API Docs for: 6.0.1
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LeachFilter Class

Extends Filter
Module: scrawlFilters

LeachFilter

Instantiation

  • scrawl.makeLeachFilter()

Purpose

  • Adds a leach filter effect to an Entity or cell. Leaching turns certain color ranges to transparency

Access

  • scrawl.filter.FILTERNAME - for the LeachFilter object

Constructor

LeachFilter

(
  • [items]
)

Parameters:

  • [items] Object optional

    Key:value Object argument for setting attributes

Methods

add

(
  • data
)

Inherited from Filter but overwritten in source\scrawlFilters.js:2447

Add function - takes data, calculates its channels and combines it with data

Parameters:

  • data Object
    • canvas getImageData object

Returns:

amended image data object

clone

(
  • items
)
chainable

Clone a Scrawl.js object, optionally altering attribute values in the cloned object

Note that any callback or fn attribute functions will be referenced by the clone, not copied to the clone; these can be overwritten with new anonymous functions by including them in the items argument object

(This function is replaced by the path extension)

Parameters:

  • items Object

    Object containing attribute key:value pairs; will overwrite existing values in the cloned, but not the source, Object

Returns:

Cloned object

Example:

var box = scrawl.makeBlock({
    width: 50,
    height: 50
    });
var newBox = box.clone({
    height: 100
    });
newBox.get('width');        //returns 50
newBox.get('height');       //returns 100

cloneImageData

(
  • original
)

cloneImageData function

Parameters:

  • original Object
    • canvas getImageData object

Returns:

cloned image data object; false on error

get

(
  • item
)

Retrieve an attribute value. If the attribute value has not been set, then the default value for that attribute will be returned.

Parameters:

  • item String

    Attribute key

Returns:

Attribute value

Example:

var box = scrawl.makeBlock({
    width: 50,
    });
box.get('width');               //returns 50
box.get('height');              //returns 0
box.get('favouriteAnimal');     //returns undefined

getAlpha

() private

getAlpha function

Returns:

numerical strength value, between 0 and 1

numberConvert

(
  • val
  • dim
)
private

Stamp helper function - convert string percentage values to numerical values

Parameters:

  • val String

    coordinate String

  • dim Number

    dimension value

Returns:

Number - value

parse

()

Turn the object into a JSON String

Returns:

object of object's currently set attributes

set

(
  • items
)
chainable

Set attribute values. Multiple attributes can be set in the one call by including the attribute key:value pair in the argument object.

An attribute value will only be set if the object already has a default value for that attribute. This restricts the ability of coders to add attributes to Scrawl objects.

Parameters:

  • items Object

    Object containing attribute key:value pairs

Returns:

This

Example:

var box = scrawl.makeBlock({
    width: 50,
    height: 50
    });
box.set({
    height: 100,
    favouriteAnimal: 'cat'
    });
box.get('width');               //returns 50
box.get('height');              //returns 100
box.get('favouriteAnimal');     //returns undefined

Properties

alpha

Number - or alternatively percentage String

Filter alpha

values between 0 (transparent) and 1 (current alpha values); or '0%' and '100%'

Default: 1

comment

String

Comment, for accessibility

Default: ''

composite

String

Filter composite operation

Only the final filter in an array of filters will determine the composite operation to be used on the cell

Default: 'source-over'

exclude

Array

The exclude array should contain a set of arrays defining the color ranges to be leached (have their alpha values set to 0) from the image. Each array within the exclude array must include the following six numbers in exactly this order:

[minRed, minGreen, minBlue, maxRed, maxGreen, maxBlue]

... where the numbers are integers between 0 and 255

Default: []

name

String

Unique identifier for each object; default: computer-generated String based on Object's type

operation

String

Unlike other filters, the leach filter uses an 'xor' GCO to stamp itself onto the canvas - this is changeable, if necessary

Default: 'xor'

timestamp

String

Creation timestamp

Default: ''

title

String

Title, for accessibility

Default: ''

type

String final

Inherited from Base but overwritten in source\scrawlFilters.js:2416

Default: 'Filter'