Formats - Page 2
July 30, 2001
Although Flash is a
vector-based application, bitmap images can be imported and
used. There are a wide variety of formats listed under [File-
Import] (Ctrl-R). The vector-based images are quite
straightforward as they can be resized easily inside the
application and even edited. Vector-based files can be imported
from
Adobe Illustrator,
FreeHand, and include Windows metafiles, Flash SWF and others.
Bitmap images can also be imported and converted into vectors,
using the Trace Bitmap option. File types include GIF,
JPG, PNG, TIFF, as well as others. To convert a file, select the
imported image and choose Modify-Trace Bitmap. In the
resulting pop-up window you can then select the Color Threshold
(increase the value, decrease the number of colors), Minimum Area
(number of surrounding pixels), Curve Fit (determines the
smoothness of the outlines) and Corner Threshold (sharp edges or
smoothed out). If the bitmaps contain a lot of complex shapes and
colors the vector image can create a larger file size than the
original. Other Flash SWF files can also be imported (unless they
are protected).
When publishing the final SWF file care must be taken as to how
it will look in the users browser. The program allows the ability
to change the bitmap compression, with the lower quality
producing smaller files and higher quality producing larger file
sizes. This may take some experimenting to determine the best
quality, while maintaining reasonable file size.
Now let's learn about the way in which movie clips, timelines,
and frames per second work within a Flash file.
Flash allows the user to create Movie Clips inside of the
file which can run independently of the main movie and other
clips. Movie Clip formats include animation, actions, buttons,
and other interactive features. Within the main movie or even
another movie clip you can tell Flash to do lots of things to
influence when the movie plays, what frame it goes to, send
variables, and other interactive aspects.
To create a movie clip simply go to 'Insert' and then 'New
Symbol' on the menu bar or press [Ctrl]+F8 on the keyboard. On
the following menu select the 'Movie Clip' option. Here we are
going to create a small animation that will play repeatedly on
the main stage of the movie while other things are happening
around it.
An example of this is importing a series of images of a man
walking and then looping them repeatedly to give the illusion
that the man is in fact walking in place. There are five
'Keyframes' with a different image on each one which create the
effect.
Flash uses a timeline to graphically represent the passing of
time in a movie clip. It is divided into Layers and
Frames. Frames enable Flash to display time within the
movie. There are two main types of frames: normal 'Keyframes'. A
keyframe is shown in the timeline as a frame with a blue dot, and
a normal frame has no dot. Keyframes can have actions assigned to
them which tell the movie to do different things when it arrives
at that frame. This could be a simple command such as to stop the
clip at a certain frame and then to begin playing again: the
beginning of a tween from one location to another.
What is a tween you ask? "Short for in-betweening, the process
of generating intermediate frames between two images to give the
appearance that the first image evolves smoothly into the second
image"
(Webopedia)
Flash can create two different types of tween animation:
motion and
shape tweening. With motion tween, the user
defines properties such as position, size, and rotation of an
instance, group, or text block at one point in time (using a
keyframe). Then at another point in time the same properties are
changed. In shape tweening, there is a shape at one point
in time and then another shape drawn at another point in time.
shape tweens cannot follow a path; rather they can only move in
straight lines.
If you take the movie clip we created and place it on the main
stage of the movie, it will loop endlessly, giving the impression
that the man is walking in one spot. With this clip on the stage
you could then create buttons that would use the 'Tell Target'
command to cause the walking to begin when the mouse is moved
over it.
We now come to one of the more 'interactive' aspects of the Flash
application — Buttons. Numerous features can be programmed
into the button functions, from simply telling the Flash file to
go on to the next frame of a scene to complex math functions and
everything in between. In an HTML file the button created simply
takes effect when the user clicks on it. But with Flash there are
numerous ways to assign values and functions to a button. The
button can be set in such a way so that if a user rolls over (or
rolls out) the button an event can happen. The event can even be
set so that Flash waits until the button is actually released to
take any action.
To assign an action to a button, select the button or movie clip
and choose 'Windows', 'Actions' from the menu. In the toolbox
located on the left side of the panel, click on the basic actions
category. Actions can be assigned in a few different ways, but perhaps
the easiest way is to simply double-click on the selection you
want to make and it will be shown in the right panel. When you
add actions to a button, Flash automatically inserts the OnMouse
Event code to trigger any selected action.
Hopefully this tutorial will give you the basic understanding
needed to start creating some wonderful Web sites with Flash and will
push you in the direction to want to learn more!
Additional Resources
Flash 5 Tutorial: Part 1
Flash 5 Tutorial: Part 2
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