How to intercept scrollEvents on tablets (which does not have a scroll mouse) ?

[regnoult axel]

Hello,

My issue is indirectly related to an unforeseen behavior on tablets because they do not have a scroll mouse and so I cannot intercept a scroll event.

Actually I am mainly working on a desktop application, but I would like to know how I could handle the following scroll event : "The users uses the scrollbar instead of the scroll mouse to scroll on the page..."

Q1 - Do you have any idea how to intercept an event realized when the user click on the scrollbar arrow or when he moves the scrollbar track ?

Q2 - Does the recommended solution will work on tablets ?

Thanks you, 

[ashwin....@gmail.com]

Checkout this guide from Apple, gives detailed information on events being generated pertaining to ios devices. https://developer.apple.com/library/safari/#documentation/AppleApplications/Reference/SafariWebContent/HandlingEvents/HandlingEvents.html

There are two approaches, 

1. using TouchStart and TouchEnd events. You can single/ double touches etc depending on the experience you want to achieve in your app.

2. using onScrollEvent and implementing a ScrollHandler. 

example to handle simple scrolling using TouchStart and End events.

HTMLPanel searchPage;

int scrollStartPosX = 0;

int scrollStartPosY = 0;

public init() {

            if (TouchEvent.isSupported()) {

searchPage.addDomHandler(this, TouchStartEvent.getType());

searchPage.addDomHandler(this, TouchMoveEvent.getType());

}

}

/* (non-Javadoc)

* @see com.google.gwt.event.dom.client.TouchStartHandler#onTouchStart(com.google.gwt.event.dom.client.TouchStartEvent)

*/

@Override

public void onTouchStart(TouchStartEvent event) {

scrollStartPosY = searchPage.getElement().getScrollTop()

+ event.getTouches().get(0).getPageY();

scrollStartPosX = searchPage.getElement().getScrollLeft()

+ event.getTouches().get(0).getPageX();

}

/* (non-Javadoc)

* @see com.google.gwt.event.dom.client.TouchMoveHandler#onTouchMove(com.google.gwt.event.dom.client.TouchMoveEvent)

*/

@Override

public void onTouchMove(TouchMoveEvent event) {

searchPage.getElement().setScrollTop(

scrollStartPosY - event.getTouches().get(0).getPageY());

searchPage.getElement().setScrollLeft(

scrollStartPosX - event.getTouches().get(0).getPageX());

event.preventDefault();

}

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