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Overview of Macromedia Flash |
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Animations are built from libraries of Symbols, or elements, which are created once and can then be used multiple times without increasing the file size. So, if a user wants to create a movie which features the company logo, that logo can be used repeatedly throughout the animation, it can be grown and shrunk, it can change colour and be distorted as required while still only counting as one entity. Furthermore, if the original symbol is modified (perhaps with a new strap line), all instances of that symbol are updated to match automatically. In order to further speed animation development time, these symbols can be shared between movies, so that the logo can be used in a second movie with just a couple of clicks of the mouse.
In order to be able to animate items on the screen (or "stage") effectively, designers are able to use multiple layers. This allows for the symbols to interact more reliably without, for instance, one image accidentally overwriting another. Related layers can be grouped into folders for ease of management, and layers can be used to mask each other, so that only certain portions of a layer are visible. A layer can be used as an "animation path" for another, allowing for an object to me moved around the screen following a hand-drawn path, rather than in a more regular manner.
Once the symbols have been created, the key to the whole animation is the Timeline. On the timeline, each layer in the animation is divided into frames. Animating can still be done in the time-honoured fashion of working frame-by-frame, whereby the designed manually constructs the contents of each frame, moving elements fractionally as needed. However, Flash also introduces the concept of "Tweens". Using this method, the designer specifies a start point and an end point for an element of animation, and Flash takes care of the element's position at all the intermediate frames (see Figure 2).
Figure 2 - The Flash timeline, showing layers and "Tweens"
In more complex animations, the entire movie can be subdivided into Scenes, allowing easier management of the various stages of the movie. Frames and symbols can be copied from one scene to another, and the movie flows seamlessly through its component scenes to a completion.