# Animation

## Introduction

If you want to give some dynamics to your documents, there are essentially two possibilities to do so:

The first alternative can be hardcoded, achieved with either some trickery (\dorecurse may sometimes help you) or with support of modules such as RawSteps.

### An example

Suppose you have a presentation and you want the content of a slide to be gradually shown on the screen like in the next example:

Slide 1

If a chicken and a half lays an egg and a half in a day and a half, how many eggs can one chicken lay in one day?


Slide 2

If a chicken and a half lays an egg and a half in a day and a half, how many eggs can one chicken lay in one day?
- What a stupid question! ONE, of course.


Slide 3

If a chicken and a half lays an egg and a half in a day and a half, how many eggs can one chicken lay in one day?
- What a stupid question! ONE, of course.
- Wrong! I'll give you one more try: how many eggs can one chicken lay in a day and a half?


Slide 4

If a chicken and a half lays an egg and a half in a day and a half, how many eggs can one chicken lay in one day?
- What a stupid question! ONE, of course.
- Wrong! I'll give you one more try: how many eggs can one chicken lay in a day and a half?
- Wait a minute ... one chicken can lay 2/3 eggs in one day, doesn't it?


The difference in how the two mentioned method would deal with it:

• In the first case your document would consist of 4 pages with the corresponding content on each page.
• In the second case you would only have one page and some JavaScript code behind the scenes taking care of the content appearing gradually on your page as you click on some button.

### Comparison

It all depends on your needs which of the two mentioned possibilities would suit you most. Here are some advantages and disadvanteges of both methods listed.

PROS CONS
Multiple pages
• almost any PDF viewer can read it
• you can quickly browse forwards/backwards with PgDown/PgUp or mouse
• may result in a huge amount of pages (and huge size as well)
• only static - you have to move it forward/backward manually
JavaScript
• complex animations possible
• good support in ConTeXt
• not supported by every PDF viewer (only Acrobat >= 6)
• even in Acrobat not always backward-compatible (may change in the next version)
• some programming practice needed
• buttons to trigger the animation have to be predefined precisely (you can't simply jump from one frame to another unless you programmed it that way)

### How to make movies?

Even if you were leaping for joy once you heard about the animations, I have to disappoint you right away: no matter how hard you try, it's not very likely that you'll ever achive much more than one, maybe some frames per second. So won't really be able to watch movies this way.

However, there's another possibility to use your nice metapost figures to make animations, pdf2swf. See http://melusine.eu.org/syracuse/metapost/animations/ and http://www.quiss.org/swftools/examples.html for examples.

## Using the animation module

### Simple example

\usemodule[animation]
\setupinteraction[state=start]

\starttext

\startanimation
{\externalfigure[dummy]A}
{\externalfigure[dummy]B}
{\externalfigure[dummy]C}
{\externalfigure[dummy]D}
\stopanimation

\stoptext


\usemodule[animation]
\setupinteraction[state=start]

\definepairedbox[animationtext][location=top,align=middle,width=\textwidth]

\starttext

\startanimation
{\placeanimationtext{The letter a}{\externalfigure[dummy]}}
{\placeanimationtext{The letter b}{\externalfigure[dummy]}}
{\placeanimationtext{The letter c}{\externalfigure[dummy]}}
{\placeanimationtext{The letter d}{\externalfigure[dummy]}}
\stopanimation

\stoptext


### Example with formulae

\usemodule[animation]

\setuppapersize[S6][S6]

\setupinteraction[state=start]

\definepairedbox[animationtext][location=top,align=middle,width=\textwidth]

\starttext

\startanimation
{\placeanimationtext{Sine norm, and}{\startformula \int_{0}^{2\pi}\sin^2(x)dx = \stopformula}}
{\placeanimationtext{Cosine norm}{\startformula\int_{0}^{2\pi}\cos^2(x)dx = \stopformula}}
{\placeanimationtext{are equal}{\startformula = \pi. \stopformula}}
\stopanimation

\stoptext


## Animating Text

TODO: presentations with pre-61

## Documentation

• JavaScript (as well as PDF) reference at [Adobe]
 TODO: Here are a lot of empty sections, and a bit more order won't hurt (See: To-Do List)