Current File : /www/varak.net/nextcloud.varak.net/lib/private/Preview/Generator.php
<?php
/**
* SPDX-FileCopyrightText: 2016 Nextcloud GmbH and Nextcloud contributors
* SPDX-License-Identifier: AGPL-3.0-or-later
*/
namespace OC\Preview;
use OCP\EventDispatcher\IEventDispatcher;
use OCP\Files\File;
use OCP\Files\IAppData;
use OCP\Files\InvalidPathException;
use OCP\Files\NotFoundException;
use OCP\Files\NotPermittedException;
use OCP\Files\SimpleFS\ISimpleFile;
use OCP\Files\SimpleFS\ISimpleFolder;
use OCP\IConfig;
use OCP\IImage;
use OCP\IPreview;
use OCP\IStreamImage;
use OCP\Preview\BeforePreviewFetchedEvent;
use OCP\Preview\IProviderV2;
use OCP\Preview\IVersionedPreviewFile;
class Generator {
public const SEMAPHORE_ID_ALL = 0x0a11;
public const SEMAPHORE_ID_NEW = 0x07ea;
/** @var IPreview */
private $previewManager;
/** @var IConfig */
private $config;
/** @var IAppData */
private $appData;
/** @var GeneratorHelper */
private $helper;
/** @var IEventDispatcher */
private $eventDispatcher;
public function __construct(
IConfig $config,
IPreview $previewManager,
IAppData $appData,
GeneratorHelper $helper,
IEventDispatcher $eventDispatcher
) {
$this->config = $config;
$this->previewManager = $previewManager;
$this->appData = $appData;
$this->helper = $helper;
$this->eventDispatcher = $eventDispatcher;
}
/**
* Returns a preview of a file
*
* The cache is searched first and if nothing usable was found then a preview is
* generated by one of the providers
*
* @param File $file
* @param int $width
* @param int $height
* @param bool $crop
* @param string $mode
* @param string|null $mimeType
* @return ISimpleFile
* @throws NotFoundException
* @throws \InvalidArgumentException if the preview would be invalid (in case the original image is invalid)
*/
public function getPreview(File $file, $width = -1, $height = -1, $crop = false, $mode = IPreview::MODE_FILL, $mimeType = null) {
$specification = [
'width' => $width,
'height' => $height,
'crop' => $crop,
'mode' => $mode,
];
$this->eventDispatcher->dispatchTyped(new BeforePreviewFetchedEvent(
$file,
$width,
$height,
$crop,
$mode,
));
// since we only ask for one preview, and the generate method return the last one it created, it returns the one we want
return $this->generatePreviews($file, [$specification], $mimeType);
}
/**
* Generates previews of a file
*
* @param File $file
* @param non-empty-array $specifications
* @param string $mimeType
* @return ISimpleFile the last preview that was generated
* @throws NotFoundException
* @throws \InvalidArgumentException if the preview would be invalid (in case the original image is invalid)
*/
public function generatePreviews(File $file, array $specifications, $mimeType = null) {
//Make sure that we can read the file
if (!$file->isReadable()) {
throw new NotFoundException('Cannot read file');
}
if ($mimeType === null) {
$mimeType = $file->getMimeType();
}
$previewFolder = $this->getPreviewFolder($file);
// List every existing preview first instead of trying to find them one by one
$previewFiles = $previewFolder->getDirectoryListing();
$previewVersion = '';
if ($file instanceof IVersionedPreviewFile) {
$previewVersion = $file->getPreviewVersion() . '-';
}
// Get the max preview and infer the max preview sizes from that
$maxPreview = $this->getMaxPreview($previewFolder, $previewFiles, $file, $mimeType, $previewVersion);
$maxPreviewImage = null; // only load the image when we need it
if ($maxPreview->getSize() === 0) {
$maxPreview->delete();
throw new NotFoundException('Max preview size 0, invalid!');
}
[$maxWidth, $maxHeight] = $this->getPreviewSize($maxPreview, $previewVersion);
if ($maxWidth <= 0 || $maxHeight <= 0) {
throw new NotFoundException('The maximum preview sizes are zero or less pixels');
}
$preview = null;
foreach ($specifications as $specification) {
$width = $specification['width'] ?? -1;
$height = $specification['height'] ?? -1;
$crop = $specification['crop'] ?? false;
$mode = $specification['mode'] ?? IPreview::MODE_FILL;
// If both width and height are -1 we just want the max preview
if ($width === -1 && $height === -1) {
$width = $maxWidth;
$height = $maxHeight;
}
// Calculate the preview size
[$width, $height] = $this->calculateSize($width, $height, $crop, $mode, $maxWidth, $maxHeight);
// No need to generate a preview that is just the max preview
if ($width === $maxWidth && $height === $maxHeight) {
// ensure correct return value if this was the last one
$preview = $maxPreview;
continue;
}
// Try to get a cached preview. Else generate (and store) one
try {
try {
$preview = $this->getCachedPreview($previewFiles, $width, $height, $crop, $maxPreview->getMimeType(), $previewVersion);
} catch (NotFoundException $e) {
if (!$this->previewManager->isMimeSupported($mimeType)) {
throw new NotFoundException();
}
if ($maxPreviewImage === null) {
$maxPreviewImage = $this->helper->getImage($maxPreview);
}
$preview = $this->generatePreview($previewFolder, $maxPreviewImage, $width, $height, $crop, $maxWidth, $maxHeight, $previewVersion);
// New file, augment our array
$previewFiles[] = $preview;
}
} catch (\InvalidArgumentException $e) {
throw new NotFoundException("", 0, $e);
}
if ($preview->getSize() === 0) {
$preview->delete();
throw new NotFoundException('Cached preview size 0, invalid!');
}
}
assert($preview !== null);
// Free memory being used by the embedded image resource. Without this the image is kept in memory indefinitely.
