unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls, ExtCtrls;typeTForm1 = class(TForm)ComboBox1: TComboBox;ComboBox2: TComboBox;ComboBox3: TComboBox;ComboBox4: TComboBox;procedure FormCreate(Sender: TObject);procedure FormPaint(Sender: TObject);procedure ComboBox1Change(Sender: TObject);procedure ComboBox2Change(Sender: TObject);procedure ComboBox3Change(Sender: TObject);procedure ComboBox4Change(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}uses GDIPOBJ, GDIPAPI, TypInfo;var StartCap,EndCap,DashCap: Integer;procedure TForm1.FormCreate(Sender: TObject);
vari: Integer;
beginComboBox1.Text := '虚线样式';ComboBox2.Text := '起点线帽';ComboBox3.Text := '中间线帽';ComboBox4.Text := '终点线帽';for i := 0 to 5 doComboBox1.Items.Add(GetEnumName(TypeInfo(TDashStyle), i));ComboBox2.Items.Add('LineCapFlat');ComboBox2.Items.Add('LineCapSquare');ComboBox2.Items.Add('LineCapRound');ComboBox2.Items.Add('LineCapTriangle');ComboBox2.Items.Add('LineCapNoAnchor');ComboBox2.Items.Add('LineCapSquareAnchor');ComboBox2.Items.Add('LineCapRoundAnchor');ComboBox2.Items.Add('LineCapDiamondAnchor');ComboBox2.Items.Add('LineCapArrowAnchor');ComboBox3.Items := ComboBox2.Items;ComboBox4.Items := ComboBox2.Items;
end;procedure TForm1.FormPaint(Sender: TObject);
constColorArr: array[0..2] of TGPColor = (aclRed, aclGreen, aclBlue);
varg: TGPGraphics;p: TGPPen;x1,x2,y: Integer;i: Integer;
beging := TGPGraphics.Create(Canvas.Handle);p := TGPPen.Create($FF000000, 16);p.SetDashStyle(TDashStyle(ComboBox1.ItemIndex));p.SetLineCap(StartCap, EndCap, DashCap);x1 := 50;x2 := ClientWidth - 50;y := 60;for i := 0 to 2 dobeginp.SetColor(ColorArr[i]);g.DrawLine(p, x1, y, x2, y);Inc(y, 40);end;p.Free;g.Free;
end;procedure TForm1.ComboBox1Change(Sender: TObject);
beginRepaint;
end;procedure TForm1.ComboBox2Change(Sender: TObject);
vari: Integer;
begini := 0;case TComboBox(Sender).ItemIndex of0 : i := LineCapFlat;1 : i := LineCapSquare;2 : i := LineCapRound;3 : i := LineCapTriangle;4 : i := LineCapNoAnchor;5 : i := LineCapSquareAnchor;6 : i := LineCapRoundAnchor;7 : i := LineCapDiamondAnchor;8 : i := LineCapArrowAnchor;9 : i := LineCapCustom;10: i := LineCapAnchorMask;end;if TComboBox(Sender) = ComboBox2 then StartCap := i;if TComboBox(Sender) = ComboBox3 then DashCap := i;if TComboBox(Sender) = ComboBox4 then EndCap := i;Repaint;
end;procedure TForm1.ComboBox3Change(Sender: TObject);
beginComboBox2Change(Sender);
end;procedure TForm1.ComboBox4Change(Sender: TObject);
beginComboBox2Change(Sender);
end;end.

窗体文件:

object Form1: TForm1Left = 0Top = 0Caption = 'Form1'ClientHeight = 165ClientWidth = 515Color = clBtnFaceFont.Charset = DEFAULT_CHARSETFont.Color = clWindowTextFont.Height = -11Font.Name = 'Tahoma'Font.Style = []OldCreateOrder = FalsePosition = poDesktopCenterOnCreate = FormCreateOnPaint = FormPaintPixelsPerInch = 96TextHeight = 13object ComboBox1: TComboBoxLeft = 8Top = 8Width = 121Height = 21ItemHeight = 13TabOrder = 0Text = 'ComboBox1'OnChange = ComboBox1Changeendobject ComboBox2: TComboBoxLeft = 135Top = 8Width = 121Height = 21ItemHeight = 13TabOrder = 1Text = 'ComboBox2'OnChange = ComboBox2Changeendobject ComboBox3: TComboBoxLeft = 262Top = 8Width = 121Height = 21ItemHeight = 13TabOrder = 2Text = 'ComboBox3'OnChange = ComboBox3Changeendobject ComboBox4: TComboBoxLeft = 389Top = 8Width = 121Height = 21ItemHeight = 13TabOrder = 3Text = 'ComboBox4'OnChange = ComboBox4Changeend
end