iscroll scrollToElement not updating currPage variable - javascript

UPDATE:
I was able to get my scroller working as desired but I feel like I have hacked around the actual issue and would love it if anyone has a more solid answer, I've updated and noted in the snippets below the new jQuery I'm using.
I'm using iScroll-4 (http://cubiq.org/iscroll-4) for an iPad/Android web app, everything's working perfectly with the swipes and scrolling but I have a table of contents at the beginning of the app that allows users to jump to specific areas of the scroller --
I'm using the iScroll function scrollToElement(element, duration) in order to jump to the different areas. Also using scrollToPage(page, duration) to allow the user to manually navigate forward and backward one page at a time.
While watching the console logs the currPageX variable updates when I navigate with the scrollToPage function and when I swipe, but when using the scrollToElement the currPageX variable does not update.
Therefore if I jump to an element and then navigate forward with scrollToPage('next', 0) it will go backwards and navigate me to the next page after the table of contents.
I have tried using the scroll.refresh() function after scrollToElement, before, putting the function inside a timeout, etc. and I can't figure out why the currPageX is not updating.
Here's a snippet of the jQuery code that I'm using the two different functions:
// TO NAVIGATE FORWARD AND BACKWARDS
$('span.control').on('click', function() {
var slideDir = $(this).attr('data-dir');
if (slideDir == 'prev') {
var tehPg = tehScroll.currPageX-1;
} else if (slideDir == 'next') {
var tehPg = tehScroll.currPageX+1;
}
tehScroll.scrollToPage(tehPg, 0);
return false;
});
// TO JUMP FROM CONTENTS
$('li[data-page="toc"] span').on('click', function() {
var toPage = $(this).attr('data-page');
tehScroll.scrollToElement('li[data-page="'+toPage+'"]', 800);
// ADDED THE FOLLOWING LINE TO MANUALLY SET currPageX after scrolling!
tehScroll.currPageX = $('#slides li[data-page="'+toPage+'"]').index();
return false;
});

Did you consider using jquery-mobile-iscrollview widget plug-in? - there is a function scrollToPage(pageX, pageY, time), works well for me...
best
M

Related

jQuery history usage

I have created a webpage that uses jQuery to show and hide elements. The obvious problem now arose; the back and forward browser buttons don't work anymore as everything is loaded within a single location.
I know the answer lies within jQuery History but after busting my head for several hours on their website and examples given here on stackoverflow, I still cant manage to:
A) create a history entry (I think i got this covered but not 100% sure)
B) animate the page transition with my own function (displayed beneath)
This is the website: www.grommit.nl
There are 4 sub-pages that require a history entry when called upon.
This code shows the transition of the "wordpress page". The other pages work in a similiar way. (so far I have only managed to generalize the last part of the pageload with the "LoadPageContent" function, the bit before that is different with every page)
var LoadPageContent = function() {
$(".sceneBody").slideDown(function() {
$(".aftertitle").css('width', '4em');
$(".mediacontainer").fadeTo('0.3s', 1,)
});
$("#goWordpress").click(function () {
$("#homeScene").fadeOut(function () {
$("#wordpressMessage").fadeIn(function() {
$(this).delay(300).slideUp(function() {
$("#wordpressPage, #grommitFixed").slideDown(function() {
LoadPageContent();
});
});
});
});
});
this is the function that is currently working as a previous button within the DOM. I would like this function to execute when the previous button is clicked.
var goBack = function() {
$(".aftertitle").css('width', '0em')
$(".mediacontainer").fadeTo('0.3s', 0, function() {
$(".scenebody, #grommitFixed").slideUp(function() {
$("*[id*=Page]:visible").each(function() {
$(this).slideUp(function() {
$("#homeScene").fadeIn();
});
});
});
});
};
In html5 you have something called pushstate, that you can use to tell the browser what to go back to. Check out:
html pushstate

