how do I trigger an Item renderer create children - actionscript-3

I have a TileList with a custom item renderer.
I need to change the children of the ItemRenderer when the dataprovider changes for the TileList.
Currently,
override protected function createChildren():void{
Works fine with the inital data, but when the data changes to a different structure I need to recreate the children somehow.
I image there has to be a way to listen to the TileList for a data change from inside the item renderer, but how? Or is that even the best route to go?

maybe this will do the job :
override public function set data( value : Object ) : void
{
super.data = value;
// things to happend when data is changed ...
}
aswell maybe updateDisplayList() shall need to be overrided aswell to match the changes with the visual components ( if there is ).

Related

MVVMCross - display view inside view

I cannot seem to find any simple examples of this.
I have a WPF UI that I wish to display a view as a child control within another view. The MvxWpfView inherits from UserControl so it should be possible, however I cannot seem to work out how to do the binding.
I get a BindingExpression path error, as it cannot find ChildView property in my ParentViewModel.
So how do I bind a view to control content?
Firstly it's possible that you just need to add the BViewModel you want displayed on AView as a property on ViewModelA
E.g.
public class AViewModel: MvxViewModel
{
public BViewModel ChildViewModel
{
get;set;//With appropriate property changed notifiers etc.
}
}
Then inside AView you just add a BView, and you can set the datacontext of BView as follows:
<UserControl DataContext="{Binding ChildViewModel}"/>
However, if you want something more flexible (and you want the presentation handled differently for different platforms) then you will need to use a Custom Presenter
Inside your setup.cs you override CreateViewPresenter:
protected override IMvxWpfViewPresenter CreateViewPresenter(Frame rootFrame)
{
return new CustomPresenter(contentControl);
}
Now create the class CustomPresenter you need to inherit from an existing presenter. You can choose between the one it's probably using already SimpleWpfPresenter or you might want to go back a bit more to basics and use the abstract implementation
The job of the presenter is to take the viewmodel you have asked it to present, and display it "somehow". Normally that mean identify a matching view, and bind the two together.
In your case what you want to do is take an existing view, and bind a part of it to the second view mode.
This shows how I have done this in WinRT - but the idea is very similar!
public override void Show(MvxViewModelRequest request)
{
if (request.ViewModelType == typeof (AddRoomViewModel))
{
var loader = Mvx.Resolve<IMvxViewModelLoader>();
var vm = loader.LoadViewModel(request, new MvxBundle());
if (_rootFrame.SourcePageType == typeof (HomeView))
{
HomeView view = _rootFrame.Content as HomeView;
view.ShowAddRoom(vm);
}
}
else
{
base.Show(request);
}
}
So what I'm doing is I'm saying if you want me to present ViewModel AddRoom, and I have a reference to the HomeView then I'm going to just pass the ViewModel straight to the view.
Inside HomeView I simply set the data context, and do any view logic I may need to do (such as making something visible now)
internal void ShowAddRoom(Cirrious.MvvmCross.ViewModels.IMvxViewModel vm)
{
AddRoomView.DataContext = vm;
}
Hopefully that makes sense! It's well worth putting a breakpoint in the show method of the presenters so you get a feel how they work - they are really simple when you get your head around them, and very powerful.

Add a property to a Button or other type of Objects

I always created additional property to MovieCLips using the syntax
myMC.myProperty
without any sort of declaration... But i can use this method only with MovieClips.. What about if i want to add a property to a button or any different type of object? I need to extend the class? Do you can me suggest how? Many thanks
You can add property to movieclips in runtime because MovieClip is dynamic class. If the class is not dynamic, you should extend it to create methods and properties.
Read about dynamic classes.
I tend to create custom classes for nearly everything.
I would extend the relevant class and set up a private var for your new property. You can then pass in the value to the constructor or add a getter/setter method to call externally.
private function _myProperty:int;
public function get myProperty():int
{
return _myProperty;
}
public function set myProperty(newVal:int):void
{
_myProperty = newVal;
}
Getter/setter methods add a few lines of code that may seem unnecessary but on big projects when you find a property is being set and you don't know why, you can put a break point in your set myProperty
Subclass is main solution.
Next works only with mx components (flex sdk 3).
Most components have data : Object property that you can freely use to store data.
Monkey patching sometimes is the only way to go. It allows you to add custom properties to flex sdk classes. I don't think you should use it in your case. But I used it to change core logic that is locked by private keyword in flex sdk.
Hope that helps.

Setting a skinState of a button in AS3

I want to set (manually) the skinState (for example 'disabled') of a button (that I skinned) in ActionScript.
For example:
I have a button skin with hostComponent: components.backend.btnMenuBakComp
The button skin has the default button states (up, over, down, ...), but I want to set one of this skinStates in ActionScript.
For example:
subMenu.btnDashboard.currentState = "disabled";
This doesn't work because the state "disabled" is not known in the component (it is only known in the skinState of btnDashboard).
How can I fix this?
Is there another solution then load a new skinClass?
Thanks
Quick and dirty
You can access the skin of any component and just set its state directly:
subMenu.btnDashboard.skin.currentState = "disabled";
That is however not a very clean way to do it. You are telling a Skin class directly what to do and completely bypassing the host component. Hence the host component has no idea of the changes that were made to its skin.
The proper way
A cleaner way to approach this is to expose a property on the host component and then tell the skin to adjust itself to possible changes by overriding the getCurrentSkinState() method.
You could for instance create a property 'enabled' and then tell the skin to update its state by calling invalidateSkinState() whenever 'enabled' is being set.
public function set enabled(value:Boolean):void {
_enabled = value;
invalidateSkinState();
}
Calling invalidateSkinState() will make the skin call getCurrentSkinState() in the next render cycle. This method will then look something like this:
override protected function getCurrentSkinState():String {
return _enabled ? "normal" : "disabled";
}
Do note that since you are skinning a Button (or a subclass of it) all that I've written here is already baked into that component. So the answer to your question might be as simple as : "just set the 'enabled' property to true.
subMenu.btnDashboard.enabled = true;

