Override the Back Button

Hi, I am trying to write an app and it is mostly working. I would now like to press the Back button and get the option to save/resume/delete the activity, rather than just exiting the app.
Any help would be great. Thanks.

jim_m_58 over 9 years ago

In your input delegate, catch the back, and when you're done, return true, indicating you handled the button.

For the save/discard, that is something you have to do in your code, as you won't get the native screen. You could use confirmation/confirmation delegate for this.

HannesLF over 9 years ago

Hi Jim - Thanks, was using the onKey(evt) but I see the onBack function now. :)

Former Member over 9 years ago

418

I am doing that, and it works as I would expect in the Simulator, but not when it is on my watch.
just trying something simple

using Toybox.WatchUi as Ui;
using Toybox.Graphics as Gfx;

var testVali = 0;

class BaseInputDelegate extends Ui.BehaviorDelegate
{
function onBack() {
testVali=testVali-1;
WatchUi.requestUpdate();
return true;
}
function onSelect() {
testVali=testVali+1;
WatchUi.requestUpdate();
return true;
}
}

class counterView extends Ui.View {

function initialize() {
View.initialize();
}

//! Load your resources here
function onLayout(dc) {
setLayout(Rez.Layouts.MainLayout(dc));
}

//! Called when this View is brought to the foreground. Restore
//! the state of this View and prepare it to be shown. This includes
//! loading resources into memory.
function onShow() {
}

//! Update the view
function onUpdate(dc) {
dc.setColor( Gfx.COLOR_TRANSPARENT, Gfx.COLOR_BLACK );
dc.clear();
dc.setColor( Gfx.COLOR_WHITE, Gfx.COLOR_TRANSPARENT );

dc.drawText((dc.getWidth() / 2), ((dc.getHeight() / 2) - 30), Gfx.FONT_SMALL, "Counter", Gfx.TEXT_JUSTIFY_CENTER);
dc.drawText((dc.getWidth() / 2), ((dc.getHeight() / 2) - 10), Gfx.FONT_NUMBER_HOT, testVali.toString(), Gfx.TEXT_JUSTIFY_CENTER);
}

//! Called when this View is removed from the screen. Save the
//! state of this View here. This includes freeing resources from
//! memory.
function onHide() {
}
}

Former Member over 9 years ago

same issue

It works fine in the Simulator but not on my Forerunner 920xt

code:

using Toybox.WatchUi as Ui;
using Toybox.Graphics as Gfx;

var testVali = 0;

class BaseInputDelegate extends Ui.BehaviorDelegate
{
function onBack() {
testVali=testVali-1;
WatchUi.requestUpdate();
return true;
}
function onSelect() {
testVali=testVali+1;
WatchUi.requestUpdate();
return true;
}
}

class counterView extends Ui.View {

function initialize() {
View.initialize();
}

//! Load your resources here
function onLayout(dc) {
setLayout(Rez.Layouts.MainLayout(dc));
}

//! Called when this View is brought to the foreground. Restore
//! the state of this View and prepare it to be shown. This includes
//! loading resources into memory.
function onShow() {
}

//! Update the view
function onUpdate(dc) {
dc.setColor( Gfx.COLOR_TRANSPARENT, Gfx.COLOR_BLACK );
dc.clear();
dc.setColor( Gfx.COLOR_WHITE, Gfx.COLOR_TRANSPARENT );

dc.drawText((dc.getWidth() / 2), ((dc.getHeight() / 2) - 30), Gfx.FONT_SMALL, "Counter", Gfx.TEXT_JUSTIFY_CENTER);
dc.drawText((dc.getWidth() / 2), ((dc.getHeight() / 2) - 10), Gfx.FONT_NUMBER_HOT, testVali.toString(), Gfx.TEXT_JUSTIFY_CENTER);
}

//! Called when this View is removed from the screen. Save the
//! state of this View here. This includes freeing resources from
//! memory.
function onHide() {
}
}