I have a checkbox in a component:
<s:CheckBox id="myCB_1" />
In my main.mxml I need to test for the state of the checkbox. I originally had all my code in main.mxml, but it was getting really long, and I thought that it was better practice to break my code into components. Also, I have other projects where the same concept will apply, so I really want to figure this out.
I have the following function :
private function checkAlarms(currentTime:Date):void
{
if (!breakfastAlarmSounded)
{
if ((currentTime.hours > breakfastTime.hours) || ((currentTime.hours == breakfastTime.hours) && (currentTime.minutes >= breakfastTime.minutes)))
{
if (myCB_1.selected)
{
playBreakfastAudioAlarm();
}
if (myCB_2.selected)
{
playBreakfastVisualAlarm();
}
breakfastAlarmSounded = true;
}
}
...
simply addressing the component, as in:
myComponent.myCB_1.selected
doesn't work. Someone mentioned that I need to create a variable in my component that refers to the id (myCB_1) of checkbox, but I don't really understand or know how to do that, and they didn't elaborate.
How do I test for the status of the CheckBox "myCB_1" in the component from within my main.mxml?
many thanks,
Mark
(newbie)
With very little information, I'm going to suspect you originally had the CheckBox included in main.mxml and moved it to a custom component. If so, you need to address the CheckBox's ID via the custom component's ID. Something like this (from main.mxml):
if(yourComponentsID.myCB_1.selected)
{
...
}
If this isn't the case, please edit your post and give us more detail.
EDIT
You said you created a new custom component and moved the CheckBox into it. Great, that's a helpful start :) When you included your new component in your main.mxml file, it should look something like this:
<component:YourNewComponent />
Of course, however you named it (and whichever namespace is used to reference it) will be different from my example, but the principle should still apply. In main.mxml, you need to give your custom component a unique ID string so you can reference it within main:
<component:YourNewComponent id="myComponent" />
From here on, you should be able to reference the component, and any public elements within it: myComponent.myCB_1.
It would be useful to provide more details about the context in which you're using this script. Nonetheless I'm going to throw out some information that may help.
In order for the script to access the component, it has to be within the scope of the component. Usually that means one of the following:
You have a <script> tag in the MXML, with code in it that references components within the same MXML file.
You have a <script source='external.as'/> tag in the MXML, where external.as is referencing components in the MXML file.
You are creating the component in your script and you have a definition for the component within ActionScript (ex. var myCB_1:CheckBox; is within the class definition).
If the script and the component aren't within the same scope then they can't see one another.
You need to refer to the checkbox through the component. Lets say that you use your component in your main like this:
<local:MyComponent id="myComponent" />
In your script, you want to refer to it:
if(myComponent.myCB_1.selected) { // do something }
Strangely enough, it works. I was getting a getting an 1119 error (Description 1119: Access of possibly undefined property myCB_1 through a reference with static type Class.) when I refer to the component with dot notation (myComponent.myCB_1.selected) and an 1120 error (Description 1120: Access of undefined property myCB_1) when not addressing it via myComponent.
With these errors I never thought to try running the thing. Long story short - it runs with or without addressing the component (???) go figure!
thanks for all the input and would love to hear any other comments.
MCE
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 would like to include an MXML file in my MXML file in the same way you can include an external file in AS3 using the include directive. Using the include directive brings the code from the external file into the original file at compile time placing it in the same scope.
For example,
Application.mxml:
<Application>
<source="external.mxml"/>
</Application>
External.mxml:
<Styles/>
<Declarations>
<Object id="test"/>
</Declarations>
I need to keep this code/mxml/xml in the external file in scope with the original. Do not ask me why I want to do this.
Another example. Here is my current code (simplified) all in 1 mxml file:
...
File1.mxml
<Button click="clickHandler()"/>
<Script>
public function clickHandler():void {
}
</Script>
...
Here is what I want:
...
File1.mxml
<Group>
<source="File2.mxml"/>
<Button click="clickHandler()"/>
<Group>
File2.mxml
<Script>
public function clickHandler():void {
trace(this); // File1.mxml
}
</Script>
...
I want to split my code out into a separate file...
~~ Update ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Though NOT what I was asking for using a "code behind" scheme achieves partial credit to breaking the code out of the view. So I create a MXML file, MyGroup.mxml or MyGroup.as and that extends Group that contains the clickHandler code.
The problem with this method is that I am then locked to the class type I'm extending, hardcoding the view. So for example I would have to extend Group if the MXML class I want to split into separate files is a Group.
I've worked on projects where this was done and it is not good. People start setting styles and visual aspects or group / view specific properties in the code behind class and later if or when we need to change it or the layout it we have end up with all these dependencies to the container. It becomes a mess. Plus, using Code Behind you can't reuse it (reuse in the way include styles.as is reused). So this is not a solution but thought I'd mention it.
