Dear Martin:
Thank you for the analysis! Let me address each point
1) Ensure the user gets events before the control does. That’s a topic for a
different thread.
Partially supported, given the current limitation of the FX event handling
mechanism. A user key binding registered via InputMap always takes precedence
over that registered by the skin.
2) Provide an API that asks a control to perform the operation identified by a
FunctionTag. This is the only way to access operations like COPY and MOVE_RIGHT
that are implemented behind the scenes.
Default or overwritten? Both are supported.
InputMap.getDefaultFunction(FunctionTag) returns the default implementation,
while InputMap.getFunction(FunctionTag) returns either the default, or custom
if it was set.
It is recommended to declare a public method (like copy()) for each function
tag in the control, which does execute(FunctionTag). This was we have full
programmatic control over functions in the input map, and ability to override
it. To access the default function, InputMap.getDefaultFunction(FunctionTag)
is your friend. We could add protected executeDefault(FunctionTag) for
convenience, but I’d rather not.
3) Provide an API that asks a control to map an Event to a FunctionTag. This
enables blocking existing mappings; if a user wants to block the default
mappings for, say, COPY they can simply discard/consume any events that the
control would map to COPY.
Supported via InputMap.registerFunction(FunctionTag, Runnable). Just do
registerFunction(COPY, () -> { }).
Side note: we might also add registerFunction(FunctionTag, BooleanSupplier) to
allow conditional consumption, though I haven’t encountered a use case for that.
If a user wants to subclass an existing control they could also use these API’s
to do full customization but only if they can guarantee that their subclass
will process events before the superclass. That, too, might be a separate
discussion.
If I understood the problem correctly - this is not needed, because for the
key bindings, the child class can simply overwrite the binding. For event
handlers, the child class can override the handling method.
I would like to discuss these API’s without getting too deep into
implementation details. With that said, I do have one implementation
suggestion: since most of the event => FunctionTag mappings are common
(SELECT_ALL is always Shortcut+A) there should be an internal shared object
containing the common mappings.
They are not. There is no SELECT_ALL in Button control, for example. Where
the hierarchy exists, so does the hierarchy of tags, for example
TextInputControl.SELECT_ALL which is applicable/used in TextField and TextArea.
But we can’t extend it to TableView, for example, as there is no common
ancestor - unless we invent one (an interface).
What do you think?
Thank you
-andy
From: Martin Fox <[email protected]>
Date: Monday, October 30, 2023 at 17:24
To: Andy Goryachev <[email protected]>
Cc: Kevin Rushforth <[email protected]>, openjfx-dev
<[email protected]>
Subject: [External] : Re: [Request for Comments] Behavior / InputMap
I was looking over the InputMap proposal with an eye toward paring it down to
the bare minimum.
>From the perspective of a user who wants to manipulate a control without
>subclassing it I think there are only a few essential components.
1) Ensure the user gets events before the control does. That’s a topic for a
different thread.
2) Provide an API that asks a control to perform the operation identified by a
FunctionTag. This is the only way to access operations like COPY and MOVE_RIGHT
that are implemented behind the scenes.
3) Provide an API that asks a control to map an Event to a FunctionTag. This
enables blocking existing mappings; if a user wants to block the default
mappings for, say, COPY they can simply discard/consume any events that the
control would map to COPY.
If a user wants to subclass an existing control they could also use these API’s
to do full customization but only if they can guarantee that their subclass
will process events before the superclass. That, too, might be a separate
discussion.
I would like to discuss these API’s without getting too deep into
implementation details. With that said, I do have one implementation
suggestion: since most of the event => FunctionTag mappings are common
(SELECT_ALL is always Shortcut+A) there should be an internal shared object
containing the common mappings.
Martin
On Oct 30, 2023, at 3:11 PM, Andy Goryachev <[email protected]> wrote:
Dear Kevin:
Thank you for providing a summary to our (lively) discussion. Even though I
think I answered these concerns, I don’t mind to have another go at it.
