By the way, I don't mean to be needlessly dismissive about the CSS idea - I
definitely see the appeal. However, component styles are set via
BeanDictionary, which maps dictionary keys (such as "backgroundColor") to Java
bean properties ("setBackGroundColor()"). JSON works really well for this:
{ redButton: {
backgroundColor: "#ff0000"
}
)
CSS could certainly also work here:
redButton: {
background-color: #ff0000;
}
A CSSSerializer would simply need to output a Dictionary (or Map) that is
equivalent to what JSONSerializer would return. In other words, it would need
to return a map of maps to the various style definitions. It would also need to
collapse "background-color" to "backgroundColor".
One of the nice things about JSON is that the property types are embedded in
the syntax. For example, in the following JSON, "foo" refers to the number 10:
{ foo: 10 }
In CSS, "foo" would have to be treated as a string ("10"). This should be OK,
because BeanAdapter should coerce "10" to the appropriate type when invoking
the setter, but it is something to consider.
I'm not personally interested in investing time in this, because I am happy
with the JSON syntax. However, if you are willing to write (or port a
compatibly-licensed) CSS serializer, I could easily see a case for including it
in the platform. I don't know that we could support selectors based on
component type, but we could definitely support untyped selectors. Based on my
own experience writing Pivot apps, I would guess that this would be sufficient.
G
On Jul 3, 2010, at 7:46 PM, Greg Brown wrote:
> OTOH, the beauty of the styling approach I'm currently proposing is that it
> would allow you (or anyone else) to author a CSS serializer that could be
> used instead of the JSON style descriptors that are currently supported.
> You'd just do this:
>
> <bxml:include bxml:id="styles" src="styles.css"/>
>
> instead of:
>
> <bxml:include bxml:id="styles" src="styles.json"/>
>
>
> On Jul 3, 2010, at 7:43 PM, Greg Brown wrote:
>
>> I'm not sure that the license for that software is compatible with the ASL
>> (though it may be). In either case, my feeling is that CSS works quite well
>> for HTML and XML, but JSON works better here. JSON is also a powerful,
>> well-established language, and it maps directly to our use cases, whereas
>> CSS doesn't.
>>
>>
>> On Jul 3, 2010, at 6:23 PM, Michael Allman wrote:
>>
>>> Greg,
>>>
>>> There is already a standard programmatic API for parsing CSS stylesheets
>>> with several Java implementations. See
>>>
>>> http://www.w3.org/Style/CSS/SAC/
>>>
>>> These parsers provide events like element selectors (which can map to
>>> component types), class condition selectors (like .example, which can map
>>> to the contents of "class" attributes) and ID condition selectors (like
>>> #exampleId, which can map to values of "id" or "wtkx:id" attributes).
>>>
>>> Is this hard to implement? The plus side is you get a very powerful, well
>>> established styling language with room to grow as needed. It simplifies
>>> the debate on implementation and requirements because we just pick which
>>> parts of CSS we want to do. Pivot does not need to claim full CSS support.
>>> We just need to document which parts it does. Adopting CSS also makes
>>> learning Pivot styling easier for web devs and designers.
>>>
>>> Cheers,
>>>
>>> Michael
>>>
>>> On Sat, 3 Jul 2010, Greg Brown wrote:
>>>
>>>> True, but it is also more complex than JSON, which so far has worked well
>>>> for us. JSON property names and value types map nicely to the Java bean
>>>> property names and values used by the skin classes. Also, we already have
>>>> a JSONSerializer - we'd have to write additional support for CSS, and I'm
>>>> not sure that is justified.
>>>>
>>>> On Jul 2, 2010, at 9:51 PM, Michael Allman wrote:
>>>>
>>>>> It would be very premature for me to provide a good example. I've barely
>>>>> started my first Pivot app. Also, I can say that this can't be done with
>>>>> Flex apps either. So I never used it there. Doesn't mean it might not
>>>>> have come in handy once or twice... I dunno. It may be practically
>>>>> useless. Although I have seen it used many times in html.
>>>>>
>>>>> This comes back to my earlier post. Why not support a subset of CSS
>>>>> syntax itself? It's a very mature spec for styling declarative ui stuff.
>>>>>
>>>>> Cheers,
>>>>>
>>>>> Michael
>>>>>
>>>>>
>>>>> On Fri, 2 Jul 2010, Greg Brown wrote:
>>>>>
>>>>>> I have been thinking about that and I have some ideas. But I would like
>>>>>> to understand how often that use case actually comes up. I know CSS
>>>>>> supports it, but in practice (in Pivot specifically) I wonder how
>>>>>> important it is?
>>>>>>
>>>>>>
>>>>>> On Jul 2, 2010, at 7:30 PM, Michael Allman wrote:
>>>>>>
>>>>>>> Hi Greg,
>>>>>>>
>>>>>>> How would one specify multiple named styles for a component element?
