《GOF设计模式》—桥接（BRIDGE）—Delphi源码示例：可移植的用户界面

示例：可移植的用户界面
说明：



代码：

unit uWindow;

interface

uses
Windows,SysUtils,Classes,Graphics;

type
TWindow = class;
TWindowImp = class;

{窗口视图}
TView = class
public
//---
procedure Draw(const AWindow: TWindow);
end;

{窗口抽象类}
TWindow = class
private
FCanvas: TCanvas;
FContents: TView;
FImp: TWindowIMP;
function GetView(): TView;
function GetWindowIMP: TWindowIMP;
procedure SetOrigin(const Value: TPoint);
procedure SetExtent(const Value: TPoint);
protected
procedure DrawLine(const p1,p2: TPoint);
procedure DrawRect(const p1,p2: TPoint);
procedure DrawPolygon(const Points: array of TPoint);
procedure DrawText(const text: string; position: TPoint);
//---
property WindowIMP: TWindowIMP read GetWindowIMP;
property View: TView read GetView;
public
constructor Create(ACanvas: TCanvas; contents: TView);
//---
procedure Open; virtual;
procedure Close(); virtual;
procedure Iconify(); virtual;
procedure Deiconfy(); virtual;
//---
procedure Raised(); virtual;
procedure Lower(); virtual;
//---
procedure DrawContents; virtual; abstract;
//---
property Origin: TPoint write SetOrigin;
property Extent: TPoint write SetExtent;
end;

TApplicationWindow = class(TWindow)
public
procedure DrawContents(); override;
procedure DrawCloseBox;
end;

TIconWindow = class(Twindow)
private
FBitmapName: string;
public
procedure DrawContents; override;
procedure DrawBorder;
//---
property BitmapName: string write FBitmapName;
end;

{窗口实现类}
TWindowImp = class
protected
procedure SetOrigin(const Value: TPoint); virtual;
procedure SetExtent(const Value: TPoint); virtual;
public
constructor Create;
//---
procedure DeviceDrawLine(const p1,p2: TPoint); virtual; abstract;
procedure DeviceDrawPolygon(const Points: array of TPoint); virtual; abstract;
procedure DeviceDrawRect(const x1,y1,x2,y2: integer); virtual; abstract;
procedure DeviceDrawText(const Text: string; x1,y1: integer); virtual; abstract;
procedure DeviceDrawBitmap(const ABitmapName: string; x1,y1: integer); virtual; abstract;
//---
property Origin: TPoint write SetOrigin;
property Extent: TPoint write SetExtent;
end;

TXWindowImp = class(TWindowImp)
private
FCanvas: TCanvas;
public
constructor Create(ACanvas: TCanvas);
//---
procedure DeviceDrawLine(const p1,p2: TPoint); override;
procedure DeviceDrawRect(const x1,y1,x2,y2: integer); override;
procedure DeviceDrawText(const Text: string; x1,y1: integer); override;
procedure DeviceDrawBitmap(const ABitmapName: string; x1,y1: integer); override;
procedure DeviceDrawPolygon(const Points: array of TPoint); override;
end;

TPMWindowImp = class(TWindowImp)
private
FCanvas: TCanvas;
public
constructor Create(ACanvas: TCanvas);
//---
procedure DeviceDrawLine(const p1,p2: TPoint); override;
procedure DeviceDrawRect(const x1,y1,x2,y2: integer); override;
procedure DeviceDrawText(const Text: string; x1,y1: integer); override;
procedure DeviceDrawBitmap(const ABitmapName: string; x1,y1: integer); override;
procedure DeviceDrawPolygon(const Points: array of TPoint); override;
end;

