Fix max preview, some resizing and caching issues and force preview providers to resize their previews properly

* introduces a method in OC_Image which doesn't stretch images when trying to make them fit in a box
* adds the method to all key providers so that they can do their job, as expected by the Preview class
* improves the caching mechanism of Preview in order to reduce I/O and to avoid filling the available disk space
* fixes some long standing issues
* **contains mostly tests**

lib/private/image.php

@@ -952,6 +952,8 @@ class OC_Image implements \OCP\IImage {
 	/**
 	 * Resizes the image to fit within a boundary while preserving ratio.
 	 *
+	 * Warning: Images smaller than $maxWidth x $maxHeight will end up being scaled up
+	 *
 	 * @param integer $maxWidth
 	 * @param integer $maxHeight
 	 * @return bool
@@ -972,6 +974,24 @@ class OC_Image implements \OCP\IImage {
 		return true;
 	}
 
+	/**
+	 * Shrinks larger images to fit within specified boundaries while preserving ratio.
+	 *
+	 * @param integer $maxWidth
+	 * @param integer $maxHeight
+	 * @return bool
+	 */
+	public function scaleDownToFit($maxWidth, $maxHeight) {
+		$widthOrig = imageSX($this->resource);
+		$heightOrig = imageSY($this->resource);
+
+		if ($widthOrig > $maxWidth || $heightOrig >$maxHeight) {
+			return $this->fitIn($maxWidth, $maxHeight);
+		}
+
+		return false;
+	}
+
 	/**
 	 * Destroys the current image and resets the object
 	 */

lib/private/preview/image.php

@@ -33,7 +33,7 @@ abstract class Image extends Provider {
 	public function getThumbnail($path, $maxX, $maxY, $scalingup, $fileview) {
 		//get fileinfo
 		$fileInfo = $fileview->getFileInfo($path);
-		if(!$fileInfo) {
+		if (!$fileInfo) {
 			return false;
 		}
 
@@ -46,15 +46,19 @@ abstract class Image extends Provider {
 
 		$image = new \OC_Image();
 
-		if($fileInfo['encrypted'] === true) {
+		if ($fileInfo['encrypted'] === true) {
 			$fileName = $fileview->toTmpFile($path);
 		} else {
 			$fileName = $fileview->getLocalFile($path);
 		}
 		$image->loadFromFile($fileName);
 		$image->fixOrientation();
+		if ($image->valid()) {
+			$image->scaleDownToFit($maxX, $maxY);
 
-		return $image->valid() ? $image : false;
+			return $image;
+		}
+		return false;
 	}
 
 }

lib/private/preview/movie.php

@@ -91,7 +91,6 @@ class Movie extends Provider {
 			$cmd = self::$ffmpegBinary . ' -y -ss ' . escapeshellarg($second) .
 				' -i ' . escapeshellarg($absPath) .
 				' -f mjpeg -vframes 1' .
-				' -s ' . escapeshellarg($maxX) . 'x' . escapeshellarg($maxY) .
 				' ' . escapeshellarg($tmpPath) .
 				' > /dev/null 2>&1';
 		}
@@ -102,7 +101,11 @@ class Movie extends Provider {
 			$image = new \OC_Image();
 			$image->loadFromFile($tmpPath);
 			unlink($tmpPath);
-			return $image->valid() ? $image : false;
+			if ($image->valid()) {
+				$image->scaleDownToFit($maxX, $maxY);
+
+				return $image;
+			}
 		}
 		unlink($tmpPath);
 		return false;

lib/private/preview/mp3.php

@@ -47,7 +47,12 @@ class MP3 extends Provider {
 			unlink($tmpPath);
 			$image = new \OC_Image();
 			$image->loadFromData($picture);
-			return $image->valid() ? $image : $this->getNoCoverThumbnail();
+
+			if ($image->valid()) {
+				$image->scaleDownToFit($maxX, $maxY);
+
+				return $image;
+			}
 		}
 
 		return $this->getNoCoverThumbnail();

lib/private/preview/office.php

@@ -29,7 +29,7 @@ abstract class Office extends Provider {
 	 */
 	public function getThumbnail($path, $maxX, $maxY, $scalingup, $fileview) {
 		$this->initCmd();
-		if(is_null($this->cmd)) {
+		if (is_null($this->cmd)) {
 			return false;
 		}
 
@@ -37,7 +37,7 @@ abstract class Office extends Provider {
 
 		$tmpDir = get_temp_dir();
 
-		$defaultParameters = ' -env:UserInstallation=file://' . escapeshellarg($tmpDir . '/owncloud-' . \OC_Util::getInstanceId().'/') . ' --headless --nologo --nofirststartwizard --invisible --norestore --convert-to pdf --outdir ';
+		$defaultParameters = ' -env:UserInstallation=file://' . escapeshellarg($tmpDir . '/owncloud-' . \OC_Util::getInstanceId() . '/') . ' --headless --nologo --nofirststartwizard --invisible --norestore --convert-to pdf --outdir ';
 		$clParameters = \OCP\Config::getSystemValue('preview_office_cl_parameters', $defaultParameters);
 
 		$exec = $this->cmd . $clParameters . escapeshellarg($tmpDir) . ' ' . escapeshellarg($absPath);
@@ -46,8 +46,8 @@ abstract class Office extends Provider {
 
 		//create imagick object from pdf
 		$pdfPreview = null;
-		try{
-			list( $dirname, , , $filename ) = array_values( pathinfo($absPath) );
+		try {
+			list($dirname, , , $filename) = array_values(pathinfo($absPath));
 			$pdfPreview = $dirname . '/' . $filename . '.pdf';
 
 			$pdf = new \imagick($pdfPreview . '[0]');
@@ -65,27 +65,33 @@ abstract class Office extends Provider {
 		unlink($absPath);
 		unlink($pdfPreview);
 
-		return $image->valid() ? $image : false;
+		if ($image->valid()) {
+			$image->scaleDownToFit($maxX, $maxY);
+
+			return $image;
+		}
+		return false;
+
 	}
 
 	private function initCmd() {
 		$cmd = '';
 
-		if(is_string(\OC_Config::getValue('preview_libreoffice_path', null))) {
+		if (is_string(\OC_Config::getValue('preview_libreoffice_path', null))) {
 			$cmd = \OC_Config::getValue('preview_libreoffice_path', null);
 		}
 
 		$whichLibreOffice = shell_exec('command -v libreoffice');
-		if($cmd === '' && !empty($whichLibreOffice)) {
+		if ($cmd === '' && !empty($whichLibreOffice)) {
 			$cmd = 'libreoffice';
 		}
 
 		$whichOpenOffice = shell_exec('command -v openoffice');
-		if($cmd === '' && !empty($whichOpenOffice)) {
+		if ($cmd === '' && !empty($whichOpenOffice)) {
 			$cmd = 'openoffice';
 		}
 
-		if($cmd === '') {
+		if ($cmd === '') {
 			$cmd = null;
 		}
 

lib/private/preview/provider.php

@@ -1,7 +1,6 @@
 <?php
 /**
  * @author Georg Ehrke <georg@owncloud.com>
- * @author Georg Ehrke <georg@ownCloud.com>
  * @author Joas Schilling <nickvergessen@owncloud.com>
  * @author Jörn Friedrich Dreyer <jfd@butonic.de>
  * @author Robin Appelman <icewind@owncloud.com>
@@ -54,7 +53,8 @@ abstract class Provider implements IProvider {
 	}
 
 	/**
-	 * get thumbnail for file at path $path
+	 * Generates thumbnail which fits in $maxX and $maxY and keeps the aspect ratio, for file at path $path
+	 *
 	 * @param string $path Path of file
 	 * @param int $maxX The maximum X size of the thumbnail. It can be smaller depending on the shape of the image
 	 * @param int $maxY The maximum Y size of the thumbnail. It can be smaller depending on the shape of the image

lib/private/preview/svg.php

@@ -35,17 +35,17 @@ class SVG extends Provider {
 	 * {@inheritDoc}
 	 */
 	public function getThumbnail($path, $maxX, $maxY, $scalingup, $fileview) {
-		try{
+		try {
 			$svg = new \Imagick();
 			$svg->setBackgroundColor(new \ImagickPixel('transparent'));
 
