I have some tabs for my website where the background-image changes when you click on them.
However when I hover over the tabs the first time after the DOM has loaded, there's a slight delay before the hover-image show, resulting in a jarring effect.
I don't know how to troubleshoot this, any ideas? :)
Live example here: http://jsfiddle.net/timkl/fjupq/ - the delay is not as long on JSFiddle's server - but it's still there.
The solution to this is to use sprites instead of separate images.
http://css-tricks.com/css-sprites/
You use a single image, and instead of changing the background source on :hover, you simply change the background position. This way, the entire image is loaded in advance.
For example, check out Stack Overflow's sprite sheet:
http://cdn.sstatic.net/stackoverflow/img/sprites.png?v=4
You don't have to take it to this extreme, you can just have one image that has both the normal and :hover states, and move it to the left/right or up/down.
A simple solution is to use javascript to pre-load the image. Include this in the HEAD of the page:
<script type="text/javascript">
var img = new Image();
img.src = "http://dummyimage.com/200x10/000000/fff"; // background image
</script>
Another way to do this is to have that image somewhere else displayed, preferably at the end of the page, as a 1px to 1px image, and have it placed outside the page layout. This will preload the image.
Related
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.
If i set a GIF image as Hover effect on an anchor, it will still remain animating even if not showed (not set as a background) so this causes that the animation starts in the middle of itself for example but this kills the nice effects its used for..
any suggestions?
thanks in advance
You can't control animation of gif images in html.
but work around of this can be is you replace the gif image with the static image on mouseover or with other event using jquery or javascript. Only by CSS it is not possible.
Example:
$("#imageGif").hover(
function() {
$(this).attr("src", "/image.gif");
},
function() {
$(this).attr("src", "/image.png");
});
I'm doing some documentation where I make heavy use of anchors for linking between pages on a wiki.
see here:
http://code.google.com/p/xcmetadataservicestoolkit/wiki/ServicesExplained#Platform_Data_Structures
The feature that really makes this work well is when the browser shows the anchor at the absolute top of the pane. When it gets confusing is when linking to an anchor shows the anchor half-way down the page since the page is scrolled down all the way
see here:
http://code.google.com/p/xcmetadataservicestoolkit/source/browse/trunk/mst-common/src/java/xc/mst/utils/Util.java#227
My solution in the wiki (first link) was to put a blank image at the bottom of the page simply to make the browser show the anchor right at the top. Is there a better way to do this? Is there a way to do it in the second link (in which I can't add a blank image)?
Putting a blank image at the bottom of your page is a bad idea, since it will expand your document to a unnecessary height.
You could throw in some javascript to apply an effect to the anchor you just travelled to, to highlight it wherever it is.
Without altering the height of your document (i.e. adding extra padding at bottom), you'll always have this issue.
However, using bit of JS/jQuery, the user experience can be improved considerably:
On clicking a named anchor:
Instead of jumping in a flash (broswer's default behavior), add a smooth scroll
add an highlight to indicate current selection (this helps tremendously in 2nd case as the user can clearly see what is current)
Created a demo to illustrate the concepts: http://jsfiddle.net/mrchief/PYsyN/9/
CSS
<style>
.current { font-weight: bold; }
</style>
JS
function smoothScroll(elemId) {
// remove existing highlights
$('.current').css({backgroundColor: "transparent"}).removeClass('current');
var top = $(elemId).offset().top;
// do a smooth scroll
$('html, body').animate({scrollTop:top}, 500, function(){
// add an highlight
$(elemId).animate({backgroundColor: "#68BFEF" }, 500, function () {
// keep tab of current so that style can be reset later
$(elemId).addClass('current');
});
});
}
// when landing directly
if (document.location.hash) {
smoothScroll(document.location.hash);
}
$('a[href*="#"]').click(function() {
// utilizing the fact that named anchor has a corresponding id element
var elemId = $(this).attr('href');
smoothScroll(elemId);
});
You can create a absolutre positioned pseudo-element with a great height to targeted block using just the following CSS (for the second link in your post:
#nums td:target a::before {
content: '';
position: absolute;
height: 700px;
}
The height must be around the height of the viewport, so the best solution is to create these styles on the fly using js. But if you don't wan't to use js, just use height: 1000px or more — if you don't mind a gap at the bottom of course.
The best part: it's only CSS and there would be no gap when no anchors are targeted.
Edit: just a sneak peek into the future: if the vw/vh units would come to other browsers (now it's only in IE9), this could be awesomely done with just CSS using height: 100vh :)
You could use Javascript / jQuery to create a white div that has the necessary height needed to put your element at the top of the browser window, and you could even remove this upon scrolling away.
