This is
page 4 of the tutorial, so if you are visiting here from a
search engine without having completed the previous page,
click here.
Fadeout Function
Our fadeout function is responsible for fading out our news
text. Let's take a look at how it is done!
- this.onEnterFrame
=
function()
{
- if
(newsMC.newsText._alpha>=0)
{
-
newsMC.newsText._alpha
-=
5;
- }
else
{
-
display();
- p++;
-
delete
this.onEnterFrame;
- }
- };
I place everything in an onEnterFrame function because I want
whatever I place to repeat smoothly for a period of time. The
easiest way to do that, would be to use an onEnterFrame function
that executes code with a speed proportional to your frame rate.
- if (newsMC.newsText._alpha>=0)
{
- newsMC.newsText._alpha
-= 5;
- }
else {
- display();
- p++;
- delete
this.onEnterFrame;
- }
In the first part of the if statement, I check to see if the
alpha of our text is greater than 0. Since we are interested in
fading out our text, ultimately we would want our text to be
invisible with an alpha of at least 0 at the end.
So, if our text is still visible with an alpha greater than
zero, I decrease the alpha by 5:
- newsMC.newsText._alpha
-= 5;
Since this code is in an onEnterFrame, the text field will
gradually decrease its alpha by 5 until the alpha of the text
field becomes less than or equal to zero. When that happens,
it's time to look at our else case!
- display(p);
- p++;
- delete
this.onEnterFrame;
First, I call our display function to display the next
caption in the series. At this point, the previous news caption
should have faded out completely, so it makes sense to display
the next item now.
I increment the value of the counter variable p to
inform Flash that I want to proceed to the next image when the
display function is called again.
Finally, I delete the onEnterFrame statement. After
displaying the new news item and incrementing the value of p,
there is no need to waste CPU cycles by keeping our onEnterFrame
to run through code that no longer needs to be run. The
delete command allows you to delete the onEnterFrame
function we declared earlier easily.
It's Over
You are now done with this tutorial
and the explanation for it. The main idea I hope you get out of
this tutorial is how to divide important responsibilities of
your code to different functions. Breaking your code into
various functions makes it easier to troubleshoot, or more
importantly, to extend your animation without having to
extensively modify the ticker's core functionality.
I have provided the source file for you to see my version of
the exact same tutorial.
Just a final word before we wrap up. If you have a question and/or want to be part of a friendly, collaborative community of over 220k other developers like yourself, post on the forums for a quick response!
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News
Ticker - Page 4