Hashchange history breaks iScroll

I have created the following application using iScroll: http://preview.na-software.co.uk/Demo/FutureLearning4/#/section-0
As the user flicks left and right or clicks the arrows in the bottom corners, the application moves the content sections it updates the history by changing the hash so that the user can move back and forth to other sections and bookmark them etc.
However! If you access a hash like: http://preview.na-software.co.uk/Demo/FutureLearning4/#/section-2 and then navigate a few sections and then use the back buttons two issues happen:
1.) It scrolls to the first screen (even though currentSection is correct, and iScroll has been told the correct section).
2.) If you click the back or forward button multiple times, you stop the animation and cause it to become confused and stick in between two sections.
Looking into the code, and seeing that the correct indexes and elements are being passed to iScroll on hashchange, and console logging out the offsets, I've discovered the issue is cause because the offsets are incorrectly set... however just doing refresh() won't fix the issue, as it will then reset the position.
Can anyone see where the problem is or see a way to fix this?
I should note that this bug ONLY happens if you come into the application on a URL that isn't section 0 and then scroll around the application. This is because the offsets will be created correctly by your interactions. But if you come into a URL like section 3, then the offsets will be incorrect and so the hashchanges don't work correctly, if that makes sense.
The hashchange method looks like:
// handle hashchange events
$(window).hashchange( function(){
// read the hash to find out what the new section number is
var nums = location.href.match(/(section)-\d+/g).map(
function(x){ return +x.replace(/\D/g,"") }
);
// set currentSection
currentSection = nums[0];
// if the hashchange was called by user scrolling
if(hashCalledByScroll){
// no need to anything as they have already updated hash and scrolled
hashCalledByScroll = false;
} else {
// find the section to scrollTo
sectionToScrollTo = $('#horizontal > .sections > .section').eq(currentSection).attr('id');
// tell iscroll to scroll to the section
horizontal.scrollToElement( '#' + sectionToScrollTo, null, null, true );
}
// hide the menu on hashchange
hideMenu();
});
Testing your site, I noticed the following: Whenever I access the site via section-3 and then enter the url for section-2, the navigation would instead send me to section-0.
I believe this is the same behaviour as you are experiencing in 1).
So I investigated and came to the following analysis:
In the function horizontal.scrollToElement( '#' + sectionToScrollTo, null, null, true )
iScroll retrieves the utils.offset(el) [iScroll.js#772] for the given el-ement. This offset tells it, where the element to scroll to is.
iScroll goes through the element and all of its offsetParents to add up their offsets. This is where things are breaking: <div class="sections"> has a negative offset to its parent, which imho it should not have.
This, in turn, messes up the scrollTo-coordinates.
To see what I am talking about: document.querySelector('.sections').offsetLeft
This has all just been analysis. My approach to fix this would be to avoid scrollToElement() and instead use scrollTo():
...
} else {
// find the section to scrollTo
sectionToScrollTo = $('#horizontal > .sections > .section').eq(currentSection).attr('id');
// tell iscroll to scroll to the section
var posLeft = -$('#' + sectionToScrollTo)[0].offsetLeft;
var posTop = -$('#' + sectionToScrollTo)[0].offsetTop;
horizontal.scrollTo(posLeft, posTop, 1000);
}
// hide the menu on hashchange
hideMenu();
});
Thus, just calculate the location of the section you want to go to yourself.
About 2) I am not sure if there is much one can do about it. Jumping around quickly breaks a lot of carousels. Maybe a delayed callback to scrollEnd, verifying the validity of the current state.
Another thing I noticed is that you can accidentally stop the transition. Try to click, hold and release the cursor midway a transition - you need to be quick.
Hope this helps.
Found not best solution and it doesn't solve main problem, but it works.
$(window).hashchange(function () {
if (hashCalledByScroll) {
hashCalledByScroll = false;
} else {
var hpage = window.location.hash;
var hpage = hpage.replace('#/section-', ''); //get number of target page
var cpage = currentSection; //number of current page
var count = parseInt(hpage) - parseInt(cpage); //difference
while (count > 0) { //if difference positive: go forward count-times
horizontal.next();
count--;
}
while (count < 0) { //if difference negative: go backward count-times
horizontal.prev();
count++;
}
}
hideMenu();
});
FIDDLE

Windows 8 Grid Template JS App, CSS manipulations dont show on all selected items in groupedItems view

