Is it possible to resize images on the fly and cache the result with Drupal?
I have some big images (e.g. 2000x2000px) and I want to display a preview of the e.g. 100x100px.
I know there is a theme_image_style function. But it seams to only create the <img> with the right size and not effectively resize the image.
I look at modules/images/image.admin.inc and they used the function [image_style_create_derivative][2].
Yes, you should use Drupal's Image styles (Configuration -> Media -> Image styles). There you should create your style.
Then, on front-end, when ever you want to display image with that style (in that resolution) you can use image_style_url() function:
https://api.drupal.org/api/drupal/modules!image!image.module/function/image_style_url/7
It accepts 2 parameters - one is image style machine name and other is image URI, which you can get if you print out all image field properties.
You can also select image styles from back-end interface...i.e. when creating a view for some image you can select to be displayed in specific image style.
In both cases those image styles are generated the first time image is used.
In response to your comment on MilanG's answer, using image_style_url() is the best option on the backend. There is also
https://www.drupal.org/project/resp_img
which may be something worth looking into. From a UX perspective, you don't want to force the user to load a 2000x2000 px image every time they load the page. Regardless of the outputted size, the image is still going to render as a 2000x2000 px image with a large size. image_style_url() or using image styles in the GUI create a new file that will load much quicker and is the preferred method.
Related
Currently, all image caption I have used are automatically placed before an image, despite me placing the caption before the image in the code.
For example,
[caption=]
.Simple diagram of data storage
image::user-guide/data-storage.png[width="600"]
Is there any way I can re-position the caption such that it appears above/before the image like how table titles are positioned above a table?
I assume you're using the standard HTML5 output of Asciidoctor. This can't be parameterized; the HTML will always render first the image and then the title element.
You could override the rendering of images in the HTML5 backend, or create your own backend to structure the output as you need.
In addition to #ahus1's answer, you might be able to achieve the presentation you desire by applying a custom stylesheet via docinfo files. See https://asciidoctor.org/docs/user-manual/#docinfo-file
For each record, I have two images, small and large size. What is the best way to show an image size according to the size of the screen?
I know I can use css and mediaquery and show the small or large image using a div display none / block, but in this way, I understand that the user has downloaded both images even if they are not displayed, is that correct? Then, the page load increases. If so, what is the best option to do this?
For this problem the most efficient way is using the User-Agent to detect if a client is desktop, tablet or mobile.
I prefer to use Mobile_Detect or jenssegers/agent (based on Mobile_Detect).
Edit
Recently I installed the Google Pagespeed Module on my server. There is a filter, resize_rendered_image_dimensions, that returns images with sizes of the current client view (exactly what you are looking for).
Some other implementation would be lazyloading with Javascript and adding dimensions to the requested url depending on the viewport sizes.
My site have 2 pages and the 2 pages contain a similar picture. If a user comes to the first page, he downloads the picture and then come to the second page, if I make the website so that the picture is shared between the 2 pages then the user no need to download the picture again?
If I want to put the same picture but different in size on the webpage, is it better to make 2 pictures by using image software editor or using CSS to change the width and the height of the picture?
you have answered your question.
if the image is from the same source, and if you have configured the caching on webserver correctly (and if the client has enabled cache), then there are no re-requests sent to view the same resource.
you dont need to create multiple images for different sizes, use html image attributes to show it in the grid dimensions you wish to.
Exception: if the original image is quite large, and you are not sure if the user will want to view the image, then create smaller image for faster loading. Thumbnails on a photo album is a good example for that. There is a program called re-sizer which accepts a folder and create a new set of images with the required dimensions
Resources below
Image Resizer
HTTP Compression
I have uploaded a photo in WordPress. I am trying to post a thumbnail of the image using a predetermined width while constraining the height proportionally.
In functions.js:
add_image_size('width-130', 130, 0, false);
On the page that outputs the thumbnail:
the_post_thumbnail('width-130');
According to the WordPress docs(http://codex.wordpress.org/Function_Reference/add_image_size), it says:
WordPress will create a copy of the post thumbnail with the specified
dimensions when you upload a new thumbnail.
Currently it is outputting the full thumbnail image with a width attribute of 130. This still requires the full size image to load, which is not what I want. I would like for WordPress to create an actual copy of the post thumbnail with the correct dimensions, and not just to set the width attribute. How can I achieve this?
I discovered my mistake.
Since I had not re-uploaded the image file, it was still trying to access the full size image which was the assigned image for that post, while adding the width attribute. Once I re-uploaded the image, the add_image_size() function is now actually creating a copy of the thumbnail with the correct dimensions.
I apologize for asking this question. If the community wants, I can close it but I figure it might be good reference for WordPress newbies such as myself.
Use this plugin to regenerate thumbnails.
http://wordpress.org/plugins/regenerate-thumbnails/
In case anyone runs across a similar problem, this may help. add_image_size generates derivatives that are smaller, but not bigger or the same size. Thus if you are trying to make a monochrome derivative image, uploading an image the same size as the monochrome, it will not be available and techniques like this one won't work.
Let's say I have a content type X that has an image for an attribute. I know I can specify different styles for that image (e.g. medium, large, thumbnail), so that crops are automatically made. But can I select/upload a particular image to use? E.g. "I'm not happy with the autocrop for this thumbnail image. I'll just upload my own."
Are there modules that allow this?
Thanks.