Responsive Image Overlay

Image overlay is a very common concept in front-end development. It is easy to implement but difficult when we deal it with different screen sizes, where we need to cover the image with the overlay each time the screen size is changed. I have gone through various blog posts when I need to implement the same for Open-event webapp and researched a solution that works for all screen sizes without any media query.

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How to add an overlay to an image ?

If we need four images in a single row nearly 300*300px.  The code below shows the markup.

image-holder : The parent class to take the image and overlay inside it.

background-image: This class takes image source.

responsive-overlay: This is the key point to make it responsive. Responsive-overlay contains a class hover-state to add overlay absolutely and a class social-links.

social-links: It adds content to hover-state.

 

<div class="image-holder">
  <img class="background-image" alt="" src="">
   <div class="responsive-overlay">
     <div class="hover-state text-center preserve3d">
       <div class="social-links vertical-align">

       </div>
     </div>
   </div>
 </div>

The styling is written with SASS in .scss file as shown below.

//overlayimage and backgroundshade can be set in config.scss

 .image-holder {
   position: relative;
   overflow: hidden;
   margin-bottom: 12px;

   .background-image {
     height: 300px;
     width: 300px;
     display: block;
     margin: 0 auto;
     background-color: $background-shade;
    }
 
   .responsive-overlay {
     @include responsiveoverlay;

    .preserve3d {
       height: 300px;
      }

    .hover-state {
     @include hoverstate;
     height: 300px;
     width: 300px;
    }

  @mixin responsiveoverlay {
     height: 100%;
     position: absolute;
     top: 0;
     width: 100%;
}

   @mixin hoverstate {
     background: $overlayimage;
     display: block;
     height: 300px;
     left: 0;
     margin: 0 auto;
     opacity: 0;
     position: relative;
     top: 0;
     -moz-transition: all 0.3s ease-out;
     -webkit-transition: all 0.3s ease-out;
     transition: all 0.3s ease-out;
     width: 300px;
     z-index: 2;
   }

This code will work for responsiveness as well. The main catch here is the responsive-overlay class which is made 100% in width but set to position absolute. The images which are 300 * 300 px in size will take an overlay of the same size because of hover-state class. Instead, if we adjust sizes of images in small screens the above code will adjust overlay on the image automatically.

Like, on tablets we can have an overlay like this.

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And on mobile screen output is like that :

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Conclusion

Responsiveness is easy if we follow correct concepts. Here, the concepts of absolute and relative positioning in CSS have done the magic. Now we can play by adding different contents and effect on hover following the same basics.

Responsive UI: Testing & Reporting

Few days back I wrote a blog about how to make a website responsive. But how do you exactly check for responsiveness of a website? Well, you can do it using your browser itself. Both Mozilla Firefox and Google Chrome provides responsive mode for testing responsiveness of websites for standard resolutions and also to drag and check for any resolution. Open Event Organizer’s Server has quite some responsive issues, so I would tell about reporting the issues as well.

Continue reading Responsive UI: Testing & Reporting

Responsive UI: Modifying Designs with Device Width

An important feature of websites these days with the advancement of smartphones is being responsive with device size. We nowadays not only worry about the various width of laptop or desktop, which don’t vary by a huge amount but also need to worry about tablets and phones which have a much lesser width. The website’s UI should not break and should be as easy to use on phones as it is on desktops/laptops. Using frameworks like bootstraps, Semantic-UI solves this problem to a large extent. But what if we need to modify certain parts by our own in case of mobile devices? How do we do that?

Continue reading Responsive UI: Modifying Designs with Device Width

Working with Absolute Positioning

During the past week, I have done a lot of work for making the feature that allow the users to view the schedule of events according to track and time. The toughest part was to have a headstart to think of the mockup that fulfills this criterion.

After the mockup, I started coding it and realized that I have to add CSS by using Javascript. The frontend needs to calculate the top of each pop-up that appears when the track is hovered and to append the box just below it.

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The interesting part was to calculate the top each time the element is hovered and to place the box at the right position by using jQuery.

Position Absolute 

The difficulty becomes maximum when we use “position : absolute “. As, it takes the element out of the layer. The element with absolute positioning is difficult to handle when it comes to responsiveness. Here also the pop-overs showing the speakers are to be made with absolute positioning.

The code snippet shows the calculation for exact position of the pop-up box.

$(document).ready(function(){

 $('.pop-box').hide();
 $('.item').hover(function (event) {

 event.preventDefault();
 event.stopPropagation();
 var track = $(event.target);
 var link = track.children(0);
 var offset =$(link).offset();

 var position= offset.top-link.height()-30;
 if( $(window).width()<600){
 var position= offset.top-link.height()-48; 
 }
 if(offset.top){
 
 $('.pop-box').hide();
 var p=$(this);
 $(p).next().show();
 var posY = event.pageY;
 nextOfpop=$(p).next();
 
 var toptrack = position ;

 $(nextOfpop).css({'top':toptrack
                 });

 $(document).mouseup(function (e)
 {
 var container = $(".pop-box");

  if (!container.is(e.target) 
  && container.has(e.target).length === 0 && (e.target)!=$('html').get(0)) 
   {
   container.hide();
   }
   });
  });
 })

This code sets the value of top of the pop-over in the variable position and copy it to toptrack that is passed to CSS to adjust the top dynamically.

Responsiveness for top

I was struggling a whole day to find out the best possible way for the responsiveness of track page. Obviously, the difficult part was the recalculation of top with the screen-size. Currently I have used $window.width() to check the width of screen and adjust the top on mobile. But, it will include more complexity when it is done for other screen sizes rather than mobile.

 if( $(window).width()<600){
 var position= offset.top-link.height()-48; 
 }

The tracks page is ready now with both light and dark theme.

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That’s how the position absolute is handled with jQuery. To remove the complexity, all the CSS except the calculation of top is written with SASS.