Flash CS3 component button tutorial

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This is part of the flash tutorials

Learning goals
  • Learn how to use the component button
Prerequisites

The following tutorials are recommended but not fully necessary

Moving on
Level and target population
  • Beginners
Quality
  • You decide ...

Introduction - menu-based slideshow with the AS 3 button component

Goal

This section should provide you with an idea how to use a built-in component via the Flash Desktop. There are other ways of using components as we shall explain later...

Design goal of the example

The goal is to make a sort of simple Flash web site. The user at all times will have a menu to the left that will allow him to navigate to different contents. We will build several versions of this. Have a look at the menu-based slide show example before you start reading. Also, we will introduce some ActionScript by using a "language" that is hopefully appropriate for non-programmers.

A menu-based flash site

Note: In the Flash button tutorial we also demonstrated how to do this with built-in and home-made buttons.

Step 1- Planning the layers

In this example we will work with five layers:

  • Actions: will include a little Action Script code
  • Buttons: will include the buttons (displayed on all "pages")
  • Pictures: Contents we want to display
  • Credits: A special page for the "who's done it" (we also could have used the pictures layer for this).
  • Background: A simple background that will remain stable.

So the timeline roughly will look like this:

Timeline of the menu-based slideshow

Create these layers now

Step 2 - Add pictures or other contents
  • Decide how many pictures you want (we took four)
  • Select the Pictures layer
  • Frame 1 is reserved for a Title page.
  • Create a few new empty keyframes (hit F7) and fill them with pictures or any other content or drawings you'd like. See button tutorial if you don't know how to import pictures. Btw pasting a picture to the stage also does the trick.
Step 3 - Get buttons from the library
  • Select the buttons layer
  • Open the component library, select "User Interface" and drag as many buttons to the stage as you have pictures. Add an extra one for the credits page.
Button of the Flash CS3/ActionScript3 component library
Step 4 - ActionScript 3 principles

ActionScript 3 does not allow to attach scripts to buttons. One can only script frames in the timeline. In order to script a component we basically have to do three things.

  1. Give a name to the component (i.e. the movie instance on the stage)
  2. Fill in some parameters, e.g. add a label for the button
  3. Add some ActionScript to the timeline that will:
    • Associate a user interaction event (e.g. user clicks) to some action function
    • Program the action function
Step 5 - Give a name to each button and change its label
  • Click on a button (make sure to lock other layers)
  • Select the Parameters panel (menu Window->Properties->Parameters)
  • Give the button instance a unique name: e.g. btn_rainbow is fine. ("btn" means "button" and "rainbow" because this button will lead to a rainbow picture). To be safe:
    • Start the label name with a letter
    • For the rest use letters, digits or the underscore "_".
    • Do not use whitespaces or punctuation characters or dashes !!
    • I suggest that you use only lower case letters (Names are case sensitive)
  • Then change the label parameter of the button. This is what the user will see. Type anything there, but don't make it too long (it's a button after all). If your text is bigger than the label, change it's width in the same panel, i.e. modify the W: field.

Notice how different it is to work with a component vs. using buttons as explained in the Flash button tutorial

Parameters of the ActionScript3 button

Make sure you did this to all buttons.

Step 6 - Open the ActionScript panel
  • Open the Action Layer, Click in Frame 1
  • Hit F9 to open the "Actions-Frame" panel. In case it is docked with the parameters, you may undock it to have some more space.
  • Then paste all the code in steps 7 to 8. Maybe open our flash-cs3-simple-slide-show-menu.fla file and copy from there.

Note: Code that is delimited by /* */ represents so-called comments, i.e. code that is not interpreted by Flash, but that we inserted just to remember what our code is supposed to do. It's always a good idea to document your code ...

