The default implementation of the render method in CompositeCell wraps each
element in a span. You could do the same and set the display style property
based on the state, and then you don't need to extend SelectionCell. While
it isn't required for very simple Cells (that only render a single element),
it makes sense to wrap each Cell in its own parent element.
Thanks,
John LaBanca
jlaba...@google.com
On Fri, Nov 5, 2010 at 12:40 PM, Ümit <uemit.se...@gmail.com> wrote:
> Ah I see ;-)
>
> However I somehow can't access the styles and the span respectively.
> The render method of the SelectionCell renders the <select> tag
> directly (I suppose the span is rendered by the CellTable itself).
> I solved my problem by extending the SelectionCell and storing a
> isVible Flag in it and then adding an additional span around it. The
> class looks like this:
>
> public class HideableSelectionCell extends SelectionCell{
> protected boolean isVisible = true;
>
> public HideableSelectionCell(List<String> options) {
> super(options);
> }
>
> @Override
> public void render(String value, Object key, SafeHtmlBuilder sb) {
> if (!isVisible)
> sb.appendHtmlConstant("<span style=\"display:none\">");
> super.render(value, key, sb);
>
> if (!isVisible)
> sb.appendHtmlConstant("</span>");
> }
>
> public void setIsVisible(boolean isVisible) {
> this.isVisible = isVisible;
> }
>
> public boolean getIsVisible(){
> return this.isVisible;
> }
> }
>
> And in the render method of the compositeCell I set the isVisible Flag
> of the cell before rendering it.
>
>
> Is that the right approach or is there some other way to access the
> Cell Span's Style directly ?
>
> Sorry for being so persistent ;-)
>
> thanks
>
> Uemit
>
> On Nov 5, 5:03 pm, John LaBanca <jlaba...@google.com> wrote:
> > Sorry, I was referring to the CSS property display, and I meant "none",
> not
> > null.
> >
> > Rendering the following will cause the span to be completely hidden and
> take
> > up no space.
> > <span style=\"display:none;\">My cell content</span>
> >
> > Thanks,
> > John LaBanca
> > jlaba...@google.com
> >
> >
> >
> >
> >
> >
> >
> > On Fri, Nov 5, 2010 at 11:24 AM, Ümit <uemit.se...@gmail.com> wrote:
> > > Thanks John for the quick response.
> >
> > > One question though. I am not sure what you mean with "setting the
> > > display to null". I checked the specific classes (SelectionCell,
> > > AbstractCell etc) but couldn't find anything which allows me to set
> > > the display to null.
> > > Maybe you can specify what you mean with display.
> >
> > > Thank in advance
> >
> > > Uemit
> >
> > > On Nov 5, 1:46 pm, John LaBanca <jlaba...@google.com> wrote:
> > > > As far as the SelectionCell, we should have a version that is
> genericized
> > > > and just use the selected index to map to the generic value. In
> general,
> > > we
> > > > probably also need an "EditCell", which is basically a two state cell
> > > that
> > > > can enter and exit edit mode. I'm sure that as people use the Cell
> > > Widgets,
> > > > we'll figure out which Cells are missing from the API.
> >
> > > > As for your immediate problem, I think the answer is that you need to
> > > > override resetFocus() to do whatever you want. Composite assumes
> that
> > > all
> > > > four elements will be there, so if you override render to change
> that,
> > > then
> > > > you need to override resetFocus() to handle the new structure.
> > > > Alternatively, you could render all four elements regardless of the
> > > state
> > > > and just set the display to null.
> >
> > > > Thanks,
> > > > John LaBanca
> > > > jlaba...@google.com
> >
> > > > On Fri, Nov 5, 2010 at 7:15 AM, Ümit <uemit.se...@gmail.com> wrote:
> > > > > I have an issue with the CompositeCell in a CellTable. My
> > > > > CompositeCell consists of 3 ActionCells and a SelectionCell.
> > > > > However the difference to a normal behaviour of a CompositeCell is
> > > > > that I don't show all Cells at the same time but based on some
> state
> > > > > in a domain object. Here is what I try to achieve:
> >
> > > > > Initial State
> > > > > Second Stage After pressing on
> Save/Cancel
> > > > > | NEW | -> (press on NEW ActionCell) -> | SELECTION SAVE CANCEL
> |
> > > > > -> | NEW |
> >
> > > > > So after pressing on the NEW ActionCell it should be hidden and the
> > > > > SelectionCell and the SAVE/CANCEL ActionCells should be shown.
> After I
> > > > > press on SAVE or CANCEL again only the NEW ActionCell should be
> shown.
> >
> > > > > For the ActionCells i just override the render method of the Cell
> to
> > > > > either not render the cell or to render it based on the state in my
> > > > > domain object.
> > > > > This looks like this:
> >
> > > > > public static class NewActioncell extends ActionCell<MyObject> {
> > > > > public NewActioncell(String
> > > > > text,com.google.gwt.cell.client.ActionCell.Delegate<MyObject>
> > > > > delegate) {
> > > > > super(text, delegate);
> > > > > }
> >
> > > > > @Override
> > > > > public void render(MyObject value, Object key, SafeHtmlBuilder
> sb)
> > > > > {
> > > > > if (value.getIsNew()) // get the state
> > > > > super.render(value, key, sb);
> > > > > }
> > > > > }
> >
> > > > > The code for the Save and Cencel Action Cells is basically the same
> > > > > apart from the fact that in the render method i will render the
> cells
> > > > > if value.getIsNew() == false
> > > > > The delegate action just sets the IsNew flag on the MyObject and
> calls
> > > > > refresh on the DataProvider.
