Develop Reference

How to get the lower co-ordinate of images in html

I have a image and it is inside a div. I want to know what would be the lower co-ordinates for the image. Like if it a rectangle with corners A,B,C and D with A as the bottom left corner I want to get the co-ordinates of that. Could you let me know how I could achieve that using JavaScript or jQuery.

You can do this with JQuery position() and return left and top
var pos = $('img').position();
$('.result').append('(x: ' + pos.left + ', y: ' + pos.top + ')');
div {
width: 200px;
height: 200px;
position: relative;
border: 1px solid black;
}
img {
position: absolute;
left: 40px;
top: 100px;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div>
<img src="http://placehold.it/50x50">
</div>
<span class="result"></span>

The best solution would be to use getBoundingClientRect()
var image = $( "img" );
var imageBounds = image.get(0).getBoundingClientRect();
var imageLeft = imageBounds.left;
var imageBottom = imageBounds.bottom;
Fiddle
But you could also use jQuery's .position() to get the top and left coordinates then to calculate the bottom and right position just add .height() or .width()
var image = $( "img" );
var imagePosition = image.position();
var imageHeight = image.height();
var imageLeft = imagePosition.left;
var imageBottom = imagePosition.top + imageHeight;
Fiddle
or without using jQuery:
var image = document.getElementById("image");
var imageBounds = image.getBoundingClientRect();
var imageLeft = imageBounds.left;
var imageBottom = imageBounds.bottom;
Fiddle

You can use .position() to get left and top coordinates(top left corner).
to get the bottom left corner just add image height to top coordinate.
$(window).load(function(){ //to make sure all images are loaded
console.log($('img').position().left);
console.log($('img').position().top + $('img').height());
});
div { padding: 30px;}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div><img src="http://placehold.it/350x150"></div>

Here is the demo on codepen: http://codepen.io/ssh33/pen/AXdVER
Waits for the image to download to get the width and height and calls GetCoordinates().
If the image has been previously cached $("#image").load() will never fire. In this case $(window).load() will call GetCoordinates() instead. GetCoordinates() checks for non-numeric width/height and retrieves it if necessary.
Recalculates on window resize.
var img_width, img_height, x, y;
$("#image").load(function() {
img_width = this.width;
img_height = this.height;
});
var GetCoordinates = function(){
if (isNaN(img_width) || isNaN(img_height)){
img_width = $("#image").width();
img_height = $("#image").height();
}
var img_left = $("#image").offset().left;
x = img_width + img_left;
var img_top = $("#image").offset().top;
y = img_height + img_top;
}
$(window).load(function() {
GetCoordinates();
});
$(window).resize(function() {
GetCoordinates();
});

Finding Image Height variable for multiple images in Jquery

I'm currently working on this script for "tooltips" on a website. I'm finding that the code I currently have will get the image height for my first tooltip image on the page ('pop1') but it ignores the rest (they come out as null).
What's the most effective way to get all the tooltip image heights, and use them every time the user scrolls over the tooltip image?
Another issue, if anyone is able to figure this one out - is that on my FULL webpage (many more divs, rows, columns, etc.) the script begins to break because clientX and clientY are being affected by the various divs and page elements.
I'd like to be able to set clientX and clientY to the exact (x, y) coordinates that the user's mouse is at, relative to the entire webpage, not relative to the page's child elements.
Thanks
Here's my JSFiddle: http://jsfiddle.net/tgs7px4f/18/
JS Code:
$('a.popper').hover(function (e) {
var target = '#' + ($(this).attr('data-popbox'));
$(target).show();
}, function () {
var target = '#' + ($(this).attr('data-popbox'));
if (!($("a.popper").hasClass("show"))) {
$(target).hide();
}
});
$('a.popper').mousemove(function (e) {
var target = '#' + ($(this).attr('data-popbox'));
// images vary in height!
// images are all 366px wide.
var imageWidth = 366;
var imageHeight = $(".popimg").height();
//alert('Image Height: ' + imageHeight);
//Offset tooltip:
//10px to the right of cursor
var imageX = e.clientX + 20;
//imageHeight up from cursor
var imageY = e.clientY - imageHeight - 20;
// Find bounds of current window, and if...
// Tooltip goes off right side:
if ((imageX + imageWidth) > $(window).width()) {
//Move tooltip left so it meets edge:
imageX = $(window).width() - imageWidth;
}
// Tooltip goes off top
if (imageY < 0) {
//Move tooltip down so it meets top:
imageY = 0;
}
$(target).css('top', imageY).css('left', imageX);
});

