C#利用GDI+绘制旋转文字等效果实例

本文实例讲述了C#利用GDI+绘制旋转文字等效果的方法，是非常实用的技巧。分享给大家供大家参考之用。具体如下：

C#中利用GDI+绘制旋转文本的文字，网上有很多资料，基本都使用矩阵旋转的方式实现。但基本都只提及按点旋转，若要实现在矩形范围内旋转文本，资料较少。经过琢磨，可以将矩形内旋转转化为按点旋转，不过需要经过不少的计算过程。利用下面的类可以实现该功能。

具体实现代码如下：

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> /// 绘制根据矩形旋转文本 /// </summary> /// <param name="s">文本</param> /// <param name="font">字体</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); // 根据旋转角度，求取旋转后字符串大小 SizeF sizeRotate = ConvertSize(size, angle); // 根据旋转后尺寸、布局矩形、布局方式计算文本旋转点 PointF rotatePt = GetRotatePoint(sizeRotate, layoutRectangle, format); // 重设布局方式都为Center StringFormat newFormat = new StringFormat(format); newFormat.Alignment = StringAlignment.Center; newFormat.LineAlignment = StringAlignment.Center; // 绘制旋转后文本 DrawString(s, font, brush, rotatePt, newFormat, angle); } /// <summary> /// 绘制根据点旋转文本，一般旋转点给定位文本包围盒中心点 /// </summary> /// <param name="s">文本</param> /// <param name="font">字体</param> /// <param name="brush">填充</param> /// <param name="point">旋转点</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); // 旋转矩形四个顶点 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); // 求取四个顶点的包围盒 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; } } }

测试代码如下：

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; // 绘制围绕点旋转的文本 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); // 绘制矩形内旋转的文本 // 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); } } }

效果如下图：

完整实例点此本站下载。

希望本文所述对大家的C#程序设计有所帮助

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