看过电影《黑客帝国》得大概都会觉得里面那种黑底绿字的效果特别炫，闲来无事，就自己用C#写了个特效控件，并可以通过调整参数达到其他效果。先看看《黑客帝国》经典的特效好了（图片经过压缩，可能不是很清楚）：
再看看项目实现后的效果（参数设置的好的话，效果还是相当不错的）：
实现方案：实现并不是特别复杂，每条显示的字符串都作为一个WordInfo对象，该对象包含了速度、颜色、字体大小、字符个数等属性。在控件类WordRain中在该项目中，定义了两个Timer，一个是m_timer用来定时重绘控件，一个是m_newtimer用来定时创建新的WordInfo对象。在WordRain中还维持了两个ArrayList，一个是m_selectlist用来显示要绘制的字符（每次重绘控件的时候都会随机获取m_charlist中的一个字符用于显示），一个是m_charlist用来保存当前显示在控件中的WordInfo对象（超出控件范围的对象要及时删除）。
注意点和相关处理如下：1. 字体较大字符串的必需在字体小的字符串之后画，避免字体小的字符串遮住字体大的字符串，影响效果。要达到这样的效果必须在每次重绘的时候，对m_charlist中的所有WordInfo对象按字体大小从小到大排序。实现如下：
public class WordInfoSorter : IComparer{int IComparer.Compare(object x, object y){if (((WordInfo)x).m_fontsize < ((WordInfo)y).m_fontsize) return -1;else if (((WordInfo)x).m_fontsize == ((WordInfo)y).m_fontsize) return 0;else return 1;}}public partial class WordRain : UserControl{//…private WordInfoSorter m_sorter;//…public WordRain(){//…m_sorter = new WordInfoSorter();//…}//…private void WordRain_Paint(object sender, PaintEventArgs e){//…m_charlist.Sort(m_sorter);//…}//…}
2. 为了保证效果，，字体较大的字符串颜色要接近前景色m_min_charcolor，字体较小的字符串颜色要更接近背景色m_max_charcolor。颜色根据字体的最大值和最小值来计算）。详见类WordInfo的SetFontAndColor()方法。
3. 同样为了保证效果，每个字符串有 m_count个字符，显示在最下面的字符颜色100%不透明，显示在最上面的字符颜色最接近透明。详见类WordInfo的GetColor()方法。
整个控件的代码如下：using System;using System.Collections.Generic;using System.ComponentModel;using System.Drawing;using System.Drawing.Drawing2D;using System.Data;using System.Linq;using System.Text;using System.Windows.Forms;using System.Collections;using System.Runtime.InteropServices;namespace myControl{public partial class WordRain : UserControl{private Timer m_timer; //重绘定时器private Timer m_newtimer; //新建字符定时器private Graphics m_g;//画布private ArrayList m_charlist;private ArrayList m_selectlist;private WordInfoSorter m_sorter;private Random m_random;public WordRain(){InitializeComponent();this.SetStyle(ControlStyles.UserPaint, true);this.SetStyle(ControlStyles.AllPaintingInWmPaint, true);this.SetStyle(ControlStyles.OptimizedDoubleBuffer, true);this.SetStyle(ControlStyles.ResizeRedraw, true);this.SetStyle(ControlStyles.Selectable, true);this.BackColor = Color.Black;m_charlist = new ArrayList();WordInfo wordinfo = new WordInfo();wordinfo.SetValue();m_charlist.Add(wordinfo);m_sorter = new WordInfoSorter();string[] arr = new string[] {"0","1","2","3","4","5","6","7","8","9"};m_selectlist = new ArrayList(arr);m_random = new Random();m_timer = new Timer();m_newtimer = new Timer();m_timer.Interval = 10;m_newtimer.Interval = 50;m_timer.Enabled = true;m_newtimer.Enabled = true;m_timer.Tick += new EventHandler(m_timer_Tick);m_newtimer.Tick += new EventHandler(m_newtimer_Tick);}private string GetStringFromArrayList(){return (string)m_selectlist[m_random.Next(m_selectlist.Count)];}void m_newtimer_Tick(object sender, EventArgs e){WordInfo wordinfo = new WordInfo();wordinfo.SetValue();m_charlist.Add(wordinfo);}void m_timer_Tick(object sender, EventArgs e){this.Invalidate();ArrayList ObjToDel = new ArrayList();foreach (WordInfo temp in m_charlist){temp.m_posy += temp.m_runspeed;if (temp.m_posy > this.Height + temp.m_fontsize * temp.m_count)ObjToDel.Add(temp);}foreach (WordInfo temp in ObjToDel){m_charlist.Remove(temp);}ObjToDel.Clear();}private void WordRain_Paint(object sender, PaintEventArgs e){m_g = e.Graphics;m_charlist.Sort(m_sorter);SetXRange(this.Width);foreach (WordInfo temp in m_charlist){using (Font font = new Font("Arial", temp.m_fontsize, GraphicsUnit.Pixel)){using(SolidBrush brush = new SolidBrush(temp.m_charcolor)){for (int i = 0; i < temp.m_count; i++){brush.Color = temp.GetColor(i);m_g.DrawString(GetStringFromArrayList(), font, brush, temp.m_posx, temp.m_posy-temp.m_fontsize*i);}}}}}//设置字体大小范围public void SetFontSizeRange(int minsize, int maxsize){if (minsize > maxsize){throw new ArgumentException("参数minsize必须小于等于参数maxsize");}if (minsize < 1 || maxsize > 50){throw new ArgumentException("参数minsize和maxsize必须在区间[1,50]内");}WordInfo.m_min_fontsize = minsize;WordInfo.m_max_fontsize = maxsize;}//设置字体渐变颜色范围public void SetFontColorRange(Color firstColor, Color lastColor){WordInfo.m_min_charcolor = firstColor;WordInfo.m_max_charcolor = lastColor;}//设置X轴所能到达的最大长度(即控件的宽度)public void SetXRange(int value){WordInfo.m_max_xpos = value;}//设置速度public void SetSpeedRange(float minspeed, float maxspeed){if (minspeed > maxspeed){throw new ArgumentException("参数minspeed必须小于等于参数maxspeed");}if (minspeed < 0.1 || maxspeed > 100.0){throw new ArgumentException("参数minspeed和maxspeed必须在区间[0.1,100.0]内");}WordInfo.m_min_runspeed = minspeed;WordInfo.m_min_runspeed = maxspeed;}//设置字符个数范围public void SetCountRange(int mincount, int maxcount){if (mincount > maxcount){throw new ArgumentException("参数mincount必须小于等于参数maxcount");}if (mincount < 1 || maxcount > 100){throw new ArgumentException("参数mincount和maxcount必须在区间[1,100]内");}WordInfo.m_min_count = mincount;WordInfo.m_max_count = maxcount;}//设置字符列表public void SetArrayValue(ArrayList list){if (list.Count == 0){throw new ArgumentException("参数list中的元素个数不能为0");}m_selectlist.Clear();m_selectlist = list;}}public class WordInfoSorter : IComparer{int IComparer.Compare(object x, object y){if (((WordInfo)x).m_fontsize < ((WordInfo)y).m_fontsize) return -1;else if (((WordInfo)x).m_fontsize == ((WordInfo)y).m_fontsize) return 0;else return 1;}}public class WordInfo{public int m_fontsize;//字体大小public float m_runspeed; //移动速度public Color m_charcolor; //最下面的字的颜色，最上面的字的颜色为背景色public float m_posx;//横坐标public float m_posy;//纵坐标public int m_count;//字符个数public ArrayList m_charList; //要显示的字符列表public static int m_max_xpos = 600;public static int m_min_count = 10;public static int m_max_count = 20;public static int m_min_fontsize = 4;public static int m_max_fontsize = 20;public static float m_min_runspeed = 0.6F;public static float m_max_runspeed = 4.2F;public static Color m_min_charcolor = Color.FromArgb(0, 255, 0);public static Color m_max_charcolor = Color.FromArgb(0, 55, 0);public static Random m_random = new