Actionscript newbie

Question

i'm exploring actionscript for the first time and was
exploring some of the templates that Flash offers. I came across a
slide animation template with this code in the first frame. can
anyone explain it to me?
// If not defined yet,
if (isLoaded == undefined) {
// Routine to move playhead to a new frame
var updateFrame = function (inc) {
var newFrame = _currentframe + inc;
gotoAndStop(newFrame);
if (_root._currentframe == 1) {
backBtn._alpha = 50;
backBtn.enabled = false;
} else {
backBtn._alpha = 100;
backBtn.enabled = true;
if (_root._currentframe == _root._totalframes) {
forwardBtn._alpha = 50;
forwardBtn.enabled = false;
} else {
forwardBtn._alpha = 100;
forwardBtn.enabled = true;
// When the forward button is pressed
forwardBtn.onPress = function () {
updateFrame(1);
// When the back button is pressed
backBtn.onPress = function () {
updateFrame(-1);
// When the keyboard keys are pressed
var keyListener = new Object();
keyListener.onKeyDown = function () {
if (Key.isDown(37)) {
// Left
updateFrame(-1);
} else if (Key.isDown(38)) {
// Up
updateFrame(-(_currentframe-1));
} else if (Key.isDown(39)) {
// Right
updateFrame(1);
} else if (Key.isDown(40)) {
// Down
updateFrame(_totalFrames + 1);
Key.addListener(keyListener);
// Call updateFrame at first to get button states correct at
start
updateFrame();
// Set loaded flag to prevent redefinition
this.isLoaded = true;
stop();

Answer 1

The isLoaded variable is because the frame containing the
code should only
play once and in case the playback head crossed the frame the
code will not
play twice.
The updateFrame function sets the appearance of UI buttons
based mostly on
the frame number.
The other functions are attached to buttons or keys to handle
their
interaction and all seem to call updateFrame.
Lon Hosford
www.lonhosford.com
Flash, Actionscript and Flash Media Server examples:
http://flashexamples.hosfordusa.com
May many happy bits flow your way!
"Brhaynes75" <[email protected]> wrote in
message
news:[email protected]...
> i'm exploring actionscript for the first time and was
exploring some of
> the
> templates that Flash offers. I came across a slide
animation template with
> this
> code in the first frame. can anyone explain it to me?
>
>
> // If not defined yet,
> if (isLoaded == undefined) {
>
> // Routine to move playhead to a new frame
> var updateFrame = function (inc) {
>
> var newFrame = _currentframe + inc;
> gotoAndStop(newFrame);
>
> if (_root._currentframe == 1) {
> backBtn._alpha = 50;
> backBtn.enabled = false;
> } else {
> backBtn._alpha = 100;
> backBtn.enabled = true;
> }
> if (_root._currentframe == _root._totalframes) {
> forwardBtn._alpha = 50;
> forwardBtn.enabled = false;
> } else {
> forwardBtn._alpha = 100;
> forwardBtn.enabled = true;
> }
> }
>
>
> // When the forward button is pressed
> forwardBtn.onPress = function () {
> updateFrame(1);
> }
>
> // When the back button is pressed
> backBtn.onPress = function () {
> updateFrame(-1);
> }
>
> // When the keyboard keys are pressed
> var keyListener = new Object();
> keyListener.onKeyDown = function () {
> if (Key.isDown(37)) {
> // Left
> updateFrame(-1);
> } else if (Key.isDown(38)) {
> // Up
> updateFrame(-(_currentframe-1));
> } else if (Key.isDown(39)) {
> // Right
> updateFrame(1);
> } else if (Key.isDown(40)) {
> // Down
> updateFrame(_totalFrames + 1);
> }
> }
> Key.addListener(keyListener);
>
>
> // Call updateFrame at first to get button states
correct at start
> updateFrame();
> }
>
> // Set loaded flag to prevent redefinition
> this.isLoaded = true;
> stop();
>