GWT MouseWheelHandler not working in Firefox
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13-09-2019 - |
Question
I'm trying to make a TextBox that will change value when someone scrolls the mouse wheel over it. Specifically, my goal is for the number in the text box to increase when i scroll up, and decrease when i scroll down. However, I'm having trouble figuring out the MouseWheelHandler. I simplified my code to just change the value to "UP" or "DOWN", but it just doesn't work. It compiles though. I also tried it with event.preventDefault(), but that didn't seem to have any effect.
private TextBox valueField = new TextBox();
...
...
valueField.addMouseWheelHandler(new MouseWheelHandler() {
public void onMouseWheel(MouseWheelEvent event) {
//event.preventDefault();
if(event.isNorth()) {
valueField.setText("UP");
} else {
valueField.setText("DOWN");
}
}
});
Edit: I just tested it in Chromium and Opera, and it worked fine. Unfortunately, it still does not work in my supported browsers (Firefox and IE).
Edit: Decided to try a native Javascript method. My Javascript skills are weak, so I still need some help.
Solution 2
I got this successfully running under Firefox using a native method that adds a mouse wheel listener to the window when the text box fires a mouseover event.
protected void onAttach() {
super.onAttach();
String fieldId = "box"+Random.nextInt(10000);
valueField.getElement().setId(fieldId);
addNativeMouseWheelListener(this, fieldId);
}
...
private native void addNativeMouseWheelListener(ValueBox instance, String id) /*-{
function mouseOverHandler(e) {
$wnd.addEventListener("DOMMouseScroll", scrollWheelMove, false);
}
function mouseOutHandler(e) {
$wnd.removeEventListener("DOMMouseScroll", scrollWheelMove, false);
}
function scrollWheelMove(e) {
e.preventDefault();
if (e.wheelDelta <= 0 || e.detail > 0 ) {
instance.@com.proprintsgear.design_lab.client.ValueBox::decreaseValue()();
} else {
instance.@com.proprintsgear.design_lab.client.ValueBox::increaseValue()();
}
instance.@com.proprintsgear.design_lab.client.ValueBox::fireChange()();
}
if($wnd.addEventListener) {
var box=$doc.getElementById(id);
box.addEventListener("mouseout",mouseOutHandler,false);
box.addEventListener("mouseover",mouseOverHandler,false);
}
}-*/;
Shortly after writing this method, I learned that the latest svn revisions of GWT have fixed the MouseWheelEvent for Firefox. However, I've already got this written, and I don't feel like downloading an unstable release, so I'll keep this until the next stable GWT release.
OTHER TIPS
I'm going to try to solve this problem with a native Javascript method. I got this to work.
private static native void addNativeMouseWheelListener(String id) /*-{
function scrollWheelMove (e) {
if ($wnd.event || $wnd.Event) {
if (!e) e = $wnd.event;
if (e.wheelDelta <= 0 || e.detail > 0 ) {
$wnd.alert("DOWN");
} else {
$wnd.alert("UP");
}
}
}
//var box=$doc.getElementById(id);
$wnd.addEventListener("DOMMouseScroll", scrollWheelMove, false);
}-*/;
Now I'm looking for a way to add a DOMMouseScroll listener to the element itself. Is this possible, or should I just create a DOMMouseScroll listener for the window whenever a user mouses over the element? Also how do I prevent the window from scrolling?