[Seaside] Brushes and state

[Mariano Montone]

James,

Our intention is to use a map in a mobile application. That is to say, both
the smalltalk server and a browser are embedded in the same device. In that
context, having some markers and moving them and receiving an update to the
server whenever the marker moves, makes sense. So, the state is the map I'm
referring to (there may be more than one map in the same page) and the
markers of each map.

This is what I have now, for example:

renderContentOn: html
    |marker|
    self map
        center: 45.5267 @ -122.8390 zoom: 11;
        setUIToDefault.

    marker := (GMarker overlayAt: 45.5267 @ -122.8390)
                          draggable: true.
    self map addOverlay: marker.
    marker onDrag: ( html gmrequest callback: [:latlng | self lat: latlng
lat lng: latlng lng ]).

That places a marker and callbacks whenever the user moves the marker across
the map.

I'm using callbacks, but that has some limitations if I want to hold the
markers, so I'll be moving the callbacks and markers to a component.

This would not make sense in a traditional client/server application, that's
why you haven't found a need for something like this, I think.

Mariano

On Thu, Jun 18, 2009 at 8:00 PM, James Foster <Smalltalk at jgfoster.net>wrote:

> Mariano,
> I'll be interested to see how this comes out. As I mentioned earlier, I
> started with a component and switched to a brush. I came to view the
> GoogleMap as a browser widget, something like a listbox, where you give it
> some data and let it draw itself. Yes, you can configure callbacks, but that
> isn't really different from other brushes. What sort of 'state' do you
> envision keeping with the map? Might that be better in a domain-specific
> component that wraps a map? I was able to implement over 40 examples and
> have not yet found a need to get more complex.
> James
>
> On Jun 18, 2009, at 2:58 PM, Mariano Montone wrote:
>
> Thanks Julian. I think a component will be ok.
>
> Mariano
>
> On Thu, Jun 18, 2009 at 1:22 PM, Julian Fitzell <jfitzell at gmail.com>wrote:
>
>> Hi Mariano,
>>
>> Off the top of my head, if I were implementing a google maps package, I
>> would do it as a component or a painter (see below). Brushes certainly
>> aren't intended to be kept around so if you have state to persist between
>> requests that's not the way to go.
>>
>> There are people who like implementing everything as brushes but the main
>> functionality of brushes is that they can be selected in arbitrary orders to
>> nest content within each other, e.g.:
>>
>> html div: [ html span: [ html paragraph: 'foo' ] ].
>>
>> Unless you plan to do be able to do:
>>
>> html div: [ html googleMap: [ html paragraph: 'foo' ] ]
>>
>> (i.e. unless the thing you are creating allows content to be put inside
>> it) I don't think there's much advantage in making your own brush. (The
>> other reason to consider using brushes of course is that they have more
>> direct access to the document).
>>
>> Even if you don't need the benefits of components (see
>> http://blog.fitzell.ca/2009/05/when-to-use-seaside-component.html ), you
>> can just create a renderable object by implementing #renderOn: and do:
>>
>> html render: (GoogleMaps new configSomeStuff; yourself)
>>
>> This process is made much clearer in 2.9 where you can subclass WAPainter,
>> implement #rendererClass to control what kind of renderer you get passed
>> (you might possibly implement the google maps thing *using* one or more
>> custom brushes and have your own renderer for them), and implement
>> #renderContentOn: as you would for a component.
>>
>> Hopefully that makes things clearer and not muddier. :)
>>
>> Julian
>>
>> On Thu, Jun 18, 2009 at 5:51 AM, Mariano Montone <
>> marianomontone at gmail.com> wrote:
>>
>>> Hello!,
>>>            I'm implementing an API for rendering Google Maps. I've
>>> decided to implement it as a brush. That's because I'm just generating
>>> javascript code. But now I have a problem: when adding support for
>>> callbacks, I need to hold some state; for example, the map the callback
>>> refers to. But I think brushes are not meant to hold state, that is
>>> something left for the components mechanism, isn't it? So I would like to
>>> know what would be the correct way of implementing it in the framework.
>>> Should I implement maps as components, or should I add state to my brushes;
>>> I may hold a state in the callback block too, but I don't think that's good.
>>>
>>> Thanks!
>>>
>>> Mariano
>>>
>>>
>>>
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>>>
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