Macromedia Flash MX Tutorial - Digital Slider

 

Properties

Name:  Digital Slider 
ID =   Version:       SWF file size = 712 Bytes        Posted: 1/16/03
Level:  Intermediate                                             
Primary Focus:  event handler method 
Secondary Focus: dragging movie clip
Approach: All the ActionScript is placed in one frame.

 

Flash Movie

ActionScript

// Macromedia Flash MX Tutorial 1

// Author: Bruce L. Bird, MINDdrops.com

// Date: January 16, 2003

// Digital Slider

//Moving slider causes continuous change in digital reading

//Initial Values

stop();

//Click and Drag Slider

// "slider" is the instance name for dragable red dot movie clip

    _root.slider.onPress = function() {

        this.startDrag(false,100,196,250,196);

    };

    _root.slider.onRelease = function() {

        this.stopDrag();

    };

    _root.slider.onReleaseOutside = function() {

       this.stopDrag();

    };

// Place position of slider in dynamic text box

// with variable name: reading

slider.onEnterFrame = function() {

    // Normalize slider position so digital reading varys from 1 to 100

    // This slider's x position varies between 100 to 250 pixels

    sliderRange = 150;

                  normalizedReading = 100*(slider._x - 100)/sliderRange;

// Now need to adjust so only get integer readings

integerReading = Math.round(normalizedReading);

reading = integerReading;

// The digital reading can now be used to manipulate other objects

// This example demonstrates changing the size of a triangle.

_root.triangle._xscale = 10+4*reading;

}

Comments

All of the ActionScript sits in frame 1 of the Action layer in the main (_root) timeline. 

In ActionScript the syntax

            movieClipInstance.onPress = function( )  { ..... }

is sometimes called an "event handler method"  which is not the same as  "event handler" (Franklin, page 73).  Other writers use the terms "anonymous function" to distinguish this syntax from "named functions" (Chun, page 99; Drol, page 95)

 

References

Chun, Russell, Macromedia Flash Advanced for Windows and Macintosh, Peachpit Press, 2003

Drol, William, Object-Oriented Macromedia Flash MX, Apress, 2002

Franklin, Derek, and Jobe Makur, Macromedia MX Advanced Training From The Source, Macromedia Press, 2002

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