R – How to convert Delphi TPageControl “tab index” to “page index”

delphitpagecontrol

I'm using a TPageControl, where certain pages are not visible.

This breaks the normal 1:1 mapping of the TabIndex and ActivePageIndex properties.

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

If I call pageControl.IndexOfTabAt(X, Y), I get a Tab Index back, but I can't directly use that as an index into the Pages[] array, as some page tabs aren't visible.

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

Best Answer

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

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

that does what you want. But you can't call it (D2007), so (unfortunately) you have to copy the code.

Related Solutions

Delphi – How to change the orientation of the label on a TPageControl

1.) set the TPageControl properties:

TabPosition := tpLeft;
OwnerDraw := True;
TabWidth := 180;    //set to any adequate value because
                    // TPageControl doesn't have a measure event handler

2.) use the following OnDrawTab code:

procedure TForm1.PageControl1DrawTab(Control: TCustomTabControl;
  TabIndex: Integer; const Rect: TRect; Active: Boolean);
var
  I: Integer;
  PageControl: TPageControl;
  TextFormat: TTextFormat;
  Text: string;
  TextRect: TRect;
begin
  PageControl := Control as TPageControl;

  Text := PageControl.Pages[TabIndex].Caption;

  for I := Length(Text) - 1 downto 1 do
  begin
    Text := Copy(Text, 1, I) + sLineBreak + Copy(Text, I+1, MaxInt);
  end;

  TextRect := Rect;
  TextRect.Left := TextRect.Left + 5;
  TextRect.Top := TextRect.Top + 3;

  TextFormat := [tfCenter];

  PageControl.Canvas.TextRect(
    TextRect,
    Text,
    TextFormat
    );
end;

3.) compile, start and enjoy !

Delphi – How to implement a close button for a TTabsheet of a TPageControl

Now with Theme support (include Windows, UxTheme, Themes units)!

type
  TFormMain = class(TForm)
    {...}
  private
    FCloseButtonsRect: array of TRect;
    FCloseButtonMouseDownIndex: Integer;
    FCloseButtonShowPushed: Boolean;
    {...}
  end;

{...}

procedure TFormMain.FormCreate(Sender: TObject);
var
  I: Integer;
begin
  PageControlCloseButton.TabWidth := 150;
  PageControlCloseButton.OwnerDraw := True;

  //should be done on every change of the page count
  SetLength(FCloseButtonsRect, PageControlCloseButton.PageCount);
  FCloseButtonMouseDownIndex := -1;

  for I := 0 to Length(FCloseButtonsRect) - 1 do
  begin
    FCloseButtonsRect[I] := Rect(0, 0, 0, 0);
  end;
end;

procedure TFormMain.PageControlCloseButtonDrawTab(Control: TCustomTabControl;
  TabIndex: Integer; const Rect: TRect; Active: Boolean);
var
  CloseBtnSize: Integer;
  PageControl: TPageControl;
  TabCaption: TPoint;
  CloseBtnRect: TRect;
  CloseBtnDrawState: Cardinal;
  CloseBtnDrawDetails: TThemedElementDetails;
begin
  PageControl := Control as TPageControl;

  if InRange(TabIndex, 0, Length(FCloseButtonsRect) - 1) then
  begin
    CloseBtnSize := 14;
    TabCaption.Y := Rect.Top + 3;

    if Active then
    begin
      CloseBtnRect.Top := Rect.Top + 4;
      CloseBtnRect.Right := Rect.Right - 5;
      TabCaption.X := Rect.Left + 6;
    end
    else
    begin
      CloseBtnRect.Top := Rect.Top + 3;
      CloseBtnRect.Right := Rect.Right - 5;
      TabCaption.X := Rect.Left + 3;
    end;

    CloseBtnRect.Bottom := CloseBtnRect.Top + CloseBtnSize;
    CloseBtnRect.Left := CloseBtnRect.Right - CloseBtnSize;
    FCloseButtonsRect[TabIndex] := CloseBtnRect;

    PageControl.Canvas.FillRect(Rect);
    PageControl.Canvas.TextOut(TabCaption.X, TabCaption.Y, PageControl.Pages[TabIndex].Caption);

    if not UseThemes then
    begin
      if (FCloseButtonMouseDownIndex = TabIndex) and FCloseButtonShowPushed then
        CloseBtnDrawState := DFCS_CAPTIONCLOSE + DFCS_PUSHED
      else
        CloseBtnDrawState := DFCS_CAPTIONCLOSE;

      Windows.DrawFrameControl(PageControl.Canvas.Handle,
        FCloseButtonsRect[TabIndex], DFC_CAPTION, CloseBtnDrawState);
    end
    else
    begin
      Dec(FCloseButtonsRect[TabIndex].Left);

      if (FCloseButtonMouseDownIndex = TabIndex) and FCloseButtonShowPushed then
        CloseBtnDrawDetails := ThemeServices.GetElementDetails(twCloseButtonPushed)
      else
        CloseBtnDrawDetails := ThemeServices.GetElementDetails(twCloseButtonNormal);

      ThemeServices.DrawElement(PageControl.Canvas.Handle, CloseBtnDrawDetails,
        FCloseButtonsRect[TabIndex]);
    end;
  end;
end;

procedure TFormMain.PageControlCloseButtonMouseDown(Sender: TObject;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
var
  I: Integer;
  PageControl: TPageControl;
begin
  PageControl := Sender as TPageControl;

  if Button = mbLeft then
  begin
    for I := 0 to Length(FCloseButtonsRect) - 1 do
    begin
      if PtInRect(FCloseButtonsRect[I], Point(X, Y)) then
      begin
        FCloseButtonMouseDownIndex := I;
        FCloseButtonShowPushed := True;
        PageControl.Repaint;
      end;
    end;
  end;
end;

procedure TFormMain.PageControlCloseButtonMouseMove(Sender: TObject;
  Shift: TShiftState; X, Y: Integer);
var
  PageControl: TPageControl;
  Inside: Boolean;
begin
  PageControl := Sender as TPageControl;

  if (ssLeft in Shift) and (FCloseButtonMouseDownIndex >= 0) then
  begin
    Inside := PtInRect(FCloseButtonsRect[FCloseButtonMouseDownIndex], Point(X, Y));

    if FCloseButtonShowPushed <> Inside then
    begin
      FCloseButtonShowPushed := Inside;
      PageControl.Repaint;
    end;
  end;
end;

procedure TFormMain.PageControlCloseButtonMouseLeave(Sender: TObject);
var
  PageControl: TPageControl;
begin
  PageControl := Sender as TPageControl;
  FCloseButtonShowPushed := False;
  PageControl.Repaint;
end;

procedure TFormMain.PageControlCloseButtonMouseUp(Sender: TObject;
  Button: TMouseButton; Shift: TShiftState; X, Y: Integer);
var
  PageControl: TPageControl;
begin
  PageControl := Sender as TPageControl;

  if (Button = mbLeft) and (FCloseButtonMouseDownIndex >= 0) then
  begin
    if PtInRect(FCloseButtonsRect[FCloseButtonMouseDownIndex], Point(X, Y)) then
    begin
      ShowMessage('Button ' + IntToStr(FCloseButtonMouseDownIndex + 1) + ' pressed!');

      FCloseButtonMouseDownIndex := -1;
      PageControl.Repaint;
    end;
  end;
end;

Looks like:

page control with buttons

Best Answer

Related Solutions

Delphi – How to change the orientation of the label on a TPageControl

Delphi – How to implement a close button for a TTabsheet of a TPageControl

Related Topic