Keyboard Shortcut to move through the tabs in a Tab Group menu (Request to improve code)

Howdy!

I've been messing around with trying to have a way to move through the tabs in a Tab Group object via the keyboard. I've got a solution, but I feel like there's probably a more elegant route. I'm looking to see if there are any thoughts on improving what i've got here.

One thing i couldn't figure out is how to get a tab handler so i don't have to constantly refer to app.TabGroup....

If nothing else, then I thought maybe posting what i've got for a solution could be helpful to others.

    function UIFigureKeyPress(app, event)
            key = event.Key; %capture the regular key that was pressed
            eventKey = event.Modifier; %capture any modifier key that was pressed

            if isequal(eventKey, "control")
                switch key
                    case 'pagedown'
                        totalTabs = numel(app.TabGroup.Children); %need the total number of tabs in the TabGroup. May inc/dec at some point
                        app.TabGroup.SelectedTab.ForegroundColor = "Black"; %return the active tab text color to black
                        if app.TabGroup.SelectedTab == app.TabGroup.Children(1) %if the active tab is the first tab then the next tab 'down' is looping back to the last tab
                            app.TabGroup.SelectedTab = app.TabGroup.Children(totalTabs);
                        else
                            for i = 2:totalTabs %otherwise the next tab down is just acitve tab - 1
                                if app.TabGroup.SelectedTab == app.TabGroup.Children(i)
                                    app.TabGroup.SelectedTab = app.TabGroup.Children(i-1);
                                    break;
                                end
                            end
                        end
                    app.TabGroup.SelectedTab.ForegroundColor = "Blue"; %set the active tab text color to blue to indicate active tab

                    case 'pageup'
                        totalTabs = numel(app.TabGroup.Children);
                        app.TabGroup.SelectedTab.ForegroundColor = "Black";%return the active tab text color to black
                        if app.TabGroup.SelectedTab == app.TabGroup.Children(7) %if the active tab is the last tab, the the next tab 'up' is looping to the first tab
                            app.TabGroup.SelectedTab = app.TabGroup.Children(1);
                        else
                            for i = 1:totalTabs-1 %otherwise the next tab up is active tab + 1
                                if app.TabGroup.SelectedTab == app.TabGroup.Children(i)
                                    app.TabGroup.SelectedTab = app.TabGroup.Children(i+1);
                                    break;
                                end
                            end
                        end
                    %set the active tab text color to blue to indicate active tab
                end
            end
        end
    end

Answer 1

[Voss]

That code can be simplified a bit:

% Window key press function: UIFigure
function kpf(app, event)

    if ~isequal(event.Modifier, "control")
        return
    end

    if strcmp(event.Key,'pagedown')
        direction = -1;
    elseif strcmp(event.Key,'pageup')
        direction = +1;
    else
        return
    end

    tg = app.TabGroup;

    tg.SelectedTab.ForegroundColor = "Black"; %return the active tab text color to black
    
    idx = find(tg.Children == tg.SelectedTab);           % index of the active tab
    new_idx = mod(idx+direction-1,numel(tg.Children))+1; % index of the new tab
    tg.SelectedTab = tg.Children(new_idx);               % make the new tab active
    
    tg.SelectedTab.ForegroundColor = "Blue"; %set the active tab text color to blue to indicate active tab
    
end

See the attached app.

Other changes made include:

• Defining a SelectionChangedFcn for TabGroup that updates the tab buttons' ForegroundColor.
• Calling that SelectionChangedFcn from a StartUpFcn in order to initialize the ForegroundColors when the app starts.
• Using WindowKeyPressFcn instead of KeyPressFcn because KeyPressFcn didn't execute when a tab button itself had focus (i.e., click a tab, hit ctrl+pageup, nothing happened; click outside a tab, hit ctrl+pageup, it works).

[ol Poot]

holy smokes. The mod being used to wrap around the array is blowing my mind. In reading about it, it seems that's one of the main uses for it in coding but gosh... that's so cool. Thanks so much for taking the time to respond. I can only hope this will be useful to others in the future. It sure was useful to me!

[Voss]

You're welcome! Any questions, let me know.

[ol Poot]

seriously. this is going to have my mind twisted for a while. It's so elegant!

[ol Poot]

one additional consideration is that this all misses the case where the user selects a new tab with the mouse instead of via the keyboard.

To combat this I've also added a callback for the TabGroupSelectionChanged

function TabGroupSelectionChanged(app, event)
    app.TabGroup.SelectedTab.ForegroundColor = "Blue";
    event.OldValue.ForegroundColor = "Black";
end

[Voss]

Glad you appreciate the use of mod()!

It's true that the user-selecting a tab needs to be handled. I included a similar function in the app attached to my answer, and it is mentioned in the answer under "Other changes made include" (first item).

[ol Poot]

ah doh! sorry. missed that.

[Voss]

No worries!