Thanks, John. It would be helpful if you could create an issue in jira to track
this.
On Jan 8, 2014, at 4:18 PM, John Hendrikx <hj...@xs4all.nl> wrote:
> On 8/01/2014 14:28, David Grieve wrote:
>> The reason things are as they are is because most properties in the core
>> classes are lazily created and I didn't want cause the property to be
>> created just to see if it was bound. But that is a particular concern for
>> the core classes and not so much for controls.
> I see, this mechanism certainly doesn't try to do that. It only works when
> the properties are created in advance.
>> I'm not sure if you are aware of the javafx.css.SimpleStyleableXXXProperty
>> classes. I'd be interested to see how your custom classes dovetail into
>> these as I'd be more than willing to consider taking your additions and
>> calling them my own… uh, um, I mean, rolling them into the source code.
> I wasn't aware of those, but I just took a look at them. They do make the
> process a little bit easier, although still require creating a CssMetaData
> object yourself. If you want to use the code or just the idea, please feel
> free -- it would be very nice for creating custom controls if it was part of
> JavaFX.
>> Have you looked at the initialization-on-demand holder pattern for creating
>> the List?
> That's the "Super-lazy instantiation pattern from Bill Pugh" ? I've seen it
> several times in the JavaFX sources, and I think it is a neat way to avoid
> certain statics from being created immediately after the class loads.
>
> However, I'm not sure if it applies here, the first getCssMetaData call
> basically is the trigger that causes all CssMetaData objects and the List to
> get created... I'm not sure how I could make it any more lazy than that.
> The Map I use in the properties themselves is static, so shouldn't cause too
> much footprint.
>
> The code I use for the one of the SimpleStyleableXXXProperty is below. It
> relies on a Map that will cache CssMetaData objects (for different instances
> of the same property in a Control) and are only created when they're needed.
> CssMetaData objects only get created one time on access, after that further
> calls just do a quick map lookup.
>
> It makes assumptions about the kind of converter needed, which could be
> parameterized further with another constructor option.
>
> public class SimpleStyleableDoubleProperty extends StyleableDoubleProperty {
> private static final Map<Class<?>, Map<String, CssMetaData<? extends
> Styleable, Number>>> CSS_META_DATA_BY_NAME_BY_CLASS = new HashMap<>();
>
> private final Object bean;
> private final String name;
> private final String cssName;
> private final double initialValue;
>
> public SimpleStyleableDoubleProperty(Object bean, String name, String
> cssName, double initialValue) {
> super(initialValue);
>
> this.bean = bean;
> this.name = name;
> this.cssName = cssName;
> this.initialValue = initialValue;
> }
>
> @Override
> public CssMetaData<? extends Styleable, Number> getCssMetaData() {
> // TODO consider synchronizing CSS_META_DATA_BY_NAME_BY_CLASS -- depends
> on whether or not this ever gets called by more than one thread.
> Map<String, CssMetaData<?, Number>> cssMetaDataByName =
> CSS_META_DATA_BY_NAME_BY_CLASS.get(bean.getClass());
>
> if(cssMetaDataByName == null) {
> cssMetaDataByName = new HashMap<>();
> CSS_META_DATA_BY_NAME_BY_CLASS.put(bean.getClass(), cssMetaDataByName);
> }
>
> CssMetaData<? extends Styleable, Number> cssMetaData =
> cssMetaDataByName.get(cssName);
>
> if(cssMetaData == null) {
> cssMetaData = new CssMetaData<Styleable, Number>(cssName,
> StyleConverter.getSizeConverter(), initialValue) {
> @Override
> public boolean isSettable(Styleable styleable) {
> return !SimpleStyleableDoubleProperty.this.isBound();
> }
>
> @Override
> public StyleableDoubleProperty getStyleableProperty(Styleable
> styleable) {
> return SimpleStyleableDoubleProperty.this;
> }
> };
> }
>
> return cssMetaData;
> }
>
> @Override
> public Object getBean() {
> return bean;
> }
>
> @Override
> public String getName() {
> return name;
> }
> }
>
> --John
>
>
>>
>> On Jan 7, 2014, at 9:34 PM, John Hendrikx<hj...@xs4all.nl> wrote:
>>
>>> Hi List,
>>>
>>> I'm in the process of adding CSS metadata to a new control, and I noticed
>>> there is a lot of boilerplate.
>>>
>>> In order to reduce this, I've created some custom classes StyleableProperty
>>> classes (SimpleStyleableXXXProperty), which reduces the boilerplate
>>> significantly without sacrificing much (if any) performance. The only
>>> thing that I cannot easily provide in this fashion is the static
>>> getClassCssMetaData method. From the documentation I understand it is
>>> there just for convience for subclass creators and is not used by the CSS
>>> engine at all -- atleast, everything seems to work.
>>>
>>> The shortened version for CSS aware properties basically looks like:
>>>
>>> private final SimpleStyleableDoubleProperty cellAlignment = new
>>> SimpleStyleableDoubleProperty(this, "cellAlignment", "-fx-cell-alignment",
>>> 0.8);
>>> private final SimpleStyleableDoubleProperty density= new
>>> SimpleStyleableDoubleProperty(this, "density", "-fx-density", 0.02);
>>> private final SimpleStyleableBooleanProperty reflectionEnabled= new
>>> SimpleStyleableBooleanProperty(this, "reflectionEnabled",
>>> "-fx-reflection-enabled", true);
>>> private final SimpleStyleableBooleanProperty clipReflections= new
>>> SimpleStyleableBooleanProperty(this, "clipReflections",
>>> "-fx-clip-reflections", true);
>>>
>>> With one small bit of supporting code in the relevant class (Skin or
>>> Control), which is basically a non-static implementation of the standard
>>> CSS List example code:
>>>
>>> private static List<CssMetaData<? extends Styleable, ?>> cssMetaData;
>>>
>>> @Override
>>> public List<CssMetaData<? extends Styleable, ?>> getCssMetaData() { //
>>> Unsynchronized. WC: list gets initialized multiple times.
>>> if(cssMetaData == null) {
>>> List<CssMetaData<? extends Styleable, ?>> metaData = new
>>> ArrayList<>(super.getCssMetaData());
>>> Collections.addAll(metaData,
>>> cellAlignment.getCssMetaData(),
>>> density.getCssMetaData(),
>>> reflectionEnabled.getCssMetaData(),
>>> clipReflections.getCssMetaData()
>>> );
>>> cssMetaData = Collections.unmodifiableList(metaData);
>>> }
>>>
>>> return cssMetaData;
>>> }
>>>
>>> Note that the List is static and lazy-final. The same goes for the
>>> getCssMetaData method in the SimpleStyleableXXXProperty classes. There is
>>> a slight performance decrease in those classes as getCssMetaData is looked
>>> up from a static Map (indexed by Class + css property name) and lazily
>>> created as needed -- a Map lookup however should be quite fast enough.
>>>
>>> I'm sure the design had good reason to do things as they are, and I'm
>>> wondering if reducing the boilerplate has left me missing something
>>> important.
>>>
>>> I welcome any insights!
>>>
>>> --John
>
