I want to drag a slider and when it is dropped, it calls a function, but when I use DragGesture my slider does not work any more.
I have read the Apple documentation, but I couldn't find out how to do this.
Try the onEditingChanged closure parameter. It receives a Bool set to true when the change begins and false when the change ends.
Slider(value: $value, in: 0...200, step: 10, onEditingChanged: { bool in
print("\(bool)")
})
Related
I'm trying to respond to a change in one of the properties of the model in a widget. To be clear, when the value of the property changes, I want to run some code to react to the change. In a parent widget I have a date picker which changes the date in the model.
I cannot get the custom setter to be called _setParentPropertyAttr...
If I include this in my widget
<span data-dojo-type="dojox/mvc/Output" data-dojo-props="value: at(rel:, 'ParentProperty')">
It works nicely. Changing the date picker outputs the current value to the page. So I can supply the value property to the output widget when the date changes in the model. But what I need to do (I think) is supply a custom property with the date property in the model when the date picker changes the value.
I realise this question is a bit vague but I can't provide the code as it's proprietary.
I've tried to break the problem down by setting a property manually within my widget as:
myProperty:0,
...
constructor
...
_setMyPropertyAttr: function(value):
{
console.log("setting myproperty");
}
....
this.set('myProperty', 5);
....
but that isn't working either.
If you set a property within a widget does that not call the custom setter?
I'm struggling a bit because there aren't so many dojo examples out there any help is much appreciated.
You can bind an event to be called when a widget's property is set/update or you can even use watch to do that.
But this only works using the set function, using someWidget.someProperty = 5; wont work.
Let me show you how dojo do it. The basic about the magic setters and getters is explained here.
_set: function(/*String*/ name, /*anything*/ value){
// summary:
// Helper function to set new value for specified property, and call handlers
// registered with watch() if the value has changed.
var oldValue = this[name];
this[name] = value;
if(this._created && !isEqual(oldValue, value)){
if(this._watchCallbacks){
this._watchCallbacks(name, oldValue, value);
}
this.emit("attrmodified-" + name, {
detail: {
prevValue: oldValue,
newValue: value
}
});
}
}
This peace of code is from dijit/_WidgetBase, the _set function is what dojo calls after a set is called, and is where it finally set the property value this[name] = value; and as you can see, it emit an event that will be called attrmodified-propertyName and also call a watchCallbacks.
For example, if in some place, we have this:
on(someWidget, 'attrmodified-myproperty', function(){
console.log(someWidget.get('myProperty'));
});
and then we use:
someWidget.set('myProperty', 'Hello World!');
The event will be triggered. Note that someWidget.myProperty = 'Hello World!' wont trigger the event registration. Also note that if in our widget we define the magic setter:
_setMyPropertyAttr: function(value) {
//do something here with value
// do more or less with other logic
//but some where within this function we need to cal "_set"
this._set('myProperty', value);
}
without calling _set, the magic wont happen.
As i said at the beginning, we can also use watch:
someWidget.watch('myProperty', function(){
console.log(someWidget.get('myProperty'));
});
Note that we can register to this events or the watch function within the same widget.
Also, as a plus, the magic setter can be triggered when creating the widget with just passing the property name in the constructor object param, this work for the declarative syntax too, for example:
var someWidget = new MyWidget({
'myProperty': 'Hello World!!'
});
and
<div data-dojo-type="MyWidget" data-dojo-props="myProperty: 'Hello World!!'"></div>
both will triggered a call to the _setMyPropertyAttr if exist, or dojo will use the magic setter in the case it doesn't exist.
Hope it helps
Consider using custom setter on your widget, where you can add your custom logic.
Example of definition of custom setter on your widget:
_setOpenAttr: function(/*Boolean*/ open){
// execute some custom logic here
this._set("open", open);
}
Example of setting a property on your widget:
widgetRef.set('open', true);
Alternatively you can could consider using dojo/store/Observable.
dojo/store/Observable store wrapper that adds support for notification of data changes.
You can read more about it on the followign link:
https://dojotoolkit.org/reference-guide/1.10/dojo/store/Observable.html
If figured out the problem. If I set a watch on the model I can then check if indiviual properties have changed in the watch function. I knew it would be something simple!
I have an edit page (in a DurandalJS single page app), where I use the .canDeactivate lifecycle method to check if there are any changes to the record, and optionally prompt them for confirmation before leaving the page.
I also have a 'Save' and 'View History' button. Is the correct thing to do to override the .canDeactivate method before calling router.navigate, to stop the modal popup invoking?
E.g.: As here:
self.onSave = function() {
self.repository.updateItem(self.model).done(function() {
self.canDeactivate = null; // Is this the correct way to do this?
router.navigate("#/home");
}
}
As this .canDeactivate will otherwise get called:
self.canDeactivate = function() {
if (!self.model.hasChanges()) {
return true;
}
return app.ShowMessage("Unsaved data will be lost", "Are you sure you wish to exit?", ["Yes", "No"]).done(function(result) {
return result !== "No";
}
};
Why dont you just set
self.model.hasChanges(false)
in your updateItem callback?
Then when your canDeactivate is called, it will return true.
Also you seem to have an error in your ShowMessage callback. I think you mean to do:
return result != "No";
I don't think the way Durandal decides whether to attempt to call a canDeactivate function is fully defined, other than the fact that if it's not in the view model, it won't try. Hence, even if it works as is, a future version of the framework could change its check to something like if (canDeactivate in viewModel) viewModel.canDeactivate(...); without further tests, and your code would break.
