Getting javascript events to an object that's covered up - javascript

I'm trying to build a jquery app where I have a fixed image and a second draggable image. I need the fixed image to display z-index on top of the moveable image -- the fixed image is a picture with an alpha cut-out hole for a face like you might find at an amusement park. The problem is that as soon as the moveable (face) image is overlapping with the fixed image, click and drag events get captured by the fixed image which is on top and don't get to the moveable image. So it's no longer moveable. Here's my code...
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8.8/jquery-ui.min.js"></script>
<div id="fixed" style="position:relative; z-index: 2">
<img src="background.png">
</div>
<div id="face" style="position:relative; z-index: 1">
<img src="face.png">
</div>
<script>
$(function() {
$("#face").draggable();
});
</script>
How can I get the face object to be draggable when it's behind the fixed background? Can I manually fire the mouse events on the object underneath? If so, how do I invoke them so the jquery-ui draggable() works properly? Can I somehow get the fixed image just not to capture events? Or do I need to write my own draggable mechanism by hand?

I think i found a pretty simple solution for you. Basically you can relay the event only when certain conditions are met (eg #face is under the #fixed). Check out this fiddle for example.
A quick look at the even data revealed that draggable only binds mousedown, so that seems to be the only event you will need to relay.
$('#face').draggable();
$('#fixed').bind('mousedown', function(e){
// TODO: IF #face is under #fixed AND mouse is over #face THEN
$('#face').trigger(e); // trigger the event on face
});

I think you might be better off creating some sort of "drag handle" to the element underneath, which would always be visible (at least while dragging is enabled). That, or a separate UI control separated from the images which would act as a "joystick" for the draggable image, so that you could move the image without having to manually drag/drop the image itself.
Think about it: lets say they drag the item underneath the top item, then drop it; how are they to pick it up again? If this is setup like you explained (a cut-out hole for a face like you might find at an amusement park), then the user would not be able to visibly see the element underneath, and as such, it would be impossible for them to interact with that element using the mouse.

Related

jQuery UI tooltip is stuck open when the source DOM element moves

I have a div that contains a few thumbnails which can be dragged and dropped. When one thumbnail is dropped over top of another thumbnail, they switch places. I do this using AngularJS and manipulating the underlying data on the $scope.
Anyway, here's the problem:
The thumbnails have tooltips that open when I hover over them. When I click and start dragging a thumbnail (let's call this one the source thumbnail), its tooltip disappears (as it should). So far so good. When I drop the thumbnail over top of the other, however, there's a brief moment where the target thumbnail's tooltip appears, since the mouse is currently hovering over the target tooltip.
A split second later, the underlying model swaps the two pieces of data, and the DOM updates to reflect the change - effectively swapping the two thumbnails. Now, the target's tooltip is STILL open, but my mouse is no longer over the target, because it was just swapped! The tooltip will remain open until I re-trigger the tooltip events at the new location.
This behaviour is observed roughly 50% of the time, but I can artificially reproduce it 100% of the time by adding a short (~1 second) delay before changing the underlying data, causing the thumbnails to switch places.
NOTE: This problem does NOT occur in Chrome, but it does in Firefox and IE. I haven't tried Safari.
Has anyone experienced this problem, or something similar? Please let me know if I can provide any further details. Thanks!
Edit: Here's a jsfiddle example that illustrates the problem: jsfiddle
<script src="http://code.jquery.com/jquery-1.11.2.min.js"></script>
<script src="http://code.jquery.com/ui/1.11.2/jquery-ui.js"></script>
<script>
$.widget.bridge('uitooltip', $.ui.tooltip);
</script>
<div ng-app="myApp">
<div ng-controller="ContentController">
<div class="indent">
<div ng-repeat="square in squares" style="width: 400px">
<item data="square" helper="helperFunction"></item>
</div>
Drag the top box onto the bottom box and keep the mouse cursor stationary for ~1 second. The tooltip will be stuck open when the boxes switch places. Dragging the bottom box to the top box, however, does not have this problem.
<br><br>
Also, this problem seems to only be present in Firefox and IE. Chrome works as expected.
</div>
</div>
</div>
You could replace the default browser tooltips with the jquery version:
$('*').tooltip({track: true});
Then you could set the tooltips to be disabled while you drag your elements:
$('.thumbnail').tooltip('disable');
On drop, enable them again:
$('.thumbnail').tooltip('enable');
http://jsfiddle.net/uHuDp/1/
Edit: for your example:
$(element).find("span.item-outer").uitooltip('disable');
$(element).find("span.item-outer").uitooltip('enable');
http://jsfiddle.net/uHuDp/260/

