问题描述
我正在尝试为某些自定义组件创建自定义属性编辑器。自定义属性编辑器旨在编辑某些集合属性，例如
I'm trying to create a custom property editor for some custom component. The custom property editor is intended to edit some set property, like
type
TButtonOption = (boOption1, boOption2, boOption3);
TButtonOptions = set of TButtonOption;
我的属性编辑器来自TSetProperty类。问题是：我的自定义属性编辑器未注册，Delphi IDE似乎使用了它自己的默认集合属性编辑器，因为属性编辑器方法内部的ShowMessage（）调用永远不会执行！我已经从头开始创建了一个示例程序包/组件，它尽可能简单，以显示此问题。这是代码：
my property editor descends from TSetProperty class. The problem is: my custom property editor doesn't get registered and Delphi IDE seems to use its own default set property editor, because ShowMessage() calls inside property editor methods never executes! I've created a sample package/component from scratch, as simple as possible, showing this issue. Here is the code:
unit Button1;
interface
uses
System.SysUtils, System.Classes, Vcl.Controls, Vcl.StdCtrls, DesignIntf, DesignEditors;
type
TButtonOption = (boOption1, boOption2, 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.
请注意：
- 我正在为具有TButtonOptions属性的所有组件注册新的属性编辑器（TMySetProperty）。我也尝试只对TButtonEx这样做，但是结果是一样的。
- 我已经在自定义属性编辑器的所有重写方法中添加了ShowMessage（）调用，而这些方法从未获得
- 我已经调试了程序包并执行RegisterPropertyEditor（）。尽管如此，我在覆盖方法中的自定义代码却永远不会执行。代码差异。
所以问题是：
为什么我的自定义属性编辑器无法注册/工作？
So the question is:Why my custom property editor does not register/work?
注意：至少在Delphi XE2，XE3，XE4和XE5中会发生此问题。其他IDE尚未经过测试，但可能具有相同的行为。
Note: This issue happens in Delphi XE2, XE3, XE4 and also XE5 at least. Other IDEs were not tested but probably have the same behavior.
推荐答案
最后，我得到了一个解决方案...经过测试，我可以想象-没有成功-我开始在DesignEditors.pas和DesignIntf.pas单元中搜索新内容。通过阅读GetEditorClass（）函数，我发现它首先检查了PropertyMapper。可以使用RegisterPropertyMapper（）函数注册属性映射器。使用它代替RegisterPropertyEditor（）可以按预期工作。这是我修改后的有效代码，还显示了一些有趣的应用程序：根据一些条件显示或隐藏基于集合的属性的一些选项：
Finally I got a solution... After testing everything I could imagine - without success - I started searching for something "new" in DesignEditors.pas and DesignIntf.pas units. Reading GetEditorClass() function, I discovered that it first checks for a PropertyMapper. A property mapper can be registered using RegisterPropertyMapper() function. Using it instead of RegisterPropertyEditor() works just as expected. Here is my modified, working code, also showing some interesting application for this: show or hide some options of my set-based property, based on some criteria:
unit Button1;
interface
uses
System.SysUtils, System.Classes, Vcl.Controls, Vcl.StdCtrls,
DesignIntf, 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.
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