen</param>
        /// <param name="color">The color to use</param>
        /// <param name="hoverColor">The color when the text is hovered over</param>
        /// <param name="selColor">The color when the text is clicked</param>
        /// <param name="id">Magic</param>
        /// <returns>ElementState indicating if the text was hovered or clicked.</returns>
        protected ElementState TextButton(SpriteFont font, string text, int xpos, int ypos, Color color, Color hoverColor, Color selColor, int id)
        {
            // measure the string so we know the bounding box
            Vector2 size = font.MeasureString(text);

            // check the bounding box (min-x, min-y, max-x, max-y) against the mouse position
            // to determine hit state (ie, is the mouse over this element)
            bool hot =
                (mouseState.X >= xpos && mouseState.X < xpos + size.X && // check x-bounds
                 mouseState.Y >= ypos && mouseState.Y < ypos + size.Y); // check y-bounds

            if (hot)
            {
                hotitem = id;
                if (activeitem == 0 && mousedown)
                {
                    activeitem = id;
                }
            }


            if (hotitem == id)
            {
                if (activeitem == id)
                {
                    color = selColor;
                }
                else
                {
                    color = hoverColor;
                }
            }

            Text(font, text, xpos, ypos, color);

            if (mousedown == false && hotitem == id)
            {
                if (activeitem == id)
                {
                    return ElementState.Clicked;
                }
                else
                {
                    return ElementState.Hovered;
                }
            }

            return ElementState.None;
        }

        #endregion

        #region Text

        /// <summary>
        /// Draw a non-clickable text label
        /// </summary>
        /// <param name="font">The font to draw the text in</param>
        /// <param name="text">The string to draw</param>
        /// <param name="xpos">The x-coordinate on screen</param>
        /// <param name="ypos">The y-coordinate on screen</param>
        protected void Text(SpriteFont font, string text, int xpos, int ypos)
        {
            Text(font, text, xpos, ypos, DefaultTextColor);
        }

        /// <summary>
        /// Draw a non-clickable text label
        /// </summary>
        /// <param name="font">The font to draw the text in</param>
        /// <param name="text">The string to draw</param>
        /// <param name="xpos">The x-coordinate on screen</param>
        /// <param name="ypos">The y-coordinate on screen</param>
        /// <param name="color">The color to use</param>
        protected void Text(SpriteFont font, string text, int xpos, int ypos, Color color)
        {
            spriteBatch.DrawString(font, text, new Vector2(xpos, ypos), color);
        }

        #endregion

        #region ImageButton
        /// <summary>
        /// Create a clickable image button
        /// </summary>
        /// <param name="sheet">The spritesheet to pull from</param>
        /// <param name="idx">The default sprite index to draw</param>
        /// <param name="hoverIdx">The sprite index to draw when the image is hovered over</param>
        /// <param name="selIdx">The sprite index to draw when the image is clicked</param>
        /// <param name="xpos">The x-coordinate on screen</param>
        /// <param name="ypos">The y-coordinate on screen</param>
        /// <param name="id">Magic</param>
        /// <returns>ElementState indicating if the image was hovered or clicked</returns>
        protected ElementState ImageButton(SpriteSheet sheet, int idx, int hoverIdx, int selIdx, int xpos, int ypos, int id)
        {
            // check the bounding box (min-x, min-y, max-x, max-y) against the mouse position
            // to determine hit state (ie, is the mouse over this element)
            bool hot =
                (mouseState.X >= xpos && mouseState.X < xpos + sheet.SpriteWidth && // check x-bounds
                 mouseState.Y >= ypos && mouseState.Y < ypos + sheet.SpriteHeight); // check y-bounds

            if (hot)
            {
                hotitem = id;
                if (activeitem == 0 && mousedown)
                {
                    activeitem = id;
                }
            }

            if (hotitem == id)
            {
                if (activeitem == id)
                {
                    idx = selIdx;
                }
                else
                {
                    idx = hoverIdx;
                }
            }

            Image(sheet, idx, xpos, ypos);

            if (mousedown == false && hotitem == id)
            {
                if (activeitem == id)
                {
                    return ElementState.Clicked;
                }
                else
                {
                    return ElementState.Hovered;
                }
            }

            return ElementState.None;
        }

        #endregion

        #region Image

        protected void Image(SpriteSheet sheet, int idx, int xpos, int ypos)
        {
            spriteBatch.Draw(sheet.Texture, new Vector2(xpos, ypos), sheet[idx], Color.White);
        }

        #endregion

        #region Background

        protected void Background(Texture2D backgroundTexture)
        {
            spriteBatch.Draw(backgroundTexture, new Rectangle(0, 0, spriteBatch.GraphicsDevice.Viewport.Width, spriteBatch.GraphicsDevice.Viewport.Height), Color.White);
        }

        #endregion

        #region Dim

        protected void Dim(Color color)
        {
            spriteBatch.Draw(DimTexture, new Rectangle(0, 0, spriteBatch.GraphicsDevice.Viewport.Width, spriteBatch.GraphicsDevice.Viewport.Height), color);
        }

        #endregion

    }