Image slider does not support retina images. Moreover, it uses only full-size images.
I do need to make a slider of 10 images with 6000x2000px (image load time ;/ ). I need to set size for them for ‘large’ or even ‘medium’. Can you help me doing it?

When image size select will be available for Image Slider as a part of VC?

Have you tested out the Retina plugin yet?

https://wordpress.org/plugins/wp-retina-2x/

It does not solve the problem. The slider is wrongly implemented.

If I was able to set desired image size, for example “large” then WP-retina-2x would make the difference.

In fact, even fixed size (i.e. large) in Fortuna includes/vc/boc_img_slider.php would be some solution. I need some help here.

$img_srcset = wp_get_attachment_image_srcset( $img_id , 'full' );
$img_sizes = wp_get_attachment_image_sizes( $img_id, 'full' );

after this line:

$att_img_url = wp_get_attachment_url( $img_id );

Then at the IMG element:

$image_output = '<img src="'. esc_url($att_img_url) .'" alt..........

add the attributes like so:

$image_output = '<img src="'. esc_url($att_img_url) .'" srcset="'.esc_attr( $img_srcset ).'" sizes = "'.esc_attr( $img_sizes ).'" alt.................

Please let me know if that does the trick for you so we add it in the next theme update!

$att_img_link = wp_get_attachment_image_src( $img_id, 'large');
				$att_img_url = $att_img_link[0];
				$att_img_title = get_the_title($img_id);
				$att_img_alt = get_post_meta($img_id, '_wp_attachment_image_alt', true);
				$img_srcset = wp_get_attachment_image_srcset($img_id, 'large');
				
				// Image output
				$image_output = '<img src="'. esc_url($att_img_url) .'" alt="'. ($show_img_alt ? esc_attr($att_img_alt) : "") .
				'" srcset="'. esc_attr( $img_srcset ) .
				'" title="'. ($show_img_title ? esc_attr($att_img_title) : "") .'"/>';

				// Slider item start 
				$str .= '<div class="img_slider_item boc_owl_lazy">';

					
				if ( 'lightbox' == $img_link ) {
					$str .= '<div class="pic">
								<a href="'. esc_url($att_img_link[0]) .'" class="mfp_popup_gal" title="'. ($show_img_title ? esc_attr($att_img_title) : "") .'">
									'.$image_output.'
									'.($show_hover_overlay ? "<div class='img_overlay'><span class='hover_icon icon_zoom'></span></div>" : "").'
								</a>
							</div>';
								
				}

However there is a issue with image loading – all images are loaded at the same time. but the worst thing is that something happens with this component height – it takes sum of heights of all images.

http://onedaystop.com/blog/karkonosze-labski-szczyt-czechy/

Looking good! Where is the slider on that URL btw?
What do you mean by “all images are loaded at the same time”?
May i see the issue you are describing on a test page pls?

In matter of custom post template – THX
Such deign with an animation and NEXT/PREV post buttons with thumbnails (like here) would be perfect!

As for the slider… Few things… first off, remove the paragraphs from the URL of your custom css: .owl-carousel .owl-item .img_slider_item img – background image. As they get HTML encoded, check your web dev tools to see that, it’s a bug that should be fixed in the latest Fortuna version.

As for the images “loaded at the same time” can you please clarify that issue again?
Also that sum of heights… I cannot reproduce this.
What device are you on?