 			$content = stream_get_contents($fileview->fopen($path, 'r'));
-			if(substr($content, 0, 5) !== '<?xml') {
+			if (substr($content, 0, 5) !== '<?xml') {
 				$content = '<?xml version="1.0" encoding="UTF-8" standalone="no"?>' . $content;
 			}
 
 			// Do not parse SVG files with references
-			if(stripos($content, 'xlink:href') !== false) {
+			if (stripos($content, 'xlink:href') !== false) {
 				return false;
 			}
 
@@ -60,6 +60,11 @@ class SVG extends Provider {
 		$image = new \OC_Image();
 		$image->loadFromData($svg);
 		//check if image object is valid
-		return $image->valid() ? $image : false;
+		if ($image->valid()) {
+			$image->scaleDownToFit($maxX, $maxY);
+
+			return $image;
+		}
+		return false;
 	}
 }

lib/public/iimage.php

@@ -170,4 +170,14 @@ interface IImage {
 	 * @since 8.1.0
 	 */
 	public function fitIn($maxWidth, $maxHeight);
+
+	/**
+	 * Shrinks the image to fit within a boundary while preserving ratio.
+	 *
+	 * @param integer $maxWidth
+	 * @param integer $maxHeight
+	 * @return bool
+	 * @since 8.1.0
+	 */
+	public function scaleDownToFit($maxWidth, $maxHeight);
 }

tests/data/testimage.eps

@@ -0,0 +1,175 @@
+%!PS-Adobe-3.0 EPSF-3.0
+%%Creator: cairo 1.14.1 (http://cairographics.org)
+%%CreationDate: Fri May 15 16:27:38 2015
+%%Pages: 1
+%%DocumentData: Clean7Bit
+%%LanguageLevel: 2
+%%BoundingBox: 0 -1 2400 1706
+%%EndComments
+%%BeginProlog
+save
+50 dict begin
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+/w { setlinewidth } bind def
+/J { setlinecap } bind def
+/j { setlinejoin } bind def
+/M { setmiterlimit } bind def
+/d { setdash } bind def
+/m { moveto } bind def
+/l { lineto } bind def
+/c { curveto } bind def
+/h { closepath } bind def
+/re { exch dup neg 3 1 roll 5 3 roll moveto 0 rlineto
+      0 exch rlineto 0 rlineto closepath } bind def
+/S { stroke } bind def
+/f { fill } bind def
+/f* { eofill } bind def
+/n { newpath } bind def
+/W { clip } bind def
+/W* { eoclip } bind def
+/BT { } bind def
+/ET { } bind def
+/pdfmark where { pop globaldict /?pdfmark /exec load put }
+    { globaldict begin /?pdfmark /pop load def /pdfmark
+    /cleartomark load def end } ifelse
+/BDC { mark 3 1 roll /BDC pdfmark } bind def
+/EMC { mark /EMC pdfmark } bind def
+/cairo_store_point { /cairo_point_y exch def /cairo_point_x exch def } def
+/Tj { show currentpoint cairo_store_point } bind def
+/TJ {
+  {
+    dup
+    type /stringtype eq
+    { show } { -0.001 mul 0 cairo_font_matrix dtransform rmoveto } ifelse
+  } forall
+  currentpoint cairo_store_point
+} bind def
+/cairo_selectfont { cairo_font_matrix aload pop pop pop 0 0 6 array astore
+    cairo_font exch selectfont cairo_point_x cairo_point_y moveto } bind def
+/Tf { pop /cairo_font exch def /cairo_font_matrix where
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+/g { setgray } bind def
+/rg { setrgbcolor } bind def
+/d1 { setcachedevice } bind def
+%%EndProlog
+%%BeginSetup
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+Q Q
+showpage
+%%Trailer
+end restore
+%%EOF

tests/lib/image.php

@@ -238,21 +238,81 @@ class Test_Image extends \Test\TestCase {
 		$this->assertEquals(15, $img->height());
 	}
 
-	public function testFitIn() {
-		$img = new \OC_Image(OC::$SERVERROOT.'/tests/data/testimage.png');
-		$this->assertTrue($img->fitIn(200, 100));
-		$this->assertEquals(100, $img->width());
-		$this->assertEquals(100, $img->height());
+	public static function sampleProvider() {
+		return [
+			['testimage.png', [200, 100], [100, 100]],
+			['testimage.jpg', [840, 840], [840, 525]],
+			['testimage.gif', [200, 250], [200, 200]]
+		];
+	}
 
-		$img = new \OC_Image(file_get_contents(OC::$SERVERROOT.'/tests/data/testimage.jpg'));
-		$this->assertTrue($img->fitIn(840, 840));
-		$this->assertEquals(840, $img->width());
-		$this->assertEquals(525, $img->height());
+	/**
+	 * @dataProvider sampleProvider
+	 *
+	 * @param string $filename
+	 * @param int[] $asked
+	 * @param int[] $expected
+	 */
+	public function testFitIn($filename, $asked, $expected) {
+		$img = new \OC_Image(OC::$SERVERROOT . '/tests/data/' . $filename);
+		$this->assertTrue($img->fitIn($asked[0], $asked[1]));
+		$this->assertEquals($expected[0], $img->width());
+		$this->assertEquals($expected[1], $img->height());
+	}
 
-		$img = new \OC_Image(base64_encode(file_get_contents(OC::$SERVERROOT.'/tests/data/testimage.gif')));
-		$this->assertTrue($img->fitIn(200, 250));
-		$this->assertEquals(200, $img->width());
-		$this->assertEquals(200, $img->height());
+	public static function sampleFilenamesProvider() {
+		return [
+			['testimage.png'],
+			['testimage.jpg'],
+			['testimage.gif']
+		];
+	}
+
+	/**
+	 * Image should not be resized if it's already smaller than what is required
+	 *
+	 * @dataProvider sampleFilenamesProvider
+	 *
+	 * @param string $filename
+	 */
+	public function testScaleDownToFitWhenSmallerAlready($filename) {
+		$img = new \OC_Image(OC::$SERVERROOT . '/tests/data/' . $filename);
+		$currentWidth = $img->width();
+		$currentHeight = $img->height();
+		// We pick something larger than the image we want to scale down
+		$this->assertFalse($img->scaleDownToFit(4000, 4000));
+		// The dimensions of the image should not have changed since it's smaller already
+		$resizedWidth = $img->width();
+		$resizedHeight = $img->height();
+		$this->assertEquals(
+			$currentWidth, $img->width(), "currentWidth $currentWidth resizedWidth $resizedWidth \n"
+		);
+		$this->assertEquals(
+			$currentHeight, $img->height(),
+			"currentHeight $currentHeight resizedHeight $resizedHeight \n"
+		);
+	}
+
+	public static function largeSampleProvider() {
+		return [
+			['testimage.png', [200, 100], [100, 100]],
+			['testimage.jpg', [840, 840], [840, 525]],
+		];
+	}
+
+	/**
+	 * @dataProvider largeSampleProvider
+	 *
+	 * @param string $filename
+	 * @param int[] $asked
+	 * @param int[] $expected
+	 */
+	public function testScaleDownWhenBigger($filename, $asked, $expected) {
+		$img = new \OC_Image(OC::$SERVERROOT . '/tests/data/' . $filename);
+		//$this->assertTrue($img->scaleDownToFit($asked[0], $asked[1]));
+		$img->scaleDownToFit($asked[0], $asked[1]);
+		$this->assertEquals($expected[0], $img->width());
+		$this->assertEquals($expected[1], $img->height());
 	}
 
 	function convertDataProvider() {

tests/lib/preview.php

@@ -1,9 +1,23 @@
 <?php
 /**
- * Copyright (c) 2013 Georg Ehrke <georg@ownCloud.com>
- * This file is licensed under the Affero General Public License version 3 or
- * later.
- * See the COPYING-README file.
+ * @author Georg Ehrke <georg@owncloud.com>
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
  */
 
 namespace Test;
@@ -12,121 +26,99 @@ class Preview extends TestCase {
 
 	const TEST_PREVIEW_USER1 = "test-preview-user1";
 