However I would highly recommend against doing so as this will expand your page where it isn't needed. It's a lot smarter to simply style the tag upon going there (through Javascript / jQuery) so it pops out to the viewer, for instance by setting the font-weight to bold or changing the background-color.
I would probably use a combination of jQuery and PHP for this:
PHP(somewhere right after your <body> element):
<?php
$anchor = explode('#', $_SERVER['REQUEST_URI']);
$anchor = $anchor[1];
echo '<div id="selected-anchor" anchor="'.$anchor.'"></div>';
?>
And then the jQuery:
<script type="text/javascript">
$(function(){
$('#selected-anchor').css('background-color', '[Whatever highlight color you want]');
});
</script>
Hope this helps.
Is it possible to change the value of src attribute of <input type='image' alt="Text will be shown if pics are disabled" src='somepic.png'../> by css?
The problem is:
I want to specify which pic will be shown as submit button just using css (so the design team will change only css files!).
If I use the alternative way like <input type="submit" class="cssclass" value=" " alt="Text will be shown if pics are disabled"/> and specify the background of this element in css - it doesn't work well if pics are disabled. - No any alternative text is shown instead of pic. However the first way solves this situation...
Please advice something
Thanks.
Here it is: http://jsfiddle.net/kizu/66JXn/
Some notes about this solution:
Use <button></button>, 'cause it can include other blocks.
You'll need a bit of extra code to make all these work in Fx and IE:
For Fx you need an extra wrapper inside (there are positioning bug) and some extra -moz- properties reset.
For IE you must shrink the original button, 'cause there are some extra padding that is hard to remove.
You place the text and another element inside, that would overlay the text. So when the images would absent, the text would be accessible.
That's it :)
No, and this is bad practice. CSS is for static content only.
What you should do, is define a template file with variables in it such as:
template.js
my_backgroundImage = "url('somepic.png')";
then your file would load
x = document.createElement('image');
x.src = my_backgroundImage
Attribute selectors might work, but they aren't very flexible. Try this one:
img[src=""] {
background-image: url('none.png');
height: 100px; /* Height of BG image */
width: 100px; /* Width of BG image */
}
It doesn't change the image's src= attribute, but it performs the same function.
Here's my idea.
You can use JavaScript to read the stylesheets of <img> tags, and modify them accordingly.
I'm talking about a class whitelist, like big, small, center and all other classes applied to the images are interpreted via JavaScript. The design team could use CSS, but it would not render in the expected manor, like this (Python + JavaScript):
for every <img> tag:
if tag.classes contains class not in whitelist:
for every class not in whitelist:
this.src = newClass.backgroundImage;
this.removeClass(newClass)
It reads the CSS for the background-image property, but it just steals the URL of the image and sets the src= attribute using that URL. Then, the JavaScript would delete that class, causing it not to render.
(This is a problem for which JS is the solution, but ignoring that:)
One option is to wrap the button and an extra div (lets call it div.overlay) in a parent container.
Set the container to to position:relative.
Set the button to only display text, as usual. Set the div.overlay to position:absolute, width and height to 100%, and left and top to 0, and a z-index higher than the button. Set the image you want to display as the background-image of div.overlay.
With images enabled, the user sees the image, and the image can be changed using only CSS.
With images, or CSS disabled, the user only sees the plaintext submit button.
You might have to do some trickery to get clicking div.overlay to submit the form, perhaps just make div.overlay a duplicate submit button. Also, who knows what Googlebot makes of overlay techniques like these.
It's ugly, but the only pure CSS solution that immediately jumps to mind is a kind of image replacement with relatively poor support. That's using :after. It's kind of a poor practice due to the misuse of :after, and the support is pretty iffy, and I think it'd be iffier for an input element, based on the last time I tried to use :after on an input...
.cssclass,
.cssclass:after{
display:block;
width:100px;
height:100px;
}
.cssclass{ position:relative; }
.cssclass:after{
position:absolute;
top:0;left:0;
content:url("button.jpg");
}
See http://www.rachaelmoore.name/best-practices/css-image-replacement-ii/ for more.
Or setting the default src to a shim and always using CSS to set the desired button as a background image. Which I just noticed you've already thought of. I imagine that should work just fine.
Ok... So I hate it when I ask a specific question and, instead of answering it, they give me some crappy work-around instead of answering the original question that I asked... But for some reason, I've decided that I'm going to do it to you.
If I understand the problem correctly, you just want to have a form button with a background image and if the background image doesn't load, you want some sort of alt text displayed to the user with the caption of the button? If that's not right, stop reading and "down arrow" me.
In apps that I've made, I've always just styled the input with a background image, but left it up to the HTML control to insert text... It's good for three reasons... buttons can be styled, developers can change the value of the text on the button without having to bother me to make a new image, and if the background image doesn't load, the button is still readable.
