C# 文字滚动特效（上下滚动）

本程序改编至网上下载的一个自定义控件，原控件是左右滚动效果，类似于跑马灯效果，由于项目需要，改编为上下滚动。

前期没有实现自动折行，今天刚加上自动折行。

using System;
using System.Collections;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Data;
using System.Windows.Forms;
using System.Collections.Generic;

namespace OI.Common.Controls
{
    /* 【原功能为文字左右滚动控件】
     * 此控件修改滚动方式为由下至上
     * 修改人：王志超
     * 时间：2014-02-10
     * 修改内容：public void DrawScrollingText(Graphics canvas)
     */

    /// <summary>
    /// Summary description for ScrollingTextControl.
    /// </summary>
    [
    ToolboxBitmapAttribute(typeof(OI.Common.Controls.ScrollingText), "ScrollingText.bmp"),
    DefaultEvent("TextClicked")
    ]
    public class ScrollingText : System.Windows.Forms.Control
    {
        private Timer timer;                            // Timer for text animation.
        private string text = "Text";                    // Scrolling text
        private float staticTextPos = ;                // The running x pos of the text
        private float yPos = ;                            // The running y pos of the text
        private ScrollDirection scrollDirection = ScrollDirection.RightToLeft;                // The direction the text will scroll
        private ScrollDirection currentDirection = ScrollDirection.LeftToRight;                // Used for text bouncing
        private VerticleTextPosition verticleTextPosition = VerticleTextPosition.Center;    // Where will the text be vertically placed
        private int scrollPixelDistance = ;            // How far the text scrolls per timer event
        private bool showBorder = true;                    // Show a border or not
        private bool stopScrollOnMouseOver = false;        // Flag to stop the scroll if the user mouses over the text
        private bool scrollOn = true;                    // Internal flag to stop / start the scrolling of the text
        private Brush foregroundBrush = null;            // Allow the user to set a custom Brush to the text Font
        private Brush backgroundBrush = null;            // Allow the user to set a custom Brush to the background
        private Color borderColor = Color.Black;        // Allow the user to set the color of the control border
        private RectangleF lastKnownRect;                // The last known position of the text

        public ScrollingText()
        {
            // Setup default properties for ScrollingText control
            InitializeComponent();

            //This turns off internal double buffering of all custom GDI+ drawing

            Version v = System.Environment.Version;

            if (v.Major < )
            {
                this.SetStyle(ControlStyles.DoubleBuffer, true);
            }
            else
            {
                this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
            }

            this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);
            this.SetStyle(ControlStyles.UserPaint, true);
            this.SetStyle(ControlStyles.ResizeRedraw, true);

            //setup the timer object
            timer = new Timer();
            timer.Interval = ;    //default timer interval
            timer.Enabled = true;
            timer.Tick += new EventHandler(Tick);
        }

        /**/
        /// <summary>
        /// Clean up any resources being used.
        /// </summary>
        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                //Make sure our brushes are cleaned up
                if (foregroundBrush != null)
                    foregroundBrush.Dispose();

                //Make sure our brushes are cleaned up
                if (backgroundBrush != null)
                    backgroundBrush.Dispose();

                //Make sure our timer is cleaned up
                if (timer != null)
                    timer.Dispose();
            }
            base.Dispose(disposing);
        }

        #region Component Designer generated code
        /**/
        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            //ScrollingText
            this.Name = "ScrollingText";
            this.Size = new System.Drawing.Size(, );
            this.Click += new System.EventHandler(this.ScrollingText_Click);
        }
        #endregion

        //Controls the animation of the text.
        private void Tick(object sender, EventArgs e)
        {
            //2014-05-10 王志超修改
            RectangleF refreshRect = new RectangleF(, , this.Size.Width, this.Size.Height);
            Region updateRegion = new Region(refreshRect);

            Invalidate(updateRegion);
            Update();

