Delphi:使组件对实时绑定(bind)可见

Question

我一直在尝试制作一个具有对视觉绑定(bind)表单可见的字符串属性的测试对象。该组件已使用适当的属性进行注册。使用XE8和Firemonkey。

我可以通过使用隐藏显示元素选择它来将其显示在可视绑定(bind)器上，但是我无法让它将 Foo 字符串绑定(bind)到 TEdit 文本属性，只读(尚未执行任何操作)将绑定(bind)到文本属性。

• 如何让它以默认类可见性显示在其中
• 为什么 Foo 字符串不绑定(bind)到文本属性

帮助文件对此的描述有点薄弱。我想我在这里错过了一些非常简单的东西。

目标代码如下。

谢谢。

unit TestOBj;

interface

uses
  System.Classes, System.SysUtils, System.StrUtils, Data.Bind.Components;

Type

  TMyLBObject = Class (TComponent)
  private
    fFooString:String;
    FReadOnly: Boolean;
    procedure SetReadOnly(const Value: Boolean);
    procedure SetFooString(const Value: String);
  protected
    function CanObserve(const ID: Integer): Boolean; override;                       
    procedure ObserverAdded(const ID: Integer; const Observer: IObserver); override;
    procedure ObserverToggle(const AObserver: IObserver; const Value: Boolean);
  published
    property Foo:String read FFooString write SetFooString;
    property ReadOnly:Boolean read FReadOnly write SetReadOnly;
  End;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Test', [TMyLBObject]);
end;

{ TMyLBObject }

function TMyLBObject.CanObserve(const ID: Integer): Boolean;
begin
  Result := False;
  if ID = TObserverMapping.EditLinkID then
    Result := True;
  if ID = TObserverMapping.ControlValueID then
    Result := True;
end;

procedure TMyLBObject.ObserverAdded(const ID: Integer;
  const Observer: IObserver);
begin
  if ID = TObserverMapping.EditLinkID then
    Observer.OnObserverToggle := ObserverToggle;
end;


procedure TMyLBObject.ObserverToggle(const AObserver: IObserver;
  const Value: Boolean);
var
  LEditLinkObserver: IEditLinkObserver;
  LSaveReadOnly: Boolean;
begin
  if Supports(AObserver, IEditLinkObserver, LEditLinkObserver) then
  begin
    if Value then
    begin
      LSaveReadOnly := ReadOnly;
      if LEditLinkObserver.IsReadOnly then
        ReadOnly := True;
      FReadOnly := LSaveReadOnly;
    end
    else
      if not (csDestroying in ComponentState) then
        ReadOnly := FReadOnly;
  end;
end;


procedure TMyLBObject.SetFooString(const Value: String);
begin
  FFooString := Value;
end;

procedure TMyLBObject.SetReadOnly(const Value: Boolean);
begin
  FReadOnly := Value;
end;


initialization
  RegisterClass(TMyLBObject);
  RegisterObservableMember(TArray<TClass>.Create(TMyLBObject), 'Foo', 'FMX');
finalization
  UnRegisterObservableMember(TArray<TClass>.Create(TMyLBObject));
end.

Answer 1

您的 TMyLBObject 组件没有 [ObservableMember('Foo')] 属性。

type
  [ObservableMember('Foo')] // <-- add this
  TMyLBObject = Class (TComponent)
    ...
  published
    property Foo:String read FFooString write SetFooString;
    ...
  End;

请参阅文档中的示例:

Tutorial: Creating LiveBindings-Enabled Components .

其中包括此注释:

The ObservableMember attribute will be used by LiveBindings components to generate expressions. RegisterObserverableMember() will be used at design time to inform the LiveBindings Designer.