CODEWITHSUNDEEP
javagwt
quarks
quarks

Reputation: 35346

GWT ScrollHandler

I have this code

@Inject
@DataField("table-col")
SimplePanel tableContainer;

@PostConstruct
public void build() {
    scroll(tableContainer.getElement(), this);
    tableContainer.addHandler(new ScrollHandler() {
        @Override
        public void onScroll(ScrollEvent scrollEvent) {
            // TODO - Does not trigger
            Window.alert("Scroll");
        }
    }, ScrollEvent.getType());
}

My question is why the tableContainer Scroll handler does now work when the similar Javascript (JSNI) handler works:

public static native void scroll(Element elem, TablePage instance) /*-{
       $wnd.$( elem ).scroll(function() {
            if (elem.scrollTop >= (elem.scrollHeight - elem.offsetHeight)) {                    
                [email protected]::scrolledToBottom()();
            }
        });
}-*/;

What could be wrong here?

Upvotes: 0

Views: 368

Answers (1)

rjeeb
rjeeb

Reputation: 491

The SimplePanel doesn't actually listen to ScrollEvent, if you want a panel with scroll support you can use ScrollPanel (which is a simple panel with scrolling support).

ScrollPanel scrollPanel = new ScrollPanel();
scrollPanel.addScrollHandler(new ScrollHandler() {
    @Override
    public void onScroll(ScrollEvent scrollEvent) {
        // TODO - Does not trigger
        Window.alert("Scroll");
    }
});

In your second way, you're actually adding the event to the element itself, and waiting the event to fired from browser to call your handler. In both ways the event is fired from the browser, but the first one doesn't actually listen to it while the second one listens to it.

Upvotes: 2

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