ActionScript Lecture Notes -

Objective #1: Use ActionScript to use actions to control a movie.

• You can work in the normal mode or the expert mode in the Script pane. The normal mode prompts you with choices as build an ActionScript statement. However, it can be awkward for those with average ActionScript experience. The expert mode requires you to type out most of your ActionScript code from scratch, however you can see a whole section of statements at once.
• When using commands such as gotoAndPlay it is best to use frame labels rather than frame numbers as parameters. By entering frame labels in frames throughout your movie's timeline, you can organize your movie better especially if its meant to be used as a web site with different static pages. I recommend creating a layer called "labels" and entering the frame labels in keyframes in that layer. To add a frame label, add a keyframe and with the frame selected, enter a label in the Property Inspector.
• The syntax rules for typing ActionScript are important to follow since it is a programming language. Do your best to type actions such as gotoAndPlay with the proper mix of upper and lowercase letters. Also, do your best to add semicolons where necessary.
• A comment statement is a statement that is typed into the code for your reference but ignored by Flash. In the following example the first statement is a comment statement,
  
  // Home button
  on (release) {
     gotoAndPlay("home");
  }
  
• Comment statements can also be typed by beginning a section of code with a /* and ending the commented section with */. See this example,
  
  /*
     Home button
  */
  on (release) {
     gotoAndPlay("home");
  }
  
• With statements like the on statement that is used with buttons, Flash waits until the mouse button is released. When the button is released, Flash executes the statement or statements that are in the curly braces { .... }
  
  Therefore you must type the gotoAndPlay action statement inside of the curly braces. Indentation and line breaks aren't important to Flash but you should follow conventional style. The following versions of code will work equivalently although the first version is the most conventional and the easiest to read:
  
  on (release) {
     gotoAndPlay("Page2");
  }
  
  on (release)
  {
     gotoAndPlay("Page2");
  }
  
  on (release) { gotoAndPlay("Page2"); }
  
  on (release)
  {gotoAndPlay("Page2")}
  
  Note that the semicolon was not typed in the last version but the code will still work only because Flash is very forgiving....in the current MX version at least.

Objective #2: Use targets and movie clip symbols.

• You should use movie clips symbols since it is good to use symbols for the sake of size optimization and efficient design but also because more can be done with movie clip symbols than with graphic symbols.
• Since a movie clip contains its own independent timeline, it is sometimes desirable to use ActionScript to control that timeline. To refer to a movie clip and/or its timeline, you must first make it a target by giving it a unique name.
• When you select a movie clip symbol that is on the Stage, you can type a target name in a field in the upper-corner of the Property Inspector. This gives the instance of the movie clip symbol a name which is unrelated to the name of the movie clip symbol itself that appears in the Library.
• Once you have named a movie clip instance, it can be referred to in a with statement like this
  
  on (release) {
     with (walkingMan) {
        gotoAndPlay("start");
     }
  }
  
  By placing the with statement inside of the curly braces to the on statement and then placing a gotoAndPlay statement inside the curly braces of the with statement, you are telling Flash that when the mouse button is released it should play the frame labelled "start" that is on the timeline of the walkingMan movie clip instance. If you incorrectly typed the following code that does not include the with statement
  
  on (release ) {
     gotoAndPlay("start");
  }
  
  then Flash would look for a frame labelled "start" on the movie's main timeline.
  
• Occasionally, you'll find the need to use a movie clip within a movie clip. For example, if a movie clip symbol instance with the name walkingMan has a nested a movie clip instance with the target name movingLegs within it, you can play a specific frame of the innermost movie clip from a button on your main movie's timeline. In this case, you should use the Insert Target Path dialog box to be sure to use the correct syntax in the with statement. Or, you could understand the necessary dot notation that is required in this case and type out the code yourself.
  
  on (release) {
     with (walkingMan.movingLegs) {
        gotoAndPlay("rightlegforward");
     }
  }
  
  In the expression walkingMan.movingLegs, the dot symbol is used to show the hierarchical, parent-child relationship between the two instances. In this example, a frame labelled "rightlegforward" must exist in the movingLegs instance. In this example, you must remember to specify the nested instance with the target name movingLegs.

Objective #3: Create interactive movie clip symbols.

• A number of actions including startDrag, stopDrag, _droptarget can be used with movie clips to make for a more interactive user experience.
• A startDrag action can be typed inside an on statement to allow the user to drag a movie clip across the stage. Select a movie clip and then type the following code into the Action pane
  
  on (press) {
     startDrag("");
  }
  
  to allow the user to drag a movie clip instance across the stage. You can also type the keyword this inside the parentheses of the startDrag action.
  