Apply gradient over page without hindering user interaction [duplicate]

I have a div that has background:transparent, along with border. Underneath this div, I have more elements.
Currently, I'm able to click the underlying elements when I click outside of the overlay div. However, I'm unable to click the underlying elements when clicking directly on the overlay div.
I want to be able to click through this div so that I can click on the underlying elements.
Yes, you CAN do this.
Using pointer-events: none along with CSS conditional statements for IE11 (does not work in IE10 or below), you can get a cross browser compatible solution for this problem.
Using AlphaImageLoader, you can even put transparent .PNG/.GIFs in the overlay div and have clicks flow through to elements underneath.
CSS:
pointer-events: none;
background: url('your_transparent.png');
IE11 conditional:
filter:progid:DXImageTransform.Microsoft.AlphaImageLoader(src='your_transparent.png', sizingMethod='scale');
background: none !important;
Here is a basic example page with all the code.
Yes, you CAN force overlapping layers to pass through (ignore) click events.
PLUS you CAN have specific children excluded from this behavior...
You can do this, using pointer-events
pointer-events influences the reaction to click-, tap-, scroll- und hover events.
In a layer that should ignore / pass-through mentioned events you set
pointer-events: none;
Children of that unresponsive layer that need to react mouse / tap events again need:
pointer-events: auto;
That second part is very helpful if you work with multiple overlapping div layers (probably some parents being transparent), where you need to be able to click on child elements and only that child elements.
Example usage:
.parent {
pointer-events:none;
}
.child {
pointer-events:auto;
}
<div class="parent">
I'm unresponsive
I'm clickable again, wohoo !
</div>
Allowing the user to click through a div to the underlying element depends on the browser. All modern browsers, including Firefox, Chrome, Safari, and Opera, understand pointer-events:none.
For IE, it depends on the background. If the background is transparent, clickthrough works without you needing to do anything. On the other hand, for something like background:white; opacity:0; filter:Alpha(opacity=0);, IE needs manual event forwarding.
See a JSFiddle test and CanIUse pointer events.
I'm adding this answer because I didn’t see it here in full. I was able to do this using elementFromPoint. So basically:
attach a click to the div you want to be clicked through
hide it
determine what element the pointer is on
fire the click on the element there.
var range-selector= $("")
.css("position", "absolute").addClass("range-selector")
.appendTo("")
.click(function(e) {
_range-selector.hide();
$(document.elementFromPoint(e.clientX,e.clientY)).trigger("click");
});
In my case the overlaying div is absolutely positioned—I am not sure if this makes a difference. This works on IE8/9, Safari Chrome and Firefox at least.
Hide overlaying the element
Determine cursor coordinates
Get element on those coordinates
Trigger click on element
Show overlaying element again
$('#elementontop').click(e => {
$('#elementontop').hide();
$(document.elementFromPoint(e.clientX, e.clientY)).trigger("click");
$('#elementontop').show();
});
I needed to do this and decided to take this route:
$('.overlay').click(function(e){
var left = $(window).scrollLeft();
var top = $(window).scrollTop();
//hide the overlay for now so the document can find the underlying elements
$(this).css('display','none');
//use the current scroll position to deduct from the click position
$(document.elementFromPoint(e.pageX-left, e.pageY-top)).click();
//show the overlay again
$(this).css('display','block');
});
I currently work with canvas speech balloons. But because the balloon with the pointer is wrapped in a div, some links under it aren't click able anymore. I cant use extjs in this case.
See basic example for my speech balloon tutorial requires HTML5