>>>>>>> Like
>>>>>>>
>>>>>>> <PushButton styles="redButton bigFont"/>
>>>>>>>
>>>>>>> Cheers,
>>>>>>>
>>>>>>> Michael
>>>>>>>
>>>>>>> On Fri, 2 Jul 2010, Greg Brown wrote:
>>>>>>>
>>>>>>>> Hi all,
>>>>>>>>
>>>>>>>> I have been thinking about this and I think I have a fairly elegant
>>>>>>>> solution that will also significantly extend the capabilities of
>>>>>>>> BXMLSerializer. I am thinking of extending the <bxml:include> tag to
>>>>>>>> support loading of arbitrary content. Currently, it only supports
>>>>>>>> includes of other BXML files, but there is no reason that it couldn't
>>>>>>>> be modified to include other types, such as JSON, XML, or even images.
>>>>>>>> All we'd have to do is determine an appropriate serializer to use for
>>>>>>>> the include - this could be inferred based on file extension or could
>>>>>>>> be specified explicitly via a "mimeType" attribute to the include tag.
>>>>>>>> The MIME type-to-serializer mappings could be configurable such that
>>>>>>>> an include could literally be used to load any type of object.
>>>>>>>>
>>>>>>>> One application of such an extension would be styling. <bxml:include>
>>>>>>>> could be used to load a "stylesheet" - a JSON file containing a "map
>>>>>>>> of maps". The format of this file would be identical to the format I
>>>>>>>> had been considering for the "named styles" approach - each key/value
>>>>>>>> pair in the file would essentially represent a "style class". For
>>>>>>>> example, the following JSON file would define a "redButton" class:
>>>>>>>>
>>>>>>>> { redButton: {
>>>>>>>> backgroundColor: "#aa0000",
>>>>>>>> color: "#ffffff"
>>>>>>>> }
>>>>>>>> }
>>>>>>>>
>>>>>>>> In a BXML document, this file could be included as follows:
>>>>>>>>
>>>>>>>> <bxml:include bxml:id="styles" src="styles.json"/>
>>>>>>>>
>>>>>>>> The "redButton" style could then be applied to a button as follows:
>>>>>>>>
>>>>>>>> <PushButton styles="$styles.redButton"/>
>>>>>>>>
>>>>>>>> Unlike the previous solution I proposed, this approach would require
>>>>>>>> no changes to the Component or Container classes whatsoever. With the
>>>>>>>> exception of extending the <bxml:include> tag, it relies entirely on
>>>>>>>> existing functionality (and existing BXML syntax, so developers will
>>>>>>>> already be familiar with it).
>>>>>>>>
>>>>>>>> There are obviously other applications as well. Some simple examples:
>>>>>>>>
>>>>>>>> <TableView>
>>>>>>>> <tableData>
>>>>>>>> <bxml:include src="table_data.json"/>
>>>>>>>> </tableData>
>>>>>>>> </TableView>
>>>>>>>>
>>>>>>>> <TreeView>
>>>>>>>> <treeData>
>>>>>>>> <bxml:include src="tree_data.xml"/>
>>>>>>>> </treeData>
>>>>>>>> </TreeView>
>>>>>>>>
>>>>>>>> One challenge might be how to specify the MIME/serializer mapping for
>>>>>>>> an include (we won't want BXMLSerializer to include all possible
>>>>>>>> mappings by default). This could be inherited from the parent
>>>>>>>> serializer, but I think that a BXML syntax for specifying it in markup
>>>>>>>> is probably a good idea.
>>>>>>>>
>>>>>>>> Anyway, I think this would be an extremely flexible and useful
>>>>>>>> addition to the serializer, and I think it also handles the styling
>>>>>>>> case pretty well. Let me know what you think.
>>>>>>>>
>>>>>>>> G
>>>>>>>>
>>>>>>>>
>>>>>>>> On Jul 2, 2010, at 1:34 PM, Greg Brown wrote:
>>>>>>>>
>>>>>>>>> FYI, named styles are turning out to be a lot more challenging than I
>>>>>>>>> expected. The solution I proposed the other day doesn't work -
>>>>>>>>> elements in BXML aren't added to the parent element until the end tag
>>>>>>>>> is processed. So, given the following structure:
>>>>>>>>>
>>>>>>>>> <Window styleClasses="{foo:{...}}">
>>>>>>>>> <BoxPane>
>>>>>>>>> <PushButton styleClass="foo"/>
>>>>>>>>> </BoxPane>
>>>>>>>>> </Window>
>>>>>>>>>
>>>>>>>>> when the styleClass attribute of the PushButton is processed, the
>>>>>>>>> BoxPane hasn't yet been added to the Window, so the "foo" style class
>>>>>>>>> name resolves to null. :-(
>>>>>>>>>
>>>>>>>>> I'll keep thinking about it, though. Suggestions are welcome.
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> G
>>>>>>>>>
>>>>>>>>
>>>>>>
>>>>
>>
>
