Button hotkey

[sfein1000]

Setup:
Linux - Debian Pixie with KDE desktop and Wayland
FPC: 3.2.2 installed using fpcupdeluxe
FPGui: 2.1.0 - compiled with unix

I would like to assign an Alt-Letter key combination to a button. In Lazarus I would jus set the caption to include & (for example &Scan would have the S underlined and Alt-S would fire the button). I can't seem to find an equivalent in fpgui. &Scan shows &Scan.

Thanks,
Steve

[graemeg]

Hi Steve,

You're right that this wasn't supported — & was only ever handled in menu items, never in buttons, so &Scan was painted literally. Good catch, and thanks for the clear report.

I've just implemented it on the develop branch. Buttons, checkboxes and radio buttons now support the same & convention you're used to from Lazarus:

btnScan.Text := '&Scan';        { S is underlined, Alt+S fires the button }
chkVerbose.Text := '&Verbose';  { Alt+V toggles it }

Use && when you want a literal ampersand in the text — 'Black && &White' paints "Black & White" with the W underlined.

A few implementation notes that may matter to you:

• Alt has to be the only modifier held. Ctrl+Alt+S and Shift+Alt+S deliberately won't fire an Alt+S accelerator, which avoids clashes with AltGr on international layouts.
• Nested widgets work — a button inside a panel or frame is found without any extra wiring on your side.
• Matching is case-insensitive, so &scan and &Scan both respond to Alt+S.
• It's UTF-8 aware, so accented accelerator characters behave correctly.

Rather than special-casing buttons, this went in as an IfpgAcceleratorTarget interface, so any widget — including your own custom ones — can opt in by implementing three small methods. Labels aren't covered yet; in the VCL a label's accelerator focuses a paired edit control, which needs a FocusControl property, so that's a separate piece of work.

There's a runnable demo at examples/gui/accelerators/ covering buttons, the && escape, a checkbox and a radio group.

This is on develop, not in the 2.1.0 release you're running, so you'll need to pull that branch to pick it up. If you'd rather stay on your current build for now, the manual workaround is a form-level OnKeyPress handler — but do use the exclusive-modifier test rather than a bare ssAlt in ShiftState, or Ctrl+Alt+S will trigger your button too:

if (ShiftState * [ssShift, ssAlt, ssCtrl] = [ssAlt]) and (KeyCode = keyS) then
begin
  btnScan.Click;
  Consumed := True;
end;

Would be great to hear how it works out on Wayland if you get a chance to try the develop branch.

[graemeg]

TfpgLabel is now supported as well, and has a FocusWidget property.

[sfein1000]

& works on buttons now. Thanks. I tried a label but the & still shows and Alt+char preceded by & did not go to the FocusWidget. Since & shows, guessing that is why, but does the FocusWidget have to be created first? What I did was:
lTest := TfpgLabel.Create(Self);
lTest.Text := '&Test Label:';
lTest.FocusWidget := sleTest;
mig.AddLayoutComponent(lTest, TfpgMigCC.Create.GrowX);
sleTest := TfpgEdit.Create(Self);
mig.AddLayoutComponent(sleTest, TfpgMigCC.Create.Wrap);

[graemeg]

Yeah, sleTest in this line is nil, so you are affectively assigning nil to FocusWidget property. At which point in renders the literal & symbol.

lTest.FocusWidget := sleTest;

Have you tried the new accelerators example?

$ pasbuild compile -m examples-gui-accelerators -p unix,debug
$ examples/gui/accelerators/target/acceltest

And this is what I see:

From the accelerators example code:

  { A label's accelerator moves focus to its FocusWidget - it never activates
    it. Without a FocusWidget assigned a label has no accelerator at all, and
    the '&' is painted literally. }
  lblName := TfpgLabel.Create(self);
  lblName.SetPosition(12, 98, 60, 22);
  lblName.Text := '&Name:';

  edName := TfpgEdit.Create(self);
  edName.SetPosition(78, 95, 160, 24);
  lblName.FocusWidget := edName;

So based on what you described, it's working as designed. Create sleTest before assigning it to FocusWidget, and it should render and work as you intended.

[sfein1000]

I compiled the accelerator test and ran it and it worked fine. I moved the edit field creation prior to the label creation so the FocusWidget would not have nil and it worked fine. Thought I had tried that once. IDK. But it works now.