-	/**
-	 * @var \OC\Files\View
-	 */
+	/** @var \OC\Files\View */
 	private $rootView;
+	/**
+	 * Note that using 756 with an image with a ratio of 1.6 brings interesting rounding issues
+	 *
+	 * @var int maximum width allowed for a preview
+	 * */
+	private $configMaxWidth = 756;
+	/** @var int maximum height allowed for a preview */
+	private $configMaxHeight = 756;
+	private $keepAspect;
+	private $scalingUp;
+
+	private $samples = [];
+	private $sampleFileId;
+	private $sampleFilename;
+	private $sampleWidth;
+	private $sampleHeight;
+	private $maxScaleFactor;
+	/** @var int width of the max preview */
+	private $maxPreviewWidth;
+	/** @var int height of the max preview */
+	private $maxPreviewHeight;
+	/** @var int height of the max preview, which is the same as the one of the original image */
+	private $maxPreviewRatio;
+	private $cachedBigger = [];
 
-	/** @var \OC\Files\Storage\Storage */
-	private $originalStorage;
-
+	/**
+	 * Make sure your configuration file doesn't contain any additional providers
+	 */
 	protected function setUp() {
 		parent::setUp();
 
-		// FIXME: use proper tearDown with $this->loginAsUser() and $this->logout()
-		// (would currently break the tests for some reason)
-		$this->originalStorage = \OC\Files\Filesystem::getStorage('/');
-
-		// create a new user with his own filesystem view
-		// this gets called by each test in this test class
+		$userManager = \OC::$server->getUserManager();
+		$userManager->clearBackends();
 		$backend = new \OC_User_Dummy();
-		\OC_User::useBackend($backend);
+		$userManager->registerBackend($backend);
 		$backend->createUser(self::TEST_PREVIEW_USER1, self::TEST_PREVIEW_USER1);
-		$user = \OC::$server->getUserManager()->get(self::TEST_PREVIEW_USER1);
-		\OC::$server->getUserSession()->setUser($user);
-		\OC\Files\Filesystem::init(self::TEST_PREVIEW_USER1, '/' . self::TEST_PREVIEW_USER1 . '/files');
+		$this->loginAsUser(self::TEST_PREVIEW_USER1);
 
-		\OC\Files\Filesystem::mount('OC\Files\Storage\Temporary', array(), '/');
+		$storage = new \OC\Files\Storage\Temporary([]);
+		\OC\Files\Filesystem::mount($storage, [], '/' . self::TEST_PREVIEW_USER1 . '/');
 
 		$this->rootView = new \OC\Files\View('');
-		$this->rootView->mkdir('/'.self::TEST_PREVIEW_USER1);
-		$this->rootView->mkdir('/'.self::TEST_PREVIEW_USER1.'/files');
+		$this->rootView->mkdir('/' . self::TEST_PREVIEW_USER1);
+		$this->rootView->mkdir('/' . self::TEST_PREVIEW_USER1 . '/files');
+
+		// We simulate the max dimension set in the config
+		\OC::$server->getConfig()
+					->setSystemValue('preview_max_x', $this->configMaxWidth);
+		\OC::$server->getConfig()
+					->setSystemValue('preview_max_y', $this->configMaxHeight);
+		// Used to test upscaling
+		$this->maxScaleFactor = 2;
+		\OC::$server->getConfig()
+					->setSystemValue('preview_max_scale_factor', $this->maxScaleFactor);
+
+		// We need to enable the providers we're going to use in the tests
+		$providers = [
+			'OC\\Preview\\JPEG',
+			'OC\\Preview\\PNG',
+			'OC\\Preview\\GIF',
+			'OC\\Preview\\TXT',
+			'OC\\Preview\\Postscript'
+		];
+		\OC::$server->getConfig()
+					->setSystemValue('enabledPreviewProviders', $providers);
+
+		// Sample is 1680x1050 JPEG
+		$this->prepareSample('testimage.jpg', 1680, 1050);
+		// Sample is 2400x1707 EPS
+		$this->prepareSample('testimage.eps', 2400, 1707);
+		// Sample is 1200x450 PNG
+		$this->prepareSample('testimage-wide.png', 1200, 450);
+		// Sample is 64x64 GIF
+		$this->prepareSample('testimage.gif', 64, 64);
 	}
 
 	protected function tearDown() {
-		\OC\Files\Filesystem::clearMounts();
-		\OC\Files\Filesystem::mount($this->originalStorage, array(), '/');
+		$this->logout();
 
 		parent::tearDown();
 	}
 
-	public function testIsMaxSizeWorking() {
-		// Max size from config
-		$maxX = 1024;
-		$maxY = 1024;
-
-		\OC::$server->getConfig()->setSystemValue('preview_max_x', $maxX);
-		\OC::$server->getConfig()->setSystemValue('preview_max_y', $maxY);
-
-		// Sample is 1680x1050 JPEG
-		$sampleFile = '/' . self::TEST_PREVIEW_USER1 . '/files/testimage.jpg';
-		$this->rootView->file_put_contents($sampleFile, file_get_contents(\OC::$SERVERROOT.'/tests/data/testimage.jpg'));
-		$fileInfo = $this->rootView->getFileInfo($sampleFile);
-		$fileId = $fileInfo['fileid'];
-
-		$largeX = 1920;
-		$largeY = 1080;
-		$preview = new \OC\Preview(self::TEST_PREVIEW_USER1, 'files/', 'testimage.jpg', $largeX, $largeY);
-
-		$this->assertEquals($preview->isFileValid(), true);
-
-		// There should be no cached copy
-		$isCached = $preview->isCached($fileId);
-
-		$this->assertNotEquals(\OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $maxX . '-' . $maxY . '-max.png', $isCached);
-		$this->assertNotEquals(\OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $maxX . '-' . $maxY . '.png', $isCached);
-		$this->assertNotEquals(\OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $largeX . '-' . $largeY . '.png', $isCached);
-
-		// The returned preview should be of max size
-		$image = $preview->getPreview();
-
-		$this->assertEquals($image->width(), $maxX);
-		$this->assertEquals($image->height(), $maxY);
-
-		// The max thumbnail should be created
-		$maxThumbCacheFile = '/' . self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $maxX . '-' . $maxY . '-max.png';
-
-		$this->assertEquals($this->rootView->file_exists($maxThumbCacheFile), true);
-
-		// A preview of the asked size should not have been created
-		$thumbCacheFile = \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $largeX . '-' . $largeY . '.png';
-
-		$this->assertEquals($this->rootView->file_exists($thumbCacheFile), false);
-
-		// 2nd request should indicate that we have a cached copy of max dimension
-		$isCached = $preview->isCached($fileId);
-		$this->assertEquals(\OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $maxX . '-' . $maxY . '.png', $isCached);
-
-		// Smaller previews should be based on the cached max preview
-		$smallX = 50;
-		$smallY = 50;
-		$preview = new \OC\Preview(self::TEST_PREVIEW_USER1, 'files/', 'testimage.jpg', $smallX, $smallY);
-		$isCached = $preview->isCached($fileId);
-
-		$this->assertEquals(\OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $maxX . '-' . $maxY . '.png', $isCached);
-
-		// A small preview should be created
-		$image = $preview->getPreview();
-		$this->assertEquals($image->width(), $smallX);
-		$this->assertEquals($image->height(), $smallY);
-
-		// The cache should contain the small preview
-		$thumbCacheFile = '/' . self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $smallX . '-' . $smallY . '.png';
-
-		$this->assertEquals($this->rootView->file_exists($thumbCacheFile), true);
-
-		// 2nd request should indicate that we have a cached copy of the exact dimension
-		$isCached = $preview->isCached($fileId);
-
-		$this->assertEquals(\OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $smallX . '-' . $smallY . '.png', $isCached);
-	}
-
+	/**
+	 * Tests if a preview can be deleted
+	 */
 	public function testIsPreviewDeleted() {
 