This is unlikely, but if you want to worry about it, you should thus delete self.canDeactivate instead of assigning it the null value.
Quote from the documentation:
To participate in the lifecycle, implement any (or none) of the
functions below on the object that you set the activator to (...)
Current implementation (activator.js, L126, 1eecbc2d3f84dc42eb7304bde761d88f300d8951):
if (item && item.canDeactivate) {
So it only checks if it's truthy (which would indicate using null works fine currently, too).
If you want to discuss the pattern, I don't see anything wrong with it, as long as it makes sense to you and everyone who should read the code.
You're not supposed to be activating and deactivating views programmatically in any critical path, so performance should be irrelevant either way (flag on view model or deletion of canDeactivate).
Let's say we have a simple Backbone View, like this:
class MyView extends Backbone.View
events:
'click .save': 'onSave'
onSave: (event) ->
event.preventDefault()
# do something interesting
I want to test that event.preventDefault() gets called when I click on my element with the .save class.
I could test the implementation of my callback function, pretty much like this (Mocha + Sinon.js):
it 'prevents default submission', ->
myView.onSave()
myView.args[0][0].preventDefault.called.should.be.true
I don't think it's working but this is only to get the idea; writing the proper code, this works. My problem here is that this way I'm testing the implementation and not the functionality.
So, my question really is: how can I verify , supposing to trigger a click event on my .save element?
it 'prevents default submission', ->
myView.$('.save').click()
# assertion here ??
Thanks as always :)
Try adding a listener on the view's $el, then triggering click on .save, then verify the event hasn't bubbled up to the view's element.
var view = new MyView();
var called = false;
function callback() { called = true; }
view.render();
// Attach a listener on the view's element
view.$el.on('click', callback);
// Test
view.$('.save').trigger('click');
// Verify
expect(called).toBeFalsy();
So you want to test that preventDefault is called when a click event is generated, correct?
Couldn't you do something like (in JavaScript. I'll leave the CoffeeScript as an exercise ;)):
var preventDefaultSpy;
before(function() {
preventDefaultSpy = sinon.spy(Event.prototype, 'preventDefault');
});
after(function() {
preventDefaultSpy.restore();
});
it('should call "preventDefault"', function() {
myView.$('.save').click();
expect(preventDefaultSpy.callCount).to.equal(1);
});
You might want to call preventDefaultSpy.reset() just before creating the click event so the call count is not affected by other things going on.
I haven't tested it, but I believe it would work.
edit: in other words, since my answer is not that different from a part of your question: I think your first approach is ok. By spying on Event.prototype you don't call myView so it's acting more as a black box, which might alleviate some of your concerns.
I'm building a Google Maps app, and have an image of a compass outside of the map. Each of the compass points is on an image map, and has its own id. I want the 45° orientation to change, depending on the compass point clicked.
Within the google maps initialize function, I have this line:
google.maps.event.addDomListener(document.getElementById('compassSouth'), 'click', map.setHeading(180));
However, that handler is fired on page load, and doesn't respond after that. It's not due to the image map - the same behavior happens if the element is a button.
I have another handler in the same format that responds to a button press, which works fine.
The code is doing exactly what you are telling it to do: It is calling the map.setHeading(180) function immediately when you execute your code.
Let's write it out line by line for clarity:
var element = document.getElementById('compassSouth');
var listener = map.setHeading( 180 );
google.maps.event.addDomListener( element, 'click', listener );
As you can see, this code calls map.setHeading(180) immediately where you write that code, and then it passes the return value from that function (which I'm now calling listener) into addDomListener().
But map.setHeading(180) doesn't return any value at all - or put another way, it returns undefined, so listener is undefined.
addDomListener() sees that undefined value and ignores it: it doesn't set any listener at all!
What you need to do instead is pass a reference to a function into addDomListener(). You could do this easily like this:
function compassClick() {
map.setHeading( 180 );
}
var element = document.getElementById('compassSouth');
google.maps.event.addDomListener( element, 'click', compassClick );
Or as you'll often see, you can make that compassClick function an anonymous function instead (now going back to code more like your original):
google.maps.event.addDomListener(
document.getElementById('compassSouth'), 'click',
function() {
map.setHeading( 180 );
}
);
I am trying to do something like : when user click on the button, the child panel will show/hide
the issue is the 'onbtnClick' function is working just once. when i click on the button the panel shows and then when i click it again nothing happens and no errors tho ! the panel should hide
By the looks of it, there isn't really much need to pass a boolean param to the function.
If you purely want a 'toggle' function, based on the panels visibility and you have a reference to the Ext component, you can use the isVisible() function:
http://docs.sencha.com/ext-js/4-1/#!/api/Ext.panel.Panel-method-isVisible
So your onBtnClick function would look something like this:
onbtnClick: function (){
var childPanel = Ext.getCmp('p');
if(childPanel.isVisible()) {
childPanel.hide();
}
else {
childPanel.show();
}
}
onbtnClick: function (){
var childPanel = Ext.getCmp('p');
if (!childPanel.isHidden()) {
childPanel.hide();
} else {
childPanel.show();
}
}
Instead isVisible() use method isHidden() because method isVisible may return false when the panel is covered by other components or is not rendered yet (even when your panel has not got hidden property (hidden = false)).
panel.getEl().toggle();
will serve your purpose.
-YP
you have setVisible, taking a boolean parameter to know what to do.
childPanel.setVisible( ! childPanel.isVisible() )
This example will actually toggle the visibility at each execution.