            //原代码如下：

            ////update rectangle to include where to paint for new position
            ////lastKnownRect.X -= 10;
            ////lastKnownRect.Width += 20;
            //lastKnownRect.Inflate(10, 5);
            ////get the display rectangle
            //RectangleF refreshRect = lastKnownRect;
            //refreshRect.X = Math.Max(0, lastKnownRect.X);
            //refreshRect.Width = Math.Min(lastKnownRect.Width + lastKnownRect.X, this.Width);
            //refreshRect.Width = Math.Min(this.Width - lastKnownRect.X, refreshRect.Width);
            ////create region based on updated rectangle
            ////Region updateRegion = new Region(lastKnownRect);
            //Region updateRegion = new Region(refreshRect);
            ////repaint the control
            //Invalidate(updateRegion);
            //Update();
        }

        //Paint the ScrollingTextCtrl.
        protected override void OnPaint(PaintEventArgs pe)
        {
            //Console.WriteLine(pe.ClipRectangle.X + ",  " + pe.ClipRectangle.Y + ",  " + pe.ClipRectangle.Width + ",  " + pe.ClipRectangle.Height);
            //Paint the text to its new position
            DrawScrollingText(pe.Graphics);
            //pass on the graphics obj to the base Control class
            base.OnPaint(pe);
        }

        protected override void OnSizeChanged(EventArgs e)
        {
            p = new PointF(, this.ClientSize.Height);
            base.OnSizeChanged(e);
        }

        PointF p;
        //Draw the scrolling text on the control
        public void DrawScrollingText(Graphics canvas)
        {
            canvas.SmoothingMode = SmoothingMode.HighQuality;
            canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
            //measure the size of the string for placement calculation
            SizeF stringSize = canvas.MeasureString(this.text, this.Font);
            //Calculate the begining x position of where to paint the text
            if (scrollOn)
            {
                //CalcTextPosition(stringSize);
            }
            //Clear the control with user set BackColor
            if (backgroundBrush != null)
            {
                canvas.FillRectangle(backgroundBrush, , , this.ClientSize.Width, this.ClientSize.Height);
            }
            else
            {
                canvas.Clear(this.BackColor);
            }

            // Draw the border
            if (showBorder)
            {
                using (Pen borderPen = new Pen(borderColor))
                    canvas.DrawRectangle(borderPen, , , this.ClientSize.Width - , this.ClientSize.Height - );
            }

            //新增：绘制背景图片
            if (this.BackgroundImage != null)
            {
                canvas.DrawImage(this.BackgroundImage, this.ClientRectangle);
            }

            //修改滚动方式为由下至上。
            //修改人：王志超
            //时间：2014-05-10
            p = new PointF(, p.Y - scrollPixelDistance);//设置偏移

            List<string> textRows = GetStringRows(canvas, this.Font, this.text, this.Size.Width);
            string strDraw = "";
            //自动折行处理
            foreach (string str in textRows)
            {
                strDraw += str + "\n";
            }
            stringSize = canvas.MeasureString(strDraw, this.Font);

            if (p.Y <= - * stringSize.Height)
                p = new PointF(, this.ClientSize.Height);//重新开始

            if (foregroundBrush == null)
            {
                using (Brush tempForeBrush = new System.Drawing.SolidBrush(this.ForeColor))
                {
                    canvas.DrawString(strDraw, this.Font, tempForeBrush, p);
                }
            }
            else
            {
                canvas.DrawString(strDraw, this.Font, foregroundBrush, p);
            }

            /*以下内容为原绘制方式*/

            //// Draw the text string in the bitmap in memory
            //if (foregroundBrush == null)
            //{
            //    using (Brush tempForeBrush = new System.Drawing.SolidBrush(this.ForeColor))
            //        canvas.DrawString(this.text, new Font("宋体", 20), tempForeBrush, 0, staticTextPos);
            //}
            //else
            //{
            //    canvas.DrawString(this.text, new Font("宋体", 20), foregroundBrush, 0, staticTextPos);
            //}

            //lastKnownRect = new RectangleF(staticTextPos, yPos, stringSize.Width, stringSize.Height);
            //EnableTextLink(lastKnownRect);
        }

