![]() ![]() It has to be admitted that there are some slight difficulties, but overcoming them isn't hard and is very instructive. You can take this approach in Android, but for various reasons it isn't the way things are usually done. ![]() In most systems this is usually achieved at the lowest possible level by using a timer to call an update function which erases the shape, does the update to the shape and then draws it at its new location. To animate something in the simplest and most direct way all you have to do is draw the shape, change the shape, erase the old graphic, and draw it again. One warning – do not assume this is all there is to know about Android animation or that this is the best way to do things. ![]() This example not only teaches you something about animation, but also about the problems of creating dynamic graphics of any kind in the Android UI. However, none of them demonstrates the fundamental way that dynamic graphics work and before you move on to learn more sophisticated ways of creating animation it is a good idea to find out how things work at the lowest level. Indeed Android has a range of different animation facilities – View animation, Value animation and so on. This might seem like a strange topic to end on, especially since we are not going to do the job in the way that most Android programmers would go about it. To bring this chapter to a close we will animate a ball bouncing around a Canvas, or a Bitmap depending how you look at it. This extract from Android Programming In Java: Starting with an App 3rd Ed (I/O Press) covers one of the graphic techniques described in Chapter 5. Animation is also a good place to first meet the problems of threading and multitasking. Android has some sophisticated UI animation features, but it is still good to know how to do the most basic of animations using raw bitmap graphics. ![]()
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December 2022
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