I need to change an image in a div and then immediately centre it on the screen by calculating its height and width and then setting its left and top values. But when I change the img src and then try to get the div's offsetHeight and clientHeight, both the values are wrong. Strangely the offsetWidth and clientWidth values are correct.
Is there a way to refresh the div and get the correct value?
Edit: It appears that changing the image src makes everything after that not work. The change to the onclick event imageObj.onclick = function() {contractImageView(imageId);};
isn't working now either. If I comment out the if statement it all starts working again.
Below is the code...
// Get the page dimensions
var pageBody = document.getElementById(currentBody);
// If you couldn't get the page body, abort.
if (!pageBody) {
return;
}
var pageBodyHeight = window.innerHeight;
var pageBodyWidth = pageBody.offsetWidth;
var imageDiv = document.getElementById(imageId);
var imageObj = imageDiv.children[0];
var paraObj = imageDiv.children[1];
// If you can't get the div or its image, then abort.
if (!imageDiv || !imageObj) {
return;
}
// Check whether the image has been loaded yet, and load if needed
if (imageObj.src.indexOf('lazy_placeholder.gif') !== -1) {
for (item in photoLazyData) {
if (item === imageDiv.parentElement.id) {
imageObj.src = photoLazyData[item][imageDiv.id];
}
}
}
// Change the images class.
imageDiv.className = 'active_design_div';
imageDiv.style.visibility = 'visible';
imageDiv.style.opacity = 1;
// Set the objects new onclick method to collapse the image
imageObj.onclick = function() {contractImageView(imageId);};
// Calculate the right size
imageDiv.style.maxHeight = pageBodyHeight + 'px';
imageDiv.style.maxWidth = pageBodyWidth + 'px';
imageObj.style.maxHeight = pageBodyHeight + 'px';
imageObj.style.maxWidth = pageBodyWidth + 'px';
// Calculate the margins.
var imageDivWidth = imageDiv.offsetWidth || imageDiv.clientWidth;
// ## THIS IS WRONG IF THE ABOVE IF STATEMENT CHANGES THE SRC ##
var imageDivHeight = imageDiv.offsetHeight || imageDiv.clientHeight;
console.log(imageDiv.offsetHeight + ' : ' + imageDiv.clientHeight);
console.log(imageDiv.offsetWidth + ' : ' + imageDiv.clientWidth);
var leftOffset = (pageBodyWidth - imageDivWidth) / 2;
var topOffset = (pageBodyHeight - imageDivHeight) /2;
// Adjust styling to make the div visible and centred.
imageDiv.style.left = String(leftOffset) + 'px';
imageDiv.style.top = String(topOffset) + 'px';
currentId = imageId;
toggleBlackDiv();
Edit: I got this working in the end using Joonas89's answer. I basically moved the if
statement that changes the src
value to another function that is called prior to the one above. This solved the onclick
problem mentioned above. I then changed the divs left/top from calculated values to 50%
as detailed by Joonas89 (but on the container div rather than the img element), along with the new transform property. The div and img already had a position value of fixed so didn't need to change that.
Are you sure u want to calculate top and left positions? Wouldent it be better to add a class like this, that always centers it
.parentDiv{
position: relative;
}
.imageElement{
position: absolute;
top: 50%;
left: 50%;
transform: translate(-50%, -50%);
}
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