How to convert Delphi TPageControl tab index to page index?

Question

I use TPageControl where some pages are not visible.

This disrupts the normal 1: 1 display of the TabIndex and ActivePageIndex properties.

In most cases, I can use ActivePageIndex (or ActivePage itself) to get the current page, but I need a dynamic tooltip, which requires me to determine which page is associated with a particular tab index.

If I call pageControl.IndexOfTabAt (X, Y), I get the tab index back, but I cannot directly use it as an index in the Pages [] array, since some tabs of the pages are not displayed.

I could iterate through the pages, ignoring the visible ones, but it looks like there should be something in VCL that does this for me already ...?

Answer 1

I look in the source for TPageControl (ComCtrls.pas), there is a private method:

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

does what you want. But you cannot call it (D2007), therefore (unfortunately) you need to copy the code.

Answer 2

Here's an old article about dragging and dropping pages. It has some logic to get the page index from position (X, Y), maybe you can use it. Something like this (untested):

 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;