-		$sampleFile = '/'.self::TEST_PREVIEW_USER1.'/files/test.txt';
+		$sampleFile = '/' . self::TEST_PREVIEW_USER1 . '/files/test.txt';
 
 		$this->rootView->file_put_contents($sampleFile, 'dummy file data');
-		
+
 		$x = 50;
 		$y = 50;
 
@@ -134,23 +126,30 @@ class Preview extends TestCase {
 		$preview->getPreview();
 
 		$fileInfo = $this->rootView->getFileInfo($sampleFile);
+		/** @var int $fileId */
 		$fileId = $fileInfo['fileid'];
+		$thumbCacheFile = $this->buildCachePath($fileId, $x, $y, true);
 
-		$thumbCacheFile = '/' . self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $x . '-' . $y . '.png';
-		
-		$this->assertEquals($this->rootView->file_exists($thumbCacheFile), true);
+		$this->assertSame(
+			true, $this->rootView->file_exists($thumbCacheFile), "$thumbCacheFile \n"
+		);
 
 		$preview->deletePreview();
 
-		$this->assertEquals($this->rootView->file_exists($thumbCacheFile), false);
+		$this->assertSame(false, $this->rootView->file_exists($thumbCacheFile));
 	}
 
+	/**
+	 * Tests if all previews can be deleted
+	 *
+	 * We test this first to make sure we'll be able to cleanup after each preview generating test
+	 */
 	public function testAreAllPreviewsDeleted() {
 
-		$sampleFile = '/'.self::TEST_PREVIEW_USER1.'/files/test.txt';
+		$sampleFile = '/' . self::TEST_PREVIEW_USER1 . '/files/test.txt';
 
 		$this->rootView->file_put_contents($sampleFile, 'dummy file data');
-		
+
 		$x = 50;
 		$y = 50;
 
@@ -158,104 +157,697 @@ class Preview extends TestCase {
 		$preview->getPreview();
 
 		$fileInfo = $this->rootView->getFileInfo($sampleFile);
+		/** @var int $fileId */
 		$fileId = $fileInfo['fileid'];
-		
-		$thumbCacheFolder = '/' . self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/';
-		
-		$this->assertEquals($this->rootView->is_dir($thumbCacheFolder), true);
+
+		$thumbCacheFolder = '/' . self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER .
+							'/' . $fileId . '/';
+
+		$this->assertSame(true, $this->rootView->is_dir($thumbCacheFolder), "$thumbCacheFolder \n");
 
 		$preview->deleteAllPreviews();
 
-		$this->assertEquals($this->rootView->is_dir($thumbCacheFolder), false);
+		$this->assertSame(false, $this->rootView->is_dir($thumbCacheFolder));
 	}
 
 	public function txtBlacklist() {
 		$txt = 'random text file';
 
-		return array(
-			array('txt', $txt, false),
-		);
+		return [
+			['txt', $txt, false],
+		];
 	}
 
 	/**
 	 * @dataProvider txtBlacklist
+	 *
+	 * @param $extension
+	 * @param $data
+	 * @param $expectedResult
 	 */
 	public function testIsTransparent($extension, $data, $expectedResult) {
 
 		$x = 32;
 		$y = 32;
 
-		$sample = '/'.self::TEST_PREVIEW_USER1.'/files/test.'.$extension;
+		$sample = '/' . self::TEST_PREVIEW_USER1 . '/files/test.' . $extension;
 		$this->rootView->file_put_contents($sample, $data);
-		$preview = new \OC\Preview(self::TEST_PREVIEW_USER1, 'files/', 'test.'.$extension, $x, $y);
+		$preview = new \OC\Preview(
+			self::TEST_PREVIEW_USER1, 'files/', 'test.' . $extension, $x,
+			$y
+		);
 		$image = $preview->getPreview();
 		$resource = $image->resource();
 
 		//http://stackoverflow.com/questions/5702953/imagecolorat-and-transparency
 		$colorIndex = imagecolorat($resource, 1, 1);
 		$colorInfo = imagecolorsforindex($resource, $colorIndex);
-		$this->assertEquals(
+		$this->assertSame(
 			$expectedResult,
 			$colorInfo['alpha'] === 127,
 			'Failed asserting that only previews for text files are transparent.'
 		);
 	}
 
-	public function testCreationFromCached() {
+	/**
+	 * We generate the data to use as it makes it easier to adjust in case we need to test
+	 * something different
+	 *
+	 * @return array
+	 */
+	public static function dimensionsDataProvider() {
+		$data = [];
+		$samples = [
+			[200, 800],
+			[200, 800],
+			[50, 400],
+			[4, 60],
+		];
+		$keepAspect = false;
+		$scalingUp = false;
+
+		for ($a = 0; $a < sizeof($samples); $a++) {
+			for ($b = 0; $b < 2; $b++) {
+				for ($c = 0; $c < 2; $c++) {
+					for ($d = 0; $d < 4; $d++) {
+						$coordinates = [
+							[
+								-rand($samples[$a][0], $samples[$a][1]),
+								-rand($samples[$a][0], $samples[$a][1])
+							],
+							[
+								rand($samples[$a][0], $samples[$a][1]),
+								rand($samples[$a][0], $samples[$a][1])
+							],
+							[
+								-rand($samples[$a][0], $samples[$a][1]),
+								rand($samples[$a][0], $samples[$a][1])
+							],
+							[
+								rand($samples[$a][0], $samples[$a][1]),
+								-rand($samples[$a][0], $samples[$a][1])
+							]
+						];
+						$row = [$a];
+						$row[] = $coordinates[$d][0];
+						$row[] = $coordinates[$d][1];
+						$row[] = $keepAspect;
+						$row[] = $scalingUp;
+						$data[] = $row;
+					}
+					$scalingUp = !$scalingUp;
+				}
+				$keepAspect = !$keepAspect;
+			}
+		}
+
+		return $data;
+	}
 
-		$sampleFile = '/'.self::TEST_PREVIEW_USER1.'/files/test.txt';
+	/**
+	 * Tests if a preview of max dimensions gets created
+	 *
+	 * @dataProvider dimensionsDataProvider
+	 *
+	 * @param int $sampleId
+	 * @param int $widthAdjustment
+	 * @param int $heightAdjustment
+	 * @param bool $keepAspect
+	 * @param bool $scalingUp
+	 */
+	public function testCreateMaxAndNormalPreviewsAtFirstRequest(
+		$sampleId, $widthAdjustment, $heightAdjustment, $keepAspect = false, $scalingUp = false
+	) {
+		//$this->markTestSkipped('Not testing this at this time');
+
+		// Get the right sample for the experiment
+		$this->getSample($sampleId);
+		$sampleWidth = $this->sampleWidth;
+		$sampleHeight = $this->sampleHeight;
+		$sampleFileId = $this->sampleFileId;
+
+		// Adjust the requested size so that we trigger various test cases
+		$previewWidth = $sampleWidth + $widthAdjustment;
+		$previewHeight = $sampleHeight + $heightAdjustment;
+		$this->keepAspect = $keepAspect;
+		$this->scalingUp = $scalingUp;
+
+		// Generates the max preview
+		$preview = $this->createPreview($previewWidth, $previewHeight);
+
+		// There should be no cached thumbnails
+		$thumbnailFolder = '/' . self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER .
+						   '/' . $sampleFileId;
+		$this->assertSame(false, $this->rootView->is_dir($thumbnailFolder));
 
-		$this->rootView->file_put_contents($sampleFile, 'dummy file data');
+		$image = $preview->getPreview();
+		$this->assertNotSame(false, $image);
 
-		// create base preview
-		$x = 150;
-		$y = 150;
+		$maxThumbCacheFile = $this->buildCachePath(
+			$sampleFileId, $this->maxPreviewWidth, $this->maxPreviewHeight, true, '-max'
+		);
 
