Converting GWT Click Events to Touch Events

Question

I am working on a Big Project and i have a lot of GWT code written. Now i am working on making the project fully compatible with Tablets like iPad and Android Tablets.

As a part of this, i have noticed that touch devices takes 300ms delay to handle click events. In this project, writing touch events again is a very tedious task. I have done a lot of researches in this and found the Google Fast Buttons API used in Google Voice Application. I tried that and its working good but requires a lot of coding and JSNI.

My question is, Is there anything else available in your knowledge to easily overcome this delay?

Answer 1

Here is a pure java implementation of the fast button.It doesn't include a single line of JNSI

package com.apollo.tabletization.shared.util;

import java.util.Date;

import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.dom.client.Touch;
import com.google.gwt.event.dom.client.HasAllTouchHandlers;
import com.google.gwt.event.dom.client.HasClickHandlers;
import com.google.gwt.user.client.DOM;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Composite;
import com.google.gwt.user.client.ui.Widget;

/** Implementation of Google FastButton {@link http://code.google.com/mobile/articles/fast_buttons.html} */
public class FastButton extends Composite {

  private boolean touchHandled = false;
  private boolean clickHandled = false;
  private boolean touchMoved = false;
  private int startY;
  private int startX;
  private int timeStart;

  public FastButton(Widget child) {
    // TODO - messages
    assert (child instanceof HasAllTouchHandlers) : "";
      assert (child instanceof HasClickHandlers) : "";
        initWidget(child);
        sinkEvents(Event.TOUCHEVENTS | Event.ONCLICK);
  }

  @Override
  public Widget getWidget() {
    return super.getWidget();
  }

  @Override
  public void onBrowserEvent(Event event) {
    timeStart = getUnixTimeStamp();
    switch (DOM.eventGetType(event)) {
      case Event.ONTOUCHSTART:
        {
          onTouchStart(event);
          break;
        }
      case Event.ONTOUCHEND:
        {
          onTouchEnd(event);
          break;
        }
      case Event.ONTOUCHMOVE:
        {
          onTouchMove(event);
          break;
        }
      case Event.ONCLICK:
        {
          onClick(event);
          return;
        }
    }

    super.onBrowserEvent(event);
  }

  private void onClick(Event event) {
    event.stopPropagation();

    int timeEnd = getUnixTimeStamp();
    if(touchHandled) {
      //Window.alert("click via touch: "+ this.toString() + "..." +timeStart+"---"+timeEnd);
      touchHandled = false;
      clickHandled = true;
      super.onBrowserEvent(event);
    }
    else {  
      if(clickHandled) {

        event.preventDefault();
      }
      else {
        clickHandled = false;
        //Window.alert("click nativo: "+ this.toString()+ "..." +(timeStart-timeEnd)+"==="+timeStart+"---"+timeEnd);
        super.onBrowserEvent(event);
      }
    }
  }

  private void onTouchEnd(Event event)  {
    if (!touchMoved) {
      touchHandled = true;
      fireClick();
    }
  }

  private void onTouchMove(Event event)  {
    if (!touchMoved) {
      Touch touch = event.getTouches().get(0);
      int deltaX = Math.abs(startX - touch.getClientX()); 
      int deltaY = Math.abs(startY - touch.getClientY());

      if (deltaX > 5 || deltaY > 5) {
        touchMoved = true;
      }
    }
  }

  private void onTouchStart(Event event) {
    Touch touch = event.getTouches().get(0);
    this.startX = touch.getClientX();
    this.startY = touch.getClientY();               
    touchMoved = false;
  }

  private void fireClick() {
    NativeEvent evt = Document.get().createClickEvent(1, 0, 0, 0, 0, false,
        false, false, false);
    getElement().dispatchEvent(evt);
  }

  private int getUnixTimeStamp() {
    Date date = new Date();
    int iTimeStamp = (int) (date.getTime() * .001);
    return iTimeStamp;
  }
}