unit Unit1;interfaceusesWindows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,Dialogs, StdCtrls, TeCanvas, ComCtrls;typeTForm1 = class(TForm)ComboBox1: TComboBox;ComboBox2: TComboBox;TrackBar1: TTrackBar;ButtonColor1: TButtonColor;procedure FormCreate(Sender: TObject);procedure FormPaint(Sender: TObject);procedure ComboBox1Change(Sender: TObject);procedure ComboBox2Change(Sender: TObject);procedure TrackBar1Change(Sender: TObject);procedure ButtonColor1Click(Sender: TObject);end;varForm1: TForm1;implementation{$R *.dfm}uses GDIPOBJ,GDIPAPI, TypInfo;varStartCap, EndCap: Integer;LineWidth: Single = 2;LineColor: TGPColor = aclRed;procedure TForm1.FormCreate(Sender: TObject);
beginwith ComboBox1.Items dobeginAdd('LineCapFlat');Add('LineCapSquare');Add('LineCapRound');Add('LineCapTriangle');Add('LineCapNoAnchor');Add('LineCapSquareAnchor');Add('LineCapRoundAnchor');Add('LineCapDiamondAnchor');Add('LineCapArrowAnchor');Add('LineCapCustom');end;ComboBox1.ItemIndex := 0;ComboBox2.Items := ComboBox1.Items;ComboBox2.ItemIndex := 0;TrackBar1.ShowSelRange := False;TrackBar1.Min := 1;TrackBar1.Max := 50;TrackBar1.Position := 2;ButtonColor1.SymbolColor := clRed;
end;procedure TForm1.FormPaint(Sender: TObject);
varg: TGPGraphics;p: TGPPen;x1,y1,x2,y2: Integer;
beging := TGPGraphics.Create(Canvas.Handle);p := TGPPen.Create(0);g.Clear(MakeColor(255,255,255));x1 := 50;x2 := ClientWidth - 50;y1 := ClientHeight div 2;y2 := y1;p.SetColor(LineColor);p.SetWidth(LineWidth);p.SetStartCap(StartCap);p.SetEndCap(EndCap);g.DrawLine(p, x1, y1, x2, y2);g.Free;p.Free;
end;procedure TForm1.ComboBox1Change(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) = ComboBox1 then StartCap := i;if TComboBox(Sender) = ComboBox2 then EndCap := i;Repaint;
end;procedure TForm1.ComboBox2Change(Sender: TObject);
beginComboBox1Change(Sender);
end;procedure TForm1.TrackBar1Change(Sender: TObject);
beginLineWidth := TrackBar1.Position;Repaint;
end;procedure TForm1.ButtonColor1Click(Sender: TObject);
beginLineColor := ColorRefToARGB(ButtonColor1.SymbolColor);Repaint;
end;end.

窗体文件:

object Form1: TForm1Left = 0Top = 0Caption = 'Form1'ClientHeight = 206ClientWidth = 315Color = clBtnFaceFont.Charset = DEFAULT_CHARSETFont.Color = clWindowTextFont.Height = -11Font.Name = 'Tahoma'Font.Style = []OldCreateOrder = FalsePosition = poDesktopCenterOnCreate = FormCreateOnPaint = FormPaintPixelsPerInch = 96TextHeight = 13object ComboBox1: TComboBoxLeft = 8Top = 8Width = 145Height = 21ItemHeight = 13TabOrder = 0Text = 'ComboBox1'OnChange = ComboBox1Changeendobject ComboBox2: TComboBoxLeft = 162Top = 8Width = 145Height = 21ItemHeight = 13TabOrder = 1Text = 'ComboBox2'OnChange = ComboBox2Changeendobject TrackBar1: TTrackBarLeft = 3Top = 182Width = 223Height = 20TabOrder = 2OnChange = TrackBar1Changeendobject ButtonColor1: TButtonColorLeft = 232Top = 177Caption = 'ButtonColor1'TabOrder = 3OnClick = ButtonColor1Clickend
end

附线帽样式常数:

LineCapFlat          = 0;   {指定平线帽}
LineCapSquare        = 1;   {指定方线帽}
LineCapRound         = 2;   {指定圆线帽}
LineCapTriangle      = 3;   {指定三角线帽}
LineCapNoAnchor      = $10; {指定没有锚}
LineCapSquareAnchor  = $11; {指定方锚头帽}
LineCapRoundAnchor   = $12; {指定圆锚头帽}
LineCapDiamondAnchor = $13; {指定菱形锚头帽}
LineCapArrowAnchor   = $14; {指定箭头状锚头帽}
LineCapCustom        = $ff; {指定自定义线帽}LineCapAnchorMask    = $f0; {定用于检查线帽是否为锚头帽的掩码}