C#中使用GDI+绘制一把漂亮的直尺(带透明度)

这是三年前研究C#与GDI+时的作品，它使用C#与GDI+绘制一把有透明度、带刻度 (以像素为单位)的直尺。

最终效果：

横向直尺：（注：设置了80%不透明度）

竖向直尺：（注：设置了100%不透明度，即完全不透明）

C#代码：

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Resources;
using System.Windows.Forms;

namespace BrawDraw.Com.Utility.Ruler
{
 public class BeautifulRuler : Form
 {
  private ToolTip   _toolTip = new ToolTip();
  private Point   _offset;
  private Rectangle  _mouseDownRect;
  private int    _resizeBorderWidth = 5;
  private Point   _mouseDownPoint;
  private ResizeRegion _resizeRegion = ResizeRegion.None;
  private ContextMenu  _menu = new ContextMenu();
  private MenuItem  _verticalMenuItem;
  private MenuItem  _toolTipMenuItem;
  private static bool showWidth = true;
  private static bool showWebSite = true;
  private const string SHORT_WEBSITE_STRING="BrawDraw.Com";
  private const string FULL_WEBSITE_STRING="http://www.BrawDraw.Com";
  private string _webSiteString;
  private Color _webSiteStringColor;

        #region ResizeRegion enum
        private enum ResizeRegion
        {
            None, N, NE, E, SE, S, SW, W, NW
        }
        #endregion

        public BeautifulRuler()
  {
            InitializeComponent();

            ResourceManager resources = new ResourceManager(typeof(BeautifulRuler));
   Icon = ((Icon)(resources.GetObject("$this.Icon")));

   SetUpMenu();

   Text = "Ruler";
   BackColor = Color.White;
   ClientSize = new Size(400, 75);
   FormBorderStyle = FormBorderStyle.None;
   Opacity = 0.75;
   ContextMenu = _menu;
   Font = new Font("Tahoma", 10);

   _webSiteStringColor = Color.Blue;
   
   SetStyle(ControlStyles.DoubleBuffer | ControlStyles.UserPaint | ControlStyles.AllPaintingInWmPaint, true);
   this.TopMost = true;
  }

        public string WebSiteString
        {
            get
            {
                if (_webSiteString == null)
                {
                    _webSiteString = FULL_WEBSITE_STRING;
                }
                return _webSiteString;
            }
            set
            {
                value = _webSiteString;
            }
        }

        public Color WebSiteStringColor
        {
            get
            {
                if (_webSiteStringColor == Color.Empty)
                {
                    _webSiteStringColor = Color.Black;
                }
                return _webSiteStringColor;
            }
            set
            {
                value = _webSiteStringColor;
            }
        }
       
        private bool IsVertical
  {
   get { return _verticalMenuItem.Checked; }
   set { _verticalMenuItem.Checked = value; }
  }

  private bool ShowToolTip
  {
   get { return _toolTipMenuItem.Checked; }
   set
   {
    _toolTipMenuItem.Checked = value;
    if (value)
    {
     SetToolTip();
    }
   }
  }

  private void SetUpMenu()
  {
   AddMenuItem("保持最顶层");
   _verticalMenuItem = AddMenuItem("竖向尺子");
   _toolTipMenuItem = AddMenuItem("工具提示");

   //默认光标停留时显示尺寸大小
   _toolTipMenuItem.Checked = true;

   MenuItem opacityMenuItem = AddMenuItem("透明度");
   AddMenuItem("-");
   AddMenuItem("退出");

   for (int i = 10; i <= 100; i += 10)
   {
    MenuItem subMenu = new MenuItem(i + "%");
    subMenu.Click += new EventHandler(OpacityMenuHandler);
    opacityMenuItem.MenuItems.Add(subMenu);
   }
  }

  private MenuItem AddMenuItem(string text)
  {
   return AddMenuItem(text, Shortcut.None);
  }

  private MenuItem AddMenuItem(string text, Shortcut shortcut)
  {
   MenuItem mi = new MenuItem(text);
   mi.Click += new EventHandler(MenuHandler);
   mi.Shortcut = shortcut;
   _menu.MenuItems.Add(mi);
   
   return mi;
  }

  protected override void OnMouseDown(MouseEventArgs e)
  {
   _offset = new Point(MousePosition.X - Location.X, MousePosition.Y - Location.Y);
   _mouseDownPoint = MousePosition;
   _mouseDownRect = ClientRectangle;

   base.OnMouseDown(e);
  }

  protected override void OnMouseUp(MouseEventArgs e)
  {
   _resizeRegion = ResizeRegion.None;
   base.OnMouseUp(e);
  }

  protected override void OnMouseMove(MouseEventArgs e)
  {
   if (_resizeRegion != ResizeRegion.None)
   {
    HandleResize();
    return;
   }