So I decided to collect all link coordinates from inside the balloons in an array.
var clickarray=[];
function getcoo(thatdiv){
thatdiv.find(".link").each(function(){
var offset=$(this).offset();
clickarray.unshift([(offset.left),
(offset.top),
(offset.left+$(this).width()),
(offset.top+$(this).height()),
($(this).attr('name')),
1]);
});
}
I call this function on each (new) balloon. It grabs the coordinates of the left/top and right/down corners of a link.class - additionally the name attribute for what to do if someone clicks in that coordinates and I loved to set a 1 which means that it wasn't clicked jet. And unshift this array to the clickarray. You could use push too.
To work with that array:
$("body").click(function(event){
event.preventDefault();//if it is a a-tag
var x=event.pageX;
var y=event.pageY;
var job="";
for(var i in clickarray){
if(x>=clickarray[i][0] && x<=clickarray[i][2] && y>=clickarray[i][1] && y<=clickarray[i][3] && clickarray[i][5]==1){
job=clickarray[i][4];
clickarray[i][5]=0;//set to allready clicked
break;
}
}
if(job.length>0){
// --do some thing with the job --
}
});
This function proofs the coordinates of a body click event or whether it was already clicked and returns the name attribute. I think it is not necessary to go deeper, but you see it is not that complicate.
Hope in was enlish...
Another idea to try (situationally) would be to:
Put the content you want in a div;
Put the non-clicking overlay over the entire page with a z-index higher,
make another cropped copy of the original div
overlay and abs position the copy div in the same place as the original content you want to be clickable with an even higher z-index?
Any thoughts?
I think the event.stopPropagation(); should be mentioned here as well. Add this to the Click function of your button.
Prevents the event from bubbling up the DOM tree, preventing any parent handlers from being notified of the event.
Just wrap a tag around all the HTML extract, for example
<a href="/categories/1">
<img alt="test1" class="img-responsive" src="/assets/photo.jpg" />
<div class="caption bg-orange">
<h2>
test1
</h2>
</div>
</a>
in my example my caption class has hover effects, that with pointer-events:none; you just will lose
wrapping the content will keep your hover effects and you can click in all the picture, div included, regards!
An easier way would be to inline the transparent background image using Data URIs as follows:
.click-through {
pointer-events: none;
background: url(data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7);
}
I think that you can consider changing your markup. If I am not wrong, you'd like to put an invisible layer above the document and your invisible markup may be preceding your document image (is this correct?).
Instead, I propose that you put the invisible right after the document image but changing the position to absolute.
Notice that you need a parent element to have position: relative and then you will be able to use this idea. Otherwise your absolute layer will be placed just in the top left corner.
An absolute position element is positioned relative to the first parent
element that has a position other than static.
If no such element is found, the containing block is html
Hope this helps. See here for more information about CSS positioning.
You can place an AP overlay like...
#overlay {
position: absolute;
top: -79px;
left: -60px;
height: 80px;
width: 380px;
z-index: 2;
background: url(fake.gif);
}
<div id="overlay"></div>
just put it over where you dont want ie cliked. Works in all.
This is not a precise answer for the question but may help in finding a workaround for it.
I had an image I was hiding on page load and displaying when waiting on an AJAX call then hiding again however...
