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Re: [e4-dev] Declarative UI in E4
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Two thoughts:
1) What do our embedded folks say? They are the ones who care deeply about bits and bytes.
2) Or are we only going to support this on desktop/server configurations if it's not already supported on a particular embedded platform? In which case, I wonder how much we care since:
a) On the web it's supported natively, so my understanding is that there would be little or no overhead (please correct me if I'm wrong, Steve)
b) On the desktop we have gigabytes and gigabytes of RAM anyway!
c) If we only support it on an embedded platform if it is supported by the platform itself, the embedded people would see very low overhead for having the feature (just method calls that are ignored).
Actually, that point (c) still gives me pause a bit, since on embedded device *any* cycle wastage is cause for concern. On the other hand, I have yet to see a desktop UI that could scale successfully to a tiny screen, so you wind up rewriting the UI for the device anyway. In which case you could simply not use the APIs you know are bad.
Or the APIs could help and throw a new IllegalOperationException("This API is not implemented on ESWT because it would waste CPU cycles on small devices."). ;-)
Dave
2009/2/4 Steve Northover
<Steve_Northover@xxxxxxxxxx>
... which uses more memory than a field
for each attribute when framework code sets every field because it doesn't
know that it shouldn't. I've seen both patterns before and there
is no good answer.
02/04/2009 02:25 PM |
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Or a field, with all attributes, null value on platforms which don't support.
> . So, Steve, you are the master of widgetry;
There might be hack involving WM_NCPAINT on win32 but you still need fields
for each attribute and this increases the Java memory used for each widget.
Kevin's point 4) is that we *do* want to support the ability to add space
around things. It's not something we can give up on, just because it's
non-trivial to implement with the current SWT API.
So how do we do this? Steve's, first take at a "random implementation
thought" fails for the reasons we have discussed. So, Steve, you are
the master of widgetry; how do we get this capability *without* paying
the double-the-os-resources penalty?
Personally, I'd like whatever the solution is to be to provided directly
by SWT, so that on platforms like WPF where (I'm guessing) it's directly
supported, we could use the native implementation.
McQ.
Kevin
McGuire---29/01/2009 10:25:08--->Perhaps it is best if CSS engine handles
all that and > SWT Widgets handles the applying of the act
>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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