src/Drupal/Component/Utility/Image.php
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'] = $height;
    return TRUE;
  }
public static function scaleDimensions(array &$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;
  }
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 ; }
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()
Scales image dimensions while maintaining aspect ratio .