I've got a model class with custom change events, which is working fine if I make a reference to that class in my mxml using;
[Bindable] private var firstClass:FirstClass;
The objects gets filled by a server side script, so don't worry, firstClass isn't null.
Anyhow, accessing firstClasses properties in mxml works perfectly fine using curly brackets. The binding works just as expected.
However, is there any way to access firstClasses properties and set them to say a label with pure Actionscript.
lblTest.text = firstClass.property;
The code above doesn't work. I suppose because it sets a fixed value to the label.
I'm aware of using BindingUtils.bindProperty to explicitly set the source and destination for the binding. However, this turned out to cause huge performance issues in my (mobile) application.
So is there a simpler, more efficient way to do this?
No. The BindingUtils uses propertyChanged events to detects when an object's property changes. You won't be able to bind something without listening to events, and the most painless way to do it is using BindingUtils.
Related
By "refresh" I am completely disposing it and then introducing it again in the application (without closing the application itself - that is). Other than than I think the question is self-explanatory.
Example:
Say I have a component named myComponent. I add that component to the application using MXMl in the standard way <components:myComponent id="myID" />. Say that when a user clicks a button (the button may be in another state), the component with id myID should be garbage-collected and a new instance of it added to the application.
How do I go about doing that? If there are multiple solutions which one is the optimal performance-wise?
I am new to Flash and Flex so excuse me if any incorrect terminology were used.
Remove all the event listeners from the old component; whatever they are using the removeEventListener method:
myButton.removeEventListener(someEvent, someEventHandlerMethod);
Then all variables that refer to the component should be set to null. If created in an MXML file, like this:
<s:Button id="myButton" />
Then all you have to do is set that value to null:
myButton = null;
Once there are no references to the component, it can safely become eligible for garbage collection.
If you want to re-created, then just re-created it. You'll have to re-create it in ActionScript, but the code isn't hard. Conceptually something like this:
myButton = new myButton();
myButton.properties = propertyValues;
myButton.addEventListener(someEvent, someEventHandlerMethod);
parentContainer.addChildAt(myButton, whateverPositionYouWantToADdTheComponentAt);
I'm not sure I see the benefit of doing this. I suspect it'll be much more efficient to tweak the existing button instance in the way you need to as opposed to destroying it and trying to replace it with the exact same thing.
I have a two way binding between a loaded flash file and the main application in flex.
BindingUtils.bindProperty(this, "micGainValue", audioPublisherApp, "micVolume");
BindingUtils.bindProperty(audioPublisherApp, "micVolume", this, "micGainValue");
micGainValue=75;
However, the setting of micGainValue does not set micVolume in the flash file. I instead tried setting micGainValue after 200 frames, and it now does set micVolume. Is there a way to test that these properties are bound and so set the value after?
EDIT:
The flash file was actually changing the value. Now the question is, why does setting micVolume not change micGainValue.
This the code from my loaded flash file:
[Bindable]
public function get micVolume():Number{
if(microphone!=null)
return microphone.gain;
return 0;
}
public function set micVolume(val:Number):void{
if(microphone!=null)
microphone.gain=val;
}
Flex databinding is implemented using events. When you use BindingUtils.bindProperty, what is happening behind the scenes is that an event listener is being added to the target object to listen for an event of type PropertyChangeEvent
If the target object does not dispatch the PropertyChangeEvent when it is changed, then binding will never be triggered.
When you add the [Bindable] attribute to properties in Flex, what you are doing is telling the framework to dispatch the PropertyChangeEvent when that property is changed. If you don't include the attribute (or put it on the class) then the event is not dispatched and binding doesn't happen.
That's why your binding is working from Flex to Flash but not the other way around- The Flex object is dispatching the required event when it is changed but the flash object is not.
Here is the info on PropertyChangeEvent
Personally, for Flash -> Flex I would dispatch my own event when the flash part changes its values and use a handler on that to update a bindable object within the Flex part. You can then bind other Flex stuff to that.
Flex 3 question:
I trying here to avoid having to bind resources to all my components labels ( ie a button) and find a way to have this automated.
Problem:
It corrupts the layout in design mode to bind directly in the mxml label="{resourceManager.getString('myResources', 'submit')}" and makes the design view useless. but when declaring bindings elsewhere, in actionScript or via a bind tag, it is counter productive and prone to many errors and miss.
Proposition:
I would like to create my own button that automatically invoke resources to localize a button label. So the author puts "Submit" in the mxml description of my button, and when running it would take the value of the label ie "submit" and use resourceManager.getString('myResources', 'submit').
but I can't find the way to override the set label function, Is it possible if yes how? else how can I go about it?
Maybe I am missing an essential process here that would make the use of resources more elegant, as well as how to override such thing as a button's label.
Thanks for your advices.
Create a component called MyButton, extending Button. Then use this:
override public function set label(value:String):void {
super.label = resourceManager.getString('myResources', value) || value;
}
Assuming the resource manager returns "null" or "undefined" this will work, and will only replace the value if it exists in "myResources".
If you don't want to override every component you need to do this with, then you can add a FlexEvent.CREATION_COMPLETE event on every component. Then use a single generic function to do your label localization.
I am trying to set one bindable variable to be bound to another. Essentially I want to create an alias. I would give up, but this seems like something that would be good to know.
essentially, I want changes in model.configView to be reflected in view, so that things bound to view.... behave the same as things bound to model.configView... in this example [Bindable]
var view = model.configView;
...
<mx:Label text="{view.lblThisLabel.name}" />
at the moment it does not, and I am getting errors that say "unable to bind to property 'lblThisLabel' on class 'Object' (class is not an IEventDispatcher)"
Not quite enough code here to really say what's going on, however you have made view bindable and that does not automatically mean that all of view's children are bindable. You'll have to go into view and make lblThisLabel bindable too.
Also it is hard for the rest of us to know how it works in your head. Perhaps you should describe that too.
Moreover, I think that even if, with your actual code, view changes should be detected, view won't be updated if assigned model.configView property is not bindable as well...
I have 2 components for example (editor.mxml using mx:windows), when I click an edit button, I want to get the current value from the other component's datafield? (datagrid.mxml using mx:window)
I do know how to access the main MXML's datagrid by parentDocument or Application.application method, but stumped block if I want to access other way as mentioned above. Keep the code as simple as possible.
You could either do dependency injection, that is, give component A a reference to component B so that they can communicate directly (example of tighter coupling,) or have both components communicate through a common mediator using events (example of more loose coupling.)
Both of those options would be implemented wherever it is that you're creating those components (A and B in this example) and adding them to the display list.
This might be more complicated than it deserves, and it smacks of Pattern-Fever, but you could use a mediator class that listens for the CLICK event from the button and knows enough about the other component to query its property. It could even transmit that data using a custom event, which the button listens for.
While this involves three classes instead of two, it often turns out to be easier to have two components that focus on looking good and one that worries about coordination.
Cheers
Try this:
FlexGlobals.topLevelApplication
This points Your root. From the root You can grab every element You want.
You can also add an id to the custom component like this,
<custom:Editor id="myCustomComponent">
</Editor:AddressForm>
and
access your datagrid's value like this,
var data:ArrayCollection = myCustomComponent.DatagridID.dataProvider;