0Mostra l'immagine ingrandita al passaggio del mouse in wordpress

As part of the recent improve­ments I’ve been mak­ing to vari­ous web­sites I wanted to make images in gal­ler­ies show enlarged ver­sions when hovered over. Fare questo con base CSS is fairly trivi­al, but I did­n’t just want to expand the ori­gin­al image, Volevo che il browser prendesse un nuovo (lar­ger) image too…

All of the images are already provid­ing a full src-set so all I needed to do was to use a little jQuery (which is already loaded by word­press any­way) to change the tar­get dis­play size to make the browser pull a lar­ger image. La cosa bella è che CSS works instantly so you get a lar­ger image using the ori­gin­al file, and then the qual­ity improves a split second later as the high­er res file gets loaded.

Il CSS

Il CSS I used is as fol­lows. L'ho semplicemente aggiunto allo style.css del mio tema (or rather child-theme — always a good idea to use one)

dt.gallery-icon a img.size-thumbnail:passa il mouse
{
trasformare: scala(3.0);
}

Appunto (1) — the above CSS applies to gal­lery images only. It is unlikely any­one would want this func­tion­al­ity for all images dis­played any­where on the page, but you might want it for the main con­tent sec­tion. You would need to check how your theme struc­tures this, but in my case the main con­tent area is a “sec­tion” so the fol­low­ing code would do the job

section.entry-content p a img.size-thumbnail:passa il mouse
{
trasformare: scala(3.0);
}

Appunto (2) — This code applies only to thumb­nail images. For medi­um images you would replace “size-thumb­nail” with “size-medi­um”, and for large with “size-large”.

Appunto (3) — Because my thumb­nails are 120x80px I want to increase them to 3x their ori­gin­al size. I already have a cus­tom image size of 360×240 that word­press cre­ates for me that is included in the src-set. For hi-dpi screens there are also even lar­ger image sizes that I have (per esempio. 720×480). Cre­at­ing addi­tion­al image sizes in word­press is easy — there are lots of good guides online if you need to do this.

Se vuoi ridimensionare a 1,5x o 2.0x, cambia semplicemente il 3.0 come desiderato

Il jQuery

Add the fol­low­ing to your (bambino) file di script del tema (assum­ing it has one). If it does­n’t have one, cre­ate your own, and ‘enqueue’ it with a cus­tom func­tion in the (bambino) funzioni del tema.php

jQuery(documento).pronto(funzione(){

  jQuery("dt.gallery-icon a img.size-thumbnail").passa il mouse(funzione(){
    jQuery(questo).attr("taglie","(larghezza massima: 360px) 100vw, 360px");
    }, funzione(){
    jQuery(questo).attr("taglie","(larghezza massima: 120px) 100vw, 120px");
  });

  //ripetere quanto sopra 5 linee qui per ogni diversa dimensione dell'immagine che si desidera modificare

});

The above code is apply­ing to images with class thumb­nail that are found inside any dt with a gal­lery-icon class — so in oth­er­words — only to images inside the word­press built-in gal­lery struc­ture. On hov­er the max-width is increased from 120 per 360 (un aumento di 3 volte per eguagliare il mio CSS!), and then the second part of the func­tion restores the ori­gin­al 120 width when the hov­er stops.

Come con il CSS sopra, you can adjust the num­bers to change how much the image enlarges, e puoi cambiare il dt.gallery-icon a img.size-thumbnail sec­tion to tar­get a dif­fer­ent ele­ment or class depend­ing on which images you want to target.

Accoda il tuo script

If your theme did­n’t have a script file and you need to enqueue your own add the fol­low­ing to your (bambino) funzioni del tema.php (assum­ing you called your script file image-zoom.js and saved it in the root folder of the theme)

wp_register_script( 'img-zoom', get_stylesheet_directory_uri() . '/image-zoom.js', schiera( 'query' ), '', vero);
wp_enqueue_script( 'img-zoom' );

Quanto sopra registrerà il tuo script, in the foot­er, mak­ing sure it is placed after jquery (so jquery should already be avail­able when it executes)

Aggiungere le dimensioni dell'immagine

For com­plete­ness here’s how to add cus­tom image sizes to word­press. Di nuovo, aggiungi questo al tuo (bambino) funzioni del tema.php

aggiungi_dimensione_immagine( 'larghezza quarto', 192, 144, falso );

Above I’ve added a new image-size called “quarter-width” with a max­im­um width of 192px and a max­im­um height of 144px. L'immagine non verrà ritagliata (quindi il falso alla fine).

Word­Press will now cre­ate images of this size auto­mat­ic­ally when you upload images (you will need to use a thumb­nail rebuild plu­gin to recre­ate the thumb­nails for already-uploaded images).

