如何将Delphi TPageControl的“tab index”转换为“page index”?

function TPageControl.PageIndexFromTabIndex(TabIndex: Integer): Integer;

那就是你想要的。

这个版本似乎有效:

function PageIndexFromTabIndex(const pageControl : TPageControl; const TabIndex: Integer): Integer;
 var
    i : Integer;
 begin
   Result := TabIndex;
   for i := 0 to Pred(pageControl.PageCount) do
     begin
       if not pageControl.Pages[i].TabVisible then
         Inc(Result);
       if TabIndex = pageControl.Pages[i].TabIndex then
         break;
     end;
  end;

Here is an old article

function TMyPageControl.GetPageIndexAtPos(X, Y: Integer) : Integer;
const
   TCM_GETITEMRECT = $130A;
var
   TabRect: TRect;
   j: Integer;    
begin
   for j := 0 to PageCount - 1 do
   begin
     Perform(TCM_GETITEMRECT, j, LParam(@TabRect)) ;
     if PtInRect(TabRect, Point(X, Y)) then
     begin
       Result := j;
       exit;
     end;
   end;
   Result := -1;
end;