delphi – 创建自定义TSetProperty属性编辑器

type
  TButtonOption = (boOption1,boOption2,boOption3);
  TButtonOptions = set of TButtonOption;

unit Button1;

interface

uses
  System.SysUtils,System.Classes,Vcl.Controls,Vcl.StdCtrls,DesignIntf,DesignEditors;

type
  TButtonOption = (boOption1,boOption3);

  TButtonOptions = set of TButtonOption;

  TButtonEx = class(TButton)
  private
    FOptions: TButtonOptions;
    function GetOptions: TButtonOptions;
    procedure SetOptions(Value: TButtonOptions);
  published
    property Options: TButtonOptions read GetOptions write SetOptions default [];
  end;

  TMySetProperty = class(TSetProperty)
  public
    function GetAttributes: TPropertyAttributes; override;
    procedure GetProperties(Proc: TGetPropProc); override;
    function GetValue: string; override;
  end;

procedure Register;

implementation

uses
  Dialogs;

// TButtonEx - sample component

function TButtonEx.GetOptions: TButtonOptions;
begin
  Result := FOptions;
end;

procedure TButtonEx.SetOptions(Value: TButtonOptions);
begin
  if FOptions <> Value then
  begin
    FOptions := Value;
  end;
end;

// register stuff

procedure Register;
begin
  RegisterComponents('Samples',[TButtonEx]);
  RegisterPropertyEditor(TypeInfo(TButtonOptions),nil,'',TMySetProperty);
end;

function TMySetProperty.GetAttributes: TPropertyAttributes;
begin
  ShowMessage('GetAttributes');
  Result := inherited GetAttributes;
end;

procedure TMySetProperty.GetProperties(Proc: TGetPropProc);
begin
  ShowMessage('GetProperties');
  inherited;
end;

function TMySetProperty.GetValue: string;
begin
  ShowMessage('GetValue');
  Result := inherited GetValue;
end;

end.

最后我得到了一个解决方案……在测试了我能想象到的一切 – 没有成功 – 我开始在DesignEditors.pas和DesignIntf??.pas单元中搜索“new”.读取GetEditorClass()函数,我发现它首先检查一个PropertyMapper.可以使用RegisterPropertyMapper()函数注册属性映射器.使用它而不是RegisterPropertyEditor()可以正常工作.这是我修改后的工作代码,也显示了一些有趣的应用程序：根据一些标准显示或隐藏基于集合的属性的一些选项：

unit Button1;

interface

uses
  System.SysUtils,DesignEditors;

type
  TButtonOption = (boOptionA,boOptionB,boOptionC);
  TButtonOptions = set of TButtonOption;

type
  TButtonEx = class(TButton)
  private
    FOptions: TButtonOptions;
    function GetOptions: TButtonOptions;
    procedure SetOptions(Value: TButtonOptions);
  published
    property Options: TButtonOptions read GetOptions write SetOptions default [];
  end;

  TMySetProperty = class(TSetProperty)
  private
    FProc: TGetPropProc;
    procedure InternalGetProperty(const Prop: IProperty);
  public
    procedure GetProperties(Proc: TGetPropProc); override;
  end;

procedure Register;

implementation

uses
  TypInfo;

// TButtonEx - sample component

function TButtonEx.GetOptions: TButtonOptions;
begin
  Result := FOptions;
end;

procedure TButtonEx.SetOptions(Value: TButtonOptions);
begin
  if FOptions <> Value then
  begin
    FOptions := Value;
  end;
end;

// Returns TMySetProperty as the property editor used for Options in TButtonEx class
function MyCustomPropMapper(Obj: TPersistent; PropInfo: PPropInfo): TPropertyEditorClass;
begin
  Result := nil;
  if Assigned(Obj) and (Obj is TButtonEx) and SameText(String(PropInfo.Name),'Options') then begin
    Result := TMySetProperty;
  end;
end;

procedure Register;
begin
  RegisterComponents('Samples',[TButtonEx]);
  // RegisterPropertyEditor does not work for set-based properties.
  // We use RegisterPropertyMapper instead
  RegisterPropertyMapper(MyCustomPropMapper);
end;

procedure TMySetProperty.GetProperties(Proc: TGetPropProc);
begin
  // Save the original method received
  FProc := Proc;
  // Call inherited,but passing our internal method as parameter
  inherited GetProperties(InternalGetProperty);
end;

procedure TMySetProperty.InternalGetProperty(const Prop: IProperty);
var
  i: Integer;
begin
  if not Assigned(FProc) then begin   // just in case
    Exit;
  end;

  // Now the interesting stuff. I just want to show boOptionA and boOptionB in Object inspector
  // So I call the original Proc in those cases only
  // boOptionC still exists,but won't be visible in object inspector
  for i := 0 to PropCount - 1 do begin
    if SameText(Prop.GetName,'boOptionA') or SameText(Prop.GetName,'boOptionB') then begin
      FProc(Prop);       // call original method
    end;
  end;
end;

end.