Develop Reference

Is there a way to resize a div based on an images size?

I am currently creating a custom media player for a customer with HTML and javascript. The customer only needs to add an empty element containing necessary data-attributes (such as preview-image, srcset, URL) to the site for the script to create a player unit.
The image and the media are siblings within the wrapping parent.
A click on the play button basically just hides the image and displays the media.
Player unit markup:
<div class="wrapper">
<img class="preview-img" src="...">
<button class="play-button">Play</button>
<iframe class="embedded-media hidden">...</iframe>
</div>
The website owner now wants the size of the player to be dependent on the size of the preview image or srcset.
I tried to use the image as wrapper, but it's not a container element.
Is there any way to size the parent depending on the images size?

Set any other element (except the image) inside the wrapper absolute and wrapper itself a inline-block, to allow automatic width. Then image makes wrapper to be the same ratio or size as itself.
When hiding the image after click, use relative positioning and z-index lower than the iframe (for example 10 in my example).
Set iframe size to 100%/100% to cover the same area as image and wrapper.
<style>
<!--
.wrapper {
display: inline-block;
position: relative;
}
.play-button {
position: absolute;
z-index: 30;
top: 0;
left: 0;
color: red;
}
.preview-img {
position: relative;
z-index: 40;
display: block;
width: 500px;
}
.embedded-media {
position: absolute;
z-index: 20;
top: 0;
left: 0;
}
-->
</style>
<div class="wrapper">
<img class="preview-img" src="https://upload.wikimedia.org/wikipedia/commons/thumb/b/b6/Image_created_with_a_mobile_phone.png/800px-Image_created_with_a_mobile_phone.png">
<button class="play-button">Play</button>
<iframe class="embedded-media hidden">...</iframe>
</div>

Resizing images of different aspect ratios to fit a div without stretching it

I'm making a portfolio website and I am trying to make a simple image browser. I have a container div with size relative to the size of the browser window. I want that div to be able to contain images of different aspect ratios and a caption of fixed height and the width relative to the width of the image. I don't want the div to stretch to contain the images, I want to resize the image (you can see what I mean in the picture below).
illustration of the problem here
I was trying to use javascript to calculate the size of the image, but failed, because I couldn't calculate the element's size before it is actually loaded. This is how I tried to do it (not thinking about the titlebar):
var divAspectRatio = containerDiv.offsetHeight/containerDiv.offsetWidth;
var imageAspectRatio = image.offsetHeight/image.offsetWidth;
if(divAspectRatio>imageAspectRatio){
image.style.height = content_in.offsetHeight;
}else{
image.style.width = content_in.offsetWidth;
}
captionDiv.style.width = image.offsetWidth;
How do I make it work?

If your background image is in a div element, add this to your css, inside the div block:
background-size: cover;
If it's in an img element, add this to your css, inside the img block:
object-fit: cover;

Try using this css element:
object-fit: cover
This way, your image will get resized to fit the containing box!

The desired layout needs some calculation as the placing of an image that has aspect ratio bigger than the aspect ratio of the container differs from one that doesn't. Also to note is that the caption area is required to be only as wide as the displayed image but has a fixed height.
The imgs are wrapped in an 'innerdiv' which will also contain the caption. On loading the image's aspect ratio is found and stored as a CSS variable. Other CSS variables are set up in advance - see the head of this snippet for those that can be chosen. Remaining calculations are done in CSS.
window.onload = function () {
const imgs = document.querySelectorAll('.container .innerdiv .img');
imgs.forEach(img => {
img.parentElement.style.setProperty('--imgratio', img.naturalWidth / img.naturalHeight);
img.parentElement.classList.add(( (img.naturalWidth / img.naturalHeight) > getComputedStyle(img).getPropertyValue("--containerratio") ) ? 'wider' : 'thinner');
});
}
* {
padding: 0;
margin: 0;
}
.container {
/* SET THE NEXT 4 VARIABLES TO WHAT YOU REQUIRE */
--unit: 1vmin; /* the basic unit - must be fixed e.g. vmin, px, ch not % */
--containerw: 40; /* width of a container in these units */
--containerratio: 1.5; /* the ratio of width to height */
--captionh: 4vmin; /* height of a caption including its units (which must be fixed e.g. vmin, px, em */
--containerh: calc(var(--containerw) / var(--containerratio));
display: inline-block;
width: calc(var(--containerw) * var(--unit));
height: calc(var(--containerh) * var(--unit));
position: relative;
border: solid;
}
.innerdiv {
display: inline-block;
position: absolute;
top: 0;
left: 0;
}
.innerdiv.thinner {
width: calc(var(--imgratio) * ((var(--containerh) * var(--unit)) - var(--captionh)));
height: 100%;
left: 50%;
transform: translateX(-50%);
}
.innerdiv.wider {
width: 100%;
height: calc((var(--containerw) / var(--imgratio)) * var(--unit) + var(--captionh));
top: 50%;
transform: translateY(-50%);
}
.img {
width: 100%;
height: auto;
}
.caption {
font-size: 2vmin;
background-color: yellow;
text-align: center;
width: 100%;
height: var(--captionh);
position: absolute;
top: calc(100% - var(--captionh));
left: 0;
}
<div class="container">
<div class="innerdiv">
<img class="img" src="https://picsum.photos/id/1016/200/300">
<div class="caption">CAPTION</div>
</div>
</div>
<div class="container">
<div class="innerdiv">
<img class="img" src="https://picsum.photos/id/1016/500/200">
<div class="caption">CAPTION</div>
</div>
</div>
<div class="container">
<div class="innerdiv">
<img class="img" src="https://picsum.photos/id/1016/300/300">
<div class="caption">CAPTION</div>
</div>
</div>

