MACROMEDIA FLASH 8-LEARNING ACTIONSCRIPT 2.0 IN FLASH - Page 576

576 Creating Interaction with ActionScript
8. Enter the following code into the Actions panel:
balance_mc.top = balance_mc._y;
balance_mc.bottom = balance_mc._y;
balance_mc.left = balance_mc._x;
balance_mc.right = balance_mc._x + 100;
balance_mc._x += 50;
balance_mc.handle_btn.onPress = function() {
startDrag(this._parent, false, this._parent.left, this._parent.top,
this._parent.right, this._parent.bottom);
};
balance_mc.handle_btn.onRelease = function() {
stopDrag();
var level:Number = Math.ceil((this._parent._x - this._parent.left -
50) * 2);
this._parent._parent.song_sound.setPan(level);
};
balance_mc.handle_btn.onReleaseOutside =
balance_mc.handle_btn.onRelease;
The startDrag() parameters left, top, right, and bottom are variables set in a
movie clip action.
9. Select Control > Test Movie to use the balance slider.
For more information about the methods of the Sound class, see Sound in the
ActionScript 2.0 Language Reference.
Detecting collisions
The hitTest() method of the MovieClip class detects collisions in a SWF file. It checks to
see if an object has collided with a movie clip and returns a Boolean value (
true or false).
You would want to know whether a collision has occurred either to test if the user has arrived
at a certain static area on the Stage, or to determine when one movie clip has reached another.
With
hitTest(), you can determine these results.
You can use the parameters of
hitTest() to specify the x and y coordinates of a hit area on
the Stage or use the target path of another movie clip as a hit area. When you specify
x and y,
hitTest() returns true if the point identified by (x, y) is a non-transparent point. When a
target is passed to
hitTest(), the bounding boxes of the two movie clips are compared. If
they intersect,
hitTest() returns true. If the two boxes do not intersect, hitTest()
returns
false.
You can also use
hitTest() to test a collision between two movie clips.
The following example shows how to detect a collision between a mouse and movie clips on
the Stage.