pics/models/Thumbnail.php

<?php
/*****************************************************************************
 * Thumbnail.php
 * Contains key class Thumbnail.
 *
 * Kabuki CMS (C) 2013-2020, Aaron van Geffen
 *****************************************************************************/

class Thumbnail
{
	private $image;
	private $image_meta;
	private $thumbnails;

	private $properly_initialised;
	private $width;
	private $height;
	private $crop_mode;

	const CROP_MODE_NONE         = 0;
	const CROP_MODE_BOUNDARY     = 1;
	const CROP_MODE_CUSTOM_FILE  = 2;
	const CROP_MODE_SLICE_TOP    = 3;
	const CROP_MODE_SLICE_CENTRE = 4;
	const CROP_MODE_SLICE_BOTTOM = 5;

	public function __construct(Image $image)
	{
		$this->image      = $image;
		$this->image_meta = $image->getMeta();
		$this->thumbnails = $image->getThumbnails();
	}

	/**
	 * @param width: width of the thumbnail.
	 * @param height: height of the thumbnail.
	 * @param crop: whether and how to crop original image to fit. [false|true|'top'|'center'|'bottom']
	 * @param fit: whether to fit the image to given boundaries [true], or use them merely as an estimate [false].
	 * @param generate: whether or not to generate a thumbnail if no existing file was found.
	 */
	public function getUrl($width, $height, $crop = true, $fit = true, $generate = false)
	{
		$this->init($width, $height, $crop, $fit);

		// Check whether we've already resized this earlier.
		$thumb_selector = $this->width . 'x' . $this->height . $this->filename_suffix;
		if (!empty($this->thumbnails[$thumb_selector]))
		{
			$thumb_filename = $this->image->getSubdir() . '/' . $this->thumbnails[$thumb_selector];
			if (file_exists(THUMBSDIR . '/' . $thumb_filename))
				return THUMBSURL . '/' . $thumb_filename;
		}

		// Do we have a custom thumbnail on file?
		$custom_selector = 'custom_' . $this->width . 'x' . $this->height;
		if (isset($this->image_meta[$custom_selector]))
		{
			$custom_filename = $this->image->getSubdir() . '/' . $this->image_meta[$custom_selector];
			if (file_exists(ASSETSDIR . '/' . $custom_filename))
			{
				// Copy the custom thumbail to the general thumbnail directory.
				copy(ASSETSDIR . '/' . $custom_filename, THUMBSDIR . '/' . $custom_filename);

				// Let's remember this for future reference.
				$this->markAsGenerated($this->image_meta[$custom_selector]);

				return THUMBSURL . '/' . $custom_filename;
			}
			else
				throw new UnexpectedValueException('Custom thumbnail expected, but missing in file system!');
		}

		// Is this the right moment to generate a thumbnail, then?
		if ($generate)
		{
			if (array_key_exists($thumb_selector, $this->thumbnails))
				return $this->generate();
			else
				throw new Exception("Trying to generate a thumbnail not previously queued by the system\n" .
					print_r(func_get_args(), true));
		}

		// If not, queue it for generation at another time, and return a URL to generate it with.
		else
		{
			$this->markAsQueued();
			return BASEURL . '/thumbnail/' . $this->image->getId() . '/' . $thumb_selector . '/';
		}
	}

	/**
	 * @param width: width of the thumbnail.
	 * @param height: height of the thumbnail.
	 * @param crop: whether and how to crop original image to fit. [false|true|'top'|'center'|'bottom']
	 * @param fit: whether to fit the image to given boundaries [true], or use them merely as an estimate [false].
	 */
	private function init($width, $height, $crop = true, $fit = true)
	{
		$this->properly_initialised = false;

		// First, assert the image's dimensions are properly known in the database.
		if ($this->image->width() === null || $this->image->height() === null)
			throw new UnexpectedValueException('Image width or height is undefined -- inconsistent database?');

		$this->width = $width;
		$this->height = $height;

		// Inferring width or height?
		if (!$this->height)
			$this->height = ceil($this->width / $this->image->ratio());
		elseif (!$this->width)
			$this->width = ceil($this->height * $this->image->ratio());

		// Inferring the height from the original image's ratio?
		if (!$fit)
			$this->height = floor($this->width / $this->image->ratio());