> >
> > > > > So far everything works as expected. As soon as I press on the NEW
> > > > > Button, the NEW Button is hidden and only the CANCEL and SAVE
> buttons
> > > > > are shown.
> >
> > > > > Now I also want to display a Select Box when SAVE and CANCEL are
> > > > > shown. The Problem with the SelectionCell is that it is bound to
> > > > > String as the Generic Type, so I can't access MyObject in its
> render
> > > > > method.
> > > > > My workaround is now to override the <X> void render method of the
> > > > > CompositeCell and hide the SelectionCell there. This looks
> something
> > > > > like that:
> >
> > > > > public static class CustomCompositeCell extends
> > > > > CompositeCell<MyObject> {
> > > > > public CustomCompositeCell(List<HasCell<MyObject, ?>> hasCells)
> {
> > > > > super(hasCells);
> > > > > }
> >
> > > > > @Override
> > > > > protected <X> void render(MyObject value, Object
> > > > > key,SafeHtmlBuilder sb, HasCell<MyObject, X> hasCell) {
> > > > > if (!(hasCell.getCell() instanceof SelectionCell) ||
> > > > > (value.getIsNew())) // check Cell and State
> > > > > {
> > > > > super.render(value, key, sb, hasCell);
> > > > > }
> > > > > }
> > > > > }
> >
> > > > > So now the SelectionCell is displayed as soon as I press on the NEW
> > > > > Button. However I get an exception in hosted and in production mode
> as
> > > > > soon as I press on cancel or save.
> > > > > The error is:
> >
> > > > > Chrome: com.google.gwt.core.client.JavaScriptException:
> (TypeError):
> > > > > Cannot read property 'nextSibling' of null
> > > > > Firefox: elem is null [Break on this error] var sib =
> > > > > elem.nextSibling;
> >
> > > > > I managed to trace the problem back to the resetFocus method of
> the
> > > > > CompositeCell class:
> >
> > > > > @Override
> > > > > public boolean resetFocus(Element parent, C value, Object key) {
> > > > > Element curChild =
> > > > > getContainerElement(parent).getFirstChildElement();
> > > > > for (HasCell<C, ?> hasCell : hasCells) {
> > > > > // The first child that takes focus wins. Only one child
> should
> > > > > ever be in
> > > > > // edit mode, so this is safe.
> > > > > if (resetFocusImpl(curChild, value, key, hasCell)) {
> > > > > return true;
> > > > > }
> > > > > curChild = curChild.getNextSiblingElement();
> > > > > }
> > > > > return false;
> > > > > }
> >
> > > > > It seems that the loop goes through all 4 Cells but one call of
> > > > > getNextSiblingElement() returns null. The interesting part is that
> the
> > > > > exception only happens when I add the selectionCell to
> CompositeCell.
> > > > > It seems that not rendering an ActionCell by overriding its render
> > > > > method doesn't cause a problem. However overriding the render
> method
> > > > > of the CompositeCell to not render the SelectionCell causes this
> > > > > Exception in the resetFocus method.
> >
> > > > > Is this a potential bug or is my approach of hiding Cells in a
> > > > > CompositeCell flawed. Maybe there is a better approach.
> >
> > > > > Thanks in advance
> >
> > > > > Uemit
> >
> > > > > --
> > > > > You received this message because you are subscribed to the Google
> > > Groups
> > > > > "Google Web Toolkit" group.
> > > > > To post to this group, send email to
> > > google-web-tool...@googlegroups.com.
> > > > > To unsubscribe from this group, send email to
> > > > > google-web-toolkit+unsubscr...@googlegroups.com<google-web-toolkit%2bunsubscr...@googlegroups.com><google-web-toolkit%2Bunsubs
> cr...@googlegroups.com><google-web-toolkit%2Bunsubs
> > > cr...@googlegroups.com>
> > > > > .
> > > > > For more options, visit this group at
> > > > >http://groups.google.com/group/google-web-toolkit?hl=en.
> >
> > > --
> > > You received this message because you are subscribed to the Google
> Groups
> > > "Google Web Toolkit" group.
> > > To post to this group, send email to
> google-web-tool...@googlegroups.com.
> > > To unsubscribe from this group, send email to
> > > google-web-toolkit+unsubscr...@googlegroups.com<google-web-toolkit%2bunsubscr...@googlegroups.com><google-web-toolkit%2Bunsubs
> cr...@googlegroups.com>
> > > .
> > > For more options, visit this group at
> > >http://groups.google.com/group/google-web-toolkit?hl=en.
>
> --
> You received this message because you are subscribed to the Google Groups
> "Google Web Toolkit" group.
> To post to this group, send email to google-web-tool...@googlegroups.com.
> To unsubscribe from this group, send email to
> google-web-toolkit+unsubscr...@googlegroups.com<google-web-toolkit%2bunsubscr...@googlegroups.com>
> .
> For more options, visit this group at
> http://groups.google.com/group/google-web-toolkit?hl=en.
>
>
--
You received this message because you are subscribed to the Google Groups
"Google Web Toolkit" group.
To post to this group, send email to google-web-tool...@googlegroups.com.
To unsubscribe from this group, send email to
google-web-toolkit+unsubscr...@googlegroups.com.
For more options, visit this group at
http://groups.google.com/group/google-web-toolkit?hl=en.
