When one call Clipboard.generalClipboard.getData() in ActionScript outside of Event.PASTE processing function it fails with following message
The Clipboard.generalClipboard object may only be read while processing a flash.events.Event.PASTE event.
Even if I dispatch Event.PASTE event and call this function within event handler it still fails.
How does it determine which event is currently being processed?
you need to lister for the real paste Event from the stage and not simulate it. This is a security issue so flash apps do not read your global clipboard data, only on user paste action.
Related
This question is related to direction provided to me in another post (see How can I stop a method using a Cancel button in visual C#?). My question, is whether there are any restrictions when creating a BackgroundWorker, as far as called methods are concerned? I have a method that executes fine outside the DoWork section of my BackgroundWorker, but the moment it is placed inside the DoWork, I get a Cross Thread error stating "Cross-thread operation not valid: Control "txtFileOutput" accessed from a thread other than the thread it was created on." I know the BackgroundWorker is working with a basic for loop and have validated that. The "txtFileOutput" control referenced in the error is a textbox, to which I'm piping output from a regex query against a file (this is the method I'm trying to call within the DoWork).
I make user-event and send it an object in another thread using postEvent(). Since the receiver can be destroyed before it process the event, I want to know the event is processed or not. But QML doc says
It is not safe to access the event after it has been posted.
Is there a way to know the event is processed or not?
I have a need to validate a field against our database to verify unique-ness. The problem I seem to be having is that the validators doValidation() exits before we've heard back from database.
How can I have the validator wait to return its payload until after we've heard from the DB?
Or perhaps a better question might be (since I think the first question is impossible), how can I set this up differently, so that I don't need to wait, or so that the wait doesn't cause the validation to automaticallly return valid?
If you're using a remote object, you can specify the method call inside your remote declaration and assign a function to the result call. The result call only runs once the remote server returns something, so it won't be run before your validation.
Do your validation call in said result function call (which you will have to create) and you should be good. Your code should go something like this:
<s:RemoteObject id="employeeService"
destination="ColdFusion"
source="f4iaw100.remoteData.employeeData"
endpoint="http://adobetes.com/flex2gateway/"
result="employeeService_resultHandler(event)"/>
**<s:method name="dataCheckCall" result="dataCheckResult(event)"/>**
<s:RemoteObject />
And in your script:
function protected dataCheckResult(event:ResultEvent):void {
**doValidate();**
}
Edit: As soon as you call "dataCheckCall" the method will start running. If, for whatever reason, you want to call this WITHIN your validator, you can do so, and then dataCheckResult will run whenever it returns with it's payload (pretend doValidate is called elsewhere). I've left a message below as well.
You are trying to fit an asynchronous process (fetching data from a DB) into a synchronous process (checking all the validators in turn).
This won't work...
You'll need to either roll your own validator framework, or use a different method of determining the legality of your controls.
P.S. The MX validators are rubbish anyway!
What I've managed to do, seems to work, mostly. I don't like it, but it at least performs the validation against the remote source.
What I've done, then, is to use an 'keyUp' event handler to spin off the database lookup portion. In the meanwhile, I set up a string variable to act as some kind of a Flag, which'll be marked as 'processing'. When the response event fires, I'll examine its contents, and either clear the flag, or set it to some kind of other error.
Then, I have created a new 'EmptyStringValidator' will check the contents of this flag, and do its job accordingly.
Its indirect, but, so far, seems to work.
I need to call FileReference.save() after a web service call has completed, but this method has a restriction: "In Flash Player, you can only call this method successfully in response to a user event (for example, in an event handler for a mouse click or keypress event). Otherwise, calling this method results in Flash Player throwing an Error exception." (from the documentation here)
This restriction is a bit vague. Does it mean that I can only call the FileReference.save() method from within an event handler function that is registered as a listener for certain types of user events? If so then exactly which user events are valid? (Perhaps there's an event that will never be dispatched by user interaction with my application and I could register an event handler function for that event type and make the save() call from within that function?)
My difficulty is that I can't safely call the FileReference.save() method until my web service returns with the data that will be used as the argument of the FileReference.save() method call, so the event that triggers the FileReference.save() call is actually a ResultEvent rather than a user event, and I'm leery of dispatching a new (faux) user event type in order to be able to trigger the FileReference.save() call unless it's definitely a user event that would never be dispatched as a result of actual user interaction with my application.