Please find the updated proposal here (same link):
https://gist.github.com/andy-goryachev-oracle/294d8e4b3094fe16f8d55f6dd8b21c09<https://urldefense.com/v3/__https:/gist.github.com/andy-goryachev-oracle/294d8e4b3094fe16f8d55f6dd8b21c09__;!!ACWV5N9M2RV99hQ!MAhFywXruyvFlvk6whGVWBb9fTI-f1D-16YuJbRGdJe52rX503CFBK8S6IamyzPVzQBcJZmg6c_Jh1CfsDxVFw$>
Let me first define what I mean by “behavior” in the context of this proposal.
A behavior is a translation layer between input events - coming either from the
control, or from some nodes contained in the skin, or from the platform itself
- into some actions. These translation mappings are maintained by a new
property in Control - the InputMap. The InputMap has two sides - one for the
user application, and another - for the skins/behaviors. Both are “public
APIs” but the latter is represented as protected methods of BehaviorBase class
which forms a foundation of the behavior part of the skins that want to use the
InputMap paradigm.
Back to individual concerns.
* We should not make anything related to Behaviors public without a full design
of how Behaviors should work, what their responsibilities are, how they
interact with Skins
And we don’t. We recommend to use BehaviorBase, but it’s still possible to use
event handlers or any other home-grown mechanism to implement skins/behaviors
and suffer from the lack of functionality as a result. If BehaviorBase is not
the right name, we can call it InputMapAccessorForSkinUse any other name.
* This proposal doesn't solve the coupling of Skins and behaviors
The skins and behaviors are tightly coupled in some cases. It is possible that
a simple control such as Button does not require tight coupling, but a complex
control such as TextArea does (see TextAreaSkin:1214).
With the InputMap, we now can separate user mappings from skin mappings and
handlers. Changing a skin will unregister all of the handlers added by the
associated behavior, leaving the user mappings intact.
* Function tags are defined in control class, but don't match the functionality
of control class
NOTE: this begs the question of whether there should always be a method on
control for each such function (even if the implementation just delegates to
the behavior
May be it was not described extensively, but it is being suggested to have one
public method for each function tag, which does invoke the said tag. This
enabled indirection via InputMap which in turn allows the app- or skin-
developer to redefine the functionality (in effect, allowing for changing the
behavior without subclassing the behavior).
So, for example, SomeControl.copy() would invoke execute(TAG_COPY), which by
default would invoke SomeControlBehavior.copy().
This proposal did not make this change for the subset of controls -
intentionally - because it can be done later in a separate PR.
* An input map should not refer to the node and be stateless and sharable among
all (or some) instances of the same class; this would mean mapping input events
to Control::method rather than to instance::method or to some arbitrary lambda
NOTE: this would depend on the previous being resolved
I think we are confusing two things. The InputMap allows for per-control
mapping, so it cannot be shareable or static. Period.
Now, the other thing is a possible requirement to allow for changing the
mapping on per-control-type basis, to overwrite the behavior for each instance
of a particular control. This I did not address because it’s an implementation
detail for that control type. I did not want to add child maps, but perhaps we
could add another API to the skin/behavior side of InputMap to allow for such a
static map.
Personally, I don’t like the idea as it basically adds nothing: event handlers
still need to be added to each control and each Node in the skin (if any) and
there is an extra complexity added. A better solution would be to subclass the
control class and add the mappings for each instance just like we do today.
* Arbitrary key mapping seems out of scope for the core of JavaFX; this sort of
mapping could be done by the application if the event order problem was solved,
and if we had public API on control for all functions that are called by the
behavior.
Arbitrary (user) key bindings are enabled by the proposed InputMap. Any
alternative proposal, in my opinion, should support this function out of the
box.
* Should Input map be immutable?
The value of InputMap is ability to change the mapping, so I don’t understand
where this requirement is coming from. Perhaps an example or a use case could
be provided?
