本文以实例讲述了Delphi实现图像文本旋转特效的解决方法，在本程序中利用的控件主要是Panel 控件、Image 控件、Edit 控件、Label 控件和Button 控件。本程序的关键是利用Delphi 的bmp_rotate()函数来实现旋转图像的功能。并巧妙地调用相关Windows API 函数来实现对文本的旋转特效。
完整的实例代码如下：
unit Unit1; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,math, StdCtrls, ExtCtrls; type TForm1 = class(TForm) Edit1: TEdit; Image1: TImage; bmprotate: TButton; Label1: TLabel; Panel1: TPanel; Image2: TImage; Panel2: TPanel; Image3: TImage; Edit2: TEdit; RotatedText: TButton; Label2: TLabel; procedure bmprotateClick(Sender: TObject); procedure RotatedTextClick(Sender: TObject); procedure FormCreate(Sender: TObject); private { Private declarations } public { Public declarations } procedure bmp_rotate(src,dst:Tbitmap;angle:extended); Procedure DrawRotatedText(TheCanvas : TCanvas; TheAngle : Integer; TheText : String); end; var Form1: TForm1; implementation {$R *.DFM} procedure TForm1.bmp_rotate(src,dst:Tbitmap;angle:extended);//图像旋转 var c1x,c1y,c2x,c2y:integer; p1x,p1y,p2x,p2y:integer; radius,n:integer; alpha:extended; c0,c1,c2,c3:tcolor; begin angle := (angle / 180) * pi; //将文本框内的内容转换角度 c1x := src.Width div 2; c1y := src.Height div 2; c2x := dst.Width div 2; c2y := dst.Height div 2; if c2x < c2y then n := c2y else n := c2x; dec (n,1); //使n 值减少1,n:=n-1 for p2x := 0 to n do begin for p2y := 0 to n do begin if p2x = 0 then alpha:= pi/2 else alpha := arctan2(p2y,p2x); radius := round(sqrt((p2x*p2x)+(p2y*p2y)));//设置旋转时的半径大小 p1x := round(radius * cos(angle+alpha)); //设置旋转时的圆心横坐标 p1y := round(radius * sin(angle+alpha)); //设置旋转时的圆心纵坐标 c0 := src.Canvas.pixels[c1x+p1x,c1y+p1y];//替换图像相关坐标处的像素 c1 := src.Canvas.pixels[c1x-p1x,c1y-p1y]; c2 := src.Canvas.pixels[c1x+p1y,c1y-p1x]; c3 := src.Canvas.pixels[c1x-p1y,c1y+p1x]; dst.Canvas.pixels[c2x+p2x,c2y+p2y]:=c0; //置换不同位置的像素点 dst.Canvas.pixels[c2x-p2x,c2y-p2y]:=c1; dst.Canvas.pixels[c2x+p2y,c2y-p2x]:=c2; dst.Canvas.pixels[c2x-p2y,c2y+p2x]:=c3; end; application.processmessages //响应其他的消息请求 end; end; procedure TForm1.bmprotateClick(Sender: TObject); Var RAngle : Extended; begin RAngle := StrToFloat(Edit1.Text); //设置旋转的角度 bmp_rotate(Image1.Picture.bitmap,Image2.Picture.bitmap, RAngle);//运行旋转函数，旋转图形 end; Procedure TForm1.DrawRotatedText(TheCanvas : TCanvas; TheAngle : Integer; TheText : String); var lf : TLogFont; tf : TFont; begin Image3.Canvas.refresh; with TheCanvas do begin Font.Name:='Arial'; Font.Size:=18; Brush.Style:= bsClear; tf:= TFont.Create; try tf.Assign(Font); GetObject(tf.Handle, Sizeof(lf), @lf); //将当前实例句柄赋给tf 这个Font 对象 lf.lfEscapement:=TheAngle*10; lf.lfOrientation := TheAngle * 10; //使输入时的横坐标线与水平线呈所指定的角度 tf.Handle := CreateFontIndirect(lf); //创建一个Font 具体对象 Font.Assign(tf); //使这个对象运用到程序中 finally tf.Free; //释放对象 end; TextOut(Image3.left, Image3.top+20 , TheText); //绘制文本到指定区域 end; end; procedure TForm1.RotatedTextClick(Sender: TObject); Var TheAngle : Integer; begin TheAngle := StrToInt(Edit2.Text); //将文本框中的文本转换角度 DrawRotatedText(Image3.Canvas, TheAngle, 'Delphi图形工作室'); //调用旋转文本函数 end; procedure TForm1.FormCreate(Sender: TObject); var tf : TFont; theText:string; begin theText:='Delphi图形工作室'; //设置文本 with Image3.Canvas do begin Font.Name := 'Arial'; //设置字体 Font.Size := 18; //设置字体大小 Brush.Style := bsClear; //设置笔刷样式 tf:= TFont.Create; //创建一个Font 具体对象 TextOut(Image3.left, Image3.top+20 , TheText); //绘制文本到指定区域 end; end; end.
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