画图学习 [2]

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    btn1: TButton;
    pnl1: TPanel;
    pb1: TPaintBox;
    procedure btn1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
var
cvs: TCanvas;

procedure TForm1.btn1Click(Sender: TObject);
begin
  pb1.Canvas.Brush.Color := clYellow;
  pb1.Canvas.FillRect(pb1.ClientRect);

  cvs := TCanvas.Create;
  cvs.Handle := GetDC(pnl1.Handle);
  cvs.Brush.Color := clBlue;
  cvs.FillRect(pnl1.ClientRect);
  cvs.Free;
end;


procedure TForm1.FormCreate(Sender: TObject);
begin
  Canvas.Pen.Color := clGreen;
  Canvas.Pen.Width := 2;
  Canvas.Brush.Color := clWhite;
end;

end.

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    btn1: TButton;
    btn2: TButton;
    procedure btn1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure btn2Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}


procedure TForm1.btn1Click(Sender: TObject);
var
  pts: array[0..3] of TPoint;
begin
  pts[0].X := btn1.Left+btn1.Width div 2;
  pts[0].Y := 10;
  pts[1].X := btn1.Left;
  pts[1].Y := 100;
  pts[2].X := btn1.Left+btn1.Width div 2;
  pts[2].Y := 200;
  pts[3].X := btn1.Left+btn1.Width;
  pts[3].Y := 100;

  Canvas.Polygon(pts);
end;


procedure TForm1.btn2Click(Sender: TObject);
var
  pts: array[0..3] of TPoint;
begin
  pts[0].X := btn2.Left+btn2.Width div 2;
  pts[0].Y := 10;
  pts[1].X := btn2.Left;
  pts[1].Y := 100;
  pts[2].X := btn2.Left+btn2.Width div 2;
  pts[2].Y := 200;
  pts[3].X := btn2.Left+btn2.Width;
  pts[3].Y := 100;
  Canvas.Polyline(pts);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Canvas.Pen.Color := clYellow;
  Canvas.Pen.Width := 2;
  Canvas.Brush.Color := clred;
end;

end.

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