I found the only way to display my image when loading the page then make it disappear and be able to click things where the image was located before hiding it was to put the image into a DIV, make the size of the DIV 10x10 pixels or small enough to prevent it causing an issue then hiding the containing div. This allowed the image to overflow the div while visible and when the div was hidden, only the divs area was affected by inability to click objects beneath and not the whole size of the image the DIV contained and was displaying.
I tried all the methods to hide the image including CSS display=none/block, opacity=0, hiding the image with hidden=true. All of them resulted in my image being hidden but the area where it was displayed to act like there was a cover over the stuff underneath so clicks and so on wouldn't act on the underlying objects. Once the image was inside a tiny DIV and I hid the tiny DIV, the entire area occupied by the image was clear and only the tiny area under the DIV I hid was affected but as I made it small enough (10x10 pixels), the issue was fixed (sort of).
I found this to be a dirty workaround for what should be a simple issue but I was not able to find any way to hide the object in its native format without a container. My object was in the form of etc. If anyone has a better way, please let me know.
I couldn't always use pointer-events: none in my scenario, because I wanted both the overlay and the underlying element(s) to be clickable / selectable.
The DOM structure looked like this:
<div id="outerElement">
<div id="canvas-wrapper">
<canvas id="overlay"></canvas>
</div>
<!-- Omitted: element(s) behind canvas that should still be selectable -->
</div>
(The outerElement, canvas-wrapper and canvas elements have the same size.)
To make the elements behind the canvas act normally (e.g. selectable, editable), I used the following code:
canvasWrapper.style.pointerEvents = 'none';
outerElement.addEventListener('mousedown', event => {
const clickedOnElementInCanvas = yourCheck // TODO: check if the event *would* click a canvas element.
if (!clickedOnElementInCanvas) {
// if necessary, add logic to deselect your canvas elements ...
wrapper.style.pointerEvents = 'none';
return true;
}
// Check if we emitted the event ourselves (avoid endless loop)
if (event.isTrusted) {
// Manually forward element to the canvas
const mouseEvent = new MouseEvent(event.type, event);
canvas.dispatchEvent(mouseEvent);
mouseEvent.stopPropagation();
}
return true;
});
Some canvas objects also came with input fields, so I had to allow keyboard events, too.
To do this, I had to update the pointerEvents property based on whether a canvas input field was currently focused or not:
onCanvasModified(canvas, () => {
const inputFieldInCanvasActive = // TODO: Check if an input field of the canvas is active.
wrapper.style.pointerEvents = inputFieldInCanvasActive ? 'auto' : 'none';
});
it doesn't work that way. the work around is to manually check the coordinates of the mouse click against the area occupied by each element.
area occupied by an element can found found by 1. getting the location of the element with respect to the top left of the page, and 2. the width and the height. a library like jQuery makes this pretty simple, although it can be done in plain js. adding an event handler for mousemove on the document object will provide continuous updates of the mouse position from the top and left of the page. deciding if the mouse is over any given object consists of checking if the mouse position is between the left, right, top and bottom edges of an element.
Nope, you can't click ‘through’ an element. You can get the co-ordinates of the click and try to work out what element was underneath the clicked element, but this is really tedious for browsers that don't have document.elementFromPoint. Then you still have to emulate the default action of clicking, which isn't necessarily trivial depending on what elements you have under there.
Since you've got a fully-transparent window area, you'll probably be better off implementing it as separate border elements around the outside, leaving the centre area free of obstruction so you can really just click straight through.