-		$preview = new \OC\Preview(self::TEST_PREVIEW_USER1, 'files/', 'test.txt', $x, $y);
-		$preview->getPreview();
+		$this->assertSame(
+			true, $this->rootView->file_exists($maxThumbCacheFile), "$maxThumbCacheFile \n"
+		);
 
-		$fileInfo = $this->rootView->getFileInfo($sampleFile);
-		$fileId = $fileInfo['fileid'];
+		// We check the dimensions of the file we've just stored
+		$maxPreview = imagecreatefromstring($this->rootView->file_get_contents($maxThumbCacheFile));
 
-		$thumbCacheFile = '/' . self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $x . '-' . $y . '.png';
+		$this->assertEquals($this->maxPreviewWidth, imagesx($maxPreview));
+		$this->assertEquals($this->maxPreviewHeight, imagesy($maxPreview));
 
-		$this->assertEquals($this->rootView->file_exists($thumbCacheFile), true);
+		// A thumbnail of the asked dimensions should also have been created (within the constraints of the max preview)
+		list($limitedPreviewWidth, $limitedPreviewHeight) =
+			$this->simulatePreviewDimensions($previewWidth, $previewHeight);
 
+		$actualWidth = $image->width();
+		$actualHeight = $image->height();
 
-		// create smaller previews
-		$preview = new \OC\Preview(self::TEST_PREVIEW_USER1, 'files/', 'test.txt', 50, 50);
-		$isCached = $preview->isCached($fileId);
+		$this->assertEquals(
+			(int)$limitedPreviewWidth, $image->width(), "$actualWidth x $actualHeight \n"
+		);
+		$this->assertEquals((int)$limitedPreviewHeight, $image->height());
+
+		// And it should be cached
+		$this->checkCache($sampleFileId, $limitedPreviewWidth, $limitedPreviewHeight);
 
-		$this->assertEquals(self::TEST_PREVIEW_USER1 . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/150-150.png', $isCached);
+		$preview->deleteAllPreviews();
+	}
+
+	/**
+	 * Tests if the second preview will be based off the cached max preview
+	 *
+	 * @dataProvider dimensionsDataProvider
+	 *
+	 * @param int $sampleId
+	 * @param int $widthAdjustment
+	 * @param int $heightAdjustment
+	 * @param bool $keepAspect
+	 * @param bool $scalingUp
+	 */
+	public function testSecondPreviewsGetCachedMax(
+		$sampleId, $widthAdjustment, $heightAdjustment, $keepAspect = false, $scalingUp = false
+	) {
+		//$this->markTestSkipped('Not testing this at this time');
+
+		$this->getSample($sampleId);
+		$sampleWidth = $this->sampleWidth;
+		$sampleHeight = $this->sampleHeight;
+		$sampleFileId = $this->sampleFileId;
+
+		//Creates the Max preview which will be used in the rest of the test
+		$this->createMaxPreview();
+
+		// Adjust the requested size so that we trigger various test cases
+		$previewWidth = $sampleWidth + $widthAdjustment;
+		$previewHeight = $sampleHeight + $heightAdjustment;
+		$this->keepAspect = $keepAspect;
+		$this->scalingUp = $scalingUp;
+
+		$preview = $this->createPreview($previewWidth, $previewHeight);
+
+		// A cache query should return the thumbnail of max dimension
+		$isCached = $preview->isCached($sampleFileId);
+		$cachedMaxPreview = $this->buildCachePath(
+			$sampleFileId, $this->maxPreviewWidth, $this->maxPreviewHeight, false, '-max'
+		);
+		$this->assertSame($cachedMaxPreview, $isCached);
 	}
 
-	/*
-	public function testScalingUp() {
+	/**
+	 * Make sure that the max preview can never be deleted
+	 *
+	 * For this test to work, the preview we generate first has to be the size of max preview
+	 */
+	public function testMaxPreviewCannotBeDeleted() {
+		//$this->markTestSkipped('Not testing this at this time');
 
-		$sampleFile = '/'.$this->user.'/files/test.txt';
+		$this->keepAspect = true;
+		$this->getSample(0);
+		$fileId = $this->sampleFileId;
 
-		$this->rootView->file_put_contents($sampleFile, 'dummy file data');
+		//Creates the Max preview which we will try to delete
+		$preview = $this->createMaxPreview();
 
-		// create base preview
-		$x = 150;
-		$y = 150;
+		// We try to deleted the preview
+		$preview->deletePreview();
+		$this->assertNotSame(false, $preview->isCached($fileId));
 
-		$preview = new \OC\Preview($this->user, 'files/', 'test.txt', $x, $y);
+		$preview->deleteAllPreviews();
+	}
+
+	public static function aspectDataProvider() {
+		$data = [];
+		$samples = 4;
+		$keepAspect = false;
+		$scalingUp = false;
+		for ($a = 0; $a < $samples; $a++) {
+			for ($b = 0; $b < 2; $b++) {
+				for ($c = 0; $c < 2; $c++) {
+					$row = [$a];
+					$row[] = $keepAspect;
+					$row[] = $scalingUp;
+					$data[] = $row;
+					$scalingUp = !$scalingUp;
+				}
+				$keepAspect = !$keepAspect;
+			}
+		}
+
+		return $data;
+	}
+
+	/**
+	 * We ask for a preview larger than what is set in the configuration,
+	 * so we should be getting either the max preview or a preview the size
+	 * of the dimensions set in the config
+	 *
+	 * @dataProvider aspectDataProvider
+	 *
+	 * @param int $sampleId
+	 * @param bool $keepAspect
+	 * @param bool $scalingUp
+	 */
+	public function testDoNotCreatePreviewsLargerThanConfigMax(
+		$sampleId, $keepAspect = false, $scalingUp = false
+	) {
+		//$this->markTestSkipped('Not testing this at this time');
+
+		$this->getSample($sampleId);
+
+		//Creates the Max preview which will be used in the rest of the test
+		$this->createMaxPreview();
+
+		// Now we will create the real preview
+		$previewWidth = 4000;
+		$previewHeight = 4000;
+		$this->keepAspect = $keepAspect;
+		$this->scalingUp = $scalingUp;
+
+		// Tries to create the very large preview
+		$preview = $this->createPreview($previewWidth, $previewHeight);
+
+		$image = $preview->getPreview();
+		$this->assertNotSame(false, $image);
+
+		list($expectedWidth, $expectedHeight) =
+			$this->simulatePreviewDimensions($previewWidth, $previewHeight);
+		$this->assertEquals($expectedWidth, $image->width());
+		$this->assertEquals($expectedHeight, $image->height());
+
+		// A preview of the asked size should not have been created since it's larger that our max dimensions
+		$postfix = $this->getThumbnailPostfix($previewWidth, $previewHeight);
+		$thumbCacheFile = $this->buildCachePath(
+			$this->sampleFileId, $previewWidth, $previewHeight, false, $postfix
+		);
+		$this->assertSame(
+			false, $this->rootView->file_exists($thumbCacheFile), "$thumbCacheFile \n"
+		);
+
+		$preview->deleteAllPreviews();
+	}
+
+	/**
+	 * Makes sure we're getting the proper cached thumbnail
+	 *
+	 * When we start by generating a preview which keeps the aspect ratio
+	 * 200-125-with-aspect
+	 * 300-300    ✓
+	 *
+	 * When we start by generating a preview of exact dimensions
+	 * 200-200    ✓
+	 * 300-188-with-aspect
+	 *
+	 * @dataProvider aspectDataProvider
+	 *
+	 * @param int $sampleId
+	 * @param bool $keepAspect
+	 * @param bool $scalingUp
+	 */
+	public function testIsBiggerWithAspectRatioCached(
+		$sampleId, $keepAspect = false, $scalingUp = false
+	) {
+		//$this->markTestSkipped('Not testing this at this time');
+
+		$previewWidth = 400;
+		$previewHeight = 400;
+		$this->getSample($sampleId);
+		$fileId = $this->sampleFileId;
+		$this->keepAspect = $keepAspect;
+		$this->scalingUp = $scalingUp;
+
+		// Caching the max preview in our preview array for the test
+		$this->cachedBigger[] = $this->buildCachePath(
+			$fileId, $this->maxPreviewWidth, $this->maxPreviewHeight, false, '-max'
+		);
+
+		$this->getSmallerThanMaxPreview($fileId, $previewWidth, $previewHeight);
+		// We switch the aspect ratio, to generate a thumbnail we should not be picked up
+		$this->keepAspect = !$keepAspect;
+		$this->getSmallerThanMaxPreview($fileId, $previewWidth + 100, $previewHeight + 100);
+
+		// Small thumbnails are always cropped
+		$this->keepAspect = false;
+		// Smaller previews should be based on the previous, larger preview, with the correct aspect ratio
+		$this->createThumbnailFromBiggerCachedPreview($fileId, 36, 36);
+
+		// 2nd cache query should indicate that we have a cached copy of the exact dimension
+		$this->getCachedSmallThumbnail($fileId, 36, 36);
+
+		// We create a preview in order to be able to delete the cache
+		$preview = $this->createPreview(rand(), rand());
+		$preview->deleteAllPreviews();
+		$this->cachedBigger = [];
+	}
+
+	/**
+	 * Initialises the preview
+	 *
+	 * @param int $width
+	 * @param int $height
+	 *
+	 * @return \OC\Preview
+	 */
+	private function createPreview($width, $height) {
+		$preview = new \OC\Preview(
+			self::TEST_PREVIEW_USER1, 'files/', $this->sampleFilename, $width,
+			$height
+		);
+
+		$this->assertSame(true, $preview->isFileValid());
+
+		$preview->setKeepAspect($this->keepAspect);
+		$preview->setScalingup($this->scalingUp);
+
+		return $preview;
+	}
+
+	/**
+	 * Creates the Max preview which will be used in the rest of the test
+	 *
+	 * @return \OC\Preview
+	 */
+	private function createMaxPreview() {
+		$this->keepAspect = true;
+		$preview = $this->createPreview($this->maxPreviewWidth, $this->maxPreviewHeight);
 		$preview->getPreview();
 