So my html was like this:
<input type="submit" id="btnSearch" class="searchButton" value="Search">
then my class may read something like:
.searchButton {
backgorund-image: url('searchButtonImage.png');
font-family: sans serif;
font-size: 10px;
color: #808080;
padding-left: 50px 0px 0px 0px; // Assuming a magnifying glass icon or whatevs is on the left and is 20-ish pixels
width: 100px; // you can put this as in-line style if you make a more generic class
}
If you want to make the BG more generic, move the width of the button to make it in-line on the button, so the devs can change the width with the text value and make your generic bg image like 200px wide.
Depending on the browser, the text might not be as nice and ani-aliased as in others, but IMO, it's a small price to pay.
(Disclaimer: Please forgive me if you copy and paste this and it doen't work. I just hand-wrote it without testing it.)
Can you do it with javascript?
I have an image on my page that, when clicked, will show another button, and also change the src attribute of the first.
Here is what I use:
<script type="text/javascript">
function apps()
{
var element = document.getElementById("app_frame");
if (element.width != "0%")
{
parent.document.getElementById("frame").setAttribute("width","100%");
parent.document.getElementById("app_frame").setAttribute("width","0%");
parent.document.getElementById("appbutton").setAttribute("src","site/main/images/apps/show.gif");
parent.document.getElementById("wthrbutton").style.visibility="hidden";
}
else
{
parent.document.getElementById("frame").setAttribute("width","65%");
parent.document.getElementById("app_frame").setAttribute("width","35%");
parent.document.getElementById("appbutton").setAttribute("src","site/main/images/apps/hide.gif");
parent.document.getElementById("wthrbutton").style.visibility="visible";
}
}
</script>
What that says, is: set the "app_frame" as variable "element",
then check variable "element" for its width.
if its width is not 0, then it gets the element "frame",
by using getElementById, and then sets the attribute "width" to 100%
you can see slightly lower down that you use the same method, but use the SRC attribute rather than width, and set it to whatever you want, in my case, site/main/images/apps/show.gif
hope that helps
When I have an <a> tag set to a specific image background like this:
HTML:
Click Here
CSS:
a {
background: transparent url(button.png);
}
and I want the background to change whenever a user hovers over the spot, like this:
CSS:
a {
background: transparent url(button_HOVER.png);
}
The hover background image flickers (takes about 1-2 seconds until it fully loads) when a user hovers over the link.
I could save the file as GIF and minify its size and loading time, but that would harm my specific image tremendously (it's big and highly graphical).
That's why I was looking for a better solution, such as perhaps counting on the browsers ability to cache images. Hence would I apply a style to a button like this:
CSS:
a {
background: transparent url(button_HOVER.png);
background: transparent url(button.png);
}
So that the image button_HOVER is first cached. It has seemingly affected the "flickering", but not completely. I thought of maybe creating a hidden tag with the HOVER image, so that maybe the result would be different.
Do you think there's a better way to solve it? (I emphasize I want to keep the file as PNG, it weighs 6-7k). Is my method efficient?
Your solution would be to put both images (hover and active) in the same image file. Positioned on top of each other. Also known as Image Sprites. The browser will load the entire image file. On hover, you just change the background position.
Assuming the active image is at the top, and the hover image is positioned directly below that..your css code would be something like:
a.link {
width:70px;
height:24px;
background: url(image.png) top no-repeat;
}
a.link:hover {
background-position: bottom;
}
Notice background-position. Here I use top and bottom. You can specific exactly in pixels too. The entire image in this example would have a width of 70pixels and height of 48pixels. Some sites put all their small icons into one image. Loads altogether, save on requests too. :)
No need for preload scripts in this case.
The basic options available are to use an html element that's hidden from the viewer, or use javascript.
The html approach is probably the simplest, though:
<div id="preloadedImageContainer">
<img src="img/to/preload_1.png" />
<img src="img/to/preload_2.png" />
</div>
with the css:
#preloadedImageContainer {position: absolute; top: -1000px; left: -1000px; }
or, with javascript:
(function($) {
var cache = [];
// Arguments are image paths relative to the current page.
$.preLoadImages = function() {
var args_len = arguments.length;
for (var i = args_len; i--;) {
var cacheImage = document.createElement('img');
cacheImage.src = arguments[i];
cache.push(cacheImage);
}
}
})(jQuery)
the jQuery approach was lifted in its entirety from this page: http://engineeredweb.com/blog/09/12/preloading-images-jquery-and-javascript.
Though the best approach would probably be, as Lyon suggests, css image sprites.
You should search about this topic "preload images" You will find ways to preload images using css and javascript.
I believe that if you put a hidden image with source equal the src of png images you will use in the css files, this will make the images loaded when the page loads, and CSS work will be just switch preloaded images.