Step 7 - Stop the animation from playing in frame one

The stop() instruction will stop Flash from playing all the frames, i.e. we want the user to stay in Frame 1 after the file loads.

stop();
Step 8 - Associate buttons with handler functions

Associate a handler function for each button instance:

Syntax: button_name.addEventListener(Event.type, function_name

Lines below mean:

  • If the user clicks on the btn_rainbow with the mouse, then the function clickHandler defined below will execute.
btn_rainbow.addEventListener(MouseEvent.CLICK, clickHandler);
btn_tecfa.addEventListener(MouseEvent.CLICK, clickHandler);
btn_bosses.addEventListener(MouseEvent.CLICK, clickHandler);
btn_my_computers.addEventListener(MouseEvent.CLICK, clickHandler);
btn_credits.addEventListener(MouseEvent.CLICK, clickHandler);
Step 9 - Write a clickHandler function

Note: you could have chosen an other name, but as rule function names should be sort of meaningful to you and people who read your program

Instead of writing a function for each button, we just created a single one. This code contains a so-called switch (or case) statement. It's syntax is the following:

switch (value) {
  case value_1 :
    /* do something */
    break;
  case value_2 :
    /* do something */
    break;
  ....
  }

In order to understand which button was clicked, we ask from the event the label of the button (event.currentTarget.label).

Then we goto frame x and ask it to stop again with the instruction gotoAndStop(x).

function clickHandler(event:MouseEvent):void {
	switch (event.currentTarget.label)
	{
		case "Rainbow" :
			gotoAndStop(2);
			break;
		case "TECFA" :
			gotoAndStop(3);
			break;
		case "Bosses" :
			gotoAndStop(4);
			break;
		case "My computers" :
			gotoAndStop(5);
			break;
		case "Credits" :
			gotoAndStop(6);
			break;
	}
}
If things go wrong
  • Make sure that your syntax is correct. One single ";" missing and your program will fail. In the ActionScript window click on the "Check syntax" icon.
  • Also indent your code properly. Simply click on the "Auto Format" icon.
  • Make sure that the Action layer extends to the end of your timeline. Put code in frame 1 and then hit F5 in the right-most frame you use ("insert frame" and 'not insert keyframe !)
  • Make really sure that your code is in frame 1 and in the Action layer.
  • Make sure that button instance names and label names are exactly the same in the Parameters panel and your Script.

Here is the picture of the timeline again:

Timeline of the menu-based slideshow

Notice the little "a" in frame 1 of the Actions layer. It means "ActionScript code inside" :)

Extra Step 1

This shows how to program a button that will open an URL in a Web Browser (look at the example file you can download).

btn_edutech_wiki.addEventListener(MouseEvent.CLICK, GoToUrl);

function GoToUrl(event:MouseEvent):void {
	var url:String =  "http://edutechwiki.unige.ch/en/Flash_components_tutorial";
	var request:URLRequest = new URLRequest(url);
	try
	{
		navigateToURL(request, '_blank');
	}
	catch (e:Error)
	{
		trace("Error occurred!");
	}
}
Results
http://tecfa.unige.ch/guides/flash/ex/components-intro/

Too complicated ?

You may write this code in a slightly simpler but less elegant way: If you have no programming knowledge, you rather may work from the code below. The result will be same, though I changed to color of the background: 3 menu-based slide show

So here is what you need to change:

(1) Event listener registration

So the principle is: For each button you got to register an event listener function. Change:

  • The number of addEventListener definitions (here we got five)
  • Make sure that each btn-xxx corresponds to names you gave to your own button instances
myButton.addEventListener(MouseEvent.CLICK, Handler_A);
(2) Define event listener functions
  • Copy/Paste/Change definitions of functions
  • So change the name of the function, e.g. clickHandler_1 into Handler_A and the frame it has to jump to.
function Handler_A(event:MouseEvent):void {
    gotoAndStop(2);
}

Note: Formatting in ECMAScript -like languages does not matter. You could have written the above line as:

function Handler_A(event:MouseEvent):void {gotoAndStop(2); }

However, make sure to keep delimiters like the { } ;  !!

Start from this complete code
/* This will stop Flash from playing all the frames
   User must stay in Frame 1 */
stop();

/* Associate a different handler function for each button instance:
   Syntax: button_name.addEventListener(Event.type, function_name
   Lines below mean:
   * If the user clicks on the btn_rainbow with the mouse,
     then the function clickHandler defined below will execute
*/
btn_rainbow.addEventListener(MouseEvent.CLICK, clickHandler1);
btn_tecfa.addEventListener(MouseEvent.CLICK, clickHandler2);
btn_bosses.addEventListener(MouseEvent.CLICK, clickHandler3);
btn_my_computers.addEventListener(MouseEvent.CLICK, clickHandler4);
btn_credits.addEventListener(MouseEvent.CLICK, clickHandler5);

