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I'm Running Delphi Dx Seattle

In Delphi VCL's TPageControl there is a onChanging event where you could stop the page control from changing tab's

procedure TForm1.pgc1Changing(Sender: TObject; var AllowChange: Boolean); begin if MessageDlg('do you want to change tab?', mtConfirmation, [mbyes, mbno], 0, mbNo) = mrno then AllowChange := false; end;

Is there a way for Delphi Firemonkey TTabControl to replicate this? e.g.
if you have two tabs and clicking on the other tab pops up a question 'do you want to change tab?'
if you click No nothing happens click yes then it changes

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1 Answer 1

Reset to default
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This is the code i ended up using - it works with windows and android haven't tested with IOS

Ended up having to override some of the components procedures

 TTabItem = class(FMX.TabControl.TTabItem) procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Single); override; end; TTabControl = class(FMX.TabControl.TTabControl) function GetTabIndex : integer; public procedure SetTabIndexv2(const Value: Integer); property TabIndex: Integer read GetTabIndex write SetTabIndexv2 default -1; end;

Here is an example of the full code

unit Unit1; interface uses System.SysUtils, System.Types, System.UITypes, System.Classes, System.Variants, FMX.Types, FMX.Controls, FMX.Forms, FMX.Graphics, FMX.Dialogs, FMX.TabControl, FMX.Controls.Presentation, FMX.StdCtrls; type TTabItem = class(FMX.TabControl.TTabItem) procedure MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Single); override; end; TTabControl = class(FMX.TabControl.TTabControl) function GetTabIndex : integer; public procedure SetTabIndexv2(const Value: Integer); property TabIndex: Integer read GetTabIndex write SetTabIndexv2 default -1; end; TForm1 = class(TForm) tbc1: TTabControl; tbtm1: TTabItem; tbtm2: TTabItem; btn1: TButton; lblTab1: TLabel; lblTab2: TLabel; procedure btn1Click(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; implementation {$R *.fmx} procedure TTabItem.MouseDown(Button: TMouseButton; Shift: TShiftState; X, Y: Single); begin if (self.TabControl.ActiveTab <> self) and ((Button = TMouseButton.mbLeft) or (ssDouble in Shift)) then begin MessageDlg('[Tab Item] do you want to do this?', System.UITypes.TMsgDlgType.mtInformation, [System.UITypes.TMsgDlgBtn.mbYes, System.UITypes.TMsgDlgBtn.mbNo], 0, procedure (const AResult: TModalResult) begin begin case AResult of mrYes: self.TabControl.ActiveTab := self; mrNo:; end; end; end); end else begin inherited; end; end; procedure TForm1.btn1Click(Sender: TObject); begin if tbc1.TabIndex = 0 then tbc1.TabIndex := 1 else tbc1.TabIndex := 0; end; { TTabControl } function TTabControl.GetTabIndex: integer; begin result := FMX.TabControl.TTabControl(Self).TabIndex; end; procedure TTabControl.SetTabIndexv2(const Value: Integer); begin if self.TabIndex <> value then begin MessageDlg('[tabcontrol] do you want to do this?', System.UITypes.TMsgDlgType.mtInformation, [System.UITypes.TMsgDlgBtn.mbYes, System.UITypes.TMsgDlgBtn.mbNo], 0, procedure (const AResult: TModalResult) begin begin case AResult of mrYes: begin FMX.TabControl.TTabControl(Self).TabIndex := value; end; mrNo : ; end; end; end); end; end; end.

if you can see any way to improve it please let me know

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