How to keep div focus when the mouse enters a child node

So I have this page here:
http://www.eminentmedia.com/development/powercity/
As you can see when you mouse over the images the div slides up and down to show more information. Unfortunately I have 2 problems that i can't figure out and I've searched but haven't found quite the right answer through google and was hoping someone could point me in the direction of a tutorial.
The first problem is that when you mouse over an image it changes to color (loads a new image), but there's a short delay when the image is loading for the first time so the user sees white. Do I have to preload the images or something in order to fix that?
My second problem is that when you move your mouse over the 'additional content area' it goes crazy and starts going up and down a bunch of times. I just don't have any idea what would cause this but i hope one of you will!
All my code is directly in the source of that page if you would like to view the source.
Thanks in advance for your help!
Yes, you have to preload the images. Thankfully, this is simple:
var images_to_preload = ['myimage.jpg', 'myimage2.jpg', ...];
$.each(images_to_preload, function(i) {
$('<img/>').attr({src: images_to_preload[i]});
});
The other thing you have to understand is that when you use jQuery you have to truly embrace it or you will end up doing things the wrong way. For example, as soon as you find yourself repeating the same piece of code in different places, you are probably doing something wrong. Right now you have this all over the place:
<div id="service" onmouseover="javascript:mouseEnter(this.id);" onmouseout="javascript:mouseLeave(this.id);">
Get that out of your head. Now. Forever. Always. Inline javascript events are not proper, especially when you have a library like jQuery at your disposal. The proper way to do what you want is this:
$(function() {
$('div.box').hover(function() {
$(this).addClass('active');
$(this).find('div.slideup').slideDown('slow');
}, function() {
$(this).removeClass('active');
$(this).find('div.slideup').slideUp('slow');
});
});
(You have to give all the #industrial, #sustainable, etc elements a class of 'box' for the above to work)
These changes will also fix your sliding problem.
I can see your images (the ones that are changing) are set in the background of a div. Here is a jquery script that preloads every image found in a css file. I have had the same problem in the past and this script solves it. It is also very easy to use:
http://www.filamentgroup.com/lab/update_automatically_preload_images_from_css_with_jquery/
I will take a look at your other problem...
1) You should be using the jquery events to drive your mouseovers. Give each div a class to indicate that its a category container and use the hover function to produce the mouseover/mouseout action you're after.
html
<div id="industrial" class="category"></div>
Javascript
$(".category").hover(
function () {
$(this).find('.container').show();
},
function () {
$(this).find('.container').hide();
}
);
I simplified the code to just do show and hide, you'll need to use your additional code to slide up and slide down.
2) Yes, you need to preload your images. Another option would be "sprite" the images. This would involve combining both the black and white and colour versions of each image into a single image. You then set it as the div's background image and simply use CSS to adjust the background-position offset. Essentially, sliding instantly from the black and white to colour images as you rollover. This technique guarentees that both images are fully loaded.

Trigger an event on a specific part of an image

I want to trigger an event handler when the user hovers on a particular part of the image, like the center of the image or the right side of the image (area would include, say, about a 100 pixels). I am not using any framework, so this is normal javascript that I am working with.
I am not sure if using image maps would work. Can anyone help?
Quirksmode about mouse position
Given the craziness involved here I would:
Use a framework (I just did something like this with Mootools)
Put absolutely positioned divs over the image and listen to events on them, instead of the image (did this too recently, a left 50% and a right 50%, way less cumbersome than tracking the mouse position).
Or go for it, quirksmode gives a decent function to get the mouse position, then you'll need to calculate the position of the image, then do the math to get the position of the mouse on the image, do the math in a mouseover event of the image, then continually check if the position meets your criteria, then do something about it when it does :)
You can use the MouseMove event to find out the location of the cursor, and then implement your own logic to calculate this position relative to the image.
See this page on getting the mouse coordinates.
i do not know how many areas you need and if they need to be especially shaped or something like that....
a straightforward solution would be placing (CSS) empty div elements "over" the image which will trigger the events
afaik it is not possible to trigger js events with an image map
An image map coupled with jquery is a great solution I've used before. I see that you're not using a framework, but it's worth a look.
Here's a little code snippet I used with an image map and mouseenter / mouseleave events.
$(".map-areas area")
.mouseenter(function() {
idx = $(".map-areas area").index(this);
showMapArea(idx);
})
.mouseleave(function() {
$(".map-hovers img").hide();
$(".map-titles img").hide();
});
I suggest putting an invisible div in the place where you want to check for mouse_over in the image. (In the case that the area you want is rectangular of course). And then trigger on mouse_over for this div.
If you want to check for non rectangular areas (that can't be a div), I would suggest that you put a div of the same size of the image on top of it. Check mouse position on that div, and use it to compare with a mask image.
Example:
MousePosOnGhostDiv_X = 76;
MousePosOnGhostDiv_Y = 145;
if(CheckColorOfMaskImage(MousePosOnGhostDiv_X,MousePosOnGhostDiv_Y)=="orange") do something.
By knowing which color it is on the mask image you can set multiple events.

