add calculating methods to bind

[Tom Eugelink]

Found it! Slightly different DoubleBinding was required (copied it from negate).

     private DoubleBinding snap(final ObservableNumberValue value, final Observable... dependencies) {
         return new DoubleBinding() {
             {
                 super.bind(value);
             }

             @Override
             public void dispose() {
                 super.unbind(value);
             }

             @Override
             protected double computeValue() {
                 return NodeUtil.snapXY(value.doubleValue());
             }

             @Override
             public ObservableList<?> getDependencies() {
                 return FXCollections.singletonObservableList(value);
             }
         };
     }



On 2014-5-21 21:34, Tomas Mikula wrote:
> Hi Tom,
>
> it seems to me that in your custom DoubleBinding implementation
> `other` is not its dependency, thus it does not react to it's
> invalidations.
>
> Tomas
>
> On Wed, May 21, 2014 at 9:25 PM, Tom Eugelink <tbee at tbee.org> wrote:
>> I came up with this:
>>
>> startXProperty().bind( *snap(*heightProperty().multiply(0.2)) )
>>
>>
>> And then:
>>
>>      private DoubleBinding snap(final ObservableNumberValue other, final
>> Observable... dependencies) {
>>          return new DoubleBinding() {
>>              {
>>                  super.bind(dependencies);
>>              }
>>
>>              @Override
>>              public void dispose() {
>>                  super.unbind(dependencies);
>>              }
>>
>>              @Override
>>              protected double computeValue() {
>>                  return NodeUtil.snap(other.doubleValue());
>>              }
>>
>>              @Override
>>              public ObservableList<?> getDependencies() {
>>                  return new
>> ImmutableObservableList<Observable>(dependencies);
>>              }
>>          };
>>      }
>>
>> But that always returns 0... I feel this should have worked.
>>
>> Tom