Get old text from change event?

Question

Can I somehow find out what was the change in the textfield? I would want to compare the old text with the new text ... the problem is, that I have multiple textAreas in a tab-editor, and all the textAreas are watched by one eventListener. I want to get a value calculated by the next formula:

globalChangeCount += thisTextArea.currentCharacterCount - thisTextArea.oldtCharacterCount

where the globalChangeCount is a value modified by all changes in any of the textAreas.

I am searching for these values through the event variable, but can't seam to find the old text of the textArea.

Answer 1

You can use event.currentTarget to get a reference to the TextArea that fired the event, and use the focusIn event to execute a function to populate a variable with the old text value.

Answer 2

Maybe you should just subclass the TextArea and create an oldText field variable you update internally after all the external listeners have been notified.

Answer 3

This may or may not be what you're looking to do:

package
{
    import mx.controls.TextArea;


    public class CountingTextArea extends TextArea
    {

        public var staleText : String = "";

        [Bindable("textChanged")]
        [NonCommittingChangeEvent("change")]
        public function get charDiff() : int
        {
            var diff : int = staleText.length - text.length;
            staleText = text;
            return diff;
        }

        public function CountingTextArea()
        {
            super();
        }
    }
}

I made it so that you can use it as a source for binding. Instead of subscribing to the event on each TextArea, you can use:

function addWatchers():void
{
    ChangeWatcher.watch(countingTextArea1, ["charDiff"], charDiffChangeHandler );
    ...
    ChangeWatcher.watch(countingTextArea5, ["charDiff"], charDiffChangeHandler );
}

With the event handler somewhere too:

function charDiffChangeHandler( event : PropertyChangeEvent ) : void
{
    trace(event.currentTarget.charDiff);
    // or
    trace(event.newValue);
}