Design view "drop" area reflects custom restrictio

[peterblazejewicz]

Hi all & team,

is there a method to restrict what types of custom components can be dropped into design view?
I was discussing such topic elsewhere:
- say base component is impementation of <ul> (unordered list) based on ComplexPanel widget. It works fine and renders fine in Design view
- say we want to rectrict at design time what can be dropped into that panel and restrict only to <li> (list items) impemented as Widget subclass.

I've tried throwing exception or use of assertion but that only works at runtime compilation. What I was wondering if there is a way to reflect that during authoring time somehow,

Code: Select all

/*@Override*/
public void add(Widget w) {
   add((ListItem) w, getElement());
}
/*@Override*/
public void insert(Widget w, int beforeIndex) {
   insert((ListItem) w, getElement(), beforeIndex, true);
}

void add(ListItem item) {
   super.add(item, getElement());
}

void insert(ListItem item, int beforeIndex) {
   super.insert(item, getElement(), beforeIndex, true);
}

which does not work (however Designer prompts error message box about contacting with support, but design view is refreshed)

some ideas?

thanks,
regards,
Peter

[Eric Clayberg]

is there a method to restrict what types of custom components can be dropped into design view?

There is no public way to do this. Even Sun's Java Bean spec does not specify a way to do this.

Special components that require unique design-time behavior require special support within the editor.

We have special design-time support classes for all of the built-in GWT panel types.

[peterblazejewicz]

hi Eric,
thaks for information,
i'll stay with maybe runtime exceptions or assertions if that will be required then,

regards,
Peter

[Eric Clayberg]

i'll stay with maybe runtime exceptions or assertions if that will be required then

For now, that will need to do. We have some thoughts on putting together a developer api for adding custom widgets, but that will take some time.