WebP is not generated if source PNG already has target size

[thausmann]

Hey, I'm trying to completely switch over to WebP and noticed some strange behaviour. Let's say I upload a PNG in Processwire of size 1280x800.

• $page->image->url ➝ correct URL (filename.webp)
• $page->image->width(800)->url ➝ correct URL (filename.800x0.webp)
• $page->image->width(1280)->url ➝ wrong URL (filename.1280x0.png), webp file is not generated
• $page->image->width(1280)->url(false) ➝ correct URL (filename.1280x0.webp) but webp file is not generated

So: When I request a size that equals the original file, no WebP conversion is happening (no webp file is created, although a new PNG is generated (...1280x0.png)).
When I use url(false), I get the expected URL but still the file is not generated. Also interesting: this issue is only occuring with PNG, not JPG.

 

My Configuration:

$config->imageSizerOptions('webpAdd', true); 
$config->imageSizerOptions('defaultGamma', -1); 

• GD
• Pageimage::url Hook from here 
• Also tried to output width(1280)->webp->url, it makes no difference
• I checked that the PNG version is not smaller in filesize (PNG=450KB, WebP (from other tool)=60KB)
• Tested with Processwire 3.0.148 and 3.0.160 dev
• I think this post is about the same issue and where I got the url(false) from.
• Setting 'useSrcUrlOnFail' => false inside $config->webpOptions results in correct output URL (filename.1280x0.webp), but still the file is not generated. So maybe the webp conversion fails? Apparently I see zero webp logs in logs/image-resizer.txt

 

"Don't use resize" seems like a solution here but this is a generic approach in my code, sometimes uploaded images are simply already in the correct size. 

Any ideas how to fix this and always get dem sweet sweet WebP images? Or did I find a bug?
Maybe @horst has an idea what the cause of this phenomenon could be? ?

[horst]

Have you also tried this:

$page->image->width(1280)->webp()->url

 

[thausmann]

16 minutes ago, horst said:

Have you also tried this:

$page->image->width(1280)->webp()->url

 

Thanks for your reply! I just tried that and apparently it gives me the same png url filename.1280x0.png.

As soon as I go 1 pixel up or down I get a webp URL. 

[horst]

17 hours ago, thausmann said:

Thanks for your reply! I just tried that and apparently it gives me the same png url filename.1280x0.png.

This is weird. Please can you post an issue on GitHub with this, so that Ryan gets informed about it?

[thausmann]

Okay, issue created: https://github.com/processwire/processwire-issues/issues/1209

As a quick fix I will re-upload my affected non-transparent PNGs with JPGs.

Another possible workaround on template level: 

if($image->width == $width) {
    $imgUrl = $image->webp->url;
} else {
    $imgUrl = $image->width($width)->webp->url;
}