EDIT FOR CLARIFICATION:
What I want:
A full screen javascript canvas which can handle touch events without those events being further interpreted by the browser, but also reserve the ability to open a new window on user action.
Examples:
I should be able to swipe my finger around without the webpage trying to scroll
I should be able to swipe my finger around without the contents of the webpage being nudged in any way (normally, when one scrolls to the end of a scroll region, the browser allows some additional spring-loaded buffer scrolling to signal to the user that it is the end of the scroll region).
I should be able to pinch and pan without the webpage zooming
etc...
The point:
I need to interpret these events accurately and in realtime MYSELF to respond to these actions WITHIN THE CANVAS. (I am doing realtime drawing via requestAnimationFrame, allowing me to react to user events without using the DOM)
The state of things currently:
This all works perfectly (except for the ability to open a new window) because I position the canvas to be the full size of the viewport (handling any window resize events), and the canvas listens to ontouchstart, ontouchmove, ontouchend, etc... events, calling evt.preventDefault() after I have handled the user input myself. This works to ensure the canvas is ALWAYS full screen, doesn't budge, and user input is accurately given to me to handle in-game.
The Problem:
One bit of user input I need to handle is the launching of a webpage when they click the region of my canvas with a "launch my webpage" button. However, window.open(mywebpage) doesn't work, because mobile safari only allows such an action in the callstack of a click event. Because I rely on ontouchstart to get responsive controls, and evt.preventDefault() in an ontouchstart event CANCELS the click event from happening, I cannot launch the webpage (it gets blocked by the browser).
My attempted solutions, and why they are insufficient:
Just use a click event rather than ontouchstart: this means I can't prevent scrolling/etc... additionally, it is not as responsive, and doesn't allow me to handle touch-and-drag events well.
Overlay a div (or an a) tag atop the canvas over the launch webpage zone, and add a click event to that: if the user clicks-and-drags starting within this tag, then it allows the page to scroll and zoom. Trying to fix this results in the same problem as before.
ORIGINAL POST:
I have a mobile application that is a full-screen canvas, which locks itself positionally (can't scroll or zoom) so that I can correctly interpret user input uninterrupted (swipes, pans, etc...).
It locks itself in by intercepting touchstart events and calling evt.preventDefault (as well as the meta viewport no-zoom stuff which as far as I can tell doesn't actually do anything?).
This works great, and is absolutely necessary to make a game (or game-like application) function.
The problem is that I also have a "go to this webpage" button. I can intercept the touchstart, and use window.open(somewebpage), but mobile popup blockers will block it. The "rules" seem to be "the webpage will be allowed to be opened iff it is done in the call stack of a user interaction, AND that interaction is a 'click' event".
I have the first part down, but if I change the event to a click event, the web page now interprets swipes as scrolls (and pinches as zooms, etc...). If I have both a click and a touchstart event, then calling evt.preventDefault() on the touchstart (which stops the scroll/zoom) also stops the click event.
If I overlay a div atop the click zone of the "launch webpage" button, then the player can scroll/zoom when their input begins in that button, which results in an unpredictable and wonky experience.
How can I launch another webpage without allowing the current webpage to scroll?
Edit: at request, here is a code snippet at least partially illustrating what I'm trying to do https://jsfiddle.net/phildo/0q8e47fk/10/.
Note that in the "real" case, the canvas takes up the full width/height of the screen, and is explicitly set accordingly on screen resize.
Preventing bounces of any kind on mobile web page is a vast problem through out the mobile devices not depending about the manufacturer. I had similar issue on Windows Phone 8 app years ago and there (quite surprisingly) was a solution dedicated to Windows environment which of course cannot applied here.
For iOS you need an iOS solution, right?
The very solution is named iNoBounce. The idea is to add the little js library to your html page, code with some good conventions and the js lib will do the dirty job of preventing the default when necessary.
The trick it actually does is not to prevent just anything, but the ones only, that are "extra" and will cause the bounce events.
With the words of iNoBounce GitHub Readme:
iNoBounce detects if the browser supports -webkit-overflow-scrolling by checking for the property on a fresh CSSStyleDeclaration. If it does, iNoBounce will listen to touchmove and selectively preventDefault() on move events that don't occur on a child of an element with -webkit-overflow-scrolling: touch set. In addition, iNoBounce will preventDefault() when the user is attemping to scroll past the bounds of a scrollable element, preventing rubberbanding on the element itself (an unavoidable caveat).
The example code asks you to use the following parts (there is a separate example code for canvas, this is only the most common solution):
// All you need is an element with `height` or `max-height`, `overflow: auto` and `-webkit-overflow-scrolling: touch`.
