We are going to look quickly now at two other tops of objects that we use within Flash authoring. This is the Movie Clip and Graphic symbols. These are objects that we create in Flash and I use for making up all of the assets within our mobile application. That could contain Vectors or Bitmaps or buttons or other nested Movie Clips but these are the main building blocks for our Flash Applications. But, there are some implications for using Movie Clips over Graphics or Graphics over Movie Clips when developing Flash Lite Applications. We are going to have to look at that now.
Movie Clips and Graphics are just different types of reusable symbols that we can use within Flash to create assets that are on our stage. This could be background or animations, really anything that is visually represented on the stage in a Flash Application. Let us convert the objects that we have got on the stage now to a Graphic and a Movie Clip just to see the difference.
Right now, I have I have got my planet_background.png Bitmap selected and I am just going to go to the Modify and Convert to Symbol option and we get that Convert to Symbol dialog box. Here, you can see the different types of symbols that we can have within our Flash Application, a Movie Clip, a Button or a Graphic. I am going to convert this one to a Graphic. I am going to give it a name. I am going to call it background and click okay. First thing you will notice is that background has a Graphic nail piece in my Library over here on the right. That background graphic now contains the Bitmap that we imported before. I can see it previewed in my Library just as it appears but it still outlined on the stage so I am going to go back and turn this outlining on the layout back to normal.
So what happened is that when we created the graphic symbol for the background, it has automatically put that object on top of where we had that before. What I am going to do is I am going to cut this background and then put it on another layer underneath. I am going to select it, edit and cut. I am going to select my content layer and go back to the edit menu and place in place which puts it back exactly where I found it. That is better. Now, I am going to grab that symbol or actually, it is a group of shapes at the moment. I am going to convert that into a Movie Clip symbol. So the same process applies Modify, Convert to Symbol or I could hit the F8 key. This time, I am going to choose Movie Clip and we are going to name that Alien Ship and click okay. Now, it too appears in my Library over on the right. Now, the main difference between Movie Clips and Graphics Symbols in a mobile application comes down to issue such as performance and file size. Flash developers have long been used to using Movie Clips as the standard symbol in their Flash Applications. We really stopped needing the use of the Graphic Symbol quite a while ago but now with mobile applications, it becomes very important.
Movie Clips by nature are more interactive than Graphics. They had their own timelines, can have missed an object within them and particularly can have action script added to them to control what happens with them at runtime. They are active objects at runtime so they take up more runtime memory and add file size to our Flash Lite Application. While graphics on the other hand, inactive at runtime so they take up less memory so Graphics are best used for things like backgrounds just as we have done here with our planet background, and Movie Clips are best used for objects that are going to be required to have animation or to be referenced for our action script to perform some top of interactivity within our application.
The other slight difference there of course is that we can give a Movie Clip an instance name but not a Graphic. And, that comes back to being able to interact with the bar action scripts. So remember that the best practice with mobile applications, try and use Graphics wherever possible. Wherever a symbol is not going to be animating or it is just going to be static on the stage, objects you want to interact with needs to be Movie Clips. Now, that we have looked at the fundamentals of authoring mobile content in Flash 8 and some best practices, we are going to start looking at how to build a well architected mobile application using Flash 8.
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