Improve checks for image dimensions extraction to avoid warnings

[milindmore22]

Bug Description

As per this support topic User seeing a warning while extracting a dimension of an image.

PHP Warning: Division by zero in /wp-content/plugins/amp/includes/sanitizers/class-amp-img-sanitizer.php on line 299

I am not able to reproduce the issue at my end by I think it might be unsupported image type or corrupted image, which returned 0 or false

As suggested by Weston we should replace isset() checks with empty() to avoid warning and apply fallback dimensions instead.

Expected Behaviour

Should not show any warrning

Screenshots

No response

PHP Version

7.4

Plugin Version

2.2.1

AMP plugin template mode

Reader

WordPress Version

5.9.1

Site Health

Site health : https://insights.amp-wp.org/admin/report/uuid/ampwp-2c37937f-1474-5871-856e-92cd1bf35954

Gutenberg Version

No response

OS(s) Affected

No response

Browser(s) Affected

No response

Device(s) Affected

No response

Acceptance Criteria

No response

Implementation Brief

No response

QA Testing Instructions

No response

Demo

No response

Changelog Entry

No response

[westonruter]

This is the line in question:

amp-wp/includes/sanitizers/class-amp-img-sanitizer.php

Line 299 in 28bc1bb

$height = ( (float) $node->getAttribute( Attribute::WIDTH ) * $dimensions['height'] ) / $dimensions['width'];

Somehow $dimensions['width'] is 0. Fixing the symptom would be to just make sure that $dimensions['width'] > 0. I wonder if it is actually false here and it is being cast to 0. I wonder if instead of checking isset() if we should rather be checking ! empty() in this method.

The value for $dimensions['height'] is most likely coming from here:

amp-wp/includes/utils/class-amp-image-dimension-extractor.php

Lines 246 to 249 in 28bc1bb

	$dimensions[ $url ] = [
	'width' => (int) $image_size[0],
	'height' => (int) $image_size[1],
	];

So perhaps wp_getimagesize() is returning a bad value?

[pooja-muchandikar]

QA Passed ✅

Images are rendering proper dimensions and no warnings are displayed.

Image type	Actual Dimension	Displayed Dimensions	Warning
JPEG	534x340	534x340	NO
PNG	1080x1920	1080x1920	NO
JPG	1280x796	1280x796	NO
PNG	920x946	920x946	NO