        /// <summary>
        /// 绘制文本自动换行（超出截断）
        /// </summary>
        /// <param name="graphic">绘图图面</param>
        /// <param name="font">字体</param>
        /// <param name="text">文本</param>
        /// <param name="recangle">绘制范围</param>
        private void DrawStringWrap(Graphics graphic, Font font, string text, Rectangle recangle)
        {
            List<string> textRows = GetStringRows(graphic, font, text, recangle.Width);
            int rowHeight = (int)(Math.Ceiling(graphic.MeasureString("测试", font).Height));
            int maxRowCount = recangle.Height / rowHeight;
            int drawRowCount = (maxRowCount < textRows.Count) ? maxRowCount : textRows.Count;
            int top = (recangle.Height - rowHeight * drawRowCount) / ;
            StringFormat sf = new StringFormat();
            sf.Alignment = StringAlignment.Near;
            sf.LineAlignment = StringAlignment.Center;
            for (int i = ; i < drawRowCount; i++)
            {
                Rectangle fontRectanle = new Rectangle(recangle.Left, top + rowHeight * i, recangle.Width, rowHeight);
                graphic.DrawString(textRows[i], font, new SolidBrush(Color.Black), fontRectanle, sf);
            }
        }

        /// <summary>
        /// 将文本分行
        /// </summary>
        /// <param name="graphic">绘图图面</param>
        /// <param name="font">字体</param>
        /// <param name="text">文本</param>
        /// <param name="width">行宽</param>
        /// <returns></returns>
        private List<string> GetStringRows(Graphics graphic, Font font, string text, int width)
        {
            int RowBeginIndex = ;
            int rowEndIndex = ;
            int textLength = text.Length;
            List<string> textRows = new List<string>();

            for (int index = ; index < textLength; index++)
            {
                rowEndIndex = index;
                if (index == textLength - )
                {
                    textRows.Add(text.Substring(RowBeginIndex));
                }
                else if (rowEndIndex +  < text.Length && text.Substring(rowEndIndex, ) == "\r\n")
                {
                    textRows.Add(text.Substring(RowBeginIndex, rowEndIndex - RowBeginIndex));
                    rowEndIndex = index += ;
                    RowBeginIndex = rowEndIndex;
                }
                else if (graphic.MeasureString(text.Substring(RowBeginIndex, rowEndIndex - RowBeginIndex + ), font).Width > width)
                {
                    textRows.Add(text.Substring(RowBeginIndex, rowEndIndex - RowBeginIndex));
                    RowBeginIndex = rowEndIndex;
                }
            }

            return textRows;
        }

        private void CalcTextPosition(SizeF stringSize)
        {
            switch (scrollDirection)
            {
                case ScrollDirection.RightToLeft:
                    if (staticTextPos < (- * (stringSize.Width)))
                        staticTextPos = this.ClientSize.Width - ;
                    else
                        staticTextPos -= scrollPixelDistance;
                    break;
                case ScrollDirection.LeftToRight:
                    if (staticTextPos > this.ClientSize.Width)
                        staticTextPos = - * stringSize.Width;
                    else
                        staticTextPos += scrollPixelDistance;
                    break;
                case ScrollDirection.Bouncing:
                    if (currentDirection == ScrollDirection.RightToLeft)
                    {
                        if (staticTextPos < )
                            currentDirection = ScrollDirection.LeftToRight;
                        else
                            staticTextPos -= scrollPixelDistance;
                    }
                    else if (currentDirection == ScrollDirection.LeftToRight)
                    {
                        if (staticTextPos > this.ClientSize.Width - stringSize.Width)
                            currentDirection = ScrollDirection.RightToLeft;
                        else
                            staticTextPos += scrollPixelDistance;
                    }
                    break;
            }

            //Calculate the vertical position for the scrolling text
            switch (verticleTextPosition)
            {
                case VerticleTextPosition.Top:
                    yPos = ;
                    break;
                case VerticleTextPosition.Center:
                    yPos = (this.ClientSize.Height / ) - (stringSize.Height / );
                    break;
                case VerticleTextPosition.Botom:
                    yPos = this.ClientSize.Height - stringSize.Height;
                    break;
            }
        }

        #region Mouse over, text link logic
        private void EnableTextLink(RectangleF textRect)
        {
            Point curPt = this.PointToClient(Cursor.Position);