		// Assert we have both, now...
		if (empty($this->width) || empty($this->height))
			throw new InvalidArgumentException('Expecting at least either width or height as argument.');

		// If we're cropping, verify we're in the right mode.
		if ($crop)
		{
			// Do we have an exact crop boundary set for these dimensions?
			$crop_selector = 'crop_' . $this->width . 'x' . $this->height;
			if (isset($this->image_meta[$crop_selector]))
				$this->crop_mode = self::CROP_MODE_BOUNDARY;

			// We won't be cropping if the thumbnail is proportional to its original.
			elseif (abs($this->ratio() - $this->image->ratio()) <= 0.025)
				$this->crop_mode = self::CROP_MODE_NONE;

			// If the original image's aspect ratio is much wider, take a slice instead.
			elseif ($this->image->ratio() > $this->ratio())
				$this->crop_mode = self::CROP_MODE_SLICE_CENTRE;

			// Slice from the top?
			elseif ($crop === 'top' || $crop === 'ct')
				$this->crop_mode = self::CROP_MODE_SLICE_TOP;

			// Slice from the bottom?
			elseif ($crop === 'bottom' || $crop === 'cb')
				$this->crop_mode = self::CROP_MODE_SLICE_BOTTOM;

			// Slice from the centre?
			elseif ($crop === 'centre' || $crop === 'center' || $crop === 'cs' || $crop === true)
				$this->crop_mode = self::CROP_MODE_SLICE_CENTRE;

			// Unexpected value? Assume no crop.
			else
				$this->crop_mode = self::CROP_MODE_NONE;
		}
		else
			$this->crop_mode = self::CROP_MODE_NONE;

		// Now, do we need to suffix the filename?
		if ($this->crop_mode !== self::CROP_MODE_NONE)
		{
			$this->filename_suffix = '_c';
			if ($this->crop_mode === self::CROP_MODE_SLICE_TOP)
				$this->filename_suffix .= 't';
			elseif ($this->crop_mode === self::CROP_MODE_SLICE_CENTRE)
				$this->filename_suffix .= 's';
			elseif ($this->crop_mode === self::CROP_MODE_SLICE_BOTTOM)
				$this->filename_suffix .= 'b';
			elseif ($this->crop_mode === self::CROP_MODE_BOUNDARY)
				$this->filename_suffix .= 'e';
		}
		else
			$this->filename_suffix = '';

		$this->properly_initialised = true;
	}

	private function generate()
	{
		if (!$this->properly_initialised)
			throw new UnexpectedValueException('The thumbnail factory was not intialised before use!');

		// Let's try some arcane stuff...
		try
		{
			if (!class_exists('Imagick'))
				throw new Exception("The PHP module 'imagick' appears to be disabled. Please enable it to use image resampling functions.");

			$thumb = new Imagick(ASSETSDIR . '/' . $this->image->getSubdir() . '/' . $this->image->getFilename());

			// The image might have some orientation set through EXIF. Let's apply this first.
			self::applyRotation($thumb);

			// Just resizing? Easy peasy.
			if ($this->crop_mode === self::CROP_MODE_NONE)
				$thumb->resizeImage($this->width, $this->height, Imagick::FILTER_LANCZOS, 1);

			// // Cropping in the center?
			elseif ($this->crop_mode === self::CROP_MODE_SLICE_CENTRE)
				$thumb->cropThumbnailImage($this->width, $this->height);

			// Exact cropping? We can do that.
			elseif ($this->crop_mode === self::CROP_MODE_BOUNDARY)
			{
				$crop_selector = 'crop_' . $this->width . 'x' . $this->height;
				list($crop_width, $crop_height, $crop_x_pos, $crop_y_pos) = explode(',', $this->image_meta[$crop_selector]);
				$thumb->cropImage($crop_width, $crop_height, $crop_x_pos, $crop_y_pos);
				$thumb->resizeImage($this->width, $this->height, Imagick::FILTER_LANCZOS, 1);
			}

			// Advanced cropping? Fun!
			else
			{
				$size = $thumb->getImageGeometry();