In a nutshell what I'm doing now is this: I have a function that is registered as a handler for a button click. In this function I make my web service call to fetch data from the server. I also have a result handler function which gets invoked when the web service call completes, and it's in here that I want to call the FileReference.save() method since it's at this point that I know that the data is ready to be saved to a file. But the aforementioned restriction is blocking me from doing this -- I get an error:
Error #2176: Certain actions, such as those that display a pop-up window,
may only be invoked upon user interaction, for example by a mouse click
or button press.
I've tried many things to get around this such as creating a second mouse click event handler function with the FileReference.save() call within and calling it after a timeout interval (to give the web service time to complete), but I keep running into the same error -- maybe that approach doesn't work since the second function isn't registered as an event listener for the event type used as its argument.
I'm new to Flex development so perhaps I'm just not thinking about this in the right way. If anyone can suggest another approach I'd really appreciate it. Thanks in advance for your comments or suggestions.
--James
Adobe does this as a sort of security measure to ensure users are the ones messing with files rather than potentially harmful code. My understanding is that they enforce this by only allowing handlers of (click?) events that originate from UI components to execute the FileReference methods, so generating your own events programmatically will not work, although I have not tried to verify this. Unfortunately the best resolution I've found is to re-work the UI a bit to conform to this constraint. In your particular situation, you could make this a two click process with a button that says something like "Prepare Download", which changes to "Download File" after the web service is complete. This is less than ideal from a user perspective, but I don't think there's much else that can be done unless you can somehow complete your web service call prior to displaying the button that triggers the FileReference.save() call.
After struggling for that for well, a couple hours I found a workaround: you can use both mouseDown AND mouseUp events instead of just click.
For instance:
s:Button
mouseDown="prepare_PDF()"
mouseUp="save_PDF()"
Works fine for me!
Happy coding!
--Thomas
As a workaround I used the ExternalInterface class. I created a javascript function with this code
function downloadFile (url) {
window.open(url);
}
An in AS3 I call
var url = 'www.example.com/downloadfile.php?file_id=xxx';
ExternalInterface.call('downloadAttachmentFile', url);
So with that I transfer the file handling to JS/HTML.
This is a comment on Thomas' answer (I don't have enough XP to comment yet): The mousedown and mouseup workaround works nicely. Just a note that if you make any changes in prepare_PDF() that need 'undoing' in save_PDF(), then its a good idea to call that code on the mouseout event as well, since there might be a case that the user mousedown's on the button, but then moves the mouse away from the button.
This was particularly relevant for my case, in which we increase the size of a watermark on an image when the user clicks the download button (that triggers the .save() call). I reduce the size of the watermark down to normal on the mousedown and mouseout events.
I had this same issue, I chose to use flash.net methods. Call flash.net.navigateToURL(url); from an actionscript or navigateToURL(url); from mxml.
What i do to solve this is to show an alert message with an anonymous function so i don't have to create a button.
Alert.show("Do you wish to download the file?", "Confirm", Alert.OK | Alert.CANCEL, this, function (eventObj:CloseEvent):void {
if (eventObj.detail == Alert.OK) {
fileReference.save(zipOut.byteArray, dateFormater_titulo.format(new Date ()) + ".zip");
}//if
}/*function*/, null, Alert.OK);
There's a few questions on stack overflow on this topic but I'm still unclear:
I know the flash engine is single threaded so when it receives an event, does it essentially break off, execute any registered event listeners (in no guaranteed order) then return to the current scope?
If I have this code:
addListener("stuff", function():void {
// some stuff
});
addListener("stuff", someFunc);
dispatch(new Event("stuff"));
trace("Done.");
I want to know:
Can I guarantee that both listeners have executed by the time I reach the trace("Done"); line?
edit:
or
can I guarantee that the current function will complete before any of the event listeners execute? ie trace("Done"); will ALWAYS execute first.
or
Neither.
It is guaranteed that both event handlers will be called before trace because user code generated events are synchronous:
Does dispatching an event interrupt a function?
From what I know, when you dispatch an event it gets added to the event queue, but won't actually run until the currently-executing event finishes. In other words, you'll trace "Done.", then your function ends, control passes back to the event handler, and only then does it (maybe) start executing one of your events.
Yes, you can guarantee both assertions in this exact situation.
Meaning, that if adding your event listeners and dispatching your event is in the same code block it will happen in sequence. However, from a practical POV that's completely useless.
#kryoko: player events get precedence over user events, but they do not 'force' themselves through. Meaning that if user code is running, the player event handling is suspended. That's why it's possible to 'freeze' a flash movie with heavy, intensive code. (Or with a simple infinite loop, of course)