What's the most effective way to get all the tooltip image heights, and use them every time the user scrolls over the tooltip image?
First of all, I suppose you mean whenever a user does a mouseover on one of the elements? However, this seems to work and it cashes the height of the image directly on the element and uses it the next time a mouseover occurs:
$('a.popper').mousemove(function (e) {
var target = '#' + ($(this).attr('data-popbox'));
// images vary in height!
// images are all 366px wide.
var imageWidth = 366;
$target = $(target);
if (!$target.attr("height")) {
var img = $target.closest(".popbox").children("img");
var imageHeight = img.height();
$target.attr("height", imageHeight);
console.log("height attribute set");
} else {
var imageHeight = +($target.attr("height")) + 0;
console.log("cached height used");
}
console.log('Image Height: ', imageHeight);
//Offset tooltip:
//10px to the right of cursor
var imageX = e.clientX + 20;
//imageHeight up from cursor
var imageY = e.clientY - imageHeight - 20;
// Find bounds of current window, and if...
// Tooltip goes off right side:
if ((imageX + imageWidth) > $(window).width()) {
//Move tooltip left so it meets edge:
imageX = $(window).width() - imageWidth;
}
// Tooltip goes off top
if (imageY < 0) {
//Move tooltip down so it meets top:
imageY = 0;
}
$(target).css('top', imageY).css('left', imageX);
});
Obviously, you should remove all the console.log statements which are for testing purposes only.
jsFiddle
Regarding your second question, it's hard to say anything concrete without another jsFiddle or additional code.

Fabricjs canvas reset after zooming

I have a fabricjs canvas that I need to be able to zoom in and out and also change the image/object inside several times.
For this I setup the canvas in the first time the page loads like this:
fabric.Object.prototype.hasBorders = false;
fabric.Object.prototype.hasControls = false;
canvas = new fabric.Canvas('my_canvas', {renderOnAddRemove: false, stateful: false});
canvas.defaultCursor = "pointer";
canvas.backgroundImageStretch = false;
canvas.selection = false;
canvas.clear();
var image = document.getElementById('my_image');
if (image != null) {
imageSrc = image.src;
if(imageSrc.length > 0){
fabric.Image.fromURL(imageSrc, function(img) {
img = scaleImage(canvas, img); //shrinks the image to fit the canvas
img.selectable = false;
canvas.centerObject(img);
canvas.setActiveObject(img);
canvas.add(img);
});
}
}
canvas.deactivateAll().renderAll();
Then when I need to change the image/object in the canvas or when the page reloads, I try to reset the canvas like this:
canvas.clear();
canvas.remove(canvas.getActiveObject());
var image = document.getElementById('my_image');
if (image != null) {
imageSrc = image.src;
if(imageSrc.length > 0){
fabric.Image.fromURL(imageSrc, function(img) {
img = scaleImage(canvas, img); //shrinks the image to fit the canvas
img.selectable = false;
canvas.centerObject(img);
canvas.setActiveObject(img);
canvas.add(img);
});
}
}
Not sure if it matters but the way I change the image is by changing the source in 'my_image' and reseting the canvas with the above method.
This works well until I use canvas.zoomToPoint, as per this thread, after this, the image/object starts changing position when I reset the zoom or click the canvas with the mouse while it is zoomed, seeming to jump at each change in the top left corner direction, eventually disappearing from view.
Reset Zoom:
canvas.setZoom(1);
resetCanvas(); //(above method)
How can I restore the image/object position?
I tried doing the initial setup instead of the reset and seamed to work visually but was in fact adding a new layer of upper canvas at each new setup so it is no good.
Is there a way to reset the canvas to original state without causing this behavior and still be able to zoom in/out correctly?

Although this question is very old, here is what I did using the current version of fabric.js 2.2.4:
canvas.setViewportTransform([1,0,0,1,0,0]);
For your information: zooming to a point is a recalculation of the viewport transformation. The upper matrix is this is the initial viewport transform matrix.

I eventually fixed the problems I was having.
To reset the zoom, instead of just setting the zoom to 1 with canvas.setZoom(1), I reapplied the canvas.zoomToPoint method to the same point but with zoom 1, to force the initial zoom but regarding the same point that was used to zoom in.
As for the problem of restoring the image position in canvas (after panning for instance) it is as simple as removing the image, centering it in the canvas and re-adding it to the canvas as was done when adding first time:
var img = canvas.getActiveObject();
canvas.remove(img);
canvas.centerObject(img);
canvas.setActiveObject(img);
canvas.add(img);
canvas.renderAll();