// Garbage Collection does NOT free this memory. We have to do it ourselves.
if ($maxPreviewImage instanceof \OCP\Image) {
$maxPreviewImage->destroy();
}
return $preview;
}
/**
* Acquire a semaphore of the specified id and concurrency, blocking if necessary.
* Return an identifier of the semaphore on success, which can be used to release it via
* {@see Generator::unguardWithSemaphore()}.
*
* @param int $semId
* @param int $concurrency
* @return false|\SysvSemaphore the semaphore on success or false on failure
*/
public static function guardWithSemaphore(int $semId, int $concurrency) {
if (!extension_loaded('sysvsem')) {
return false;
}
$sem = sem_get($semId, $concurrency);
if ($sem === false) {
return false;
}
if (!sem_acquire($sem)) {
return false;
}
return $sem;
}
/**
* Releases the semaphore acquired from {@see Generator::guardWithSemaphore()}.
*
* @param false|\SysvSemaphore $semId the semaphore identifier returned by guardWithSemaphore
* @return bool
*/
public static function unguardWithSemaphore(false|\SysvSemaphore $semId): bool {
if ($semId === false || !($semId instanceof \SysvSemaphore)) {
return false;
}
return sem_release($semId);
}
/**
* Get the number of concurrent threads supported by the host.
*
* @return int number of concurrent threads, or 0 if it cannot be determined
*/
public static function getHardwareConcurrency(): int {
static $width;
if (!isset($width)) {
if (function_exists('ini_get')) {
$openBasedir = ini_get('open_basedir');
if (empty($openBasedir) || strpos($openBasedir, '/proc/cpuinfo') !== false) {
$width = is_readable('/proc/cpuinfo') ? substr_count(file_get_contents('/proc/cpuinfo'), 'processor') : 0;
} else {
$width = 0;
}
} else {
$width = 0;
}
}
return $width;
}
/**
* Get number of concurrent preview generations from system config
*
* Two config entries, `preview_concurrency_new` and `preview_concurrency_all`,
* are available. If not set, the default values are determined with the hardware concurrency
* of the host. In case the hardware concurrency cannot be determined, or the user sets an
* invalid value, fallback values are:
* For new images whose previews do not exist and need to be generated, 4;
* For all preview generation requests, 8.
* Value of `preview_concurrency_all` should be greater than or equal to that of
* `preview_concurrency_new`, otherwise, the latter is returned.
*
* @param string $type either `preview_concurrency_new` or `preview_concurrency_all`
* @return int number of concurrent preview generations, or -1 if $type is invalid
*/
public function getNumConcurrentPreviews(string $type): int {
static $cached = [];
if (array_key_exists($type, $cached)) {
return $cached[$type];
}
$hardwareConcurrency = self::getHardwareConcurrency();
switch ($type) {
case "preview_concurrency_all":
$fallback = $hardwareConcurrency > 0 ? $hardwareConcurrency * 2 : 8;
$concurrency_all = $this->config->getSystemValueInt($type, $fallback);
$concurrency_new = $this->getNumConcurrentPreviews("preview_concurrency_new");
$cached[$type] = max($concurrency_all, $concurrency_new);
break;
case "preview_concurrency_new":
$fallback = $hardwareConcurrency > 0 ? $hardwareConcurrency : 4;
$cached[$type] = $this->config->getSystemValueInt($type, $fallback);
break;
default:
return -1;
}
return $cached[$type];
}
/**
* @param ISimpleFolder $previewFolder
* @param ISimpleFile[] $previewFiles
* @param File $file
* @param string $mimeType
* @param string $prefix
* @return ISimpleFile
* @throws NotFoundException
*/
private function getMaxPreview(ISimpleFolder $previewFolder, array $previewFiles, File $file, $mimeType, $prefix) {
// We don't know the max preview size, so we can't use getCachedPreview.
