Re: [e4-dev] Declarative UI in E4

[yves.yang@xxxxxxxxxxx]

For my perspective, CSS relies on UI model which is not 100% compatible
with SWT, and it is designed to meet for a simple Web page style, not for
RIA.

For the first reason, as Tom and Kevin said, we cannot support 100% CSS.
For the second reason, we cannot be limited by CSS either. To bypass the
limitation of CSS, we need another concept.

In XWT, we have started to implement the XAML style.

There is another powerful concept in XAML, which is in fact part of the UI
styling: Control template. A control template can override an existing UI
type. For example, if we define a Control template as Button somewhere in
a structure tree, all buttons under the tree will use this control,
instead of the SWT standard's.

yves
>>Perhaps it is best if CSS engine handles all that and
>> SWT Widgets handles the applying of the actual style.
>
> That's how I imagined it would work.  We don't need SWT to parse styles (I
> can do that part), we just need API access to realize the styling on
> screen (I can't do that part).
>
> That way too, you can do something other than CSS as a format/parser (e.g.
> XAML).
>
> At a very high level, to me the main issues are:
>
> 1) We need to modernize the look of Eclipse, and to do so we need:
> a) externalized styling
> b) ensure the workbench allows things to be styled (presently some hard
> coded decisions, we're working on that)
> c) take advantage of advanced styling on those platforms which support it.
>
> 2) Not all platforms support the same set of styling capabilities.  SWT
> has done a fantastic job in the past of providing parity behaviour across
> multiple OS', but sometimes at the cost of it being lowest common
> denominator.  For styling, I think things can be looser since we're not
> talking behavioural compatibility: an app can look different across OS'
> provided it looks good on all, the layout works correctly, etc. So we need
> a best effort strategy with graceful fallback under the control of the
> application, for those willing to pay the price. To do so, we need SWT to
> provide access to those advanced styling capabilities, and report somehow
> when they are unavailable.
>
> 3) I don't want to abandon native widgets in our search for higher gloss.
> That is, I don't want to custom draw every widget say to get CSS3 borders.
> Personally, I'd forgo padding if necessary. However, I'd like to
> understand better what styling capabilities are available to us on various
> platforms and exercise those better.
>
> 4) We need to add space around the widgets, it's actually extremely
> important from a styling point of view. We should be able to do so
> declaratively, ideally from CSS.  At present we cannot rely on the
> existance of a parent composite with the right layout manager to enact
> that spacing.  I'm not sure how we solve this if SWT doesn't support it
> and without doing something horrible like wrapping every widget in a
> composite, since all that does is move the OS resource cost issue.
>
> Kevin
>
> e4-dev-bounces@xxxxxxxxxxx wrote on 01/29/2009 07:49:46 AM:
>
>> Do you mean a list of CSS properties that needs to be supported by the
>> SWT (and eSWT) widgets?
>>
>> I guess we are talking about a Widget#setStyle( String styleString )
>> API now. Do we want a similiar API function on Display? That would
>> make SWT implementations to handle all the cascade rules and the CSS
>> selectors etc. Perhaps it is best if CSS engine handles all that and
>> SWT Widgets handles the applying of the actual style.
>> --
>> Gorkem
>>
>>
>> 2009/1/28 Steve Northover <Steve_Northover@xxxxxxxxxx>:
>> >
>> > Then there is a mapping for some attributes and not others. We need
> the list
>> > and then decide which ones might be implemented (and the utility of
>> > implementing them).
>> >
>> > Random implementation thoughts:
>> >
>> > To implement margins (and other attributes) for every widget would
> increase
>> > the memory usage on platforms where these attributes are not supported
