Extending Builders: Layout Builders

[Tom Schindl]

Hi,

Let me retry - I hope this doesn't get too long.

FXML is simply a serialization definition to serialize ANY given
java-object graph.

Let's take your example:

<HBox>
  <Label
    fx:id="arrow"
    alignment="center"
    text=""
    maxWidth="Infinity">
    <HBox.C vgrow="ALWAYS"  hgrow="ALWAYS"/>
  <Label>
</HBox>

which means in full blown FXML without default-attributes

<HBox>
  <children>
  <Label
    fx:id="arrow"
    alignment="center"
    text=""
    maxWidth="Infinity">
    <constraint>
      <HBox.C vgrow="ALWAYS"  hgrow="ALWAYS"/>
    </constraint>
  <Label>
  </children>
</HBox>

So written in Java-Code it means

HBox box = new HBox();
Label l = new Label();
l.set...
HBox.C c = new HBox.C();
c.set...
l.setConstraint(c);
box.getChildren().add(l);

Definately not what you want because your layout-containers code looks
like this:

HBox box = new HBox();
Label l = new Label();
l.set...
HBox.C c = new HBox.C();
c.set...
box.add(l,c);

Which clearly violates the generic serialisation which says sub-elements
are always added (if it is a list) / set (single attribute) on the
attribute they are the child of.

So if we take your proposed FXML as shown above we have a problem
because when we follow the general serialization/deserialization
strategy we'd have to have a layoutConstraint-Property on the *Node*
although things like layouts only make sense when you add the node
inside a layout-container but not if it is e.g. a child of a Group, ...

To summerize: My point - I fully agree with you that when coding the UI
in Java your layout-container additions make a whole lot of sense but
they break the serialization infrastructure because the addition is not
done on the attribute itself (children) but through the owner of the
attribute (HBox).

Tom

Am 22.11.12 19:51, schrieb Tom Eugelink:
> Not sure I understand what you are trying to say here. Each layout has
> different and much deviating constraints, so they cannot be unified into
> one model.
> 
> I think I summarized it well in my blogpost: "All information about the
> layout of a single node should be stored in one place." This means
> absolute layout can suffice with the X,Y,W,H information available in
> the nodes (and thus allow binding), but all more advanced layouts
> require a separate constraint class.
> 
> Tom
> 
> 
> 
> 
> On 2012-11-21 22:42, Tom Schindl wrote:
>> the nice thing about the current expression with static calls is that
>> the semantics for adding children are always the same whether your
>> target is a Layout-Container or e.g. a Group.
>>
>> You always call add on the target your specified. Your way of layout
>> containers expects two different things to happen:
>> * for layout container you want to call add on the owner because you
>>    want to pass the constraint object
>> * you can add on the list itself for stuff like Group but also Tables
>>
>> Not to forget how would you like set the constraint when you not add to
>> a list e.g. when using a borderpane?
>>
>> Tom
>>
>> Am 21.11.12 19:02, schrieb Tom Eugelink:
>>> I suspect the constraints were already "out" before FXML, but this would
>>> be a fairly acceptable notation:
>>>
>>> |<HBox>
>>>      <Label  fx:id="arrow"  alignment="center"   text=""
>>> maxWidth="Infinity">        |
>>> ||        <HBox.Cvgrow="ALWAYS"  hgrow="ALWAYS"|/>
>>>      <Label>
>>> </HBox>
>>> |
>>>
>>>
>>> Or:
>>>
>>> |<HBox>
>>>      <Label  fx:id="arrow"  alignment="center"   text=""
>>> maxWidth="Infinity"|||HBox.C.vgrow="ALWAYS"  HBox.C.hgrow="ALWAYS"|/>
>>> </HBox>
>>> |
>>>
>>>
>>>
>>> On 2012-11-21 17:46, Tom Schindl wrote:
>>>> Am 21.11.12 09:46, schrieb Richard Bair:
>>>>> I wanted constraint classes from the start. There was a problem
>>>>> there, which I don't accurately remember now, but I do want to see
>>>>> some discussion around deprecating (or at least no longer depending
>>>>> on) the static methods and having some constraint classes again.
>>>> They've probably been harder to implement in FXML?
>>>>
>>>> Tom
>>>>
>>>>
>>
> 


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