-		$fileInfo = $this->rootView->getFileInfo($sampleFile);
-		$fileId = $fileInfo['fileid'];
+		return $preview;
+	}
+
+	/**
+	 * Makes sure the preview which was just created has been saved to disk
+	 *
+	 * @param int $fileId
+	 * @param int $previewWidth
+	 * @param int $previewHeight
+	 */
+	private function checkCache($fileId, $previewWidth, $previewHeight) {
+		$postfix = $this->getThumbnailPostfix($previewWidth, $previewHeight);
+
+		$thumbCacheFile = $this->buildCachePath(
+			$fileId, $previewWidth, $previewHeight, true, $postfix
+		);
+
+		$this->assertSame(
+			true, $this->rootView->file_exists($thumbCacheFile), "$thumbCacheFile \n"
+		);
+	}
+
+	/**
+	 * Computes special filename postfixes
+	 *
+	 * @param int $width
+	 * @param int $height
+	 *
+	 * @return string
+	 */
+	private function getThumbnailPostfix($width, $height) {
+		// Need to take care of special postfix added to the dimensions
+		$postfix = '';
+		$isMaxPreview = ($width === $this->maxPreviewWidth
+						 && $height === $this->maxPreviewHeight) ? true : false;
+		if ($isMaxPreview) {
+			$postfix = '-max';
+		}
+		if ($this->keepAspect && !$isMaxPreview) {
+			$postfix = '-with-aspect';
+		}
+
+		return $postfix;
+	}
+
+	private function getSmallerThanMaxPreview($fileId, $previewWidth, $previewHeight) {
+		$preview = $this->createPreview($previewWidth, $previewHeight);
+
+		$image = $preview->getPreview();
+		$this->assertNotSame(false, $image);
 
-		$thumbCacheFile = '/' . $this->user . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/' . $x . '-' . $y . '.png';
+		// A thumbnail of the asked dimensions should also have been created (within the constraints of the max preview)
+		list($limitedPreviewWidth, $limitedPreviewHeight) =
+			$this->simulatePreviewDimensions($previewWidth, $previewHeight);
 
-		$this->assertEquals($this->rootView->file_exists($thumbCacheFile), true);
+		$this->assertEquals($limitedPreviewWidth, $image->width());
+		$this->assertEquals($limitedPreviewHeight, $image->height());
 
+		// And it should be cached
+		$this->checkCache($fileId, $limitedPreviewWidth, $limitedPreviewHeight);
 
