PropertyResolver (library)
Overview
Summary
A set of routines to safely get, or gracefully skip, potentially unreachable properties
Contents
Concept
There are various properties on objects in Flash which throw errors when accessed, namely properties relating to color and tint on Stage elements.
To demonstrate, create a new Symbol on the stage, then run the following code:
trace($selection[0].tintPercent);
Flash will throw a meaningless "The following JavaScript error(s) occurred: " error, with no further details, and the script will halt.
The reason for this is that tintPercent is only accessible if the element has a colorMode of "tint". This is where the PropertyResolver class comes into play. If you need to access potentially script-halting properties on an object, you can first test it with the PropertyResolver methods.
Usage
The following properties (and more will be added as they are found) currently throw these kinds of errors:
- element.brightness
- element.tintColor
- element.tintPercent
If you find yourself needing to acess these properties, consider using the PropertyResolver class. For example, the xJSFL Table library uses the PropertyResolver class, otherise it errors when printing summaries of stage elements.
API
testObject(object)
Tests whether an element is one of the few elements that needs resolving
The following example preemptively tests an element to see if it may have properties that need resolving
if(PropertyResolver.testObject(object))
{
var needsResolving = PropertyResolver.testProperty('tintPercent');
trace(needsResolving);
};
true
testProperty(name)
Tests a property name to see if a property name needs resolving
The following example tests a property name to see if it needs resolving:
var needsResolving = PropertyResolver.testProperty('tintPercent');
trace(needsResolving);
true
resolve(element, name)
Resolves the property value of an element
The following example demonstrates how resolve() is used to grab properties without Flash throwing an error:
// grab the element
var element = $selection[0];
// set its colorMode to "tint"
element.colorMode = 'tint';
// grab properties
trace('>' + PropertyResolver.resolve(element, 'tintPercent'));
trace('>' + element.tintPercent)
// set its colorMode to "none"
element.colorMode = 'none';
// grab properties
trace('>' + PropertyResolver.resolve(element, 'tintPercent'));
trace('>' + element.tintPercent)
>100 >100 >undefined The following JavaScript error(s) occurred:
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