1

I've developed an inherited TCheckBox that needs some style fixes.

I've achieved this in the past with other firemonkey controls by overriding the "GetStyleObject" method and doing the necessary fixes "on the fly", over the original style object.

My intention with this "cleaner" approach is to allow the user to load any default firemonkey style, and still be able to code my own version of some styled controls.

Ex.:

type

  TMyCheckBox = class(TCheckBox)
  protected
    function GetStyleObject: TFmxObject; override;
  end;

function TMyCheckBox.GetStyleObject: TFmxObject;
begin
  Result := inherited;
  {do the required changes over the returned object}
end;

However, with this code, strangely "TMyCheckBox.GetStyleObject" never gets called, but with other controls like custom "TreeViewItem" it does...

Any thoughts?

Thank you all in advance.

António Cálix
  • 65
  • 3

1 Answers1

1

OK I had the same problem and here is how i solved them:

  1. Add FMX.Styles to the uses clause
  2. Create protected procedure called

    Procedure AppendStyle;

  3. Create protected virtual function:

    function GetClassStyleName: String; virtual;

  4. Define private variable
    FStyle : TFMXObject;

See the code below for explanation: Here is the code of my component:

Procedure TPlayerButton.AppendStyle;
var
  StyleObject : TFmxObject;
  BinStream   : TMemoryStream;
begin
  BinStream := TMemoryStream.Create;
  Try
    StyleObject := GetStyleObject;
      Try
        BinStream.WriteComponent(StyleObject);
        BinStream.Position := 0;
        FStyle := TStyleStreaming.LoadFromStream(BinStream)
      Finally
        StyleObject.Free;
      End;
  Finally
    BinStream.Free
  End;
End;

function TPlayerButton.GetClassStyleName: String;
begin
  Result := GetClassName + 'style';
  Delete(Result, 1, 1);
end;

` 4. In the component constructor add as last lines:

constructor TPlayerButton.Create(AOwner: TComponent);
begin
   inherited Create(AOwner);
   ...
   FStyle := nil;
   AppendStyle;
   StyleLookup                 := 'PlayerButtonStyle';
End;

Remember to free FStyle in the destructor;

if Assigned(FStyle) Then FreeAndNil(FStyle);

Everywhere replace TPlayerButton with the class name of your component.

VERY IMPORTANT: Remember when place a first component on a form to right click on it and select Edit Defalut Style

When Delphi style editor appear just close them. Now your style definition is added to the stylebook. You dont need to do this for next components placed ot the Form

Hope this will help you.

Sevast
  • 109
  • 1
  • 5
  • Not quite what i was looking for, i don't intend to use this by design time, only at runtime and without creating an additional style to cause more overhead on fmx resources, the target is to "tamper" or "refine" the default style of any default object by runtime, preserving its structural integrity, but nice effort... ;-) – António Cálix Oct 09 '17 at 02:46