-		// create bigger previews - with scale up
-		$preview = new \OC\Preview($this->user, 'files/', 'test.txt', 250, 250);
+		$this->cachedBigger[] = $preview->isCached($fileId);
+	}
+
+	private function createThumbnailFromBiggerCachedPreview($fileId, $width, $height) {
+		$preview = $this->createPreview($width, $height);
+
+		// A cache query should return a thumbnail of slightly larger dimensions
+		// and with the proper aspect ratio
 		$isCached = $preview->isCached($fileId);
+		$expectedCachedBigger = $this->getExpectedCachedBigger();
+
+		$this->assertSame($expectedCachedBigger, $isCached);
+
+		$image = $preview->getPreview();
+		$this->assertNotSame(false, $image);
+	}
+
+	/**
+	 * Picks the bigger cached preview with the correct aspect ratio or the max preview if it's
+	 * smaller than that
+	 *
+	 * For non-upscaled images, we pick the only picture without aspect ratio
+	 *
+	 * @return string
+	 */
+	private function getExpectedCachedBigger() {
+		$foundPreview = null;
+		$foundWidth = null;
+		$foundHeight = null;
+		$maxPreview = null;
+		$maxWidth = null;
+		$maxHeight = null;
+
+		foreach ($this->cachedBigger as $cached) {
+			$size = explode('-', basename($cached));
+			$width = (int)$size[0];
+			$height = (int)$size[1];
+
+			if (strpos($cached, 'max')) {
+				$maxWidth = $width;
+				$maxHeight = $height;
+				$maxPreview = $cached;
+				continue;
+			}
+
+			// We pick the larger preview with no aspect ratio
+			if (!strpos($cached, 'aspect') && !strpos($cached, 'max')) {
+				$foundPreview = $cached;
+				$foundWidth = $width;
+				$foundHeight = $height;
+			}
+		}
+		if ($foundWidth > $maxWidth && $foundHeight > $maxHeight) {
+			$foundPreview = $maxPreview;
+		}
+
+		return $foundPreview;
+	}
+
+	/**
+	 * A small thumbnail of exact dimensions should be in the cache
+	 *
+	 * @param int $fileId
+	 * @param int $width
+	 * @param int $height
+	 */
+	private function getCachedSmallThumbnail($fileId, $width, $height) {
+		$preview = $this->createPreview($width, $height);
+
+		$isCached = $preview->isCached($fileId);
+		$thumbCacheFile = $this->buildCachePath($fileId, $width, $height);
+
+		$this->assertSame($thumbCacheFile, $isCached, "$thumbCacheFile \n");
+	}
+
+	/**
+	 * Builds the complete path to a cached thumbnail starting from the user folder
+	 *
+	 * @param int $fileId
+	 * @param int $width
+	 * @param int $height
+	 * @param bool $user
+	 * @param string $postfix
+	 *
+	 * @return string
+	 */
+	private function buildCachePath($fileId, $width, $height, $user = false, $postfix = '') {
+		$userPath = '';
+		if ($user) {
+			$userPath = '/' . self::TEST_PREVIEW_USER1 . '/';
+		}
+
+		return $userPath . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId
+			   . '/' . $width . '-' . $height . $postfix . '.png';
+	}
+
+	/**
+	 * Stores the sample in the filesystem and stores it in the $samples array
+	 *
+	 * @param string $fileName
+	 * @param int $sampleWidth
+	 * @param int $sampleHeight
+	 */
+	private function prepareSample($fileName, $sampleWidth, $sampleHeight) {
+		$imgData = file_get_contents(\OC::$SERVERROOT . '/tests/data/' . $fileName);
+		$imgPath = '/' . self::TEST_PREVIEW_USER1 . '/files/' . $fileName;
+		$this->rootView->file_put_contents($imgPath, $imgData);
+		$fileInfo = $this->rootView->getFileInfo($imgPath);
+
+		list($maxPreviewWidth, $maxPreviewHeight) =
+			$this->setMaxPreview($sampleWidth, $sampleHeight);
+
+		$this->samples[] =
+			[
+				'sampleFileId'     => $fileInfo['fileid'],
+				'sampleFileName'   => $fileName,
+				'sampleWidth'      => $sampleWidth,
+				'sampleHeight'     => $sampleHeight,
+				'maxPreviewWidth'  => $maxPreviewWidth,
+				'maxPreviewHeight' => $maxPreviewHeight
+			];
+	}
+
+	/**
+	 * Sets the variables used to define the boundaries which need to be respected when using a
+	 * specific sample
+	 *
+	 * @param $sampleId
+	 */
+	private function getSample($sampleId) {
+		// Corrects a rounding difference when using the EPS (Imagick converted) sample
+		$filename = $this->samples[$sampleId]['sampleFileName'];
+		$splitFileName = pathinfo($filename);
+		$extension = $splitFileName['extension'];
+		$correction = ($extension === 'eps') ? 1 : 0;
+		$maxPreviewHeight = $this->samples[$sampleId]['maxPreviewHeight'];
+		$maxPreviewHeight = $maxPreviewHeight - $correction;
+
+		$this->sampleFileId = $this->samples[$sampleId]['sampleFileId'];
+		$this->sampleFilename = $this->samples[$sampleId]['sampleFileName'];
+		$this->sampleWidth = $this->samples[$sampleId]['sampleWidth'];
+		$this->sampleHeight = $this->samples[$sampleId]['sampleHeight'];
+		$this->maxPreviewWidth = $this->samples[$sampleId]['maxPreviewWidth'];
+		$this->maxPreviewHeight = $maxPreviewHeight;
+		$ratio = $this->maxPreviewWidth / $this->maxPreviewHeight;
+		$this->maxPreviewRatio = $ratio;
+	}
+
+	/**
+	 * Defines the size of the max preview
+	 *
+	 * @fixme the Imagick previews don't have the exact same size on disk as they're calculated here
+	 *
+	 * @param int $sampleWidth
+	 * @param int $sampleHeight
+	 *
+	 * @return array
+	 */
+	private function setMaxPreview($sampleWidth, $sampleHeight) {
+		// Max previews are never scaled up
+		$this->scalingUp = false;
+		// Max previews always keep the aspect ratio
+		$this->keepAspect = true;
+		// We set this variable in order to be able to calculate the max preview with the proper aspect ratio
+		$this->maxPreviewRatio = $sampleWidth / $sampleHeight;
+		$maxPreviewWidth = min($sampleWidth, $this->configMaxWidth);
+		$maxPreviewHeight = min($sampleHeight, $this->configMaxHeight);
+		list($maxPreviewWidth, $maxPreviewHeight) =
+			$this->applyAspectRatio($maxPreviewWidth, $maxPreviewHeight);
+
+		return [$maxPreviewWidth, $maxPreviewHeight];
+	}
+
+	/**
+	 * Calculates the expected dimensions of the preview to be able to assess if we've got the
+	 * right result
+	 *
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 *
+	 * @return array
+	 */
+	private function simulatePreviewDimensions($askedWidth, $askedHeight) {
+		$askedWidth = min($askedWidth, $this->configMaxWidth);
+		$askedHeight = min($askedHeight, $this->configMaxHeight);
+
+		if ($this->keepAspect) {
+			// Defines the box in which the preview has to fit
+			$scaleFactor = $this->scalingUp ? $this->maxScaleFactor : 1;
+			$newPreviewWidth = min($askedWidth, $this->maxPreviewWidth * $scaleFactor);
+			$newPreviewHeight = min($askedHeight, $this->maxPreviewHeight * $scaleFactor);
+			list($newPreviewWidth, $newPreviewHeight) =
+				$this->applyAspectRatio($newPreviewWidth, $newPreviewHeight);
+		} else {
+			list($newPreviewWidth, $newPreviewHeight) =
+				$this->fixSize($askedWidth, $askedHeight);
+		}
+
+		return [(int)$newPreviewWidth, (int)$newPreviewHeight];
+	}
+
+	/**
+	 * Resizes the boundaries to match the aspect ratio
+	 *
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 *
+	 * @return \int[]
+	 */
+	private function applyAspectRatio($askedWidth, $askedHeight) {
+		$originalRatio = $this->maxPreviewRatio;
+		if ($askedWidth / $originalRatio < $askedHeight) {
+			$askedHeight = round($askedWidth / $originalRatio);
+		} else {
+			$askedWidth = round($askedHeight * $originalRatio);
+		}
+
+		return [(int)$askedWidth, (int)$askedHeight];
+	}
+
+	/**
+	 * Clips or stretches the dimensions so that they fit in the boundaries
+	 *
+	 * @param int $askedWidth
+	 * @param int $askedHeight
+	 *
+	 * @return array
+	 */
+	private function fixSize($askedWidth, $askedHeight) {
+		if ($this->scalingUp) {
+			$askedWidth = min($this->configMaxWidth, $askedWidth);
+			$askedHeight = min($this->configMaxHeight, $askedHeight);
+		}
 
-		$this->assertEquals($this->user . '/' . \OC\Preview::THUMBNAILS_FOLDER . '/' . $fileId . '/150-150.png', $isCached);
+		return [(int)$askedWidth, (int)$askedHeight];
 	}
-	*/
 }

tests/lib/preview/bitmap.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+class Bitmap extends Provider {
+
+	public function setUp() {
+		parent::setUp();
+
+		$fileName = 'testimage.eps';
+		$this->imgPath = $this->prepareTestFile($fileName, \OC::$SERVERROOT . '/tests/data/' . $fileName);
+		$this->width = 2400;
+		$this->height = 1707;
+		$this->provider = new \OC\Preview\Postscript;
+	}
+
+}

tests/lib/preview/image.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+class Image extends Provider {
+
+	public function setUp() {
+		parent::setUp();
+
+		$fileName = 'testimage.jpg';
+		$this->imgPath = $this->prepareTestFile($fileName, \OC::$SERVERROOT . '/tests/data/' . $fileName);
+		$this->width = 1680;
+		$this->height = 1050;
+		$this->provider = new \OC\Preview\JPEG();
+	}
+
+}

tests/lib/preview/movie.php

@@ -0,0 +1,46 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+class Movie extends Provider {
+
+	public function setUp() {
+		$avconvBinary = \OC_Helper::findBinaryPath('avconv');
+		$ffmpegBinary = ($avconvBinary) ? null : \OC_Helper::findBinaryPath('ffmpeg');
+
+		if ($avconvBinary || $ffmpegBinary) {
+			parent::setUp();
+
+			\OC\Preview\Movie::$avconvBinary = $avconvBinary;
+			\OC\Preview\Movie::$ffmpegBinary = $ffmpegBinary;
+
+			$fileName = 'testimage.mp4';
+			$this->imgPath = $this->prepareTestFile($fileName, \OC::$SERVERROOT . '/tests/data/' . $fileName);
+			$this->width = 560;
+			$this->height = 320;
+			$this->provider = new \OC\Preview\Movie;
+		} else {
+			$this->markTestSkipped('No Movie provider present');
+		}
+	}
+
+}

tests/lib/preview/mp3.php

@@ -0,0 +1,36 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+class MP3 extends Provider {
+
+	public function setUp() {
+		parent::setUp();
+
+		$fileName = 'testimage.mp3';
+		$this->imgPath = $this->prepareTestFile($fileName, \OC::$SERVERROOT . '/tests/data/' . $fileName);
+		$this->width = 200;
+		$this->height = 200;
+		$this->provider = new \OC\Preview\MP3;
+	}
+
+}