            //if (curPt.X > textRect.Left && curPt.X < textRect.Right
            //    && curPt.Y > textRect.Top && curPt.Y < textRect.Bottom)
            if (textRect.Contains(curPt))
            {
                //Stop the text of the user mouse's over the text
                if (stopScrollOnMouseOver)
                    scrollOn = false;

                this.Cursor = Cursors.Hand;
            }
            else
            {
                //Make sure the text is scrolling if user's mouse is not over the text
                scrollOn = true;

                this.Cursor = Cursors.Default;
            }
        }

        private void ScrollingText_Click(object sender, System.EventArgs e)
        {
            //Trigger the text clicked event if the user clicks while the mouse
            //is over the text.  This allows the text to act like a hyperlink
            if (this.Cursor == Cursors.Hand)
                OnTextClicked(this, new EventArgs());
        }

        public delegate void TextClickEventHandler(object sender, EventArgs args);
        public event TextClickEventHandler TextClicked;

        private void OnTextClicked(object sender, EventArgs args)
        {
            //Call the delegate
            if (TextClicked != null)
                TextClicked(sender, args);
        }
        #endregion

        #region Properties
        [
        Browsable(true),
        CategoryAttribute("Scrolling Text"),
        Description("The timer interval that determines how often the control is repainted")
        ]
        public int TextScrollSpeed
        {
            set
            {
                timer.Interval = value;
            }
            get
            {
                return timer.Interval;
            }
        }

        [
        Browsable(true),
        CategoryAttribute("Scrolling Text"),
        Description("How many pixels will the text be moved per Paint")
        ]
        public int TextScrollDistance
        {
            set
            {
                scrollPixelDistance = value;
            }
            get
            {
                return scrollPixelDistance;
            }
        }

        [
        Browsable(true),
        CategoryAttribute("Scrolling Text"),
        Description("The text that will scroll accros the control")
        ]
        public string ScrollText
        {
            set
            {
                text = value;
                this.Invalidate();
                this.Update();
            }
            get
            {
                return text;
            }
        }

        //[
        //Browsable(true),
        //CategoryAttribute("Scrolling Text"),
        //Description("What direction the text will scroll: Left to Right, Right to Left, or Bouncing")
        //]
        //public ScrollDirection ScrollDirection
        //{
        //    set
        //    {
        //        scrollDirection = value;
        //    }
        //    get
        //    {
        //        return scrollDirection;
        //    }
        //}

        //[
        //Browsable(true),
        //CategoryAttribute("Scrolling Text"),
        //Description("The verticle alignment of the text")
        //]
        //public VerticleTextPosition VerticleTextPosition
        //{
        //    set
        //    {
        //        verticleTextPosition = value;
        //    }
        //    get
        //    {
        //        return verticleTextPosition;
        //    }
        //}

        [
        Browsable(true),
        CategoryAttribute("Scrolling Text"),
        Description("Turns the border on or off")
        ]
        public bool ShowBorder
        {
            set
            {
                showBorder = value;
            }
            get
            {
                return showBorder;
            }
        }

        [
        Browsable(true),
        CategoryAttribute("Scrolling Text"),
        Description("The color of the border")
        ]
        public Color BorderColor
        {
            set
            {
                borderColor = value;
            }
            get
            {
                return borderColor;
            }
        }

        //[
        //Browsable(true),
        //CategoryAttribute("Scrolling Text"),
        //Description("Determines if the text will stop scrolling if the user's mouse moves over the text")
        //]
        //public bool StopScrollOnMouseOver
        //{
        //    set
        //    {
        //        stopScrollOnMouseOver = value;
        //    }
        //    get
        //    {
        //        return stopScrollOnMouseOver;
        //    }
        //}

        [
        Browsable(true),
        CategoryAttribute("Behavior"),
        Description("Indicates whether the control is enabled")
        ]
        new public bool Enabled
        {
            set
            {
                timer.Enabled = value;
                base.Enabled = value;
            }

            get
            {
                return base.Enabled;
            }
        }

        [
        Browsable(false)
        ]
        public Brush ForegroundBrush
        {
            set
            {
                foregroundBrush = value;
            }
            get
            {
                return foregroundBrush;
            }
        }

        [
        ReadOnly(true)
        ]
        public Brush BackgroundBrush
        {
            set
            {
                backgroundBrush = value;
            }
            get
            {
                return backgroundBrush;
            }
        }
        #endregion
    }

    public enum ScrollDirection
    {
        RightToLeft,
        LeftToRight,
        TopToBottom,
        BottomToTop,
        Bouncing
    }

    public enum VerticleTextPosition
    {
        Top,
        Center,
        Botom
    }
}