spinner component

[Jonathan Giles]

We've just made available the UX specs for Date Picker and Spinner here:
http://openjdk.java.net/projects/openjfx/ux/index.html

-- Jonathan


On 17/12/2011 6:16 p.m., Tom Eugelink wrote:
> I would like to propose the addition of a spinner control to OpenJFX.
>
> A spinner control for all means and purposes is a listview where only 
> one cell is visible (rendered) at a time. Moving to the next and 
> previous cell is done via clicking with the mouse on arrows or using 
> keyboard presses. The control's API could look like:
>
> Class: *Spinner<T> extends Control*
> T denotes the type it is holding; String, Integer, any bean.
>
> Properties:
> *- ObjectProperty<T> valueProperty()
> *  The value property holds the currently displayed (selected) value
> *
> - ObjectProperty<Boolean> cyclicProperty()
> *  Cyclic means that the spinners cycles back to the beginning when 
> the end of the list of values is reached, e.g. december -> next -> 
> januari, or vice versa (januari -> previous -> december).
>
> Methods:
> *- public void decrease()
> *  programatically select the previous value
> *
> - public void increase()
> *  programatically select the next value
>
> Events
> *- ObjectProperty<EventHandler<CycleEvent>> onCycleProperty()
> *  OnCycle method gets called when the spinners cycles (see cyclic 
> property).
>
> A value change event is not needed, since registering to the value 
> property will take care of that.  Detecting a cycle based on value 
> changes is cumbersome, so hence the OnCycle event.
>
>
> Implementation considerations:
>
> Since this actually is a list-with-just-one-cell, adopting a cell 
> factory may be a good idea.
>
> Even though a spinner is a list-with-just-one-cell, using a list as 
> its data source is restrictive, because lists always have a lower and 
> upper bound. For example, take a spinner that selects a year: the 
> value "year" has no natural lower and upper bound. It could have in 
> certain situations, but as a concept it has not. Therefor I would like 
> to propose the usage of a data provider, in this case a 
> single-value-linear-data-provider. Such a data provider uses a 
> BigInteger to represent the current value and can increment or decrement.
>
> Data provide API:
> - *public BigInteger getPreviousIdx(BigInteger idx);*
>   Calculate the previous index given the provided one, returning null 
> if there is no previous. (Spinner may cycle.)
>
> - *public BigInteger getNextIdx(BigInteger idx);*
>   Calculate the next index given the provided one, returning null if 
> there is no next. (Spinner may cycle.)
>
> - *public T getValue(BigInteger idx);*
>   Return the value for the specified index, could return null as a 
> valid value
>
> - *public BigInteger getIdx(T value);*
>   Return the idx for the specified value, returning null means the 
> value does not exist
>
> The DataProvider can be based on an actual list, or on an 
> implementation allowing the endless selection of a year.
>
> A initial (but fully working) implementation can be found at 
> http://code.google.com/p/jfxtras/source/browse/controls/src/main/java/jfxtras/scene/control/SpinnerX.java 
> (screenshot attached to the email).
>
> Tom
>
>
>