Dynamic menus

I've always done this...

// for use with dynamic menus. limited to 16 entries because of Menu.MAX_SIZE
const _symbols = [
:symbol0,
:symbol1,
:symbol2,
:symbol3,
:symbol4,
:symbol5,
:symbol6,
:symbol7,
:symbol8,
:symbol9,
:symbol10,
:symbol11,
:symbol12,
:symbol13,
:symbol14,
:symbol15
];

class XMarksMenu extends Ui.Menu
{
function initialize(marks) {
Menu.initialize();

var n = marks.size();
if (Menu.MAX_SIZE < n) {
n = Menu.MAX_SIZE;
}

for (var i = 0; i < n; ++i) {
Menu.addItem(marks["name"], _symbols);
}
}
}

class XMarksMenuDelegate extends Ui.MenuInputDelegate
{
hidden var _M_marks;
hidden var _M_callback;

function initialize(marks, callback) {
MenuInputDelegate.initialize();
_M_marks = marks;
_M_callback = callback;
}

function onMenuItem(item) {
for (var i = 0; i < _symbols.size(); ++i) {
if (symbols== item) {
return _M_callback.invoke(_M_marks);
}
}

return false;
}
}

//
// var menu = new XMarksMenu(marks);
// var delegate = new XMarksMenuDelegate(marks, self.method(:onMarkSelected));
// Ui.pushView(menu, delegate, Ui.SLIDE_UP);
//
[/code]

I don't really like it because it relies on a global, but I don't really see any other way to do it. Maybe someone else will have a better suggestion..

Travis

I'm pretty sure you can use anything for the id of a menu. I glanced at the API code and don't see any type enforcement on that parameter. You will just get passed back what you provide, so you can do this:

for (var i = 0; i < n; ++i) {
Menu.addItem(marks["name"],i);
}[/CODE]

or I suppose probably even this:

for (var i = 0; i < n; ++i) {
Menu.addItem(marks["name"],marks["name"]);
}[/CODE]

There must be something in the code I missed when I looked through that is converting the parameter to a symbol.

Sorry for the misinformation.

Thanks for the work guys. Travis, you have done a much more thorough exploration of the issue than I could, and have hit the nail on the head. Incidentally, I opted for your array of symbols solution while waiting for an answer. You have also alerted me to a potential user challenge with the Menu.MAX_SIZE which I hadn't spotted.
Some thoughts on the Menu:

• The emulator displays a menu header, but the VA-HR doesn't.
  
• The emulator doesn't respond reliably to a menu click.
  
• It would be a great enhancement if the onMenuItem could return the passed object, not limited to a symbol.
  

The menu is the simulator is just a generic menu, as the menu on the actual devices is device dependant. On the real vivoactive, for example, each menu item is a full screen and you left/right swipe to switch between screens, but looks like the menu on other devices in the sim.
The menu title not being shown on the va-hr native menu, is another example of a generic vs device specific thing.

As far as #2, with the generic menu with the va-hr, the current item is the one in the middle, and if you tap on that (for touch devices), it's picked. If you tap on the one under the middle one, it moves up to be the middle one. That's just the generic menu thing again.

You'll also see a "generic" version of things like the NumberPicker and TextPicker in the sim.

It would be a great enhancement if the onMenuItem could return the passed object, not limited to a symbol.

I've created a request ticket for this.

Copied all that. Thanks for the great feedback and explanations.

It would be a great enhancement if the onMenuItem could return the passed object, not limited to a symbol.

Agreed. In the meantime, you could use this. It is a generic menu implementation that keeps all of the menu logic in the menu itself, and calls back to your code with an object reference. You supply an array (or a dictionary with integer keys from 0) of objects, and the name of the field you want to use for display purposes.

// for use with dynamic menus. limited to 16 entries because of Menu.MAX_SIZE
const _symbols = [
:symbol0,
:symbol1,
:symbol2,
:symbol3,
:symbol4,
:symbol5,
:symbol6,
:symbol7,
:symbol8,
:symbol9,
:symbol10,
:symbol11,
:symbol12,
:symbol13,
:symbol14,
:symbol15
];

class XMenuOverflowException extends Lang.Exception
{
function initialize() {
Exception.initialize();
}

function getErrorMessage() {
return "Too many menu items";
}
}

class XMenu extends Ui.Menu
{
// could also use a callback function to get the display string
// given an object, but this seems simpler and covers the bases..

function initialize(objects, field) {
Menu.initialize();

var n = objects.size();
if (MAX_SIZE < n) {
throw new XMenuOverflowException();
}

for (var i = 0; i < n; ++i) {
Menu.addItem(objects[field], _symbols);
}
}
}

class XMenuInputDelegate extends Ui.MenuInputDelegate
{
hidden var _M_objects;
hidden var _M_callback;

function initialize(objects, callback) {
MenuInputDelegate.initialize();
_M_objects = objects;
_M_callback = callback;
}

function onMenuItem(item) {
for (var i = 0; i < _symbols.size(); ++i) {
if (_symbols== item) {
return _M_callback.invoke(_M_objects);
}
}

return false;
}
}
[/code]

In your case, where you want to show a menu that uses the name in each map entry, you'd use this...

// assume this is the input data
var _array = [
{ "name" => "A", "lat" => 1.0, "lon" => 1.0 },
{ "name" => "B", "lat" => 2.0, "lon" => 2.0 },
{ "name" => "C", "lat" => 3.0, "lon" => 3.0 }
];

// show field by the name of the object
var menu = new XMenu(_array, "name");
var delegate = new XMenuInputDelegate(_array, self.method(:onMenuItem));
Ui.pushView(menu, delegate, Ui.SLIDE_UP);


This trick can work with arrays of objects as well as arrays of dictionaries. You'd just have to specify :name as the field parameter so the XMenu would access the name member of the object. You could do arrays of arrays as well by specifying the index.

Travis

At least in the simulator, if you pass a number for the key, it does get converted in to a Symbol. But if you get the hashCode from that symbol, it is the original number. Not sure if you can really guarantee this, or if it works with any/all the devices. I'll do some checking.

//Delegate
function onMenu()
{
...
menu.addItem("item",45)
...
}

//MenuDelegate
function onMenuItem(item)
{
var iItem = item.hashCode(); //gives 45.
...
}