Question

I’m trying to iterate all the controls on a form and enable ClearType font smoothing. Something like this:

procedure TForm4.UpdateControls(AParent: TWinControl); var   I: Integer;   ACtrl: TControl;   tagLOGFONT: TLogFont; begin   for I := 0 to AParent.ControlCount-1 do   begin     ACtrl:= AParent.Controls[I];      // if ParentFont=False, update the font here...      if ACtrl is TWinControl then       UpdateControls(Ctrl as TWinControl);   end; end; 

Now, is there a easy way to check if ACtrl have a Font property so i can pass the Font.Handle to somethink like:

GetObject(ACtrl.Font.Handle, SizeOf(TLogFont), @tagLOGFONT); tagLOGFONT.lfQuality := 5; ACtrl.Font.Handle := CreateFontIndirect(tagLOGFONT); 

Thank you in advance.

Answer 1

You use TypInfo unit, more specifically methods IsPublishedProp and GetOrdProp.

In your case, it would be something like:

if IsPublishedProp(ACtrl, 'Font') then   ModifyFont(TFont(GetOrdProp(ACtrl, 'Font'))) 

A fragment from one of my libraries that should put you on the right path:

function ContainsNonemptyControl(controlParent: TWinControl;   const requiredControlNamePrefix: string;   const ignoreControls: string = ''): boolean; var   child   : TControl;   iControl: integer;   ignored : TStringList;   obj     : TObject; begin   Result := true;   if ignoreControls = '' then     ignored := nil   else begin     ignored := TStringList.Create;     ignored.Text := ignoreControls;   end;   try     for iControl := 0 to controlParent.ControlCount-1 do begin       child := controlParent.Controls[iControl];       if (requiredControlNamePrefix = '') or          SameText(requiredControlNamePrefix, Copy(child.Name, 1,            Length(requiredControlNamePrefix))) then       if (not assigned(ignored)) or (ignored.IndexOf(child.Name) < 0) then       if IsPublishedProp(child, 'Text') and (GetStrProp(child, 'Text') <> '') then         Exit       else if IsPublishedProp(child, 'Lines') then begin         obj := TObject(cardinal(GetOrdProp(child, 'Lines')));         if (obj is TStrings) and (Unwrap(TStrings(obj).Text, child) <> '') then           Exit;       end;     end; //for iControl   finally FreeAndNil(ignored); end;   Result := false; end; { ContainsNonemptyControl }