I'm using the Win8 Grid View Template to display infos from a news site. In the lower menu bar i have implemented a function wich shuts off the titles, so that only the pictures are still visible.
This function is in a "global.js" file which is included in the "default.html" so it's available everywhere and it looks like this:
//function to turn titles off and on
function titleToggle() {
var titles = document.getElementsByClassName("item-overlay");
for (var i = 0; i < titles.length; i++) {
if (Global.titlesAreOn) {
titles[i].style.display = "none";
}
else {
titles[i].style.display = "";
}
}
Global.titlesAreOn = !Global.titlesAreOn;
};
So when i call this function from the menu bar it works for the first items, but when i scroll the end of the groupedItems view (hubview) the titles are still there. When i then scroll back to the beginning the titles are there again too.
I'm also calling the titleToggle function from the ready() function of the "groupedItems.js" to check whether or not to display the titles depending on a global variable. When i do that (whenever i come back to the hubpage) it works all the way, just as expected.
ui.Pages.define("/pages/groupedItems/groupedItems.html", {
navigateToGroup: function (key) {
nav.navigate("/pages/groupDetail/groupDetail.html", { groupKey: key });
},
ready: function (element, options) {
appbar.winControl.disabled = false;
appbar.winControl.hideCommands(["fontSizeBt"]);
appbar.winControl.showCommands(["titleToggle"]);
if (Global.titlesAreOn == false) {
Global.titlesAreOn = true;
Global.titleToggle();
}
I made a short video to show the problem, because its kinda hard to explain --> http://youtu.be/h4FpQf1fRBY I hope you get the idea?
Why does it work when i call it from the ready() function?
Does anyone have an idea? Is it some kind of automatic item caching in order to have better performance? And how could this be solved?
Greets and thanks!
First, here is why this might be happening - WinJS is using single page navigation for the app experience. This means that when you navigate to a new page, actually you don't. Instead the content is removed from the page and the new content is loaded in the same page. It is possible that at the moment you press the button not all elements have been loaded in the DOM and therefore they cannot be manipulated by your function. This is why when you call it from the ready() function it works - all contents are loaded in the DOM. It is generally better to do things in the ready() function.
About the behavior when you slide back left and the items are again reloaded with titles - for some reason the listView items are reloading. Maybe you are using live data from the news site and they are refreshing with the listView control's template again. I cannot know, but it doesn't matter. Hiding the elements is not the best approach I think. It is better to have two templates - one with a title element and one without. The button click handler should get the listView controls(they have to be loaded) and change their templates.
ready: function (element, options) {
var button = document.getElementById('btn');
button.addEventListener("click", btnClickHandler);
}
And the handler:
function btnClickHandler(e) {
var listView = document.getElementById("listView").winControl;
var template2 = document.getElementById("template2");
listView.itemTemplate = template2;
};

Hammer.js Carousel Start Pane

Heyho,
I´am working on a project in my university and I´d like to use "Hammer.js".
I´ve downloaded the Carousel-Example and it works perfectly for me.
But I would like to start a the middle pane of my code and it´s not so simple I think.
It´s something like this:
http://img203.imageshack.us/img203/6326/schemeas.jpg
so Hammer.js starts always with the green screen. But I like to start with the yellow one.
I´ve added one swipe right to the init function but it looks horrible when the page is loading and could not be the goal ^^
I hope anyone of you have an idea how to solve my problem.
Try calling
carousel.showPane(1);
That will display the second pane instantly. You will want to put this near the bottom, right after where it says.
carousel.init();
If you're feeling adventurous you could try and make it automatically start with that pane as there's a variable inside the Carousel function called current_pane which is set to a default of 0 (the first pane). Altering this may work too but might require more code somewhere else. Experiment!
edit
NULL is right, it does animate it. Here's a more in depth method to set it without animation:
I found that the method responsible for changing which pane is showing was the setContainerOffset mthod which could be passed a variable to animate it. I previously told you to use showPane(2) but that then called
setContainerOffset(offset, true)
which caused the animation occur. What you should do instead is make a slightly different version of showPane...
this.setPane = function( index ) {
// between the bounds
index = Math.max(0, Math.min(index, pane_count-1));
current_pane = index;
var offset = -((100/pane_count)*current_pane);
setContainerOffset(offset, false);
};
You'll find it's almost identical to showPane except for the name and the fact that it calls setContainerOffset with animation: false. This will immediately show the pane of your choice and can be called using
carousel.setPane(index);
What I've done is added this to the init function so that it looks like this:
this.init = function() {
setPaneDimensions();
var c = this;
$(window).on("load resize orientationchange", function() {
setPaneDimensions();
c.setPane(current_pane);
//updateOffset();
})
};
Now you can change
var current_pane = 0;
to whatever you want and the carousel will always start with that pane when it's initialised! simple!

Jquery/Javascript not working on Firefox. Why?

I just found out that my script is working fine in Chrome, but not in FireFox - and I can't figure out why.
This is the site in development: www.fireflycovers.com
The script should execute when one of the round green buttons is clicked. (scrolls the window to the next container)
The script looks like this at the moment:
$('.scroll').css('display' , 'block');
$('.scroll').on('click', function(e) {
var container = $(this).parent();
// Scans if last container in group
while (document != container[0] &&
container.find('~.col, ~:has(.col)').length == 0) {
// If so, search siblings of parent instead
var container = container.parent(),
nextdiv = container.nextAll('.col, :has(.col)').first();
}
// Back to first .col (when no next .col)
if (nextdiv.length == 0) {
nextdiv = $(document).find('.col:first')
};
// Animates scrolling to new position
$('body').animate({scrollTop:nextdiv.offset().top}, 1000);
return false;
});
});
Did you try debugging at all? As in, putting console.log statements throughout your method to see what the values of things are at certain times and watching it execute? Anyway, does using this help at all?
$('body,html').animate({scrollTop:nextdiv.offset().top}, 1000);
Verified from Animate scrollTop not working in firefox
You need html because firefox behaves differently when it comes to overflow.

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