Delphi控件开发(四)双击头像切换

bit := TBitmap.Create;
  bit.LoadFromFile('d:\vcl\aa.bmp');
  StretchBlt(Canvas.Handle,0,0,100,100,bit.Canvas.Handle,0,0,bit.Width,bit.Height,SRCCOPY );

unit Myhead;

interface

uses
  Windows, SysUtils, Classes, Controls, Graphics, jpeg;

type
  TMyhead = class(TCustomControl)
  private
    { Private declarations }
    FIsOn: Boolean;
    FPicOn: TJPEGImage;
    FPicOff: TJPEGImage;
    procedure SetIsOn(const Value: Boolean);
  protected
    { Protected declarations }
    procedure Paint;override;
    procedure Click;override;
  public
    { Public declarations }
    constructor Create(A: TComponent);override;
    destructor Destroy;override;
  published
    { Published declarations }
    property IsOn: Boolean read FIsOn write SetIsOn;
    property Width;
    property Height;
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Samples', [TMyhead]);
end;

{ TMyhead }

procedure TMyhead.Click;
begin
  IsOn := not FIsOn;
  inherited;
end;

constructor TMyhead.Create(A: TComponent);
begin
  inherited Create(A);
  FPicOn := TJPEGImage.Create;
  FPicOn.LoadFromFile('d:\vcl\aa.jpg');
  FPicOff := TJPEGImage.Create;
  FPicOff.LoadFromFile('d:\vcl\b.jpg');
end;

destructor TMyhead.Destroy;
begin
  FPicOn.Free;
  FPicOff.Free;
  inherited Destroy;
end;

procedure TMyhead.Paint;
begin
  inherited;
  if FIsOn then
  begin
    Canvas.StretchDraw(Rect(0,0,Width,Height), FPicOn);
  end
  else
  begin
    Canvas.StretchDraw(Rect(0,0,Width,Height), FPicOff);
  end;
end;

procedure TMyhead.SetIsOn(const Value: Boolean);
begin
  FIsOn := Value;
  Invalidate;
end;

end.