See below snippet - here I do the same - zooming together, but degrouping the objects in case somebody clicks on it.
The problem to get to original object properties can be solved, ungrouping the group and creating copies of them and reattaching - a bit annoying, but the only solution I found.
<script id="main">
// canvas and office background
var mainGroup;
var canvas = this.__canvas = new fabric.Canvas('c');
fabric.Object.prototype.transparentCorners = false;
fabric.Object.prototype.originX = fabric.Object.prototype.originY = 'center';
createOnjects(canvas);
// events - zoom
$(canvas.wrapperEl).on('mousewheel', function(e) {
var target = canvas.findTarget(e);
var delta = e.originalEvent.wheelDelta / 5000;
if (target) {
target.scaleX += delta;
target.scaleY += delta;
// constrain
if (target.scaleX < 0.1) {
target.scaleX = 0.1;
target.scaleY = 0.1;
}
// constrain
if (target.scaleX > 10) {
target.scaleX = 10;
target.scaleY = 10;
}
target.setCoords();
canvas.renderAll();
return false;
}
});
// mouse down
canvas.on('mouse:up', function(options) {
if (options.target) {
var thisTarget = options.target;
var mousePos = canvas.getPointer(options.e);
if (thisTarget.isType('group')) {
// unGroup
console.log(mousePos);
var clone = thisTarget._objects.slice(0);
thisTarget._restoreObjectsState();
for (var i = 0; i < thisTarget._objects.length; i++) {
var o = thisTarget._objects[i];
if (o._element.alt == "officeFloor")
continue;
else {
if (mousePos.x >= o.originalLeft - o.currentWidth / 2 && mousePos.x <= o.originalLeft + o.currentWidth / 2
&& mousePos.y >= o.originalTop - o.currentHeight / 2 && mousePos.y <= o.originalTop + o.currentHeight / 2)
console.log(o._element.alt);
}
}
// remove all objects and re-render
canvas.remove(thisTarget);
canvas.clear().renderAll();
var group = new fabric.Group();
for (var i = 0; i < clone.length; i++) {
group.addWithUpdate(clone[i]);
}
canvas.add(group);
canvas.renderAll();
}
}
});
// functions
function createOnjects(canvas) {
// ToDo: jQuery.parseJSON() for config file (or web service)
fabric.Image.fromURL('pics/OfficeFloor.jpg', function(img) {
var back = img.set({ left: 100, top: 100 });
back._element.alt = "officeFloor";
back.hasControls = false;
fabric.Image.fromURL('pics/me.png', function(img) {
var me = img.set({ left: -420, top: 275 });
me._element.alt = "me";
console.log(me);
var group = new fabric.Group([ back, me], { left: 700, top: 400, hasControls: false });
canvas.clear().renderAll();
canvas.add(group);
// remove all objects and re-render
});
});
}
</script>

Auto scrolling to element in scrollable div

I have 5 elements that are within a div larger than the screen (on a mobile phone).
I want the user to be able to click on one of the elements and have that element scroll to the centre of the screen.
I've tried writing this with jQuery myself, but I can't seem to get the logic quite right. I've got it kind of moving but the element selected doesn't go to the centre of the screen.
Here's a Fiddle of what I have do far: http://jsfiddle.net/geQ64/1/
Here's the JS from the fiddle also:
$(window).on('load', function() {
$('.tab-3').trigger('click');
var width = $(window).width();
if (width < 651) {
$('.ul-wrap').scrollLeft( $('.tab-3').offset().left );
}
});
$('.single-tabs').on('click', function() {
var offset = $('.tabs').width();
offset = offset/5;
var center = offset/2;
var tab = $(this).data('tab');
$('.tabs-content').hide();
$('.tab'+ tab +'').show();
var width = $(window).width();
if (width > 650) {
var arrow = tab*20-12;
$('.arrow-up').css('margin-left', '' + arrow + '%');
} else {
tab = tab - 1;
var position = offset * tab - center;
$('.ul-wrap').scrollLeft(position);
}
});

Found a fix, here's the JS is anyone needs it.
The - 55 in the var position is for an arrow that sits in the centre of the page below the elements I'm moving with this script.
$(window).on('load', function() {
$('.tab-3').trigger('click');
var width = $(window).width();
if (width < 651) {
var offset = $('.tabs').width();
offset = offset/7;
var center = offset/2;
var position = offset * 2 + center - 50;
$('.ul-wrap').animate({
scrollLeft: position
}, 200);
}
});
$('.single-tabs').on('click', function() {
var offset = $('.tabs').width();
offset = offset/7;
var center = offset/2;
var tab = $(this).data('tab');
$('.tabs-content').hide();
$('.tab'+ tab +'').show();
var width = $(window).width();
if (width > 650) {
var arrow = tab*20-12;
$('.arrow-up').css('margin-left', '' + arrow + '%');
} else {
tab = tab - 1;
var position = offset * tab + center - 50;
$('.ul-wrap').animate({
scrollLeft: position
}, 200);
}

Reverse script function from Y-axis to X-axis

I saw this on another website, when you scroll down the page(vertically) it triggers an animation, where a circle rotates in place. How can I reverse this so the animation triggers when I scroll horizontally
$(document).ready(function() {
$(window).scroll(function(e) {
var top = $(document).scrollTop();
var wHeight = Math.max(640,$(window).height());
if (top < wHeight) {
//$('.bg').css('top',70+top/2);
$('.bg .maze').css({
'-webkit-transform':'rotate('+top+'deg)',
'-moz-transform':'rotate('+top+'deg)',
'-o-transform':'rotate('+top+'deg)',
'-ms-transform':'rotate('+top+'deg)',
'transform':'rotate('+top+'deg)'
});
}
});
});

You have to use jQuery::scrollLeft() instead of jQuery::scrollTop(), and compare it to the window width:
var left = $(document).scrollLeft();
var wWidth = Math.max(640,$(window).width());
if (left < wWidth) { /* ... */ }