C#利用GDI+绘制旋转文字等效果

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。

usingSystem;

usingSystem.Collections.Generic;

usingSystem.Drawing;

usingSystem.Drawing.Drawing2D;

namespaceRotateText

{

publicclassGraphicsText

{

PRivateGraphics_graphics;

publicGraphicsText()

{

}

publicGraphicsGraphics

{

get{return_graphics;}

set{_graphics=value;}

}

///<summary>

///绘制根据矩形旋转文本

///</summary>

///<paramname="s">文本</param>

///<paramname="font">字体</param>

///<paramname="brush">填充</param>

///<paramname="layoutRectangle">局部矩形</param>

///<paramname="format">布局方式</param>

///<paramname="angle">角度</param>

publicvoidDrawString(strings,Fontfont,Brushbrush,RectangleFlayoutRectangle,StringFormatformat,floatangle)

{

//求取字符串大小

SizeFsize=_graphics.MeasureString(s,font);

//根据旋转角度，求取旋转后字符串大小

SizeFsizeRotate=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

PointFrotatePt=GetRotatePoint(sizeRotate,layoutRectangle,format);

//重设布局方式都为Center

StringFormatnewFormat=newStringFormat(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>

///<paramname="s">文本</param>

///<paramname="font">字体</param>

///<paramname="brush">填充</param>

///<paramname="point">旋转点</param>

///<paramname="format">布局方式</param>

///<paramname="angle">角度</param>

publicvoidDrawString(strings,Fontfont,Brushbrush,PointFpoint,StringFormatformat,floatangle)

{

//Savethematrix

MatrixmtxSave=_graphics.Transform;

MatrixmtxRotate=_graphics.Transform;

mtxRotate.RotateAt(angle,point);

_graphics.Transform=mtxRotate;

_graphics.DrawString(s,font,brush,point,format);

//Resetthematrix

_graphics.Transform=mtxSave;

}

privateSizeFConvertSize(SizeFsize,floatangle)

{

Matrixmatrix=newMatrix();

matrix.Rotate(angle);

//旋转矩形四个顶点

PointF[]pts=newPointF[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

floatleft=float.MaxValue;

floatright=float.MinValue;

floattop=float.MaxValue;

floatbottom=float.MinValue;

foreach(PointFptinpts)

{

//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;

}

SizeFresult=newSizeF(right-left,bottom-top);

returnresult;

}

privatePointFGetRotatePoint(SizeFsize,RectangleFlayoutRectangle,StringFormatformat)

{

PointFpt=newPointF();

switch(format.Alignment)

{

caseStringAlignment.Near:

pt.X=layoutRectangle.Left+size.Width/2f;

break;

caseStringAlignment.Center:

pt.X=(layoutRectangle.Left+layoutRectangle.Right)/2f;

break;

caseStringAlignment.Far:

pt.X=layoutRectangle.Right-size.Width/2f;

break;

default:

break;

}

switch(format.LineAlignment)

{

caseStringAlignment.Near:

pt.Y=layoutRectangle.Top+size.Height/2f;

break;

caseStringAlignment.Center:

pt.Y=(layoutRectangle.Top+layoutRectangle.Bottom)/2f;

break;

caseStringAlignment.Far:

pt.Y=layoutRectangle.Bottom-size.Height/2f;

break;

default:

break;

}

returnpt;

}

}

}

测试代码如下：

[csharp]view%20plaincopy

1. usingSystem;
2. usingSystem.Collections.Generic;
3. usingSystem.ComponentModel;
4. usingSystem.Data;
5. usingSystem.Drawing;
6. usingSystem.Windows.Forms;
8. namespaceRotateText
9. {
10. publicpartialclassFormMain:Form
11. {
12. privateFont_font=newFont("Arial",12);
13. privateBrush_brush=newSolidBrush(Color.Black);
14. privatePen_pen=newPen(Color.Black,1f);
15. privatestring_text="CrowSoft";
17. publicFormMain()
18. {
19. InitializeComponent();
20. }
22. pr