Random();public WordInfo(){this.m_count = 1;this.m_fontsize = 0;this.m_runspeed = 0;this.m_posx = 0;this.m_posy = 0;this.m_charcolor = Color.FromArgb(0, 255, 0);}//获取字体大小的随机值private int GetFontSize(){int i = m_random.Next();return i % (m_max_fontsize – m_min_fontsize) + m_min_fontsize;}//获取速度的随机值private float GetSpeed(){int i = m_random.Next();int j = m_random.Next();return i % (m_max_runspeed – m_min_runspeed) + m_min_runspeed+ (j%10)/10.0F;}//获取颜色的随机值private Color GetColor(){int min_r = m_min_charcolor.R;int min_g = m_min_charcolor.G;int min_b = m_min_charcolor.B;int max_r = m_max_charcolor.R;int max_g = m_max_charcolor.G;int max_b = m_max_charcolor.B;int r = m_random.Next((min_r > max_r ? max_r : min_r), (min_r < max_r ? max_r : min_r));int g = m_random.Next((min_g > max_g ? max_g : min_g), (min_g < max_g ? max_g : min_g));int b = m_random.Next((min_b > max_b ? max_b : min_b), (min_b < max_b ? max_b : min_b));return Color.FromArgb(r, g, b);}//设置字体和颜色(字体越小，颜色越接近m_max_charcolor)private void SetFontAndColor(){int i = m_random.Next();int fontpart = i % (m_max_fontsize – m_min_fontsize);this.m_fontsize = m_min_fontsize + fontpart;float percent = ((float)fontpart) / ((float)(m_max_fontsize – m_min_fontsize));int min_r = m_min_charcolor.R;int min_g = m_min_charcolor.G;int min_b = m_min_charcolor.B;int max_r = m_max_charcolor.R;int max_g = m_max_charcolor.G;int max_b = m_max_charcolor.B;int rpart = (int)(Math.Abs(min_r – max_r) * percent);int gpart = (int)(Math.Abs(min_g – max_g) * percent);int bpart = (int)(Math.Abs(min_b – max_b) * percent);int r = min_r > max_r ? (max_r + rpart) : (max_r – rpart);int g = min_g > max_g ? (max_g + gpart) : (max_g – gpart);int b = min_b > max_b ? (max_b + bpart) : (max_b – bpart);this.m_charcolor = Color.FromArgb(r, g, b);}//获取x轴坐标private float GetXPos(){int i = m_random.Next(m_max_xpos-1);return (float)(i + m_random.Next(10) / 10.0F);}//获取随机个数private int GetCount(){return m_random.Next(m_min_count, m_max_count);}//设置相关值public void SetValue(){this.m_count = this.GetCount();this.SetFontAndColor();this.m_runspeed = this.GetSpeed();this.m_posy = m_count*m_fontsize*(-1.0F);this.m_posx = this.GetXPos();}//获取颜色public Color GetColor(int index){if (this.m_count == 1)return this.m_charcolor;if (index == 0)return this.m_charcolor;int rpart = (Math.Abs(m_charcolor.R – m_max_charcolor.R)) / m_count * index;int gpart = (Math.Abs(m_charcolor.G – m_max_charcolor.G)) / m_count * index;int bpart = (Math.Abs(m_charcolor.B – m_max_charcolor.B)) / m_count * index;int r = m_charcolor.R > m_max_charcolor.R ? (m_charcolor.R – rpart) : (m_charcolor.R + rpart);int g = m_charcolor.G > m_max_charcolor.G ? (m_charcolor.G – gpart) : (m_charcolor.G + gpart);int b = m_charcolor.B > m_max_charcolor.B ? (m_charcolor.B – bpart) : (m_charcolor.B + bpart);return Color.FromArgb(255-index*255/m_count, m_charcolor);}}}项目地址如下：?shareid=1966732572&uk=3508115909
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回首往事，日子里竟全是斑澜的光影，