   Point clientCursorPos = PointToClient(MousePosition);
   Rectangle resizeInnerRect = ClientRectangle;
   resizeInnerRect.Inflate(-_resizeBorderWidth, -_resizeBorderWidth);

   bool inResizableArea = ClientRectangle.Contains(clientCursorPos) && !resizeInnerRect.Contains(clientCursorPos);

   if (inResizableArea)
   {
    ResizeRegion resizeRegion = GetResizeRegion(clientCursorPos);
    SetResizeCursor(resizeRegion);

    if (e.Button == MouseButtons.Left)
    {
     _resizeRegion = resizeRegion;
     HandleResize();
    }
   }
   else
   {
    Cursor = Cursors.Default;

    if (e.Button == MouseButtons.Left)
    {
     Location = new Point(MousePosition.X - _offset.X, MousePosition.Y - _offset.Y);
    }
   }

   base.OnMouseMove(e);
  }

  protected override void OnResize(EventArgs e)
  {
   if (ShowToolTip)
   {
    SetToolTip();
   }

   base.OnResize(e);
  }

  private void SetToolTip()
  {
   _toolTip.SetToolTip(this, string.Format("宽度: {0} 像素/n高度: {1} 像素", Width, Height));
  }

  protected override void OnKeyDown(KeyEventArgs e)
  {
   switch (e.KeyCode)
   {
    case Keys.Right:
    case Keys.Left:
    case Keys.Up:
    case Keys.Down:
     HandleMoveResizeKeystroke(e);
     break;

    case Keys.Space:
     ChangeOrientation();
     break;
   }

   base.OnKeyDown(e);
  }

  private void HandleMoveResizeKeystroke(KeyEventArgs e)
  {
   if (e.KeyCode == Keys.Right)
   {
    if (e.Control)
    {
     if (e.Shift)
     {
      Width += 1;
     }
     else
     {
      Left += 1;
     }
    }
    else
    {
     Left += 5;
    }
   }
   else if (e.KeyCode == Keys.Left)
   {
    if (e.Control)
    {
     if (e.Shift)
     {
      Width -= 1;
     }
     else
     {
      Left -= 1;
     }
    }
    else
    {
     Left -= 5;
    }
   }
   else if (e.KeyCode == Keys.Up)
   {
    if (e.Control)
    {
     if (e.Shift)
     {
      Height -= 1;
     }
     else
     {
      Top -= 1;
     }
    }
    else
    {
     Top -= 5;
    }
   }
   else if (e.KeyCode == Keys.Down)
   {
    if (e.Control)
    {
     if (e.Shift)
     {
      Height += 1;
     }
     else
     {
      Top += 1;
     }
    }
    else
    {
     Top += 5;
    }
   }
  }

  private void HandleResize()
  {
   int diff = 0;
   switch (_resizeRegion)
   {
    case ResizeRegion.E:
     diff = MousePosition.X - _mouseDownPoint.X;
     Width = _mouseDownRect.Width + diff;
     break;

    case ResizeRegion.S:
     diff = MousePosition.Y - _mouseDownPoint.Y;
     Height = _mouseDownRect.Height + diff;
     break;

    case ResizeRegion.SE:
     Width = _mouseDownRect.Width + MousePosition.X - _mouseDownPoint.X;
     Height = _mouseDownRect.Height + MousePosition.Y - _mouseDownPoint.Y;
     break;

    case ResizeRegion.NW:
     Width = _mouseDownRect.Width - MousePosition.X + _mouseDownPoint.X;
     Height = _mouseDownRect.Height - MousePosition.Y + _mouseDownPoint.Y;
     break;

                default:
                    break;
   }
           

   int tmp;
   int height=Height;
   int width=Width;
   if (IsVertical)
   {
    tmp = Height;
    height = Width;
    width = tmp;
   }
   //当窗口过小时，保持一定大小
   if(Width<30) Width=30;
   if(Height<20) Height=20;

   if(height<30)
   {
    showWidth=false;
   }
   else
   {
    showWidth=true;
   }

   if(height>66 && (width>60 && width<200))
   {
    showWebSite=true;
    _webSiteString = SHORT_WEBSITE_STRING;
   }
   else if(height<66 || width<40)
   {
    showWebSite=false;
    _webSiteString = FULL_WEBSITE_STRING;
   }
   else
   {
    showWebSite=true;
    _webSiteString = FULL_WEBSITE_STRING;
   }

            this.Invalidate();
  }

  private void SetResizeCursor(ResizeRegion region)
  {
   switch (region)
   {
    case ResizeRegion.N:
    case ResizeRegion.S:
     Cursor = Cursors.SizeNS;
     break;
    
    case ResizeRegion.E:
    case ResizeRegion.W:
     Cursor = Cursors.SizeWE;
     break;

    case ResizeRegion.NW:
    case ResizeRegion.SE:
     Cursor = Cursors.SizeNWSE;
     break;

