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In order to produce the effect of simple animation, we must be
able to control the time that a figure remains on the screen and be
able to erase a figure.
To PAUSE the screen display:
Pausing the screen display can
be accomplished with the use of the following method:
public static void pause (int
time)
{
try
//opens an exception handling statement
{
Thread.sleep(time);
}
catch(InterruptedException e)
//captures the
exception
{
}
}
Thread.sleep(5000) will sleep for approximately 5 seconds.
Alternate coding:
public static void sleep( long millis, int
nanos ) throws
InterruptedException
Parameters:
millis - the length of time to sleep in milliseconds.
nanos - 0-999999 additional nanoseconds to sleep.
Description: Causes the currently executing thread to sleep (cease
execution) for the specified
number of milliseconds plus the specified number of
nanoseconds. |
To ERASE a figure:
To erase a figure, simply draw
the figure on top of itself in the background color.
Formula Process for Animation
1. Draw the figure to be animated in its
starting position.
2. Determine the smallest x (or y) value
contained in the drawing.
3. Rewrite the "formula" to create the figure
by substituting x (or y) for the smallest value and adjusting the
subsequent values.
4. Determine the x (or y) coordinate of the
last position of the figure after its movement.
5. Determine if the object will move one or
more pixels at a time.
6. Establish a for loop (using the variable x
(or y) to place the figure in its various locations during movement.
7. Inside of the loop, draw the figure in its
original color by setting COLOR. Determine the length of the
"pause" that will show the figure before it moves to its next
location. Change the COLOR to match the background and draw
the figure again to erase it.
| Figure in Starting Position: |
Figure Written with Formula: |
|
 |
 |
| Record the coordinates of the
figure in its starting position before the animation begins. |
This arrow is going to move
horizontally to the right. The smallest x-value is 10.
The number 10 was replaced with x, and all other x coordinates
were written in terms of x. |
It was decided for
this arrow that the x-values would range from a starting value
of 10 to and ending value of 110 with the figure being redrawn
every 5 pixels.
for (int i = 20; i <= 110, i = i + 5) |
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