* Changes to the Behavior system should focus on replacing complete behaviors,
and being able to use these by default for a certain subset of controls (like
-fx-skin provide in CSS)
As I mentioned earlier, the skin and its behavior might be tightly coupled. So
if a use case exists for changing the behavior, we already have a solution - a
custom skin. May be a use case or an example of why we can’t do that with the
existing architecture would help here.
And finally, I would like to emphasize that even though the InputMap proposal
is fairly well developed and validated using a number of non-trivial controls
and some new controls (RichTextArea
https://github.com/andy-goryachev-oracle/jfx/pull/1<https://urldefense.com/v3/__https:/github.com/andy-goryachev-oracle/jfx/pull/1__;!!ACWV5N9M2RV99hQ!MAhFywXruyvFlvk6whGVWBb9fTI-f1D-16YuJbRGdJe52rX503CFBK8S6IamyzPVzQBcJZmg6c_Jh1ACM9EGvA$>
), I am not against modifying/enhancing it based on the community feedback. I
hope we can get to a good solution in a reasonable time frame, or we all would
have to learn react and program in javascript.
Cheers,
-andy
From: openjfx-dev <[email protected]> on behalf of Kevin Rushforth
<[email protected]>
Date: Friday, October 27, 2023 at 16:34
To: openjfx-dev <[email protected]>
Subject: Re: [Request for Comments] Behavior / InputMap
I've mostly caught up on the (lively) discussion surrounding this feature
request.
It is clear that we do not yet have general agreement on the direction this
proposal should take, so let's continue to discuss the proposal, its
shortcomings, and any alternative approaches.
We should start by making sure that the motivation for doing this -- what
problem is being solved -- is well understood. Andy will rework the initial
sections of the proposal to make it more clear.
If I can summarize what I see are the main concerns that have been raised:
* We should not make anything related to Behaviors public without a full design
of how Behaviors should work, what their responsibilities are, how they
interact with Skins
* This proposal doesn't solve the coupling of Skins and behaviors
* Function tags are defined in control class, but don't match the functionality
of control class
NOTE: this begs the question of whether there should always be a method on
control for each such function (even if the implementation just delegates to
the behavior
* An input map should not refer to the node and be stateless and sharable among
all (or some) instances of the same class; this would mean mapping input events
to Control::method rather than to instance::method or to some arbitrary lambda
NOTE: this would depend on the previous being resolved
* Arbitrary key mapping seems out of scope for the core of JavaFX; this sort of
mapping could be done by the application if the event order problem was solved,
and if we had public API on control for all functions that are called by the
behavior.
* Should Input map be immutable?
* Changes to the Behavior system should focus on replacing complete behaviors,
and being able to use these by default for a certain subset of controls (like
-fx-skin provide in CSS)
There are probably other concerns as well.
Finally, one of the comments made, which I completely agree with, is that API
design needs to come first. It needs to be fully fleshed out, and needs to be
forward-looking. We should only expose as public API what is needed to solve
the problem and no more.
Let's continue the discussion with this in mind.
-- Kevin
On 9/29/2023 3:44 PM, Andy Goryachev wrote:
Dear fellow JavaFX developers:
For some time now, we’ve been working to identify missing features in JavaFX
that hinder application development. We’ve been working on adding some of the
missing features (for which we’ll have a separate announcement), but I feel
that engaging wider community is a rather important part of the process.
I would like to share with you one such missing feature - ability to extend
behavior of the existing components (and make the task of creating new
components easier) by adding a public InputMap and BehaviorBase.
Please find the actual proposal here
https://gist.github.com/andy-goryachev-oracle/294d8e4b3094fe16f8d55f6dd8b21c09<https://urldefense.com/v3/__https:/gist.github.com/andy-goryachev-oracle/294d8e4b3094fe16f8d55f6dd8b21c09__;!!ACWV5N9M2RV99hQ!MAhFywXruyvFlvk6whGVWBb9fTI-f1D-16YuJbRGdJe52rX503CFBK8S6IamyzPVzQBcJZmg6c_Jh1CfsDxVFw$>
We are very much interested in your feedback. Thank you in advance.
-andy
