C#利用GDI+繪制旋轉文字等效果實例

2020-01-24 02:24:04

字體：大中小

來源：轉載

供稿：網友

本文實例講述了C#利用GDI+繪制旋轉文字等效果的方法，是非常實用的技巧。分享給大家供大家參考之用。具體如下：

C#中利用GDI+繪制旋轉文本的文字，網上有很多資料，基本都使用矩陣旋轉的方式實現。但基本都只提及按點旋轉，若要實現在矩形范圍內旋轉文本，資料較少。經過琢磨，可以將矩形內旋轉轉化為按點旋轉，不過需要經過不少的計算過程。利用下面的類可以實現該功能。

具體實現代碼如下：

using System; using System.Collections.Generic; using System.Drawing; using System.Drawing.Drawing2D; namespace RotateText {   public class GraphicsText   {     private Graphics _graphics;     public GraphicsText()     {      }     public Graphics Graphics     {       get { return _graphics; }       set { _graphics = value; }     }     /// <summary>     /// 繪制根據矩形旋轉文本     /// </summary>     /// <param name="s">文本</param>     /// <param name="font">字體</param>     /// <param name="brush">填充</param>     /// <param name="layoutRectangle">局部矩形</param>     /// <param name="format">布局方式</param>     /// <param name="angle">角度</param>     public void DrawString(string s, Font font, Brush brush, RectangleF layoutRectangle, StringFormat format, float angle)     {       // 求取字符串大小       SizeF size = _graphics.MeasureString(s, font);        // 根據旋轉角度，求取旋轉后字符串大小       SizeF sizeRotate = ConvertSize(size, angle);        // 根據旋轉后尺寸、布局矩形、布局方式計算文本旋轉點       PointF rotatePt = GetRotatePoint(sizeRotate, layoutRectangle, format);        // 重設布局方式都為Center       StringFormat newFormat = new StringFormat(format);       newFormat.Alignment = StringAlignment.Center;       newFormat.LineAlignment = StringAlignment.Center;        // 繪制旋轉后文本       DrawString(s, font, brush, rotatePt, newFormat, angle);     }     /// <summary>     /// 繪制根據點旋轉文本，一般旋轉點給定位文本包圍盒中心點     /// </summary>     /// <param name="s">文本</param>     /// <param name="font">字體</param>     /// <param name="brush">填充</param>     /// <param name="point">旋轉點</param>     /// <param name="format">布局方式</param>     /// <param name="angle">角度</param>     public void DrawString(string s, Font font, Brush brush, PointF point, StringFormat format, float angle)     {       // Save the matrix       Matrix mtxSave = _graphics.Transform;        Matrix mtxRotate = _graphics.Transform;       mtxRotate.RotateAt(angle, point);       _graphics.Transform = mtxRotate;        _graphics.DrawString(s, font, brush, point, format);        // Reset the matrix       _graphics.Transform = mtxSave;     }     private SizeF ConvertSize(SizeF size, float angle)     {       Matrix matrix = new Matrix();       matrix.Rotate(angle);       // 旋轉矩形四個頂點       PointF[] pts = new PointF[4];       pts[0].X = -size.Width / 2f;       pts[0].Y = -size.Height / 2f;       pts[1].X = -size.Width / 2f;       pts[1].Y = size.Height / 2f;       pts[2].X = size.Width / 2f;       pts[2].Y = size.Height / 2f;       pts[3].X = size.Width / 2f;       pts[3].Y = -size.Height / 2f;       matrix.TransformPoints(pts);       // 求取四個頂點的包圍盒       float left = float.MaxValue;       float right = float.MinValue;       float top = float.MaxValue;       float bottom = float.MinValue;       foreach(PointF pt in pts)       {         // 求取并集         if(pt.X < left)           left = pt.X;         if(pt.X > right)           right = pt.X;         if(pt.Y < top)           top = pt.Y;         if(pt.Y > bottom)           bottom = pt.Y;       }       SizeF result = new SizeF(right - left, bottom - top);       return result;     }     private PointF GetRotatePoint(SizeF size, RectangleF layoutRectangle, StringFormat format)     {       PointF pt = new PointF();        switch (format.Alignment)       {         case StringAlignment.Near:           pt.X = layoutRectangle.Left + size.Width / 2f;           break;         case StringAlignment.Center:           pt.X = (layoutRectangle.Left + layoutRectangle.Right) / 2f;           break;         case StringAlignment.Far:           pt.X = layoutRectangle.Right - size.Width / 2f;           break;         default:           break;       }       switch (format.LineAlignment)       {         case StringAlignment.Near:           pt.Y = layoutRectangle.Top + size.Height / 2f;           break;         case StringAlignment.Center:           pt.Y = (layoutRectangle.Top + layoutRectangle.Bottom) / 2f;           break;         case StringAlignment.Far:           pt.Y = layoutRectangle.Bottom - size.Height / 2f;           break;         default:           break;       }       return pt;     }   } }

測試代碼如下：

using System; using System.Collections.Generic; using System.ComponentModel; using System.Data; using System.Drawing; using System.Windows.Forms;  namespace RotateText {   public partial class FormMain : Form   {     private Font _font = new Font("Arial", 12);     private Brush _brush = new SolidBrush(Color.Black);     private Pen _pen = new Pen(Color.Black, 1f);     private string _text = "Crow Soft";      public FormMain()     {       InitializeComponent();     }      protected override void OnPaint(PaintEventArgs e)     {       base.OnPaint(e);        GraphicsText graphicsText = new GraphicsText();       graphicsText.Graphics = e.Graphics;        // 繪制圍繞點旋轉的文本       StringFormat format = new StringFormat();       format.Alignment = StringAlignment.Center;       format.LineAlignment = StringAlignment.Center;        graphicsText.DrawString(_text, _font, _brush, new PointF(100, 80), format, 45f);       graphicsText.DrawString(_text, _font, _brush, new PointF(200, 80), format, -45f);       graphicsText.DrawString(_text, _font, _brush, new PointF(300, 80), format, 90f);       graphicsText.DrawString(_text, _font, _brush, new PointF(400, 80), format, -60f);        // 繪制矩形內旋轉的文本       // First line       RectangleF rc = RectangleF.FromLTRB(50, 150, 200, 230);       RectangleF rect = rc;       format.Alignment = StringAlignment.Near;        e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, 30);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Near;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, -30);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Center;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, -90);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Far;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, 70);        // Second line       rect = rc;       rect.Location += new SizeF(0, 100);       format.Alignment = StringAlignment.Center;        e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, 40);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Near;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, 30);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Center;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, -70);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Far;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, 60);        // Third line       rect = rc;       rect.Location += new SizeF(0, 200);       format.Alignment = StringAlignment.Far;        e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, -30);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Near;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, -30);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Center;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, 90);        rect.Location += new SizeF(180, 0);       format.LineAlignment = StringAlignment.Far;       e.Graphics.DrawRectangle(_pen, rect.Left, rect.Top, rect.Width, rect.Height);       graphicsText.DrawString(_text, _font, _brush, rect, format, 45);     }   } }

效果如下圖：