Re: [e4-dev] Declarative UI in E4

[Kevin McGuire <Kevin_McGuire@xxxxxxxxxx>]

>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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