This new image size will NOT show up for inser­tion in the edit­or though. To make it avail­able also add the fol­low­ing code to your functions.php

funzione my_custom_image_sizes( $taglie ) {
    return array_merge( $taglie, schiera(
        'quarter-width' => __('Larghezza quarto'),
    ) );
}

Rispettare le impostazioni esistenti

Un'altra cosa che potresti voler fare (to ensure respons­ive images work well) is to cre­ate lar­ger (i.e. ciao dpi) thumb­nail sizes that respect the GUI of wheth­er to crop thumb­nails or not. To do that use the code below which as you will see is slightly mod­i­fied from the more basic one above

aggiungi_dimensione_immagine( 'resp-thumb-2x', (get_option( 'thumbnail_size_w' ) == 0 ? 0 : '240'), 160, get_option( 'ritaglio_miniatura' ) );

Il codice sopra verifica la presenza di 2 things — firstly it checks to see if the crop option is set, e se lo è, it mir­rors it for our new respons­ive size. Controlla anche se la larghezza è impostata su 0 (i.e. no max­im­um) in which case our new image will also have no max­im­um either. I called the new image size “resp-thumb-2x” as it is a ‘respons­ive’ copy of the thumb­nail that is twice as large (for hi-dpi screens with double the nor­mal pixel dens­ity). I have also cre­ated a num­ber of oth­er sizes to make a fairly com­plete set.

Note — Since my ori­gin­al thumb­nails were 120×80 I want my new ones to be 240×160 so those are the sizes I have spe­cified (hardcoded). It would be pos­sible to get both the height and width spe­cified for the ori­gin­al thumb­nail and mul­tiply both by 2 to make this func­tion fully gen­er­ic, but I did­n’t do so when I was devel­op­ing it so I will leave that to you to fig­ure out!

Un ultimo consiglio

Se, come me, you cre­ate your own full set of new image sizes, you may not want word­press to cre­ate it’s own extra hid­den sizes. In addi­tion to the ori­gin­al image, and the thumb­nail, the medi­um, e l'immagine grande, word­press also cre­ate a “post-thumb­nail”, a “medi­um-large”, a 1536×1536 and a 2048×2048. These are dis­abled in 2 dif­fer­ent ways…

Per rimuovere il 1536 e 2048 le immagini sono dirette

rimuovi_dimensione_immagine( '1536x1536' ); //Rimuovi il 1536 we dont need it
remove_image_size( '2048x2048' ); //Rimuovi il 2048 non ne abbiamo bisogno

The post-thumb and medi­um-large are slightly more complicated

//remove the built-in medium-large
add_filter('dimensioni_immagine_intermedia', funzione($taglie) {
    return array_diff($taglie, ['medio grande']);
});

//remove the built-in post-thumbnail
add_filter('dimensioni_immagine_intermedia', funzione($taglie) {
    return array_diff($taglie, ['post-miniatura']);
});

Note that remov­ing the post-thumb­nail seems to some­times have strange effects on the image lib­rary in the editor.

Un'ultima nota finale

When decid­ing on image sizes (for lar­ger images, less so thumb­nails) you ideally want a size that com­mon aspect ratio images will always res­ize nicely to. For that reas­on I recom­mend the fol­low­ing sizes

Note how the widths spe­cified pro­duce whole num­ber heights for all 3 of the most com­mon aspect ratios. Non lo otterrai con larghezze come 150 or 200.

Also note the pat­tern in increases. Saltare 2 righe nella tabella e la dimensione raddoppia! Le righe pari (288,576,1152 e 1535) are also 1.5x the pre­vi­ous size so these work well on semi-hi-dpi screens using a 50% aumento dpi. Usando questo set di 7 sizes you have a good range of usable options for most view­ports AND a good set of respons­ive images that word­press will auto­mat­ic­ally add to the src-set since they will have con­sist­ent aspect ratios with no frac­tions that would lead to qual­ity loss or cropping.

Cur­rently for thumb­nails I tend to either have unlim­ited width allowed OR I hard crop to a fixed 3:2 ratio so I use whole num­ber sizes for thumb­nails but I may even­tu­ally tweak my theme and extend the above sys­tem back­wards by hav­ing options 48px and 96px wide (nota che non c'è alcun valore tra questi 2 that would work unfor­tu­nately — and since I use 60px wide mini thumb­nails I haven’t opted to extend back­wards). 72px funzionerebbe per entrambi 4:3 e 3:2 (e 64px funzionerebbero con 4:3 e 16:9). Since a major­ity of my images are taken on my dSLR these are typ­ic­ally 3:2 (the same as the aspect ratio of tra­di­tion­al 35mm film) quindi potrei usare anche questa dimensione, che poi funzionerebbe con le taglie grandi fino in fondo, but the lar­ger sizes are not cropped where­as my thumb­nails are — I’m happy for lar­ger images to be both land­scape and por­trait, but I want thumb­nails to typ­ic­ally be land­scape only to fit with my design, so that’s why I haven’t exten­ded back­wards. Hope­fully as more and more logos are avail­able as SVG'S, e una volta JPEG-XL arriverà nei browser nel prossimo futuro, molto di questo sarà risolto.

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