如何使单个组件支持VCL和FMX？

Question

我有一个TComponent控制一些UI.此组件旨在通过使用条件来支持VCL和Firemonkey.此类条件指示我的组件是接受VCL控件还是FMX控件.目前预计此条件在应用程序级别定义,以指示组件在运行时是否管理VCL或FMX控件.

我想将我的组件发布到IDE中,同时支持VCL和FMX,与条件共享相同的单元.但是,根据当前是否正在使用VCL或FMX,属性名称/类型会有所不同.

例如...

type
  TMyComponent = class(TComponent)
  published
    {$IFDEF USE_FMX}
    property TabControl: TTabControl read FTabControl write SetTabControl;
    {$ENDIF}
    {$IFDEF USE_VCL}
    property PageControl: TPageControl read FPageControl write SetPageControl;
    {$ENDIF}
  end;

我的目标是能够将这个非可视组件放到VCL或FMX表单上,并在对象检查器中自动显示适当的框架特定属性.

如何注册通过条件共享VCL和FMX代码的组件？

Answer 1

我强烈建议您不要尝试创建特定于框架的属性。我建议改为创建单独的特定于框架的适配器组件，然后您可以根据需要将这些适配器之一分配给您的主要组件，例如：

unit MyComponentUI;

interface

uses
  Classes;

type
  TMyComponentUIControl = class(TComponent)
  public
    procedure DoSomethingWithControl; virtual; abstract;
    ...
  end;

implementation

...

end.

unit MyComponentFmxUI;

uses
  MyComponentUI,
  FMX.TabControl;

type
  TMyComponentUIControl_FMXTabControl = class(TMyComponentUIControl)
  private
    FTabControl: TTabControl;
    procedure SetTabControl(Value: TTabControl);
  protected
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
  public
    procedure DoSomethingWithControl; override;
  published
    property TabControl: TTabControl read FTabControl write SetTabControl;
  end;

procedure Register;

implementation

uses
  FMX.Controls;

procedure TMyComponentUIControl_FMXTabControl.DoSomethingWithControl; 
begin
  if FTabControl <> nil then
  begin
    ...
  end;
end;

procedure TMyComponentUIControl_FMXTabControl.SetTabControl(Value: TTabControl);
begin
  if FTabControl <> Value then
  begin
    if FTabControl <> nil then FTabControl.RemoveFreeNotification(Self);
    FTabControl := Value;
    if FTabControl <> nil then FTabControl.FreeNotification(Self);
  end;
end;

procedure TMyComponentUIControl_FMXTabControl.Notification(AComponent: TComponent; Operation: TOperation);
begin
  inherited;
  if (Operation = opRemove) and (AComponent = FTabControl) then
    FTabControl := nil;
end;

procedure Register;
begin
  GroupDescendantsWith(TMyComponentUIControl_FMXTabControl, TControl);
  RegisterComponents('My Component', [TMyComponentUIControl_FMXTabControl]);
end;

end.

unit MyComponentVclUI;

interface

uses
  MyComponentUI,
  Vcl.ComCtrls;

type
  TMyComponentUIControl_VCLPageControl = class(TMyComponentUIControl)
  private
    FPageControl: TPageControl;
    procedue SetPageControl(Value: TPageControl);
  protected
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
  public
    procedure DoSomethingWithControl; override;
  published
    property PageControl: TPageControl read FPageControl write SetPageControl;
  end;

procedure Register;

implementation

uses
  Vcl.Controls;

procedure TMyComponentUIControl_VCLPageControl.DoSomethingWithControl; 
begin
  if FPageControl <> nil then
  begin
    ...
  end;
end;

procedure TMyComponentUIControl_VCLPageControl.SetPageControl(Value: TPageControl);
begin
  if FPageControl <> Value then
  begin
    if FPageControl <> nil then FPageControl.RemoveFreeNotification(Self);
    FPageControl := Value;
    if FPageControl <> nil then FPageControl.FreeNotification(Self);
  end;
end;

procedure TMyComponentUIControl_VCLPageControl.Notification(AComponent: TComponent; Operation: TOperation);
begin
  inherited;
  if (Operation = opRemove) and (AComponent = FPageControl) then
    FPageControl := nil;
end;

procedure Register;
begin
  GroupDescendantsWith(TMyComponentUIControl_VCLPageControl, TControl);
  RegisterComponents('My Component', [TMyComponentUIControl_VCLPageControl]);
end;

end.

unit MyComponent;

interface

uses
  Classes,
  MyComponentUI;

type
  TMyComponent = class(TComponent)
  private
    FUIControl: TMyComponentUIControl;
    procedure SetUIControl(Value: TMyComponentUIControl);
  protected
    procedure Notification(AComponent: TComponent; Operation: TOperation); override;
  public
    procedure DoSomething;
  published
    property UIControl: TMyComponentUIControl read FUIControl write SetUIControl;
  end;

procedure Register;

implementation

procedure TMyComponent.DoSomething;
begin
  ...
  if FUIControl <> nil then
    FUIControl.DoSomethingWithControl;
  ...
end;

procedure TMyComponent.SetUIControl(Value: TMyComponentUIControl);
begin
  if FUIControl <> Value then
  begin
    if FUIControl <> nil then FUIControl.RemoveFreeNotification(Self);
    FUIControl := Value;
    if FUIControl <> nil then FUIControl.FreeNotification(Self);
  end;
end;

procedure TMyComponent.Notification(AComponent: TComponent; Operation: TOperation);
begin
  inherited;
  if (Operation = opRemove) and (AComponent = FUIControl) then
    FUIControl := nil;
end;

procedure Register;
begin
  RegisterComponents('My Component', [TMyComponent]);
end;

end.

通过使用GroupDescendentsWith()到组中的每个适配器与任一FMX.Controls.TControl或Vcl.Controls.TControl，这允许IDE过滤以基于在父项目中使用的框架设计时的组件：

在VCL表单设计器上，您只会TMyComponentUIControl_VCLPageControl在“工具选项板”中看到 可用。

在FMX表单设计器上，您只会TMyComponentUIControl_FMXTabControl在“工具选项板”中看到可用。

在DataModule Designer上，除非将TDataModule.ClassGroup属性设置为VCL或FMX组，否则将看不到任何一个适配器。然后，您将在“工具面板”中看到适当的适配器。