One of the most influencing factors behind the new features we add to Degrafa comes from the community. As Degrafa has progressed we make sure to follow the Degrafa Group as much as possible to help guide people on how to use it and answer questions.

In some cases it’s hard to help because the version in question just doesn’t support what the person is asking about. When these scenarios come up we take notes and add it to our “to do” list to see if we can provide a solution in a way that elegantly fits into the roadmap for Degrafa.

One scenario that came up was the ability to load a bitmap from an external URL to be used in a Degrafa Fill. Currently you have to embed a bitmap to use it in a fill. However, Degrafa Beta 3 will allow to specify any external bitmap source to be used in a Fill. This will be no real effort to achieve this if loading images from the same domain as your application, but you’ll also be able to use images from an external domain that provides a permissive crossdomain.xml file, like Flickr.

Another recent addition to the existing COLOURlovers API, was support for runtime ‘pattern’ loading via crossdomain permissions, from COLOURlovers.com. The way we’re implementing this makes it pretty easy for users to take advantage of.

Below is a simple example using the ColourLovers API and runtime loaded random ‘patterns’ used as BitmapFills. That’s to give you an idea of what’s possible. After that a quick explanation of how easy it will be to use runtime loaded images in your BitmapFills.

View Sample

Loading BitmapFill images from your own domain

If you are loading images from the same domain as your Flex application, no access permissions are needed, and using a runtime loaded BitmapFill is very easy*.

If you have your images in an images directory within the same directory as your main application swf, then you would normally specify the source as follows:

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<BitmapFill
      id="localExternalBitmapFill"
      source="images/myImage.png"
      angle="45" />

That’s basically all there is to it! When the image has loaded the fill will appear, for the Geometry item(s) that use(s) it. The additional delay is an indeterminate time after your Flex application has initialized, simply because your image is not embedded and it takes a little time to load. If you use the same source url assigned to multiple BitmapFills (you may for example use the same external image, but have different settings applied in another BitmapFill), then the external image file is only loaded once, and only one set of BitmapData is generated for all the BitmapFills that use it.

Loading BitmapFill images from External Domains

These examples relate to using a Flickr source:

a) A simple, one-off example:

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<BitmapFill
      id="bitmapFill"
      source="http://static.flickr.com/15/88928122_0f06ac7417.jpg"
      rotation="45"
      smooth="true" />

The above works as is, because flickr has the crossdomain permission policy file in the default location expected by the flash player at http://static.flickr.com/crossdomain.xml. This example can be expressed in another way as a separation of basePath and relative url as in the following example.

b) Loading multiple images from a single external location, managed with a LoadingLocation:

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<utilities:LoadingLocation
      id="flickr"
      basePath="http://static.flickr.com/"
      policyFile="http://static.flickr.com/crossdomain.xml" />
<paint:BitmapFill
      id="bitmapFill"
      loadingLocation="{flickr}"
      source="15/88928122_0f06ac7417.jpg"
      rotation="45"
      smooth="true" />
<paint:BitmapFill
      id="bitmapFill2"
      loadingLocation="{flickr}"
      source="142/325447236_ac4c1b9b3a.jpg"
      rotation="30"
      smooth="true" />

The above is likely to be suited to applications which have collections of external assets hosted externally, and where the location of the assets (domain) may change at some point in time. By setting up a single LoadingLocation to reference a basePath and policyFile (particularly if the policy file granting access is not using the default name and/or in the default location) you can make code maintenance easier if/when the external location of the assets changes.

As you can see the use of external images from within mxml is quick and easy. Watch out for more additions in the Degrafa Fills arena coming up before too long in another beta3 preview post.

*However you should also be aware that if your domain is accessed with both http://www.mydomain.com and http://mydomain.com then you may still need a crossdomain.xml file that grants permission to both, if you specify absolute urls for the local domain image files. The reason for this is that if you specify a url for the image that is on a different subdomain than that under which the application swf has been accessed, flash player security rules come into play and the flash player will seek permission via a policy file - which will fail to be granted it doesn’t exist. You should be ok using relative urls.