  You should follow up the code above with the code
  
  on (release) {
     stopDrag( );
  }
  
  to allow the user to drop the movie clip that he/she is dragging.
  
  Furthermore, you can use the _droptarget and setProperty actions to make a movie clip instance disappear when the user drops it over top of another named movie clip instance. In the example below
  
  on (press) {
     startDrag("");
  }
  
  on (release) {
     stopDrag( );
     if (_droptarget=="/targetInstance") {
        setProperty("_root.draggedInstance", _visible, false);
     }
  }
  
  the movie clip instance with the name draggedInstance can be dragged across the screen if this code is typed into its Action pane. However, when it is overtop of the movie clip instance with the name targetInstance, it will suddenly disappear. The _droptarget function requires the forward slash in front of the instance name in the double quotes. Note that _root is typed out to provide the full absolute path of the draggedInstance target. You can tell that _visible is a property of a movie clip since it begins with an underscore.
  
• You can use ActionScript to change properties of a movie clip instance such as position, rotation, color, size, and visibility.

Objective #4: Define and use variables in ActionScript statements.

• A variable is used in a programming language to store a numeric or text value for the purpose of using that value later in the program. A variable can be used to store the current score to a game or a user's choice from a menu. When you create a variable you must give it a name that contains no spaces such as score or userScore and you set it equal to a given value with an equals sign. The following statement sets the variable score equal to zero.
  
  score = 0;
  
  You might want to place a statement like that in the Action pane with frame 1 selected. You can also perform arithmetic on variables and store the result in another variable. Consider the following example
  
  totalScore = partOneScore + partTwoScore;
  
  in which the variable totalScore is now equal to the sum of partOneScore plus partTwoScore after the statement executes. Do not type such statements with the variable that you want the new value to be stored in on the right side of the equals symbol since
  
  partOneScore + partTwoScore = totalScore;
  
  would cause a syntax error.
  
• Mathematical operators *, /, +, -, and % (modulus) can be used with variables in assignment statements like the examples above. Be careful when using the addition + operator though. Flash will sometimes concatenate two numbers together by default. That is the variable sum will store the string value "32" after the following statement executes
  
  sum = 3 + 2;
  
  so you may need to use the Number function to force Flash to treat a value as a number
  
  sum = Number(3) + Number(2);
  
• Variables can also store strings (i.e. words or phrases) which must be surrounded by double quotes. Example,
  
  name = "Santa Claus";
  
• An if statement can be used to determine whether a certain condition is true or false and, if it's true, you can specify that a given action take place. Even though we haven't studied variables yet in the following example assume that there is a variable named score that stores a whole number such as 3
  
  on (release) {
     if (score = = 3) {
       gotoAndPlay(25);
     }
  }
  
  When the user releases the mouse button the code inside of the curly braces to the on statement will execute. Then, if and only if the number currently stored in the variable score is 3, Flash will play frame number 25. If the variable score is not equal to 3 then nothing special happens and the movie plays whatever frame it normally would have played. Inside the parentheses of an if action is a condition that is tested to either be true or false. A double equals symbol must be used when you want to test whether a variable's value is equal to a certain number or not. Other operators that can be used in place of the double equals symbol are < , >, <= , >=, and != (not equal to).
• You can also use an if else statement or an if elseif conditional statement. For example,
  
  on (release) {
     if (score > 10) {
        gotoAndPlay("gameOverWinner");
     }
     else {
        gotoAndPlay("gameOverLoser");
     }
  }
  
  on (release) {
     if (score >10) {
        gotoAndPlay("congratulations");
     }
     elseif (score > 5) {
        gotoAndPlay("okay");
     }
     elseif (score > 0) {
        gotoAndPlay("belowAverage");
     }
  }
  
• Three kinds of loops, while, do/while and for, can be used to make a set of statements execute over and over again.
  
• The + operator is the concatenation operator in Flash and can be used to join two strings together into one string as in
  
  wholeName = firstName + " " + lastName;

Objective #5: Use input and dynamic text fields to add interactivity to a Flash movie.

• When you use the Text tool to create text, you are creating static text by default. With a text field selected, you can change it to input text or dynamic text in the Property Inspector. An input text field allows the user to type text into the text field when the movie file executes. A dynamic text field is used instead of static text when you want to change the text that is entered there using ActionScript when the movie executes. Either way, be sure to specify a unique name (that includes no spaces) in the Var area of the Property Inspector for an input or dynamic text field. This variable name can then be used in your ActionScript code to refer to the text that the user typed into an input text field or to change the text that appears in a dynamic text field. For example, if a dynamic text field had the name gameScore typed into its Var field, the following statement would make the value 100 appear in the text field when the statement executes
  
  gameScore = 100;