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