Free Flash Tutorials, Actionscript, Random Pattern Background

Random Pattern Background

Category	: Flash	Views	: 30482
Version	: 8	Rating	:	3.1/5 (32 votes) Currently 3.09/5 1 2 3 4 5
Type	: Text	Source File	: random-pattern-background.zip
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Free Flash Tutorials, Actionscript, Random Pattern Background

Code Explanation

import flash.display.BitmapData

This line of code imports the BitmapData library to our code so we can create a BitmapData object to hold our image

var patNr = 4;

The number of patterns we have available to load.

nPattern.onRelease = function() {

Event for when the user clicks the pattern button.

var img = "pat" + Math.ceil(Math.random() * patNr);

Variable to use as identifier when we load the image from the library; the variable will be "pat" plus a random number between 1 and patNr.
Because "Math.random() * patNr" would return a number between 0 and patNr and I don't have a pattern with the identifier "pat0" I need to round up the random number so I never get 0. For that we use the following function:

Math.ceil(number);

This function will always round a floating point up.

_root.createEmptyMovieClip("holder", 1);

Create a new Movie Clip to place a pattern.

var imgBitmap = BitmapData.loadBitmap(img);

This variable is a Bitmap object created with the function loadBitmap(identifier), this function will load a bitmap from the library using the identifier.

holder.clear();

Erase any previous pattern on the Movie Clip.

holder.beginBitmapFill(imgBitmap);

Start filling the Movie Clip with the pattern bitmap.

holder.lineTo(550, 0); holder.lineTo(550, 400); holder.lineTo(0, 400); holder.lineTo(0, 0);

Draw around the stage to make the pattern fill everything.

holder.endFill();

Stop filling the bitmap.

nPattern.swapDepths(33);

Swap the depth of the button so it always stays on top of the pattern and the user can see it.