Drupal 8.0.0 beta 12. More info: https://www.drupal.org/node/2514176

core/lib/Drupal/Component/Utility/Image.php

@@ -0,0 +1,66 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Utility\Image.
+ */
+
+namespace Drupal\Component\Utility;
+
+/**
+ * Provides helpers to operate on images.
+ *
+ * @ingroup utility
+ */
+class Image {
+
+  /**
+   * Scales image dimensions while maintaining aspect ratio.
+   *
+   * The resulting dimensions can be smaller for one or both target dimensions.
+   *
+   * @param array $dimensions
+   *   Dimensions to be modified - an array with components width and height, in
+   *   pixels.
+   * @param int $width
+   *   (optional) The target width, in pixels. If this value is NULL then the
+   *   scaling will be based only on the height value.
+   * @param int $height
+   *   (optional) The target height, in pixels. If this value is NULL then the
+   *   scaling will be based only on the width value.
+   * @param bool $upscale
+   *   (optional) Boolean indicating that images smaller than the target
+   *   dimensions will be scaled up. This generally results in a low quality
+   *   image.
+   *
+   * @return bool
+   *   TRUE if $dimensions was modified, FALSE otherwise.
+   *
+   * @see image_scale()
+   */
+  public static function scaleDimensions(array &$dimensions, $width = NULL, $height = NULL, $upscale = FALSE) {
+    $aspect = $dimensions['height'] / $dimensions['width'];
+
+    // Calculate one of the dimensions from the other target dimension,
+    // ensuring the same aspect ratio as the source dimensions. If one of the
+    // target dimensions is missing, that is the one that is calculated. If both
+    // are specified then the dimension calculated is the one that would not be
+    // calculated to be bigger than its target.
+    if (($width && !$height) || ($width && $height && $aspect < $height / $width)) {
+      $height = (int) round($width * $aspect);
+    }
+    else {
+      $width = (int) round($height / $aspect);
+    }
+
+    // Don't upscale if the option isn't enabled.
+    if (!$upscale && ($width >= $dimensions['width'] || $height >= $dimensions['height'])) {
+      return FALSE;
+    }
+
+    $dimensions['width'] = $width;
+    $dimensions['height'] = $height;
+    return TRUE;
+  }
+
+}