Adobe 38039481 User Guide - Page 77

FLASH CS3 71 User Guide About nested movie clips and parent-child hierarchy When you create a movie clip instance in a Flash document, the movie clip's Timeline is nested inside the main Timeline of the document. Each movie clip symbol has its own Timeline. You can also nest a movie clip instance inside another movie clip symbol. When a movie clip is nested inside another movie clip, or inside a document, it becomes a child of that movie clip or document, which becomes the parent. Relationships between nested movie clips are hierarchical: modifications made to the parent affect the child. The root Timeline for each level is the parent of all the movie clips on its level, and because it is the topmost Timeline, it has no parent. In the Movie Explorer, you can view the hierarchy of nested movie clips in a document. To understand movie clip hierarchy, consider the hierarchy on a computer: the hard disk has a root directory (or folder) and subdirectories. The root directory is analogous to the main (or root) Timeline of a Flash document: it is the parent of everything else. The subdirectories are analogous to movie clips. You can use the movie clip hierarchy in Flash to organize related objects. For example, you could create a Flash document containing a car that moves across the Stage. You can use a movie clip symbol to represent the car and set up a motion tween to move it across the Stage. To add wheels that rotate, you can create a movie clip for a car wheel, and create two instances of this movie clip, named frontWheel and backWheel. Then you can place the wheels on the car movie clip's Timeline-not on the main Timeline. As children of car, frontWheel and backWheel are affected by any changes made to car; they move with the car as it tweens across the Stage. To make both wheel instances spin, you can set up a motion tween that rotates the wheel symbol. Even after you change frontWheel and backWheel, they continue to be affected by the tween on their parent movie clip, car; the wheels spin, but they also move with the parent movie clip car across the Stage. For a video tutorial about using multiple timelines, see www.adobe.com/go/vid0128. See also "Using symbols, instances, and library assets" on page 207 About absolute paths An absolute path starts with the name of the level into which the document is loaded and continues through the display list until it reaches the target instance. You can also use the alias _root to refer to the topmost Timeline of the current level. For example, an action in the movie clip california that refers to the movie clip oregon could use the absolute path _root.westCoast.oregon. The first document to open in Flash Player is loaded at level 0. You must assign each additional loaded document a level number. When you use an absolute reference in ActionScript to reference a loaded document, use the form _levelX, where X is the level number into which the document is loaded. For example, the first document that opens in Flash Player is called _level0; a document loaded into level 3 is called _level3. To communicate between documents on different levels, you must use the level name in the target path. The following example shows how the portland instance would address the atlanta instance located in a movie clip called georgia (georgia is at the same level as oregon): _level5.georgia.atlanta