Here is a code behind example,
MyGroupBehind.mxml:
<Group>
<Script>
public function clickHandler():void {
trace(this); // File1.mxml
}
</Script>
</Group>
MyGroupAhead.mxml:
<MyGroupBehind>
<Button click="clickHandler()"/>
</MyGroupBehind>
MXML is converted into a class by the compiler, so there is no way to do what you are asking.
Personally, I think that is a good thing. Breaking things up into separate files does not equal "more organized". In fact I would say it achieves the exact opposite effect. You would do better to focus on a proper component structure, IMHO.
Just start typing the name of your custom component, then press Ctrl+Space. Code completion will populate a list of possible things you might want to add, including the name of your component. Use the down arrow to select your component's name, then press enter. Code completion will set up the namespace and start the tag for your component. If you go to the end of the line and type "/>" (no quotes), voila! you will have an inline tag that represents your custom MXML component.
First of all, any external mxml should be a valid XML. Now, as long as you have a valid MXML file, you simply add it by its name like below:
<Application>
<external:External/>
</Application>
Where 'external' is the namespace for your External.mxml file.
Say my MXML file is called Example in the views folder. Simply call it within the parent MXML file you want this to be in
e.g.
<views:Example/>
I'm currently working on a custom component which extends Canvas (let's call it SuperCanvas) ; it's basically a container that let you zoom & pan its contents.
It would be too long to explain why, but I can't use scrollRect, so I was forced to declare a Canvas object (called innerCanvas)... inside my SuperCanvas (I know, not very nice =/)
I would like to know if there's a proper way to "redirect" the creation of my component's children in this canvas.
Let me explain:
<comp:SuperCanvas id="superCanvas">
<mx:Image id="img" source="image.jpg"/>
<mx:Label id="lbl" text="Sample"/>
</comp:SuperCanvas>
With this, img and lbl are added to my SuperCanvas. I want them to be added to superCanvas.innerCanvas instead.
I can't override the add/removeChild methods to do the "redirection", since I won't be able to add this innerCanvas...
So I tried this :
<comp:SuperCanvas>
<comp:innerCanvas>
<mx:Image id="img" source="image.jpg"/>
<mx:Label id="lbl" text="Sample"/>
</comp:innerCanvas>
</comp:SuperCanvas>
But Flex complains that "In initializer for 'contents': type mx.controls.Image is not assignable to target type mx.containers.Canvas". I read I could use an array of UIComponents with a [ArrayElementType] metatag, and manually instanciate objects, but I I'm looking for a simplier (and probably proper) solution.
I also saw the childDescriptor property (which contains descriptions for every child defined in the MXML file), but it's read-only, so I can't pass it to my innerCanvas.
If I'm not clear enough, do not hesitate to ask me precisions, english isn't my native tongue, so it's pretty hard to explain things well =/
Any help would be greatly appreciated, I'm totally stuck.
EDIT:
My SuperCanvas class (minus the imports and the zoom & pan logic that doesn't matter here) :
public class SuperCanvas extends Canvas
{
public innerCanvas:Canvas = new Canvas();
public function SuperCanvas()
{
super();
addChild( innerCanvas );
}
}
This blog entry details an approach where you add components to the SuperCanvas, but then move them all to the inner canvas after creation. So that's one workaround.
Alternatively, you could set the DefaultProperty to be a dataProvider-type object, and then add things to the inner canvas from there, rather than making them children of the SuperCanvas first.
Addition:
I ran across this blog entry which, among other things, talks about the Panel component and how it handles this problem. You might look at it and at the Panel source code.
Are there any way to declare a child component in mxml which is private/protected or even static?
Sure we can do this inside a script tag, but are there any other way?
Ashier suggests using the "Exclude" metadata tag, but Maskit offers its limitations and suggests alternative solutions:
http://blog.ashier.com/2008/03/25/hiding-properties-in-flex-components/
http://smaskit.blogspot.com/2008/07/making-mxml-subcomponent-private.html
In the strict meaning of these terms, no you can't do that using mxml. The second link posted by Luis contains some workarounds for private/protected behavior.
I found a solution to the static question. I wanted a quick memo pad that could be accessed anywhere in the mobile app, without one instance overwriting edits left open in a different screen.
I created a memo pad mxml control, and then placed it inside a declarations section in the top level application mxml. In each view that I wanted the memo to appear in, I added:
import mx.core.FlexGlobals;
import components.QuickMemo;
private var memo:QuickMemo;
In the view creation complete:
memo = FlexGlobals.topLevelApplication.memo;
In the viewActivation code, I added:
memo.visible = false;
addElement(memo);
In the viewDeactivation code, I included:
removeElement(memo);
The net effect is that only one instance of the memo exists at any time, and that one instance opens in whatever state it existed in the last view it appeared in.
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.