    default:
     Cursor = Cursors.SizeNESW;
     break;
   }
  }

  private ResizeRegion GetResizeRegion(Point clientCursorPos)
  {
   if (clientCursorPos.Y <= _resizeBorderWidth)
   {
    if (clientCursorPos.X <= _resizeBorderWidth)    return ResizeRegion.NW;
    else if (clientCursorPos.X >= Width - _resizeBorderWidth) return ResizeRegion.NE;
    else              return ResizeRegion.N;
   }
   else if (clientCursorPos.Y >= Height - _resizeBorderWidth)
   {
    if (clientCursorPos.X <= _resizeBorderWidth)    return ResizeRegion.SW;
    else if (clientCursorPos.X >= Width - _resizeBorderWidth) return ResizeRegion.SE;
    else              return ResizeRegion.S;
   }
   else
   {
    if (clientCursorPos.X <= _resizeBorderWidth)    return ResizeRegion.W;
    else              return ResizeRegion.E;
   }
  }

  protected override void OnPaint(PaintEventArgs e)
  {
            base.OnPaint(e);
   Graphics graphics = e.Graphics;
   
   int height = Height;
   int width = Width;

   if (IsVertical)
   {
    graphics.RotateTransform(90);
    graphics.TranslateTransform(0, -Width + 1);
    height = Width;
    width = Height;
   }

   LinearGradientBrush lgb=new LinearGradientBrush(
    new Point(0,0),
    new Point(0,height),
    Color.Black,
    Color.White
    );
   //定义参与渐变的色彩
   Color[] colors=
    {
     Color.White,
     Color.White,
     Color.FromArgb(228,232,238),
     Color.FromArgb(202,212,222),
     Color.FromArgb(228,232,238),
     Color.White,
     Color.White
    };
   float[] positions=
    {
     0.0f,
     0.1f,
     0.36f,
     0.5f,
     0.64f,
     0.9f,
     1.0f
    };
   ColorBlend clrBlend = new ColorBlend();
   clrBlend.Colors=colors;
   clrBlend.Positions=positions;
   lgb.InterpolationColors=clrBlend;

   graphics.FillRectangle(lgb,0,0,width,height);

   DrawRuler(graphics, width, height);
  }

  private void DrawRuler(Graphics g, int formWidth, int formHeight)
  {
   // 边框
   g.DrawRectangle(Pens.Black, 0, 0, formWidth - 1, formHeight - 1);
 
   // 宽度
   if(showWidth)
   {
    g.DrawString(formWidth + " 像素", Font, Brushes.Black, 10, (formHeight / 2) - (Font.Height / 2));
   }
            // 显示站点
   if(showWebSite)
   {
    g.DrawString(WebSiteString, Font,new SolidBrush(WebSiteStringColor), 80, (formHeight / 2) - (Font.Height / 2));
   }

            // 刻度
   for (int i = 0; i < formWidth; i++)
   {
    if (i % 2 == 0)
    {
     int tickHeight;
     if (i % 100 == 0)
     {
      tickHeight = 15;
      DrawTickLabel(g, i.ToString(), i, formHeight, tickHeight);
     }
     else if (i % 10 == 0)
     {
      tickHeight = 10;
     }
     else
     {
      tickHeight = 5;
     }
     
     DrawTick(g, i, formHeight, tickHeight);
    }
   }
  }

  private void DrawTick(Graphics g, int xPos, int formHeight, int tickHeight)
  {
   // 顶部
   g.DrawLine(Pens.Black, xPos, 0, xPos, tickHeight);

   // 底部
   g.DrawLine(Pens.Black, xPos, formHeight, xPos, formHeight - tickHeight);
  }

  private void DrawTickLabel(Graphics g, string text, int xPos, int formHeight, int height)
  {
   // 顶部数字
   g.DrawString(text, Font, Brushes.Black, xPos, height);
   
   // 底部数字
   g.DrawString(text, Font, Brushes.Black, xPos, formHeight - height - Font.Height);
  }

  [STAThread]
  static void Main()
  {
   Application.EnableVisualStyles();
            Application.Run(new BeautifulRuler());
  }

  private void OpacityMenuHandler(object sender, EventArgs e)
  {
   MenuItem mi = (MenuItem)sender;
   Opacity = double.Parse(mi.Text.Replace("%", "")) / 100;
  }

  private void MenuHandler(object sender, EventArgs e)
  {
   MenuItem mi = (MenuItem)sender;
   
   switch (mi.Text)
   {
    case "退出":
     Close();
     break;

    case "工具提示":
     ShowToolTip = !ShowToolTip;
     break;

    case "竖向尺子":
     ChangeOrientation();
     break;

    case "保持最顶层":
     mi.Checked = !mi.Checked;
     TopMost = mi.Checked;
     break;

    default:
     MessageBox.Show("未有菜单项目。");
     break;
   }
  }

        // 改变尺子放置方向（横向/竖向）
  private void ChangeOrientation()
  {
   IsVertical = !IsVertical;
   int width = Width;
   Width = Height;
   Height = width;
            this.Invalidate();
  }

        private void InitializeComponent()
        {
            this.SuspendLayout();
            this.ClientSize = new System.Drawing.Size(292, 266);
            this.Name = "Form1";
            this.DoubleClick += new System.EventHandler(this.Form1_DoubleClick);
            this.ResumeLayout(false);

        }

        private void Form1_DoubleClick(object sender, EventArgs e)
        {
            System.Diagnostics.Process.Start("iexplore.exe", "http://www.brawdraw.com");
        }
 }
}