/* Each function defines where to move the playhead in the animation.
   E.g. clickHandler2 will go to frame 3 and then stop
   */

function clickHandler1(event:MouseEvent):void {
	gotoAndStop(2);
}
function clickHandler2(event:MouseEvent):void {
	gotoAndStop(3);
}
function clickHandler3(event:MouseEvent):void {
	gotoAndStop(4);
}
function clickHandler4(event:MouseEvent):void {
	gotoAndStop(5);
}
function clickHandler5(event:MouseEvent):void {
	gotoAndStop(6);
}

/* This shows how to open an URL in a WebBrowser */

btn_edutech_wiki.addEventListener(MouseEvent.CLICK, GoToUrl);

function GoToUrl(event:MouseEvent):void {
	var request:URLRequest = new URLRequest("http://edutechwiki.unige.ch/en/Flash_components_tutorial");
	navigateToURL(request, '_blank');
}
Results
http://tecfa.unige.ch/guides/flash/ex/components-intro/

You work with Flash 8 ?

The AS3 script above will not work in Flash 8. You have to work with the AS2 component library. This also means that you'd have to delete the buttons in the above example if you want to convert to AS2. If you make a fresh start, no problem, the component button looks and behaves almost the same as its AS3 version as you can see in the screen capture below:

The AS2 button component
  • Just change the label and if necessary the width parameter (E.g. we set W: to the left to 400 since the btn_edutech_wiki needs to be large).
Parameters of the ActionScript2 button

Make sure that you open a new ActionScript 2 file (or if work in CS3 and forgot, change the Publish Setting to AS2 before you start using buttons.

ActionScript 2 code

ActionScript 2 code is much simpler. The (good) reason why the much more powerful ActionScript 3 is more complicated is that ActionScript 3 allows to program Flash *.swf without even opening the Flash authoring environment. It's a language also made for programmers who do not necessarily like this frame-based tool and who prefere to develop with an IDE like Adobe Flex.

Anyhow, here is the code inserted in frame 1 of the "Action" layer:

stop();

btn_rainbow.onPress = function() { gotoAndStop(2); };
btn_tecfa.onPress = function() { gotoAndStop(3); };
btn_bosses.onPress = function() { gotoAndStop(4); };
btn_my_computers.onPress = function() { gotoAndStop(5); };
btn_credits.onPress = function() { gotoAndStop(6); };

btn_edutech_wiki.onPress = function () {
  getURL("http://edutechwiki.unige.ch/en/Flash_components_tutorial", "_blank");
};

As you can see, it is much simpler. We just use the following syntax:

name_of_button_instance.onPress = function () {
gotoAndStop (N);
};

Note: Instead of putting this code in the Action layer in one single script, we also could have attached it to the buttons as we did in the Flash button tutorial's simple slide show.

Results
http://tecfa.unige.ch/guides/flash/ex/components-intro/

Improvements to be made / exercise

  • If you got more and/or bigger pictures, you actually should not include the pictures in the *.swf, but rather load these from the Internet.

You then have to use how to use/program a preloader (we will cover this in some other tutorial).

  • You may add text (labels) to each picture
  • You also could add another URL button (e.g. I should add one to the TECFA Logo on top left).
Exercise
  • Add some contents to frame one and add a "home" button to navigate there.

Customizing buttons

You can customize button skins, but this is not easy.

  • Double click the button on the stage

However, before you try this:

  • Be aware that you can change width and height simply though the parameters panel
  • Color will adapt to background (buttons are transparent)

Read more about Customizing the Button at Adobe

Component buttons in an animation example

You may consult this example in order learn:

  • that one can add a button anywhere in the timeline
  • how to work with scenes

Scenes can be understood as fragments of a long timeline (likes scenes in a theatre). They have the following advantage:

  • The timeline becomes shorter and more manageable
  • You can test scenes independantly

To add a scene:

  • Menu insert scene
  • To rename a scene: menu Window->Other panels->Scene; then double-click on the scene

To navigate from one scene to another, use code like this:

The following code will move the user to a scene called "Credits" in frame 1 and stop after she presses the "credits_btn".

credits_btn.addEventListener(MouseEvent.CLICK, goCredit);

function goCredit(event:MouseEvent):void {
	gotoAndStop(1,"Credits");
}

The following code will move the user to a scene called "Animation" in frame 1 and play

restart_btn.addEventListener(MouseEvent.CLICK, restart);

function restart(event:MouseEvent):void {
	gotoAndPlay(1,"Animation");
}
Example and code