<script src="inobounce.js"></script>
<style>
ul {
height: 115px;
border: 1px solid gray;
overflow: auto;
-webkit-overflow-scrolling: touch;
}
</style>
Source:
[1] https://github.com/lazd/iNoBounce
Edit:
I found out you did not limit yourself to iOS. For other browsers, try
[2] https://developer.mozilla.org/en-US/docs/Web/CSS/overscroll-behavior
which introduces overscroll-behavior setting, that you can set to none to disable bounces.
It will work only on Android, not ie or iOS.
For mobile Windows Phone I had the solution like this:
div.wp8ScrollFix {
-ms-touch-action: none;
}
which effectively does the same as iNoBounce, now with single CSS line for the div containing the canvas.
Edit2:
For a search of semi universal solution, I could find that
-touch-action: none;
applied to div element that includes the canvas, you can disable default touch events and for the canvas, define your own.
The solution works on any other than Safari browsers. As in [3] there may be some variants like
-ms-touch-action: none;
but I suppose they are now all same without prefixes. The [3] solution is very old and world has changed a lot from those days.
The sad thing is, the browser support is same at least 2019 [4] and maybe now also.
Sources:
[3] jQuery / HTML5 / gwt app for WP8 (Lumia 920) device: vertical css scroll fix
[4] https://css-tricks.com/almanac/properties/t/touch-action/
Problem
Show a div on top of full screen canvas element that intercepts normal click events on element canvas.
Solution
Aside from click events, you need to intrrcept the following touch events:
touchstart
touchend
touchmove
touchcancel
Additional Info
You only preventDefault on the canvas events so you should still be able to create a clickable/touchable element in the canvas that shows a div outside the canvas positioned with a z-index higher than the canvas element by setting on display: block on the div. The div should also have 100vh and 100vw set foe width and height respectively and be position: fixed. The div should also have a button to hide again display: none.
References
https://stackoverflow.com/a/51127296/806876
I am trying to make a button that increments a counter when you click the button however, it needs to be able to respond to fast taps. I have set the viewport scaling to none so that the fast taps don't just zoom in but even with fastclick.js it's still not registering every tap.
If I use the touchend event instead of click it responds appropriately but then I lose desktop taps and if I use touchend and mouseup/click then iOS responds to all the touchends as well as the mouseup/clicks every few taps.
Any foolproof ways for responding to fast, successive taps in iOS and still working on desktop and other touch devices?
I'm making a small full-screen canvas game to be played on mobile. It involves swiping around the screen with your finger. I have the canvas listening for touch events (down, move, up).
Unfortunately, the browser tries to interpret swipes left and right as browser tab navigation, and swipes up and down as hide/show URL. I don't care if the URL is hidden or not, I just want everything to stay still.
As a result of everything moving, it intermittently stops recognizing inputs to the canvas.
The way I have it set up is a canvas that takes the size of the screen, set its position to fixed at 0,0. This is to prevent scrolling (which works, except for the hide/show url thing).
If you want to see an example, here's where I'm hosting it:
http://phildogames.com/scratch/sust/index.html?game=window (you won't be able to interact on desktop because it's listening for touch events, but if you view it on mobile you should be able to open and close the windows).
tl;dr: I want to tell the browser to simply pass swipes (well, all touch events) to the dom and stop interpreting them as intents to scroll, switch tabs, hide/show URL, etc..
Thanks!
I was able to solve your problem by simply preventing touches on the body.
var myBody = document.getElementById('dabody');
myBody.addEventListener('touchstart', function(e){
e.preventDefault()
});
You can throw that in console to test. Tested on iOS Safari and Android Chrome.
I am creating an application that allows users to draw on the screen using the HTML5 Canvas tag.
This works great when using a mouse, and I even got it working on android using jquery touch.
The problem comes when using a windows 7 or 8 tablet. The reason for why it wont work is simple, the browser tries to scroll instead of mousedown and drag.
The reason why it works on android and not windows is due to the fact that android supports ontouchstart and ontouchend while I can't get it to work on windows tablets.
So, is there any way to get the browser to stop trying to scroll and draw on the screen?
Thanks.
I am working on a website which has an canvas on it. I have an image in the canvas, and what I want to do is pinch to zoom the image (the web page will eventually be on a touch screen). I am using jGestures for detecting pinch event. However, I wonder if there is a way to test on a Mac computer, because when I do pinch on mac trackpad, it zooms the webpage, not the canvas, which means that the pinch on trackpad does not apply to my canvas tag, it zooms my webpage (the font, the width, the height). I also wonder if magic trackpad or magic mouse can do it. Could anyone help?
If you have Xcode you could run the iOS simulator. The simulator would allow you to pinch. Hold down Option key and you should be able to mouse click to zoom in and out.
I got multitouch working on my MacBook's trackpad with npTUIOClient (see article) with an old version of Chrome. Think it was v.10 or so.