Bindable property change event in Flex

Can anyone please help me solve this mystery:
I've got a component called Box.as that has following two properties, and have their getters & setters defined:
private var _busy:Boolean;
private var _errorMessage:String;
In MXML that uses this component I define it like this:
<components:Box skinClass="skins.components.BoxSkin"
busy="{presenter.boxBusy}"
errorMessage="{presenter.boxErrorMessage}"/>
Where presenter variable is defined here in MXML and a Presenter class has boxBusy and boxErrorMessage variables defined as bindable property change events:
[Bindable(event="propertyChange")]
function get boxBusy():Boolean;
function set boxBusy(value:Boolean):void;
[Bindable(event="propertyChange")]
function get boxErrorMessage():String;
function set boxErrorMessage(value:String):void;
PROBLEM is that whenever I change boxErrorMessage for the presenter, I see the affect in MXML but nothing happens at all when I change boxBusy. Is there something extra I need to do with boolean variable?
Thanks a lot in advance.
You should omit the (event="propertyChange") specification from your [Bindable] metadata tags on both boxBusy and boxErrorMessage. Also, make sure your get/set methods are declared public.
So, the property, boxBusy, would look something like this:
[Bindable]
public function get boxBusy():Boolean { return _busy; }
public function set boxBusy(value:Boolean):void { _busy = value; }
When you qualify [Bindable] with (event="..."), you're telling Flex, "I will dispatch the named event whenever the binding should be updated".
If you omit the event specification, then flex assumes that the event is named propertyChange. But that's not all it does. It also automatically "wraps" your setter with generated code that transparently dispatches a 'propertyChange' event any time the setter is used to modify the value. This is described in more detail here, at adobe livedocs.
So... by explicitly specifying (event="propertyChange"), you disable flex's default behavior. Even though you're using the default event name, flex will not generate the wrapper code -- instead, it will expect you to dispatch the event from your code, at the appropriate time.
I imagine that your boxErrorMessage property appears to be working, because some other [Bindable] property of your class is changing in the same pass -- thus dispatching propertyChange, and causing your boxErrorMessage binding to update as a side-effect.
It is completely possible that if you are setting busyBox to true the first time the setter is getting called but it will not get called again if you again try to set to true. The code that is by the flex compiler when you use the [Bindable] tag will adds a check to see if you are setting the new value to what the getter will currently will return. If that is the cause it isn't called.
If you were to oscillate between true and false it would get called every time because the new value differs from the current value. But setting it to true-true-true-true-false would only result in it getting called the first time to set to your and the last time to set to false.

How to modify map element key

I have a container that holds map of elements.
class MyContainer{
.....
Map<String,MyElement> elements = new ...
...
}
Each element has name property. The key in the map is the element's name. i.e. the method insert is as follows:
void addElement(MyElement elem){
elements.put(elem.getName,elem);
}
I need to use the map data structure, because I have many read operations based on the element name.
The problem is that I need to support modification of the element's name. Changing element name must derive changes in the map. (insert the element with a new key otherwise I won't be able to find that element)
I have thought about two options:
add setName method to MyElement class that will update the container that its name was changed.
don't add setName method to MyElement class, add rename element method to the container, the container will be in charge of updating both the element name and the key in the map.
Option 1 means I have to maintain reference from each element to the container. (this part of the program should maintain low memory footprint).
What do you say? do you see a better option?
I would fire a property change notification on the setName method of the element and handle it in the container object which is listening that notification.
First of all, note that if MyElement can conceivably be used in a context without MyContainer, then option 1 is out.
MyContainer has an obvious relation with MyElement, since its code references MyElement instances through its map. The reverse is not true: the code in MyElement does not need to reference MyContainer. So option 2 is better.
Perhaps, though, you could go for a third hybrid option:
MyElement has a rename method that only changes its own name, and MyContainer has a rename method which calls MyElement.rename and moves the object in the map to the new key.
If the element is only used in this container.
Put the rename operation on the container.
Make the rename method on the element private so another programmer can't accidentally change just the element and forget to update the container.
Option 2 is the simplest and most efficient, thus my choice.
Clearly you know that, so what's the dillema?
Another option is to make a MyString class, that will serve as both a std::string AND a reference to MyContainer. MyString's modifying methods would be in charge of re-maping, and you'd still have a low footprint. E.g.:
class MyString;
class MyElement {
...
MyString name;
...
};
MyContainer * aContainer = new MyContainer;
new MyElement(MyString("Yaron Cohen",aContainer), ...); /* MyString need to be explicit only upon MyElement construction. takes care of inserting into container. */
...
MyElement * someElement = aContainer["Yaron Cohen"]; /* just std::string for lookup */
someElement->name = "Dana International": /* MyString takes care of remapping */
Note that this option supprts multiple keys and containers as well, e.g. FirstName, LastName (if only these were unique...)
Another option is if MyContainer is a singleton.
One more thing to consider is, how often does name change?