Two overlapping images via CSS and JS

I am trying to enable a user to drag an image (e.g. a face) on another image (e.g. a map square). I implemented the drag&drop with an Angular directive and it kinda work. What is not working is the position of the dropped image (the face): it is not overlaying, but it is being placed below the map square.
The starting HTML code is generated via ng-repeat, but the resulting element is this:
<span style="display: inline-block;position:relative;">
<img src="map_square.jpg" class="map-image">
</span>
When dropping, it becomes:
<span style="display: inline-block">
<img src="map_square.jpg" class="map-image">
<img src="face.jpg" class="face-image-on-map">
</span>
This is my CSS code:
.map-image {
position: relative;
max-width: 42px;
z-index: 0;
}
.face-image-on-map {
position: absolute;
width: 100%;
max-width: 42px;
z-index: 100;
opacity: .8;
}
As a result of this, I would expect the face image to be over the map square, both being inside the span-delimited area (42*42px).
Instead, the face image is outside the span area, below the map square (actually, it is over another map square image, i.e. the one below the actual target).
Changing position of the face causes the face image to be placed on the right of the target (far away from it).
How can I fix this?

I think you're missing the top and the left property in .face-image-on-map.
So I would recommend this:
.face-image-on-map {
position: absolute;
top: 0; /* Positoning: distance from top border */
left: 0; /* Positioning: distance from left border */
width: 100%;
max-width: 42px;
z-index: 100;
opacity: .8;
}
(See the W3Schools page for more information)
Hope this is want you wanted :)

How to put an img element behind a transparent img element?

I have two img elements and I want the first image.png to go behind the transparent image.png. I have tried a lot of different things (z-index, transparent background color, rgba background color, positioning absolute and relative, nesting one in a div, making them both divs). Right now i've been trying to use a transparent .png image. The image .png is actually behind it, but it still shows through it. Please help.
html:
<body>
<main class="site-wrapper">
<div class="carnival"></div>
<div id="images">
<img id="divbox" src="images/divbox.png">
<img id="clown1" src="images/clown1.png">
</div>
</main>
</body>
js: (i did the styles in js b/c I was interested in learning how to do it that way):
//styles
//divbox:
document.getElementById('divbox').style.display = "inline-block";
document.getElementById('divbox').style.transform = "skew(-2deg)";
document.getElementById('divbox').style.marginTop = "21%";
document.getElementById('divbox').style.marginLeft = "47.6%";
document.getElementById('divbox').style.height = "200px";
document.getElementById('divbox').style.width = "200px";
document.getElementById('divbox').style.border = "1px solid orange";
document.getElementById('divbox').style.position = "absolute";
document.getElementById('divbox').style.zIndex = "2";
//clown1:
document.getElementById('clown1').style.display = "inline-block";
document.getElementById('clown1').style.transform = "rotate(90deg)";
document.getElementById('clown1').style.marginTop = "21%";
document.getElementById('clown1').style.marginLeft = "53%";
document.getElementById('clown1').style.border = "1px solid green";
document.getElementById('clown1').style.position = "relative";
document.getElementById('clown1').style.zIndex = "1";
Thanks for any help, please let me know if I can answer questions.
UPDATE:
Sorry for not being clearer. I have now achieved getting the image behind the other image, but since the image ontop is transparent, the image behind is showing. How do I stop this?
Here is an example of what is happening:
http://oi61.tinypic.com/2mw9egx.jpg
Notice the orange border is ontop so it is definitely ontop.
UPDATE 2:
This should make it really clear what I want. Again sorry for the confusion:
http://oi59.tinypic.com/eamb0n.jpg

