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This chapter is from the book

Animating the Cursor

The centerpiece of any video demonstration is the animation. In this tutorial, you use two different types of animation: frame-by-frame or tweened. Frame-by-frame animation is manually created, much like the flip-books that children make. Each keyframe contains slightly different content, such that as you move through it, the appearance of motion is created. You may not realize it, but you have already done the frame-by-frame portion of this project: The sequencing of bitmaps in successive keyframes, precisely positioned, is a frame-by-frame animation.

The second type of animation used in this lesson is tweened. Tweening refers to a technique used by traditional animators during the heyday of Walt Disney Studios. Senior animators would storyboard and create character designs, and then create the keyframes of the sequences. Junior animators were then tasked with creating all of the frames in between, hence the term tween. Flash has two kinds of tweening: shape and motion. Shape tweening, which you won't use in this project, morphs one shape into another.

With motion tweening, you specify the beginning and ending points and the number of steps in between: Flash does the rest. In this project, you will use motion tweening to handle the animation of the cursor. Motion tweening can get surprisingly sophisticated, since Flash has controls for acceleration, deceleration, and rotation, as well as the capability to animate along a path, instead of in a straight line. In this project, however, you'll need to animate only along straight lines, without rotation, acceleration, or deceleration.

  1. In the cursor layer of frame 10, drag a copy of cursor_white.gif from the screenshots folder of the library onto the stage.

    The bitmap file, cursor_white.gif, is a screenshot of the Flash cursor. You may know that all graphics exist in rectangular boxes, without exceptions. If you click on the arrow once it's on the stage, you'll see the rectangular area around the arrow. And yet, you can see what lies beneath the cursor between the bounding area and the arrow itself. I created this effect by taking the screenshot of the arrow into Macromedia Fireworks, cropping it down to the small size you see, and then setting the background as transparent. The GIF format allows you to save objects with indexed transparency. Indexed transparency simply refers to designating all of the pixels of a certain color as transparent.

    By making the surrounding pixels of the arrow cursor transparent, you can lay it over the screenshot, and it looks like any regular cursor. This in turn lets you animate the cursor and give the effect of a full-motion video—as if someone recorded a person actually using the software.


    You might be wondering if using full-motion video wouldn't be easier than manually splitting screenshots and cursors and animating both separately using two different approaches. That approach is not a good idea because full-motion video is a sequence of file-intensive bitmap images. The file size would make downloading prohibitive. The final version of the file you are making is a little over 100k, or a 20- to 30-second download for someone using a 56K modem, and a nearly instantaneous download over an intranet network.

    Figure 21

  2. With the arrow cursor still selected, press F8 (a shortcut for Insert > Convert to Symbol). In the Convert to Symbol dialog box, name it arrow_MC, and leave its behavior at the default, Movie Clip. Click OK.

    The arrow cursor on the stage is no longer the bitmap object you dragged from the library; it is now a movie clip symbol. If you select it, you'll notice that its appearance is different—its bounding box is blue and the registration point now appears in the center.

    The most basic rule of tweened animation is that you can tween only symbols. You cannot tween bitmaps, text blocks, or vector art (e.g., drawn with the rectangle tool). And even though the arrow was in the library, it was just a bitmap GIF file, and Flash could not tween it.

    You can use one of two types of symbol for your tweening: movie clip and graphic symbol. I chose to use movie clip because it is the more flexible and powerful symbol. Only use graphic symbols when you know for sure that you will never need to add any other frames to the symbol and that you will never need to modify the symbol with a script. One seldom knows either of these for certain, so movie clip is usually the safer choice. As you work through the projects of this book, you'll appreciate the difference more clearly. For now, use movie clips.

    The cursor is now ready to be tweened.

    Figure 22

  3. Still in frame 10 of the cursor layer, drag the cursor so it is randomly placed somewhere near the center of the page.

    The exact location is not all that important. Just make sure you don't put it right next to the application drop-down menu near the top of the screen (the one that has Dreamweaver 4 selected).

  4. Single-click frame 19 of the cursor layer, and press F6. With this new keyframe selected, drag the arrow cursor to the application drop-down button.

    Every motion tween is surrounded by two keyframes. The first designates the starting position, while the second designates the ending position. Since the next step of the tutorial is to open the application drop-down menu, you need to move the cursor over to it. When you have finished this step, you have defined the beginning and ending points of the animation.

  5. Choose any frame in between the two keyframes, and choose Insert > Create Motion Tween.

    The timeline changes as soon as you add the tween. An arrow points from the begin keyframe (10) to the end keyframe (19), and the region in between is colored blue.

    Figure 23

  6. Select frame 20 in the cursor layer, and choose Insert > Clear Keyframe. Immediately, with frame 20 still selected, choose Insert > Keyframe.

    This may seem like an odd exercise: Why remove a keyframe, then turn around and add it back? The reason is that initially the keyframe was empty. When you removed it and inserted a new keyframe, the cursor from frame 19 was copied into the new keyframe. The location of the cursor was also copied. This way, the cursor won't jump in between steps.

  7. Select frame 29 and press F6 to add a new keyframe. Drag the arrow cursor so it is convincingly pointing at the highlighted Flash MX menu item in the drop-down menu. Add a motion tween to this frame segment as well.

    Here you are repeating steps 3 to 5, and animating the transition from pages 2 to 3.

    Figure 24

  8. Continue in this fashion, until you have added motion tweens to all of the segments up to frame 89, and remove the keyframe in frame 90.

    If you are not sure where the cursor should point in each segment, refer to the instructions in the text dialog boxes below.

    Frame 90 is the last segment of the animation. You do not need to tween the cursor between frames 90 and 99. However, the cursor should still be visible and in the same location you left it in frame 89.

    As you place the cursors, you can also move the dialog boxes in frames 60 and 70, if they interfere with the animation. Neither dialog box should block any part of the animation.

  9. Position the playhead in frame 1, and choose Control > Play to preview the animation.

    The animation runs through, and everything connects just fine. The simulation is starting to look convincing. But there is still a problem: Sometimes the cursor seems to race across the screen, and other times it seems to crawl. The reason is that every segment is 10 frames long, and at the default 12 frames per second, each segment lasts 5 / 6 of a second. But sometimes the cursor moves 75 pixels in a segment, and other times it moves hundreds of pixels.

    To even out the speed, you need to adjust the number of frames in the segments. In segments that seem too slow—where the cursor doesn't move very far—you need to remove a few frames. Conversely, where the cursor seems to fly too quickly, you need to add a few frames.

  10. To add frames to an animation, position the playhead in the middle of a segment, between keyframes; no frames should be selected. Press F5 (Insert > Frame). To remove frames, position the playhead in the same way, and press Shift+F5 (Insert > Remove Frames). While you are at it, remove frames 2 to 9, so the animation begins right after the first frame, and likewise remove all of the frames between the last two keyframes.

    Each time you press F5 (or Shift+F5), a single frame is added (or removed). Getting the timing right is a matter of trial and error. In addition, you do not need to be mathematically perfect about the speed, as cursors don't move at a steady rate in reality. All you are trying to do is even out the speed so it is not conspicuous one way or the other.


    Be sure that you do not inadvertently select any frames when inserting or removing frames in this step. If you select a frame in one layer and then press F5 to insert a new frame, it will insert the frame only in that one layer. By clicking the playhead itself, you position the playhead in a frame, but no frame is actually selected. That way, when you insert new frames, you insert the new frames in every layer.

    Figure 25

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