WP_Image_Editor_Imagick::thumbnail_image( int $dst_w, int $dst_h, string $filter_name = 'FILTER_TRIANGLE', bool $strip_meta = true ): void|WP_Error

Description

Compatibility

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$dst_wint

The destination width.

$dst_hint

The destination height.

$filter_namestringoptional

The Imagick filter to use when resizing. Default 'FILTER_TRIANGLE'.Default: 'FILTER_TRIANGLE'

$strip_metabooloptional

Strip all profiles, excluding color profiles, from the image. Default true.Default: true

Return value

void|WP_Error

Performance profile

How much work a call to WP_Image_Editor_Imagick::thumbnail_image() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class

Trivial

Touches nothing outside its own arguments.

Scaling

Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions

64–202

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 297.

Plugin surface

2 hooks

Third-party callbacks on 'image_strip_meta', 'image_max_bit_depth' run inside this call, and their cost is not bounded by anything here.

Called by

2

2 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• hookthird-party callbacksapply_filters()called directly

What one call costs · 240 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost WP_Image_Editor_Imagick::thumbnail_image() can have, taken from its control-flow graph on PHP 8.5.

This body has more branch combinations than are worth enumerating, so the table covers the outcomes found first rather than every one that exists.

Hooks and filters fired · 2

2 hooks fire while WP_Image_Editor_Imagick::thumbnail_image() runs, in this order:

1. 1
   apply_filters( image_strip_meta )filterline 642 (+39 into the body)

   Filters whether to strip metadata from images when they're resized.

2. 2
   apply_filters( image_max_bit_depth )filterline 800 (+197 into the body)

   Filters the maximum bit depth of resized images.

Uses · 3

• apply_filters()Calls the callback functions that have been added to a filter hook.
• WP_Image_Editor_Imagick::strip_meta()Strips all image meta except color profiles from an image.
• WP_Error::__construct()Initializes the error.

Used by · 2

• WP_Image_Editor_Imagick::crop()Crops Image.
• WP_Image_Editor_Imagick::resize()Resizes current image.

Source code

View on Trac ↗View on GitHub ↗

603	protected function thumbnail_image( $dst_w, $dst_h, $filter_name = 'FILTER_TRIANGLE', $strip_meta = true ) {604		$allowed_filters = array(605			'FILTER_POINT',606			'FILTER_BOX',607			'FILTER_TRIANGLE',608			'FILTER_HERMITE',609			'FILTER_HANNING',610			'FILTER_HAMMING',611			'FILTER_BLACKMAN',612			'FILTER_GAUSSIAN',613			'FILTER_QUADRATIC',614			'FILTER_CUBIC',615			'FILTER_CATROM',616			'FILTER_MITCHELL',617			'FILTER_LANCZOS',618			'FILTER_BESSEL',619			'FILTER_SINC',620		);621 622		/**623		 * Set the filter value if '$filter_name' name is in the allowed list and the related624		 * Imagick constant is defined or fall back to the default filter.625		 */626		if ( in_array( $filter_name, $allowed_filters, true ) && defined( 'Imagick::' . $filter_name ) ) {627			$filter = constant( 'Imagick::' . $filter_name );628		} else {629			$filter = defined( 'Imagick::FILTER_TRIANGLE' ) ? Imagick::FILTER_TRIANGLE : false;630		}631 632		/**633		 * Filters whether to strip metadata from images when they're resized.634		 *635		 * This filter only applies when resizing using the Imagick editor since GD636		 * always strips profiles by default.637		 *638		 * @since 4.5.0639		 *640		 * @param bool $strip_meta Whether to strip image metadata during resizing. Default true.641		 */642		if ( apply_filters( 'image_strip_meta', $strip_meta ) ) {643			$this->strip_meta(); // Fail silently if not supported.644		}645 646		try {647			/**648			 * Special handling for certain types of PNG images:649			 * 1. For PNG images, we need to specify compression settings and remove unneeded chunks.650			 * 2. For indexed PNG images, the number of colors must not exceed 256.651			 * 3. For indexed PNG images with an alpha channel, the tRNS chunk must be preserved.652			 * 4. For indexed PNG images with true alpha transparency (an alpha channel > 1 bit), we need to avoid saving653			 * the image using ImageMagick's 'png8' format,  because that supports only binary (1 bit) transparency.654			 *655			 * For #4 we want to check whether the image has a 1-bit alpha channel before resizing,  because resizing656			 * may cause the number of alpha values to multiply due to antialiasing. If the original image had only a657			 * 1-bit alpha channel, then a 1-bit alpha channel should be good enough for the resized images.658			 *659			 * Perform all the necessary checks before resizing the image and store the results in variables for later use.660			 */661			$is_png                                      = false;662			$is_indexed_png                              = false;663			$is_indexed_png_with_alpha_channel           = false;664			$is_indexed_png_with_true_alpha_transparency = false;665 666			if ( 'image/png' === $this->mime_type ) {667				$is_png = true;668 669				if (670					is_callable( array( $this->image, 'getImageProperty' ) )671					&& '3' === $this->image->getImageProperty( 'png:IHDR.color-type-orig' )672				) {673					$is_indexed_png = true;674 675					if (676						is_callable( array( $this->image, 'getImageAlphaChannel' ) )677						&& $this->image->getImageAlphaChannel()678					) {679						$is_indexed_png_with_alpha_channel = true;680 681						if (682							is_callable( array( $this->image, 'getImageChannelDepth' ) )

Changelog

Introduced in 4.5.0. Unchanged from 6.7.7 through 7.1.0.

1. 6.7.7
2. 6.8.8
3. 6.9.7
4. 7.0.4
5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data

Generated from the wordpress-develop 6.9.7 tag, from src/wp-includes/class-wp-image-editor-imagick.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.

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