Symbolizing things

Animate revolves around symbols. Symbols are a very efficient way of building movies, as a symbol only needs to be loaded once. After it has been loaded, you can create as many copies - known as instances - as you want to. More importantly, every instance of a symbol can have properties independently applied to it. You can adjust the size, orientation, and skew. You can also apply tinting, control the brightness, adjust the alpha (transparency) level. There are three basic types of symbols that Animate uses. The Graphic symbol, the Movie symbol and the Button symbol.

Graphic symbols are just a drawing converted into a symbol. The drawing can be as simple or complex as you desire, and can even contain other symbols as part of it. These tend to be vector based, but it is possible to use bitmaps for graphics. Flash used a very compact binary format for vector images making them take significantly less space than bitmaps in many cases. Animates’ HTML5 exporting converts these vectors into Create.js shapes which take up significantly more space, especially if you are not letting Animate compress the images.

A movie symbol is essentially a movie within the main movie. You have as much control over an Animate movie symbol as you do over the resulting movie. You are not limited to having a single level of movie clip as movie symbols can contain other movies as part of them, which can contain movie symbols within them which can contain movie symbols within them and so on. While this recursive nature of movie clips adds a lot of flexibility to creating animations, movie clip objects are fairly heavy in memory and processing requirements so having too many nested movie clips can slow things down substantially.

A Button is simply a special symbol that has special actions associated with it whenever the mouse is over it or the mouse has been clicked while over it. To be more precise, a button has 4 frames associated with it. The up frame is simply the normal appearance of the button. The over frame is how the button looks when the mouse is over it. The down frame is what the button looks like when the mouse is over it and the mouse button has been pressed. Finally, the hit frame defines the over/hit areas.

The hit frame may seem confusing to people new to Animate. This frame is not actually seen by the viewer, but is instead used by Animate. How it works is any area in the hit frame that is solid will react to the mouse being over it while an area that is not solid will be ignored. While touch users will not get the mouse over effect, the hit area is used for determining if a touch results in a down event.

Some of you may be wondering why you would want or need such a thing? Couldn't you just use the existing button image? The answer to that is you could, but then the button would only work if the user had his or her mouse positioned in a solid part of the image. In some cases, such as with our Play the Game button, we want the button to react if the mouse is within a block or an area that covers more than the frames cover. Conversely, you may not want a rectangular region or even the entire button to be clickable. The hit mask gives you total control over where the button can be clicked.

As an example, here is a button that I use for switching a sound from enabled to disabled. The top right image is the normal image and is what the user will see normally. The top-middle image is what will be shown to mouse users who move the mouse pointer over the image. The top-right image is what is shown when the button is clicked or touched. Finally, the bottom image is the hit map that is used for determining if the mouse is over the image.

Symbols can be created in animate simply by drawing something and then selecting the drawing and choosing the “convert to symbol” option from the right-click menu or the modify menu from the menu bar. Creating a symbol adds it to the library. Empty symbols can also be created from within the library, though personally this is not something I do. The library is a file-folder structure allowing you to easily arrange your symbols to make finding and working with them much more efficient. This is especially true when you get to larger projects that contain hundreds or thousands of objects.

Libraries also have the benefit of being sharable between projects. Animate makes it easy to move symbols between different libraries allowing you to create a standard set of library symbols that can be copied between libraries. There are also built in tools for converting a selection of library symbols into image atlases or stand alone files which can come in handy for environments where animators create assets in animate then hand them off to developers who are using pure JavaScript (or other language for non-HTML projects) for creating the application.