I would do something like the following jsFiddle: http://jsfiddle.net/7gdx48fu/. Might need to reload a couple times to see a good example of the overlay working.
Create a wrapper DIV for your two images. Set that wrapper DIV's to position: relative so we can use absolute positioning on one of the images it contains. By doing this we prevent the absolute positioned image from potentially aligning itself elsewhere in the page, like the upper left corner of the browser window.
Then, set the position of our overlay image, the transparent PNG, to position: absolute along with top: 0 and left: 0 to align it with the first images upper left corner.
You can do this without using z-index if you watch the order you include your images. Place the image you want behind the transparent PNG in the markup first followed by the transparent PNG.
<div class="img-container">
<img src="http://lorempixel.com/200/200/city/">
<img class="overlay" src="http://lorempixel.com/200/200/city">
</div>
.img-container {
position: relative;
}
.overlay {
position: absolute;
top: 0;
left: 0;
opacity: 0.25; /* using this to replicate the transparent PNG */
}
EDIT
The OP's requirements have changed to include how to prevent an image behind a transparent image from showing through the transparent image.
Here is an updated jsFiddle: http://jsfiddle.net/7gdx48fu/2/.
This approach I wrapped the transparent PNG in a wrapper DIV and set it's background color. I used white in my example but you may use any color.
<div class="img-container">
<img src="http://lorempixel.com/200/200/city/">
<div class="overlay">
<img src="http://lorempixel.com/200/200/city">
</div>
</div>
.img-container {
position: relative;
}
.overlay {
position: absolute;
top: 0;
left: 0;
background-color: white;
top: 15px; /* shifting overlay for illustrative purposes - not use case code */
left: 15px; /* shifting overlay for illustrative purposes - not use case code */
}
.overlay img {
opacity: 0.25; /* using this to replicate the transparent PNG */
}
Not perfect but I'm unsure of how else to proceed.
EDIT 2
It seems the OP wants to do a form of masking. You can do this with overflow: hidden.
I have updated the jsFiddle: http://jsfiddle.net/7gdx48fu/4/
In this updated answer I have kept the wrapper DIV and set it with a fixed width and height. Then applied overflow: hidden. What we are doing here is creating an invisible window that will only show content when it is within the dimensions of the window.
To have the image appear as if it is coming out of the base layer image simply adjust the position of the image inside the wrapper DIV. For the jsFiddle simply play with the value of top in .mask img.
This will need a little tweaking for the proper placement and size of the .mask DIV to fit your needs but hopefully points you in the right direction.
<div class="img-container">
<img src="http://lorempixel.com/200/200/city/">
<div class="mask">
<img src="http://lorempixel.com/200/50/city">
</div>
</div>
.img-container {
position: relative;
}
.mask {
position: absolute;
top: 25px;
left: 25px;
height: 100px;
width: 100px;
overflow: hidden;
border: 1px solid red; /* for illustrative purposes */
}
.mask img {
position: relative;
top: 25px;
}

Have you tried the css opacity property ?
#clown1{ opacity:0.3;}

make both images' position absolute instead of relative
for the above to work, some common ancestor (i.e. #images) must have a non-default position too (e.g. relative)
forget zIndex - all else being equal, the latter element will be "topmost"
put all the above in a CSS style sheet instead of in JS code!
Forgetting the other transformations and margins, etc, the core CSS that you need is:
#images {
position: relative;
}
#divbox, #clown1 {
position: absolute;
}

Put them both in a parent container. Make the parent have position: relative and put both images having position:absolute. That way they will stack.(Something like that that I didn't check The order of img's could be wrong - play around a bit.
CSS:
.parent > img.transparent {
position: absolute;
}
.parent > img {
position: absolute; opacity: 0.5
}
HTML:
<div class="parent" style="position:relative">
<img src="other.png" class="transparent"/>
<img src="transparent.gif"/>
</div>
Some more explanation: When you make a parent/ancestor element's position relative it means that its contents that are absolute will be relative to the parent and not to the whole window

Scale image properly but fit inside div

I am making an image gallery. This is the HTML for the image:
<div style="width: 84%; height: 100%; float: left; text-align: center;"><img
id="mainimage" style="height: 100%;"
src="http://www.gymheroapp.com/workouts/img/spinner.gif"/></div>
<!-- Loading spinner is temp image, will be replaced by Javascript later -->
It works fine when the image is square, or the width is not too much more than the height. It breaks when the width is too great, though. Example of image overflowing:
Is there a way I could check whether there is overflow within my Javascript? Something like this:
image.setAttribute('height', '100%')
image.removeAttribute('width')
if (image.isOverflowing()) {
image.setAttribute('width', '100%')
image.removeAttribute('height')
}
Even better, is there any way to scale the image properly but fit it withing the containing div?

jquery example
Best fit:
$('img').on('load',function(){
var css;
var ratio=$(this).width() / $(this).height();
var pratio=$(this).parent().width() / $(this).parent().height();
if (ratio<pratio) css={width:'auto', height:'100%'};
else css={width:'100%', height:'auto'};
$(this).css(css);
});
Edit to account for caveat where image is in cache
$('img').on('bestfit',function(){
var css;
var ratio=$(this).width() / $(this).height();
var pratio=$(this).parent().width() / $(this).parent().height();
if (ratio<pratio) css={width:'auto', height:'100%'};
else css={width:'100%', height:'auto'};
$(this).css(css);
}).on('load', function(){
$(this).trigger('bestfit');
}).trigger('bestfit');

Heres a simple CSS solution:
html, body { height: 100%; }
#gallery { height: 100%; width: 100%; position: relative; }
#gallery img {
/* CSS Hack will make it width 100% and height 100% */
position: absolute;
top: 0px;
right: 0px;
bottom: 0px;
left: 0px;
/* Maintain aspect ratio */
max-height: 100%;
max-width: 100%;
}
<div id="gallery">
<img src="http://cl.vvmonnickendam.nl/files/large/87" alt="Awesome blabla gedoe">
</div>
Fiddle example