再学 GDI+[63]: 路径画刷(3) SetFocusScales、GetFocusScales

本例效果图:

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代码文件:

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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.

窗体文件:

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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