Tuesday, October 09, 2007

More details about Databinding and GWT

I promised in the morning that I'll blog more details about giving GWT-Developers access to concepts provided by Eclipse.

Currently my port provides:
- Core-Databinding + PEMF-Observables (for standard values (no lists at the moment))
- Support for Perspectives (untested but available in code)
- ViewPart-Implementation
- Access to the low-level-bits of the Command-framework (AbstractHandler and friends)
- A first draft implementation of ExtensionPointRegistry

This is currently not a straight port and the API is in some situations different but I'll resolve this later on.

Maybe some code example help you to understand the idea behind my work.

Starting up the application:

public class DemoApplication extends Plugin {

* This is the entry point method.
public void start() {
Workbench.createAndRunWorkbench(new WorkbenchAdvisor());

public String getPluginXML() {
"<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"+
"<?eclipse version=\"3.2\"?>\n"+
" <extension\n"+
" point=\"org.eclipse.ui.views\">\n"+
" <view\n"+
" name=\"Range of Product\"\n"+
" allowMultiple=\"false\"\n"+
" class=\"at.bestsolution.gwt.demo.client.ui.views.ProductRangeViewPart\"\n"+
" id=\""+IConstants.PRODUCT_RANGE_VIEW_PART+"\">\n"+
" </view>\n"+
" <view\n"+
" name=\"Product\"\n"+
" allowMultiple=\"true\"\n"+
" class=\"at.bestsolution.gwt.demo.client.ui.views.ProductEditingViewPart\"\n"+
" id=\""+IConstants.PRODUCT_EDITING_VIEW_PART+"\">\n"+
" </view>\n"+
" </extension>\n"+

public String getPluginName() {
return "at.bestsolution.gwt.demo";

Setting up a TreeViewer:

public Widget createPartControl() {

VerticalPanel panel = new VerticalPanel();
panel.setSize("100%", "100%");
Tree tree = new Tree();
tree.setSize("100%", "100%");
panel.setCellHeight(tree, "100%");
panel.setCellWidth(tree, "100%");

final TreeViewer viewer = new TreeViewer(tree);
viewer.setContentProvider(new TreeContentProvider());
viewer.setLabelProvider(new LabelProvider());
viewer.addSelectionChangedListener(new SelectionChangedListener());
// ...

And finally binding a control to a model element:

TextBox box = new TextBox();
table.setWidget(0, 1, box);

IObservableValue targetObservableValue = GWTObservables.observeText(box, GWTObservables.Change);
IObservableValue modelObservableValue = PEMFObservablesFactory.observeValue(Realm.getDefault(), product, Product.ID);
UpdateValueStrategy targetToModel = new UpdateValueStrategy();
UpdateValueStrategy modelToTarget = new UpdateValueStrategy();
modelToTarget.setConverter(new IntegerToStringConverter());
ctx.bindValue(targetObservableValue, modelObservableValue, targetToModel, modelToTarget);

The final result looks like this:

Doing RCP-Like programming with GWT

After having spent some time on GWT + Databinding I can now report success on porting over the Core-Databinding framework to GWT with fairly no changes from what is found in the Eclipse-CVS-Repository.

But to do real programming in GWT there's more you need (Views, Editors, Commands, Actions, ...) so I've also taken over the other core ideas from Eclipse into a GWT-Lib I called gjface (it isn't a straight port of the Eclipse-API currently because of the lack of time but it's fairly usebable already).

I've also created a Demo-Application you can find here and if you are interested how this Application is created you can get the source from here. I have only tested it on Firefox so it might be that it's not working on IE currently.

I'll blog later today how this all works together but if you want to take an in depth look I'm at ESE!