Re: Tree scrolling issue

This issue is solved successfully.  I put this solution if any one faced such issue. This may help him.

The issue with Event.ONMOUSEDOWN in super.onBrowserEvent(event); and do some weird behaviour.

So I implemented onBrowserEvent in tree panel. When the Event.ONMOUSEDOWN  is fired, then avoid call of super.onBrowserEvent(event); but Tree node have images like open (+) and  close(-). That event only allow to fire.

so make condition don't fire any event  except open (+) and  close(-) image of tree node. and scrolling problem solved.

@Override

public void onBrowserEvent(Event event) {

int eventType = DOM.eventGetType(event);

switch (eventType) {

case Event.ONCLICK:

case Event.ONKEYDOWN:

case Event.ONKEYPRESS:

case Event.ONKEYUP:

return;

case Event.ONMOUSEDOWN:

       Element e = DOM.eventGetTarget(event);

       if (e.getTagName().equals("IMG")) {

       if( e.getAttribute("title")!=null)

       {

       if(e.getAttribute("title").equals("Add Item") || e.getAttribute("title").equals("Import Child Items") || e.getAttribute("title").equals("Attach files") ||

        e.getAttribute("title").equals("Delete Item"))

       {

         return;

       }

       }

       }

       else

       {

        return;

       }

default:

break;

}

super.onBrowserEvent(event);

 

}

On Tuesday, 3 September 2013 18:47:20 UTC+5:30, Bhumika Thaker wrote:

Hi, 

I am facing issue with scrolling while  selecting  tree item in tree. 

While tree is bigger then it's root panel, scroll is coming.  If I click on any item, it will just adjust scroll first then second time I have to do same thing. It will do selection as expected. But The problem with  I don't want twice click / selection. It should do in first attempt only.

As I goggled then find similar this problem like http://code.google.com/p/google-web-toolkit/issues/detail?id=1467

See below code, This is not my actual code implementation, It is sample example to find actual root cause.

public class TestGWTScroll implements EntryPoint {

@Override

public void onModuleLoad() {

ScrollPanel scrollPanel=new ScrollPanel();

scrollPanel.setHeight("200px");

scrollPanel.setWidth("100px");

CustomTree  tree=new CustomTree();

tree.setTitle("tEST");

TreeItem item=tree.addItem(new HTML("Node1"));

item.addItem(new HTML("Child1 Item------------------------------------------->"));

item.addItem(new HTML("Child2"));

tree.addItem(new HTML("Node2"));

tree.addItem(new HTML("Node3"));

scrollPanel.add(tree);

RootPanel.get().add(scrollPanel);

}

class CustomTree extends Tree

{

@Override

public void onBrowserEvent(Event event) {

int eventType = DOM.eventGetType(event);

switch (eventType) {

case Event.ONCLICK:

case Event.ONKEYDOWN:

case Event.ONKEYPRESS:

case Event.ONKEYUP:

//case Event.ONMOUSEDOWN

return;

case Event.ONMOUSEDOWN:

 if ((DOM.eventGetCurrentTarget(event) == getElement())

              && (event.getButton() == Event.BUTTON_LEFT)) {

 //How to open selected tree item

 }

default:

break;

}

super.onBrowserEvent(event);

}

}

}

As I found, The problem is with Dom event Event.ONMOUSEDOWN. 

1) You find in code then I commented Case Event.ONMOUSEDOWN. if I return this event,  it works perfect. Doesn't do scrolling first while mouse left key pressed. But tree open (+) operation stopped. Because Then open node event is handle inside this event.

2) So I decide to these events manually but how I don't know. As I found its all implementation methods are private.

Just example elementClicked is private not accessible. So this option is also not work for me.

   case Event.ONMOUSEDOWN: {

        // Currently, the way we're using image bundles causes extraneous events

        // to be sunk on individual items' open/close images. This leads to an

        // extra event reaching the Tree, which we will ignore here.

        // Also, ignore middle and right clicks here.

        if ((DOM.eventGetCurrentTarget(event) == getElement())

            && (event.getButton() == Event.BUTTON_LEFT)) {

          elementClicked(DOM.eventGetTarget(event));

        }

        break;

      }

How can I resolve this issue? From that tree open activity and scrolling issue work perfect for me.

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