// It might have been generated with a higher resolution than the current value.
foreach ($previewFiles as $node) {
$name = $node->getName();
if (($prefix === '' || str_starts_with($name, $prefix)) && strpos($name, 'max')) {
return $node;
}
}
$maxWidth = $this->config->getSystemValueInt('preview_max_x', 4096);
$maxHeight = $this->config->getSystemValueInt('preview_max_y', 4096);
return $this->generateProviderPreview($previewFolder, $file, $maxWidth, $maxHeight, false, true, $mimeType, $prefix);
}
private function generateProviderPreview(ISimpleFolder $previewFolder, File $file, int $width, int $height, bool $crop, bool $max, string $mimeType, string $prefix) {
$previewProviders = $this->previewManager->getProviders();
foreach ($previewProviders as $supportedMimeType => $providers) {
// Filter out providers that does not support this mime
if (!preg_match($supportedMimeType, $mimeType)) {
continue;
}
foreach ($providers as $providerClosure) {
$provider = $this->helper->getProvider($providerClosure);
if (!($provider instanceof IProviderV2)) {
continue;
}
if (!$provider->isAvailable($file)) {
continue;
}
$previewConcurrency = $this->getNumConcurrentPreviews('preview_concurrency_new');
$sem = self::guardWithSemaphore(self::SEMAPHORE_ID_NEW, $previewConcurrency);
try {
$preview = $this->helper->getThumbnail($provider, $file, $width, $height);
} finally {
self::unguardWithSemaphore($sem);
}
if (!($preview instanceof IImage)) {
continue;
}
$path = $this->generatePath($preview->width(), $preview->height(), $crop, $max, $preview->dataMimeType(), $prefix);
try {
$file = $previewFolder->newFile($path);
if ($preview instanceof IStreamImage) {
$file->putContent($preview->resource());
} else {
$file->putContent($preview->data());
}
} catch (NotPermittedException $e) {
throw new NotFoundException();
}
return $file;
}
}
throw new NotFoundException('No provider successfully handled the preview generation');
}
/**
* @param ISimpleFile $file
* @param string $prefix
* @return int[]
*/
private function getPreviewSize(ISimpleFile $file, string $prefix = '') {
$size = explode('-', substr($file->getName(), strlen($prefix)));
return [(int)$size[0], (int)$size[1]];
}
/**
* @param int $width
* @param int $height
* @param bool $crop
* @param bool $max
* @param string $mimeType
* @param string $prefix
* @return string
*/
private function generatePath($width, $height, $crop, $max, $mimeType, $prefix) {
$path = $prefix . (string)$width . '-' . (string)$height;
if ($crop) {
$path .= '-crop';
}
if ($max) {
$path .= '-max';
}
$ext = $this->getExtension($mimeType);
$path .= '.' . $ext;
return $path;
}
/**
* @param int $width
* @param int $height
* @param bool $crop
* @param string $mode
* @param int $maxWidth
* @param int $maxHeight
* @return int[]
*/
private function calculateSize($width, $height, $crop, $mode, $maxWidth, $maxHeight) {
/*
* If we are not cropping we have to make sure the requested image
* respects the aspect ratio of the original.
*/
if (!$crop) {
$ratio = $maxHeight / $maxWidth;
if ($width === -1) {
$width = $height / $ratio;
}
if ($height === -1) {
$height = $width * $ratio;
}
$ratioH = $height / $maxHeight;
$ratioW = $width / $maxWidth;
/*
* Fill means that the $height and $width are the max
* Cover means min.
