本例效果圖:
代碼文件:unit Unit1;
interface
uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls, CheckLst, ExtCtrls, TeCanvas, ComCtrls;
type
TForm1 = class(TForm)
TrackBar1: TTrackBar;
TrackBar2: TTrackBar;
procedure FormCreate(Sender: TObject);
procedure FormDestroy(Sender: TObject);
procedure FormPaint(Sender: TObject);
procedure TrackBar1Change(Sender: TObject);
procedure TrackBar2Change(Sender: TObject);
end;
var
Form1: TForm1;
implementation
{$R *.dfm}
uses GDIPOBJ, GDIPAPI;
var
rect: TGPRect;
pb: TGPPathGradientBrush;
procedure TForm1.FormCreate(Sender: TObject);
var
path: TGPGraphicsPath;
ColorSurround: TGPColor;
num: Integer;
begin
rect := MakeRect(10, 10, ClientWidth-40, ClientHeight-40);
path := TGPGraphicsPath.Create;
path.AddEllipse(rect);
pb := TGPPathGradientBrush.Create(path);
pb.SetCenterColor(aclLime);
ColorSurround := aclBlack;
num := 1;
pb.SetSurroundColors(@ColorSurround, num);
path.Free;
DoubleBuffered := True;
TrackBar1.Max := 100;
TrackBar2.Max := 100;
end;
procedure TForm1.FormDestroy(Sender: TObject);
begin
pb.Free;
end;
procedure TForm1.FormPaint(Sender: TObject);
var
g: TGPGraphics;
p: TGPPen;
x,y: Single;
begin
g := TGPGraphics.Create(Canvas.Handle);
p := TGPPen.Create(aclRed);
g.FillEllipse(pb, rect);
pb.SetCenterPoint(MakePoint(rect.X + rect.Width div 2, rect.Y + rect.Height div 2));
{SetFocusScales}
pb.SetFocusScales(TrackBar1.Position / 100, TrackBar2.Position / 100);
{GetFocusScales}
pb.GetFocusScales(x, y);
Text := Format('%f,%f',[x,y]);
p.Free;
g.Free;
end;
procedure TForm1.TrackBar1Change(Sender: TObject);
begin
Repaint;
end;
procedure TForm1.TrackBar2Change(Sender: TObject);
begin
Repaint;
end;
end.
窗體文件:object Form1: TForm1
Left = 0
Top = 0
Caption = 'Form1'
ClientHeight = 164
ClientWidth = 208
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = -11
Font.Name = 'Tahoma'
Font.Style = []
OldCreateOrder = False
Position = poDesktopCenter
OnCreate = FormCreate
OnDestroy = FormDestroy
OnPaint = FormPaint
PixelsPerInch = 96
TextHeight = 13
object TrackBar1: TTrackBar
Left = 0
Top = 143
Width = 200
Height = 23
ShowSelRange = False
TabOrder = 0
OnChange = TrackBar1Change
end
object TrackBar2: TTrackBar
Left = 185
Top = 0
Width = 23
Height = 156
Orientation = trVertical
ShowSelRange = False
TabOrder = 1
OnChange = TrackBar2Change
end
end