				// Taking a horizontal slice from the top or bottom of the original image?
				if ($this->crop_mode === self::CROP_MODE_SLICE_TOP || $this->crop_mode === self::CROP_MODE_SLICE_BOTTOM)
				{
					$crop_width = $size['width'];
					$crop_height = floor($size['width'] / $this->width * $this->height);
					$target_x = 0;
					$target_y = $this->crop_mode === self::CROP_MODE_SLICE_TOP ? 0 : $size['height'] - $crop_height;
				}
				// Otherwise, we're taking a vertical slice from the centre.
				else
				{
					$crop_width = floor($size['height'] / $this->height * $this->width);
					$crop_height = $size['height'];
					$target_x = floor(($size['width'] - $crop_width) / 2);
					$target_y = 0;
				}

				$thumb->cropImage($crop_width, $crop_height, $target_x, $target_y);
				$thumb->resizeImage($this->width, $this->height, Imagick::FILTER_LANCZOS, 1);
			}

			// What sort of image is this? Fall back to PNG if we must.
			switch ($thumb->getImageFormat())
			{
				case 'JPEG':
					$ext = 'jpg';
					break;

				case 'GIF':
					$ext = 'gif';
					break;

				case 'PNG':
				default:
					$thumb->setFormat('PNG');
					$ext = 'png';
					break;
			}

			// So, how do we name this?
			$thumb_filename = substr($this->image->getFilename(), 0, strrpos($this->image->getFilename(), '.')) .
				'_' . $this->width . 'x' . $this->height . $this->filename_suffix . '.' . $ext;

			// Ensure the thumbnail subdirectory exists.
			$target_dir = THUMBSDIR . '/' . $this->image->getSubdir();
			if (!is_dir($target_dir))
				mkdir($target_dir, 0755, true);

			if (!is_writable($target_dir))
				throw new Exception('Thumbnail directory is not writable!');

			// No need to preserve every detail.
			$thumb->setImageCompressionQuality(80);

			// Save it in a public spot.
			$thumb->writeImage($target_dir . '/' . $thumb_filename);

			// Let's remember this for future reference...
			$this->markAsGenerated($thumb_filename);

			$thumb->clear();
			$thumb->destroy();

			// Finally, return the URL for the generated thumbnail image.
			return THUMBSURL . '/' . $this->image->getSubdir() . '/' . $thumb_filename;
		}
		catch (ImagickException $e)
		{
			throw new Exception('ImageMagick error occurred while generating thumbnail. Output: ' . $e->getMessage());
		}
	}

	private static function applyRotation(Imagick $image)
	{
		switch ($image->getImageOrientation())
		{
			// Clockwise rotation
			case Imagick::ORIENTATION_RIGHTTOP:
				$image->rotateImage("#000", 90);
				break;

			// Counter-clockwise rotation
			case Imagick::ORIENTATION_LEFTBOTTOM:
				$image->rotateImage("#000", 270);
				break;

			// Upside down?
			case Imagick::ORIENTATION_BOTTOMRIGHT:
				$image->rotateImage("#000", 180);
		}

		// Having rotated the image, make sure the EXIF data is set properly.
		$image->setImageOrientation(Imagick::ORIENTATION_TOPLEFT);
	}

	private function ratio()
	{
		return $this->width / $this->height;
	}

	private function updateDb($filename)
	{
		if (!$this->properly_initialised)
			throw new UnexpectedValueException('The thumbnail factory was not intialised before use!');

		$mode = !empty($this->filename_suffix) ? substr($this->filename_suffix, 1) : '';
		$success = Registry::get('db')->insert('replace', 'assets_thumbs', [
			'id_asset' => 'int',
			'width' => 'int',
			'height' => 'int',
			'mode' => 'string-3',
			'filename' => 'string-255',
		], [
			'id_asset' => $this->image->getId(),
			'width' => $this->width,
			'height' => $this->height,
			'mode' => $mode,
			'filename' => $filename,
		]);

		if ($success)
		{
			$thumb_selector = $this->width . 'x' . $this->height . $this->filename_suffix;
			$this->thumbnails[$thumb_selector] = $filename !== 'NULL' ? $filename : null;

			// For consistency, write new thumbnail filename to parent Image object.
			// TODO: there could still be an inconsistency if multiple objects exists for the same image asset.
			$this->image->getThumbnails()[$thumb_selector] = $this->thumbnails[$thumb_selector];

			return $success;
		}
		else
			throw new UnexpectedValueException('Thumbnail queuing query failed');
	}

	private function markAsQueued()
	{
		$this->updateDb('NULL');
	}

	private function markAsGenerated($filename)
	{
		$this->updateDb($filename);
	}
}