Re: [udig-devel] A developer moment on Glyphs

[dzwiers@xxxxxxxxxxxxxxx]

Hi Jody,

I will assume that your generation is based of the featureType as opposed to an
actual feature (as was the case yesterday).

David

Quoting Jody Garnett <jgarnett@xxxxxxxxxxxxxxx>:

> This should eventually go up on the wiki - but since I finally broke
> down and made a state machine I thought I should share.
> 
>  From LayerGenerateLabelDecorator.decorateImage
> 
>      * We are not allowed to block, test if generation is needed and
> start up the queue.
>      * <p>
>      * State Table of Image \ Image Descriptor:
>      * <pre><code>
>      *          | null         | icon
>      * ---------+--------------+---------------------+
>      * disposed | queue        | image =             |
>      *  or null |   layer      |  icon.createImage() |
>      * ---------+--------------+---------------------+
>      * image    | both         | image               |
>      *          +--------------+---------------------+
>      * </code></pre>
>      * This attempts to reduce the amount of flicker
>      * experienced as the layer figures out its glyph
>      * in the face of *many* events.
>      * </p>
>      * <p>
>      * Everyone gives us events - who gives us icons?
>      * <ul>
>      * <li>If the user has given the layer an icon we don't need to
> generate anything.
>      * <li>piccaso will wait on the queue and generate icons, and
> refresh the decorator.
>      * <li>We will get the refresh and generate an Image from the Icon,
>      *     we can use this image when we are nexted refreshed.
>      * <li>A random eclipse code will dispose our Images, and refrsh us
>      *    (We can still generate our images from the saved icon).
>      * <li>The listener *hack* will watch for changes to layer,if any
> look interesting
>      *     the icon will be cleared and we will be refreshed. We still have
>      *     our image so their will be no downtime while waiting for piccaso
>      *     to make us a new Icon.
>      * </ul>
>      * So what happens for a layer that we cannot generate a icon for?
> We will
>      * place it in the queue *every* time. Who knows maybe style or
> something will
>      * change and we can do better then the default.
>      * </p>
> 
> Any mistakes with this plan will be obvious next time I run, but if you
> see anything
> obvious let me know.
> 
> Cheers,
> Jody
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