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.