TWindowSystemFactory = class
public
constructor Create;
destructor Destroy; override;
//---
class function Instance(): TWindowSystemFactory;
function MakeWindowImp(ACanvas: TCanvas): TWindowImp;
end;

implementation

var
FFactory: TWindowSystemFactory;

procedure TView.Draw(const AWindow: TWindow);
begin
AWindow.DrawText('abc',Point(12,12));
end;

constructor TWindow.Create(ACanvas: TCanvas; contents: TView);
begin
FCanvas := ACanvas;
FContents := contents;
end;

procedure TWindow.Open;
begin
end;

procedure TWindow.Close();
begin
end;

procedure TWindow.Iconify();
begin
end;

procedure TWindow.Deiconfy();
begin
end;

procedure TWindow.SetExtent(const Value: TPoint);
begin
self.WindowIMP.Extent := Value;
end;

procedure TWindow.Raised();
begin
end;

procedure TWindow.Lower();
begin
end;

procedure TWindow.DrawLine(const p1,p2: TPoint);
begin
self.WindowIMP.DeviceDrawLine(p1,p2);
end;

procedure TWindow.DrawRect(const p1,p2: TPoint);
begin
self.WindowIMP.DeviceDrawRect(p1.x,p1.y,p2.x,p2.y);
end;

procedure TWindow.DrawPolygon(const Points: array of TPoint);
begin
self.WindowIMP.DeviceDrawPolygon(Points);
end;

procedure TWindow.DrawText(const text: string; position: TPoint);
begin
self.WindowIMP.DeviceDrawText(text,position.X,position.Y);
end;

function TWindow.GetWindowIMP: TWindowIMP;
begin
if FImp = nil then
FImp := TWindowSystemFactory.Instance.MakeWindowImp(FCanvas);
//---
Result := FImp;
end;

function TWindow.GetView(): TView;
begin
Result := FContents;
end;

procedure TWindow.SetOrigin(const Value: TPoint);
begin
self.WindowIMP.Origin := Value;
end;

constructor TWindowSystemFactory.Create;
begin
if FFactory = nil then
FFactory := Self
else
abort;
end;

destructor TWindowSystemFactory.Destroy;
begin
FFactory := nil;
//---
inherited;
end;

class function TWindowSystemFactory.Instance(): TWindowSystemFactory;
begin
if FFactory = nil then
FFactory := TWindowSystemFactory.Create;
//---
Result := FFactory;
end;

function TWindowSystemFactory.MakeWindowImp(ACanvas: TCanvas): TWindowImp;
//---
function GetImpNameByIni: string;
begin
Result := 'PM';
end;
var
AImpName: string;
begin
AImpName := GetImpNameByIni;
//---
if AImpName = 'PM' then
Result := TPMWindowImp.Create(ACanvas)
else if AImpName = 'X' then
Result := TXWindowImp.Create(ACanvas)
else
Result := TPMWindowImp.Create(ACanvas);
end;

constructor TWindowImp.Create;
begin
end;

procedure TWindowImp.SetExtent(const Value: TPoint);
begin
end;

procedure TWindowImp.SetOrigin(const Value: TPoint);
begin
end;

procedure TApplicationWindow.DrawCloseBox;
begin
self.DrawRect(Point(10,10),Point(50,50));
end;

procedure TApplicationWindow.DrawContents();
begin
self.View.Draw(self);
end;

procedure TIconWindow.DrawBorder;
begin
self.DrawRect(Point(10,10),Point(50,50));
self.DrawText('123',Point(12,12));
end;

procedure TIconWindow.DrawContents();
begin
if FBitmapName <> '' then
self.WindowIMP.DeviceDrawBitmap(FBitmapName,0,0);
//----
self.WindowIMP.DeviceDrawLine(Point(10,10),Point(50,50));
end;

constructor TXWindowImp.Create(ACanvas: TCanvas);
begin
inherited Create;
//---
FCanvas := ACanvas;
end;

procedure TXWindowImp.DeviceDrawBitmap(const ABitmapName: string; x1,y1:
integer);
//---
procedure _XDrawBitmap;
var
AGraphic: TBitmap;
begin
AGraphic := TBitmap.Create;
try
AGraphic.LoadFromFile(ABitmapName);
FCanvas.Draw(0,0,AGraphic);
finally
AGraphic.Free;
end;
end;
begin
_XDrawBitmap;
end;

