Layouts with constraint classes

[Daniel Zwolenski]

Ah ok, from your example code it looks like you want to use variables in
FXML to define your constraints - getting into that territory of CSS-like
style definitions that Richard was talking about?

Assuming this is what you want, this can be done in the current setup using
the ridiculously under-documented <fx:define> thing.

I knocked up a very rough sample for you quickly. The FXML looks like this:

  <BorderPane xmlns:fx="http://javafx.com/fxml">

    <fx:define>
        <HBoxConstraints fx:id="noGrow" hgrow="NEVER"/>
        <HBoxConstraints fx:id="growLots" hgrow="ALWAYS"/>
    </fx:define>

    <center>
        <HBox>
            <Label text="I don't grow" style="-fx-background-color:green"
Constraints.constraints="$noGrow"/>
            <Label text="I grow big"
style="-fx-background-color:yellow" Constraints.constraints="$growLots"/>
        </HBox>
    </center>

  </BorderPane>

(see
https://code.google.com/p/zenjava-playtime/source/browse/trunk/layouts/src/main/resources/fxml/example.fxml
)

I made a base Constraints class with a static helper method on it (called
via "Constraints.constraints" in the FXML above):

https://code.google.com/p/zenjava-playtime/source/browse/trunk/layouts/src/main/java/com/playtime/layouts/Constraints.java

And then a specific instance of HBoxConstraints:

https://code.google.com/p/zenjava-playtime/source/browse/trunk/layouts/src/main/java/com/playtime/layouts/HBoxConstraints.java

Obviously you would add others, like VBoxConstraints, GridPaneConstraints,
etc. All pretty trivial. These helper classes could easily be included in
something like JFXtras.

So I stick with the stance that FXML is more or less OK here (not to say I
wouldn't improve it lots in other areas), and really your conversation is
about the Java API which is nicely decoupled to what can/can't be done in
FXML. Kudos to Richard and the JFX team for designing the builders right.




On Fri, Nov 30, 2012 at 9:20 PM, Tom Eugelink <tbee at tbee.org> wrote:

> On 2012-11-30 10:59, Daniel Zwolenski wrote:
>
>> It just doesn't do it the exact way you suggest where you specify
>> multiple possibilities directly in the child in case it ends up in a
>> different parent - not an approach I agree with anyway (see my previous
>> comments), but that's just my opinion.
>>
>
> Just to make sure my suggestion is not misunderstood, it does not specify
> multiple possibilities in the child, but in the layout.
>
> <HBox>
>     <HBox.C for="arrow" vgrow="NEVER"  valignment="RIGHT"/>
> </HBox>
>
> <HBox>
>     <Label  fx:id="arrow"  alignment="center" text="">
>         <HBox.C vgrow="ALWAYS"  valignment="LEFT" maxWidth="Infinity"/>
>     <Label>
> </HBox>
>