wp-optimize / vendor / rosell-dk / webp-convert / src / Convert / Helpers / JpegQualityDetector.php

JpegQualityDetector.php in WP-Optimize – Cache, Compress images, Minify & Clean database to boost page speed & performance 3.6.0, at vendor/rosell-dk/webp-convert/src/Convert/Helpers/JpegQualityDetector.php

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1	<?php
2
3	namespace WebPConvert\Convert\Helpers;
4
5	use ExecWithFallback\ExecWithFallback;
6
7	/**
8	* Try to detect quality of a jpeg image using various tools.
9	*
10	* @package WebPConvert
11	* @author Bjørn Rosell <[email protected]>
12	* @since Class available since Release 2.0.0
13	*/
14	class JpegQualityDetector
15	{
16
17	/**
18	* Try to detect quality of jpeg using imagick extension.
19	*
20	* Note that the detection might fail for two different reasons:
21	* 1) Imagick is not installed
22	* 2) Imagick for some reason fails to detect quality for some images
23	*
24	* In both cases, null is returned.
25	*
26	* @param string $filename A complete file path to file to be examined
27	* @return int\|null Quality, or null if it was not possible to detect quality
28	*/
29	private static function detectQualityOfJpgUsingImagick($filename)
30	{
31	if (extension_loaded('imagick') && class_exists('\\Imagick')) {
32	try {
33	$img = new \Imagick($filename);
34
35	// The required function is available as from PECL imagick v2.2.2
36	if (method_exists($img, 'getImageCompressionQuality')) {
37	$quality = $img->getImageCompressionQuality();
38	if ($quality === 0) {
39	// We have experienced that this Imagick method returns 0 for some images,
40	// (even though the imagemagick binary is able to detect the quality)
41	// ie "/test/images/quality-undetectable-with-imagick.jpg". See #208
42	$quality = null;
43	}
44	return $quality;
45	}
46	} catch (\Exception $e) {
47	// Well well, it just didn't work out.
48	// - But perhaps next method will work...
49	} catch (\Throwable $e) {
50	}
51	}
52	return null;
53	}
54
55
56	/**
57	* Try to detect quality of jpeg using imagick binary.
58	*
59	* Note that the detection might fail for three different reasons:
60	* 1) exec function is not available
61	* 2) the 'identify' command is not available on the system
62	* 3) imagemagick for some reason fails to detect quality for some images
63	*
64	* In the first two cases, null is returned.
65	* In the third case, 92 is returned. This is what imagemagick returns when it cannot detect the quality.
66	* and unfortunately we cannot distinguish between the situation where the quality is undetectable
67	* and the situation where the quality is actually 92 (at least, I have not found a way to do so)
68	*
69	* @param string $filename A complete file path to file to be examined
70	* @return int\|null Quality, or null if it was not possible to detect quality
71	*/
72	private static function detectQualityOfJpgUsingImageMagick($filename)
73	{
74	if (ExecWithFallback::anyAvailable()) {
75	// Try Imagick using exec, and routing stderr to stdout (the "2>$1" magic)
76
77	try {
78	ExecWithFallback::exec(
79	"identify -format '%Q' " . escapeshellarg($filename) . " 2>&1",
80	$output,
81	$returnCode
82	);
83	//echo 'out:' . print_r($output, true);
84	if ((intval($returnCode) == 0) && (is_array($output)) && (count($output) == 1)) {
85	return intval($output[0]);
86	}
87	} catch (\Exception $e) {
88	// its ok, there are other fish in the sea
89	} catch (\Throwable $e) {
90	}
91	}
92	return null;
93	}
94
95
96	/**
97	* Try to detect quality of jpeg using graphicsmagick binary.
98	*
99	* It seems that graphicsmagick is never able to detect the quality! - and always returns
100	* the default quality, which is 75.
101	* However, as this might be solved in future versions, the method might be useful one day.
102	* But we treat "75" as a failure to detect and shall return null in that case.
103	*
104	* @param string $filename A complete file path to file to be examined
105	* @return int\|null Quality, or null if it was not possible to detect quality
106	*/
107	private static function detectQualityOfJpgUsingGraphicsMagick($filename)
108	{
109	if (ExecWithFallback::anyAvailable()) {
110	// Try GraphicsMagick
111	try {
112	ExecWithFallback::exec(
113	"gm identify -format '%Q' " . escapeshellarg($filename) . " 2>&1",
114	$output,
115	$returnCode
116	);
117	if ((intval($returnCode) == 0) && (is_array($output)) && (count($output) == 1)) {
118	$quality = intval($output[0]);
119
120	// It seems that graphicsmagick is (currently) never able to detect the quality!
121	// - and always returns 75 as a fallback
122	// We shall therefore treat 75 as a failure to detect. (#209)
123	if ($quality == 75) {
124	return null;
125	}
126	return $quality;
127	}
128	} catch (\Exception $e) {
129	} catch (\Throwable $e) {
130	}
131	}
132	return null;
133	}
134
135
136	/**
137	* Try to detect quality of jpeg.
138	*
139	* Note: This method does not throw errors, but might dispatch warnings.
140	* You can use the WarningsIntoExceptions class if it is critical to you that nothing gets "printed"
141	*
142	* @param string $filename A complete file path to file to be examined
143	* @return int\|null Quality, or null if it was not possible to detect quality
144	*/
145	public static function detectQualityOfJpg($filename)
146	{
147
148	//trigger_error('warning test', E_USER_WARNING);
149
150	// Test that file exists in order not to break things.
151	if (!file_exists($filename)) {
152	// One could argue that it would be better to throw an Exception...?
153	return null;
154	}
155
156	// Try Imagick extension, if available
157	$quality = self::detectQualityOfJpgUsingImagick($filename);
158
159	if (is_null($quality)) {
160	$quality = self::detectQualityOfJpgUsingImageMagick($filename);
161	}
162
163	if (is_null($quality)) {
164	$quality = self::detectQualityOfJpgUsingGraphicsMagick($filename);
165	}
166
167	return $quality;
168	}
169	}
170