procedure TXWindowImp.DeviceDrawLine(const p1,p2: TPoint);
//---
procedure _XDrawLine;
begin
with FCanvas do
begin
with Pen do
begin
Color := clRed;
Width := 1;
Style := psSolid;
end;
//---
MoveTo(p1.X,p1.X);
LineTo(p2.X,p2.X);
end;
end;
begin
_XDrawLine;
end;

procedure TXWindowImp.DeviceDrawPolygon(const Points: array of TPoint);
//---
procedure _XDrawPolygon;
begin
with FCanvas do
begin
with Pen do
begin
Color := clRed;
Width := 1;
Style := psSolid;
end;
Brush.Color := clWhite;
//---
Polygon(Points);
end;
end;
begin
_XDrawPolygon;
end;

procedure TXWindowImp.DeviceDrawRect(const x1,y1,x2,y2: integer);
//---
procedure _XDrawRect;
begin
with FCanvas do
begin
with Pen do
begin
Color := clRed;
Width := 1;
Style := psSolid;
end;
Brush.Color := clWhite;
//---
Rectangle(x1,y1,x2,y2);
end;
end;
begin
_XDrawRect;
end;

procedure TXWindowImp.DeviceDrawText(const Text: string; x1,y1: integer);
//---
procedure _XDrawString;
begin
with FCanvas do
begin
with Font do
begin
Name := '宋体';
Size := 11;
Color := clRed;
end;
TextOut(x1,y1,Text);
end;
end;
begin
_XDrawString;
end;

constructor TPMWindowImp.Create(ACanvas: TCanvas);
begin
inherited Create;
//---
FCanvas := ACanvas;
end;

procedure TPMWindowImp.DeviceDrawBitmap(const ABitmapName: string; x1,y1:
integer);
//---
procedure _PMDrawBitmap;
var
AGraphic: TBitmap;
begin
AGraphic := TBitmap.Create;
try
AGraphic.LoadFromFile(ABitmapName);
FCanvas.StretchDraw(Rect(0,0,AGraphic.Width div 2,AGraphic.Height div 2),AGraphic);
finally
AGraphic.Free;
end;
end;
begin
_PMDrawBitmap;
end;

procedure TPMWindowImp.DeviceDrawLine(const p1,p2: TPoint);
//---
procedure _PMDrawLine;
begin
with FCanvas do
begin
with Pen do
begin
Color := clBlue;
Width := 1;
Style := psDot;
end;
//---
MoveTo(p1.X,p1.X);
LineTo(p2.X,p2.X);
end;
end;
begin
_PMDrawLine;
end;

procedure TPMWindowImp.DeviceDrawPolygon(const Points: array of TPoint);
//---
procedure _PMDrawPolygon;
begin
with FCanvas do
begin
with Pen do
begin
Color := clBlue;
Width := 1;
Style := psDot;
end;
Brush.Color := clWhite;
//---
Polygon(Points);
end;
end;
begin
_PMDrawPolygon;
end;

procedure TPMWindowImp.DeviceDrawRect(const x1,y1,x2,y2: integer);
//---
procedure _PMDrawRect;
begin
with FCanvas do
begin
with Pen do
begin
Color := clBlue;
Width := 1;
Style := psDot;
end;
Brush.Color := clYellow;
//---
Rectangle(x1,y1,x2,y2);
end;
end;
begin
_PMDrawRect;
end;

procedure TPMWindowImp.DeviceDrawText(const Text: string; x1,y1: integer);
//---
procedure _PMDrawString;
begin
with FCanvas do
begin
with Font do
begin
Name := '宋体';
Size := 11;
Color := clBlue;
end;
TextOut(x1,y1,Text);
end;
end;
begin
_PMDrawString;
end;

end.

procedure TForm1.Button1Click(Sender: TObject);

var
AWindow: TWindow;
AView: TView;
begin
AView := TView.Create;
AWindow := TApplicationWindow.Create(self.Canvas,AView);
try
AWindow.DrawContents;
finally
AWindow.Free;
AView.Free;
end;
end;