>> > natively (ie. everywhere except Dojo, Flex).  We could add one field
> that
>> > contained a pointer to the memory for all the attributes but
> experience has
>> > shown that this field always gets set and even more memory is used.  I
> could
>> > imagine an implementation of the margin code where there were multiple
>> > operating system handles for each native widget and the real native
> widget
>> > (ie. the table or whatever) was offset.  This would effectively double
> the
>> > operating system resource usage for every widget in Eclipse, even when
> no
>> > margins etc. were set.  Doesn't sound good to me.
>> >
>> >
>> >
>> > Kevin McGuire/Ottawa/IBM@IBMCA
>> > Sent by: e4-dev-bounces@xxxxxxxxxxx
>> >
>> > 01/28/2009 03:07 PM
>> >
>> > Please respond to
>> > E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
>> > To
>> > E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
>> > cc
>> > Subject
>> > Re: [e4-dev] Declarative UI in E4
>> >
>> >
>> >
>> >
>> >
>> >> Kevin, does the CSS code you are playing with now support things like
>> >> "font-weight"?
>> >
>> > Yes.
>> >
>> >
>> >
>> >
>> > Steve Northover/Ottawa/IBM@IBMCA
>> > Sent by: e4-dev-bounces@xxxxxxxxxxx
>> >
>> > 01/28/2009 02:24 PM
>> >
>> > Please respond to
>> > E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
>> >
>> > To
>> > E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
>> > cc
>> > Subject
>> > Re: [e4-dev] Declarative UI in E4
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > You bring up a point that has been danced around for a while (sorry if
> it
>> > was discussed and I missed it).  It's fine to accept and parse CSS
> formats
>> > but what are the valid attributes that we set, SWT API only?  In the
> code
>> > you typed, if the platform was Dojo, then the CSS you provided is
> native and
>> > could just be applied to the widget.  Not so on win32 or even
> Flexwhere the
>> > CSS attributes are non-standard too.
>> >
>> > Kevin, does the CSS code you are playing with now support things like
>> > "font-weight"?
>> >
>> > Tom Schindl <tom.schindl@xxxxxxxxxxxxxxx>
>> > Sent by: e4-dev-bounces@xxxxxxxxxxx
>> >
>> > 01/28/2009 02:03 PM
>> >
>> > Please respond to
>> > E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
>> >
>> > To
>> > E4 Project developer mailing list <e4-dev@xxxxxxxxxxx>
>> > cc
>> > Subject
>> > Re: [e4-dev] Declarative UI in E4
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> > Hi Steve,
>> >
>> > Do you think SWT could implement interpretation of CSS-Informations
> for
>> > us (I don't speak about the much more heavy weight parsing and
> CSS-Rules)?
>> >
>> > There are things we can't solve without an underlying support from
> SWT.
>> > One such example is padding on the Text-Widget because naturally
>> > Component-nesting (which can be used to implement margins) is not
> possible.
>> >
>> > If I could dream. I'd like SWT to provide an API like
> Widget#setStyle()
>> > which allows me to pass in CSS-String like this:
>> >
>> > Text widget = new Text(parent,SWT.BORDER);
>> > widget.setStyle("margin-left: 5px; margin-top: 10px; padding-left:
> 10px;
>> > font-weight: bold;");
>> >
>> > Do you have any idea how we could implement padding with the current
>> > SWT-API?
>> >
>> > Tom
>> >
>> > Steve Northover schrieb:
>> >>
>> >> I too believe that styling should be at the widget level (but this is
> no
>> >> surprise given who I am).
>> >>
>> >> RE: Qt
>> >> It seems to me that a Qt implementation could use native CSS styling
> to
>> >> support the features you mention.  The computeSize() API would pick
> up
>> >> these attributes (provided it is implemented natively).  All of the
> CSS
>> >> and Declarative UI discussions I have seen so far have ignored native
>> >> styling, probably because the only platforms of SWT that could/do
>> >> support it are RAP, Flex and Dojo.  My current thinking is that the
> CSS
>> >> styling in e4 will not be native (ie. it's implemenation will be in
> Java
>> >> and portable).  Kevin?
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