tests/lib/preview/office.php

@@ -0,0 +1,43 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+class Office extends Provider {
+
+	public function setUp() {
+		$libreofficeBinary = \OC_Helper::findBinaryPath('libreoffice');
+		$openofficeBinary = ($libreofficeBinary) ? null : \OC_Helper::findBinaryPath('openoffice');
+
+		if ($libreofficeBinary || $openofficeBinary) {
+			parent::setUp();
+
+			$fileName = 'testimage.odt';
+			$this->imgPath = $this->prepareTestFile($fileName, \OC::$SERVERROOT . '/tests/data/' . $fileName);
+			$this->width = 595;
+			$this->height = 842;
+			$this->provider = new \OC\Preview\OpenDocument;
+		} else {
+			$this->markTestSkipped('No Office provider present');
+		}
+	}
+
+}

tests/lib/preview/provider.php

@@ -0,0 +1,187 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+abstract class Provider extends \Test\TestCase {
+
+	/** @var string */
+	protected $imgPath;
+	/** @var int */
+	protected $width;
+	/** @var int */
+	protected $height;
+	/** @var \OC\Preview\Provider */
+	protected $provider;
+	/** @var int */
+	protected $maxWidth = 1024;
+	/** @var int */
+	protected $maxHeight = 1024;
+	/** @var bool */
+	protected $scalingUp = false;
+	/** @var int */
+	protected $userId;
+	/** @var \OC\Files\View */
+	protected $rootView;
+	/** @var \OC\Files\Storage\Storage */
+	protected $storage;
+
+	protected function setUp() {
+		parent::setUp();
+
+		$userManager = \OC::$server->getUserManager();
+		$userManager->clearBackends();
+		$backend = new \OC_User_Dummy();
+		$userManager->registerBackend($backend);
+
+		$userId = $this->getUniqueID();
+		$backend->createUser($userId, $userId);
+		$this->loginAsUser($userId);
+
+		$this->storage = new \OC\Files\Storage\Temporary([]);
+		\OC\Files\Filesystem::mount($this->storage, [], '/' . $userId . '/');
+
+		$this->rootView = new \OC\Files\View('');
+		$this->rootView->mkdir('/' . $userId);
+		$this->rootView->mkdir('/' . $userId . '/files');
+
+		$this->userId = $userId;
+	}
+
+	protected function tearDown() {
+		$this->logout();
+
+		parent::tearDown();
+	}
+
+	public static function dimensionsDataProvider() {
+		return [
+			[-rand(5, 100), -rand(5, 100)],
+			[rand(5, 100), rand(5, 100)],
+			[-rand(5, 100), rand(5, 100)],
+			[rand(5, 100), -rand(5, 100)],
+		];
+	}
+
+	/**
+	 * Launches all the tests we have
+	 *
+	 * @dataProvider dimensionsDataProvider
+	 *
+	 * @param int $widthAdjustment
+	 * @param int $heightAdjustment
+	 */
+	public function testGetThumbnail($widthAdjustment, $heightAdjustment) {
+		$ratio = round($this->width / $this->height, 2);
+		$this->maxWidth = $this->width - $widthAdjustment;
+		$this->maxHeight = $this->height - $heightAdjustment;
+
+		// Testing code
+		/*print_r("w $this->width ");
+		print_r("h $this->height ");
+		print_r("r $ratio ");*/
+
+		$preview = $this->getPreview($this->provider);
+		// The TXT provider uses the max dimensions to create its canvas,
+		// so the ratio will always be the one of the max dimension canvas
+		if (!$this->provider instanceof \OC\Preview\TXT) {
+			$this->doesRatioMatch($preview, $ratio);
+		}
+		$this->doesPreviewFit($preview);
+	}
+
+	/**
+	 * Adds the test file to the filesystem
+	 *
+	 * @param string $fileName name of the file to create
+	 * @param string $fileContent path to file to use for test
+	 *
+	 * @return string
+	 */
+	protected function prepareTestFile($fileName, $fileContent) {
+		$imgData = file_get_contents($fileContent);
+		$imgPath = '/' . $this->userId . '/files/' . $fileName;
+		$this->rootView->file_put_contents($imgPath, $imgData);
+
+		$scanner = $this->storage->getScanner();
+		$scanner->scan('');
+
+		return $imgPath;
+	}
+
+	/**
+	 * Retrieves a max size thumbnail can be created
+	 *
+	 * @param \OC\Preview\Provider $provider
+	 *
+	 * @return bool|\OCP\IImage
+	 */
+	private function getPreview($provider) {
+		$preview = $provider->getThumbnail($this->imgPath, $this->maxWidth, $this->maxHeight, $this->scalingUp, $this->rootView);
+
+		$this->assertNotEquals(false, $preview);
+		$this->assertEquals(true, $preview->valid());
+
+		return $preview;
+	}
+
+	/**
+	 * Checks if the preview ratio matches the original ratio
+	 *
+	 * @param \OCP\IImage $preview
+	 * @param int $ratio
+	 */
+	private function doesRatioMatch($preview, $ratio) {
+		$previewRatio = round($preview->width() / $preview->height(), 2);
+		$this->assertEquals($ratio, $previewRatio);
+	}
+
+	/**
+	 * Tests if a max size preview of smaller dimensions can be created
+	 *
+	 * @param \OCP\IImage $preview
+	 */
+	private function doesPreviewFit($preview) {
+		$maxDimRatio = round($this->maxWidth / $this->maxHeight, 2);
+		$previewRatio = round($preview->width() / $preview->height(), 2);
+
+		// Testing code
+		/*print_r("mw $this->maxWidth ");
+		print_r("mh $this->maxHeight ");
+		print_r("mr $maxDimRatio ");
+		$pw = $preview->width();
+		$ph = $preview->height();
+		print_r("pw $pw ");
+		print_r("ph $ph ");
+		print_r("pr $previewRatio ");*/
+
+		if ($maxDimRatio < $previewRatio) {
+			$this->assertLessThanOrEqual($this->maxWidth, $preview->width());
+			$this->assertLessThan($this->maxHeight, $preview->height());
+		} elseif ($maxDimRatio > $previewRatio) {
+			$this->assertLessThan($this->maxWidth, $preview->width());
+			$this->assertLessThanOrEqual($this->maxHeight, $preview->height());
+		} else { // Original had to be resized
+			$this->assertLessThanOrEqual($this->maxWidth, $preview->width());
+			$this->assertLessThanOrEqual($this->maxHeight, $preview->height());
+		}
+	}
+}

tests/lib/preview/svg.php

@@ -0,0 +1,41 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+class SVG extends Provider {
+
+	public function setUp() {
+		$checkImagick = new \Imagick();
+		if (count($checkImagick->queryFormats('SVG')) === 1) {
+			parent::setUp();
+
+			$fileName = 'testimagelarge.svg';
+			$this->imgPath = $this->prepareTestFile($fileName, \OC::$SERVERROOT . '/tests/data/' . $fileName);
+			$this->width = 3000;
+			$this->height = 2000;
+			$this->provider = new \OC\Preview\SVG;
+		} else {
+			$this->markTestSkipped('No SVG provider present');
+		}
+	}
+
+}

tests/lib/preview/txt.php

@@ -0,0 +1,37 @@
+<?php
+/**
+ * @author Olivier Paroz <owncloud@interfasys.ch>
+ *
+ * @copyright Copyright (c) 2015, ownCloud, Inc.
+ * @license AGPL-3.0
+ *
+ * This code is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License, version 3,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License, version 3,
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+namespace Test\Preview;
+
+class TXT extends Provider {
+
+	public function setUp() {
+		parent::setUp();
+
+		$fileName = 'lorem-big.txt';
+		$this->imgPath = $this->prepareTestFile($fileName, \OC::$SERVERROOT . '/tests/data/' . $fileName);
+		// Arbitrary width and length which won't be used to calculate the ratio
+		$this->width = 500;
+		$this->height = 200;
+		$this->provider = new \OC\Preview\TXT;
+	}
+
+}