Ignore mouse interaction on overlay image

I have a menu bar with hover effects, and now I want to place a transparent image with a circle and a "handdrawn" text over one of the menu items. If I use absolute positioning to place the overlay image above the menu item, the user will not be able to click the button and the hover effect will not work.
Is there any way to somehow disable mouse interaction with this overlay image so that the menu will keep on working just as before even though it's beneath an image?
Edit:
Because the menu was generated with Joomla I could not tweak just one of the menu items. And even if I could, I did not feel a Javascript solution was appropriate. So in the end I "marked" the menu item with an arrow outside the menu-item element. Not as nice as I had wanted it to be, but it worked out okey anyway.
The best solution I've found is with CSS Styling:
#reflection_overlay {
background-image:url(../img/reflection.png);
background-repeat:no-repeat;
width: 195px;
pointer-events:none;
}
pointer-events attribute works pretty good and is simple.
So I did this and it works in Firefox 3.5 on Windows XP. It shows a box with some text, an image overlay, and a transparent div above that intercepts all clicks.
<div id="menuOption" style="border:1px solid black;position:relative;width:100px;height:40px;">
sometext goes here.
<!-- Place image inside of you menu bar link -->
<img id="imgOverlay" src="w3.png" style="z-index:4;position:absolute;top:0px;left:0px;width:100px;height:40px;" \>
<!-- Your link here -->
<a href="javascript:alert('Hello!')" >
<div id="mylinkAction" style="z-index:5;position:absolute;top:0px;left:0px;width:100px;height:40px;">
</div>
</a>
</div>
What I've done:
I've crafted a div and sized it to be what a menu option could be sized to, 100x40px (an arbitrary value, but it helps with illustrating the sample).
The div has an image overlay, and a link overlay. The link contains a div sized to be the same as the 'menuOption' div. This way a user click is captured across the whole box.
You will need to provide your own image when testing. :)
Caveat:
If you expect your menu button to respond to the user interaction (for example, changing color to simulate a button), then you will need extra code attached to the javascript you will invoke on the tag, this extra code could address the 'menuOption' element through the DOM and change it's color.
Also, there is no other way I know of that you can take a click event, and have it register on an element underneath a visible page element. I've tried this as well this summer, and found no other solution but this.
Hope this helps.
PS:
The writeup on events at quirksmode went a long way to help me understand how events behave in browsers.
Give the button a higher z-index property than the hand-drawn image:
<img src="hand_drawn_image.gif" style="z-index: 4">
however, make sure you test it in all major browsers. IE interprets z-index differently from FF.
For somebody to come up with more details, you would have to post more info, a link would be best.
Building on what Pekka Gaiser said, I think the following will work. Taking his example and reworking it:
<a href="#" style="z-index: 5">
<!-- Place image inside of you menu bar link -->
<img src="hand_drawn_image.gif" style="z-index: 4">
<!-- Your link here -->
</a>
Here you should be able to place an event on the underlying a-tag and, unless your image has an event, initiates a capture (!IE browsers) and then kills propagation of the event.
If you need a bit more help, let us know a bit more about the situation.
If the image will be statically positioned, you can capture the click event from the image as it bubbles up, by placing the img tag inside the menu item element.
<div onclick="menuclick()">
<img src="overlay.png" style="position:absolute;" />
</div>

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