*/
if ($mode === IPreview::MODE_FILL) {
if ($ratioH > $ratioW) {
$height = $width * $ratio;
} else {
$width = $height / $ratio;
}
} elseif ($mode === IPreview::MODE_COVER) {
if ($ratioH > $ratioW) {
$width = $height / $ratio;
} else {
$height = $width * $ratio;
}
}
}
if ($height !== $maxHeight && $width !== $maxWidth) {
/*
* Scale to the nearest power of four
*/
$pow4height = 4 ** ceil(log($height) / log(4));
$pow4width = 4 ** ceil(log($width) / log(4));
// Minimum size is 64
$pow4height = max($pow4height, 64);
$pow4width = max($pow4width, 64);
$ratioH = $height / $pow4height;
$ratioW = $width / $pow4width;
if ($ratioH < $ratioW) {
$width = $pow4width;
$height /= $ratioW;
} else {
$height = $pow4height;
$width /= $ratioH;
}
}
/*
* Make sure the requested height and width fall within the max
* of the preview.
*/
if ($height > $maxHeight) {
$ratio = $height / $maxHeight;
$height = $maxHeight;
$width /= $ratio;
}
if ($width > $maxWidth) {
$ratio = $width / $maxWidth;
$width = $maxWidth;
$height /= $ratio;
}
return [(int)round($width), (int)round($height)];
}
/**
* @param ISimpleFolder $previewFolder
* @param ISimpleFile $maxPreview
* @param int $width
* @param int $height
* @param bool $crop
* @param int $maxWidth
* @param int $maxHeight
* @param string $prefix
* @return ISimpleFile
* @throws NotFoundException
* @throws \InvalidArgumentException if the preview would be invalid (in case the original image is invalid)
*/
private function generatePreview(ISimpleFolder $previewFolder, IImage $maxPreview, $width, $height, $crop, $maxWidth, $maxHeight, $prefix) {
$preview = $maxPreview;
if (!$preview->valid()) {
throw new \InvalidArgumentException('Failed to generate preview, failed to load image');
}
$previewConcurrency = $this->getNumConcurrentPreviews('preview_concurrency_new');
$sem = self::guardWithSemaphore(self::SEMAPHORE_ID_NEW, $previewConcurrency);
try {
if ($crop) {
if ($height !== $preview->height() && $width !== $preview->width()) {
//Resize
$widthR = $preview->width() / $width;
$heightR = $preview->height() / $height;
if ($widthR > $heightR) {
$scaleH = $height;
$scaleW = $maxWidth / $heightR;
} else {
$scaleH = $maxHeight / $widthR;
$scaleW = $width;
}
$preview = $preview->preciseResizeCopy((int)round($scaleW), (int)round($scaleH));
}
$cropX = (int)floor(abs($width - $preview->width()) * 0.5);
$cropY = (int)floor(abs($height - $preview->height()) * 0.5);
$preview = $preview->cropCopy($cropX, $cropY, $width, $height);
} else {
$preview = $maxPreview->resizeCopy(max($width, $height));
}
} finally {
self::unguardWithSemaphore($sem);
}
$path = $this->generatePath($width, $height, $crop, false, $preview->dataMimeType(), $prefix);
try {
$file = $previewFolder->newFile($path);
$file->putContent($preview->data());
} catch (NotPermittedException $e) {
throw new NotFoundException();
}
return $file;
}
/**
* @param ISimpleFile[] $files Array of FileInfo, as the result of getDirectoryListing()
* @param int $width
* @param int $height
* @param bool $crop
* @param string $mimeType
* @param string $prefix
* @return ISimpleFile
*
* @throws NotFoundException
*/
private function getCachedPreview($files, $width, $height, $crop, $mimeType, $prefix) {
$path = $this->generatePath($width, $height, $crop, false, $mimeType, $prefix);
foreach ($files as $file) {
if ($file->getName() === $path) {
return $file;
}
}
throw new NotFoundException();
}
/**
* Get the specific preview folder for this file
*
* @param File $file
* @return ISimpleFolder
*
* @throws InvalidPathException
* @throws NotFoundException
* @throws NotPermittedException
*/
private function getPreviewFolder(File $file) {
// Obtain file id outside of try catch block to prevent the creation of an existing folder
$fileId = (string)$file->getId();
try {
$folder = $this->appData->getFolder($fileId);
} catch (NotFoundException $e) {
$folder = $this->appData->newFolder($fileId);
}
return $folder;
}
/**
* @param string $mimeType
* @return null|string
* @throws \InvalidArgumentException
*/
private function getExtension($mimeType) {
switch ($mimeType) {
case 'image/png':
return 'png';
case 'image/jpeg':
return 'jpg';
case 'image/webp':
return 'webp';
case 'image/gif':
return 'gif';
default:
throw new \InvalidArgumentException('Not a valid mimetype: "' . $mimeType . '"');
}
}
}
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