单选按钮和复选框

单选按钮（RadioButton）和复选按框（CheckBox）都是很常用的组件，尤其是在对话框中。单选按钮（RadioButton）是一种具有排他性的选择组件，用户每一次只能选择其中的一个（在同一个容器组件中，如同一Form上或RadioBox中）。而复选框（CheckBox）则不同，可以同时选择多个。

　　两种组件都有一个Checked属性，用于标识和检测是否被选中。我们使用这两个组件，给上一节（Memo组件介绍）的例程（简单编辑器）添加一些新的功能，使它可以选择字体颜色和字体的样式。

　　程序的界面如下图所示：

　　程序如下：

unit Unit1; interface uses Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls; type TForm1 = class(TForm) Memo1: TMemo; Button1: TButton; SaveDialog1: TSaveDialog; OpenDialog1: TOpenDialog; Button2: TButton; Button3: TButton; Button4: TButton; Button5: TButton; Button6: TButton; Button7: TButton; RadioButton1: TRadioButton; RadioButton2: TRadioButton; RadioButton3: TRadioButton; CheckBox1: TCheckBox; CheckBox2: TCheckBox; CheckBox3: TCheckBox; procedure Button1Click(Sender: TObject); procedure FormCreate(Sender: TObject); procedure Button2Click(Sender: TObject); procedure Button5Click(Sender: TObject); procedure Button6Click(Sender: TObject); procedure Button3Click(Sender: TObject); procedure Button4Click(Sender: TObject); procedure Button7Click(Sender: TObject); procedure RadioButton1Click(Sender: TObject); procedure RadioButton2Click(Sender: TObject); procedure RadioButton3Click(Sender: TObject); procedure CheckBox1Click(Sender: TObject); procedure CheckBox2Click(Sender: TObject); procedure CheckBox3Click(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; implementation {$R *.DFM} procedure TForm1.Button1Click(Sender: TObject); begin memo1.Lines.Add('在末端添加文本'); end; procedure TForm1.FormCreate(Sender: TObject); begin memo1.Lines.Text:='这里是Memo组件示例'; memo1.Font.Color:=clRed; //设定文本的初始颜色为红色，因为RadioButton1是默认选中的 end; procedure TForm1.Button2Click(Sender: TObject); begin if Memo1.SelLength>0 then Memo1.CutToClipboard; end; procedure TForm1.Button5Click(Sender: TObject); begin if savedialog1.Execute then memo1.Lines.SaveToFile(savedialog1.FileName); end; procedure TForm1.Button6Click(Sender: TObject); begin if Opendialog1.Execute then memo1.Lines.LoadFromFile(opendialog1.FileName); end; procedure TForm1.Button3Click(Sender: TObject); begin if Memo1.SelLength>0 then Memo1.CopyToClipboard; end; procedure TForm1.Button4Click(Sender: TObject); begin if Memo1.SelLength=0 then Memo1.PasteFromClipboard; end; procedure TForm1.Button7Click(Sender: TObject); begin close; end; procedure TForm1.RadioButton1Click(Sender: TObject); begin if radiobutton1.Checked=true then //判断是否被选中 Memo1.Font.color:=clRed; //改变颜色 end; procedure TForm1.RadioButton2Click(Sender: TObject); begin if radiobutton2.Checked=true then Memo1.Font.Color:=clBlue; end; procedure TForm1.RadioButton3Click(Sender: TObject); begin if radiobutton3.Checked=true then Memo1.Font.Color:=clGreen; end; procedure TForm1.CheckBox1Click(Sender: TObject); begin if checkbox1.Checked=true then Memo1.Font.Style:=Memo1.Font.Style+[fsBold] else Memo1.Font.Style:=Memo1.Font.Style-[fsBold]; end; procedure TForm1.CheckBox2Click(Sender: TObject); begin if checkbox2.Checked=true then Memo1.Font.Style:=Memo1.Font.Style+[fsItalic] else Memo1.Font.Style:=Memo1.Font.Style-[fsItalic]; end; procedure TForm1.CheckBox3Click(Sender: TObject); begin if checkbox3.Checked=true then Memo1.Font.Style:=Memo1.Font.Style+[fsUnderline] else Memo1.Font.Style:=Memo1.Font.Style-[fsUnderline]; end; end.