Changeset 38086

Timestamp:

07/18/2016 02:13:45 AM (8 years ago)

Author:

joemcgill

Message:

Media: Prevent image_get_intermediate_size() from returning cropped images.

When $size is passed to image_get_intermediate_size() as an array of width
and height values and an exact image size matching those values isn't available,
the function loops through the available attachment sizes and returns the
smallest image larger than the requested dimensions with the same aspect ratio.

The aspect ratio check is skipped for the 'thumbnail' size to provide a fallback
for small sizes when no other image option is available. This resulted in a poor
selection when the size requested was smaller than the 'thumbnail' dimensions
but a larger size matching the requested ratio existed.

This refactors the internals of image_get_intermediate_size() to ensure the
'thumbnail' size is only returned as a fallback to small sizes once all other
options have been considered, and makes the control flow easier to follow.

This also introduces a new helper function, wp_image_matches_ratio() for
testing whether the aspect ratios of two sets of dimensions match. This function
is also now used in wp_calculate_image_srcset() during the selection process.

Props flixos, joemcgill.
Fixes #34384, #34980.

Location:

trunk

Files:

• src/wp-includes/media.php (modified) (4 diffs)
• tests/phpunit/tests/image/intermediate_size.php (modified) (1 diff)

trunk/src/wp-includes/media.php

@@ -593 +593 @@
 
 /**
+ * Helper function to test if aspect ratios for two images match.
+ *
+ * @since 4.6.0
+ *
+ * @param int $source_width  Width of the first image in pixels.
+ * @param int $source_height Height of the first image in pixels.
+ * @param int $target_width  Width of the second image in pixels.
+ * @param int $target_height Height of the second image in pixels.
+ * @return bool True if aspect ratios match within 1px. False if not.
+ */
+function wp_image_matches_ratio( $source_width, $source_height, $target_width, $target_height ) {
+    /*
+     * To test for varying crops, we constrain the dimensions of the larger image
+     * to the dimensions of the smaller image and see if they match.
+     */
+    if ( $source_width > $target_width ) {
+        $constrained_size = wp_constrain_dimensions( $source_width, $source_height, $target_width );
+        $expected_size = array( $target_width, $target_height );
+    } else {
+        $constrained_size = wp_constrain_dimensions( $target_width, $target_height, $source_width );
+        $expected_size = array( $source_width, $source_height );
+    }
+
+    // If the image dimensions are within 1px of the expected size, we consider it a match.
+    $matched = ( abs( $constrained_size[0] - $expected_size[0] ) <= 1 && abs( $constrained_size[1] - $expected_size[1] ) <= 1 );
+
+    return $matched;
+}
+
+/**
  * Retrieves the image's intermediate size (resized) path, width, and height.
  *
@@ -624 +654 @@
  *     @type int    $width  Width of image
  *     @type int    $height Height of image
- *     @type string $path   Optional. Image's absolute filesystem path. Only returned if registered
- *                          size is passed to `$size` parameter.
- *     @type string $url    Optional. Image's URL. Only returned if registered size is passed to `$size`
- *                          parameter.
+ *     @type string $path   Image's absolute filesystem path.
+ *     @type string $url    Image's URL.
  * }
  */
 function image_get_intermediate_size( $post_id, $size = 'thumbnail' ) {
-    if ( !is_array( $imagedata = wp_get_attachment_metadata( $post_id ) ) )
+    if ( ! $size || ! is_array( $imagedata = wp_get_attachment_metadata( $post_id ) ) || empty( $imagedata['sizes'] )  ) {
         return false;
-
-    // get the best one for a specified set of dimensions
-    if ( is_array($size) && !empty($imagedata['sizes']) ) {
+    }
+
+    $data = array();
+
+    // Find the best match when '$size' is an array.
+    if ( is_array( $size ) ) {
         $candidates = array();
 
@@ -641 +672 @@
             // If there's an exact match to an existing image size, short circuit.
             if ( $data['width'] == $size[0] && $data['height'] == $size[1] ) {
-                list( $data['width'], $data['height'] ) = image_constrain_size_for_editor( $data['width'], $data['height'], $size );
-
-                /** This filter is documented in wp-includes/media.php */
-                return apply_filters( 'image_get_intermediate_size', $data, $post_id, $size );
+                $candidates[ $data['width'] * $data['height'] ] = $data;
+                break;
             }
-            // If it's not an exact match but it's at least the dimensions requested.
+
+            // If it's not an exact match, consider larger sizes with the same aspect ratio.
             if ( $data['width'] >= $size[0] && $data['height'] >= $size[1] ) {
-                $candidates[ $data['width'] * $data['height'] ] = $_size;
+                // If '0' is passed to either size, we test ratios against the original file.
+                if ( 0 === $size[0] || 0 === $size[1] ) {
+                    $same_ratio = wp_image_matches_ratio( $data['width'], $data['height'], $imagedata['width'], $imagedata['height'] );
+                } else {
+                    $same_ratio = wp_image_matches_ratio( $data['width'], $data['height'], $size[0], $size[1] );
+                }
+
+                if ( $same_ratio ) {
+                    $candidates[ $data['width'] * $data['height'] ] = $data;
+                }
             }
         }
 
         if ( ! empty( $candidates ) ) {
-            // find for the smallest image not smaller than the desired size
-            ksort( $candidates );
-            foreach ( $candidates as $_size ) {
-                $data = $imagedata['sizes'][$_size];
-
-                // Skip images with unexpectedly divergent aspect ratios (crops)
-                // First, we calculate what size the original image would be if constrained to a box the size of the current image in the loop
-                $maybe_cropped = image_resize_dimensions($imagedata['width'], $imagedata['height'], $data['width'], $data['height'], false );
-                // If the size doesn't match within one pixel, then it is of a different aspect ratio, so we skip it, unless it's the thumbnail size
-                if ( 'thumbnail' != $_size &&
-                  ( ! $maybe_cropped
-                    || ( $maybe_cropped[4] != $data['width'] && $maybe_cropped[4] + 1 != $data['width'] )
-                    || ( $maybe_cropped[5] != $data['height'] && $maybe_cropped[5] + 1 != $data['height'] )
-                  ) ) {
-                  continue;
-                }
-                // If we're still here, then we're going to use this size.
-                list( $data['width'], $data['height'] ) = image_constrain_size_for_editor( $data['width'], $data['height'], $size );
-
-                /** This filter is documented in wp-includes/media.php */
-                return apply_filters( 'image_get_intermediate_size', $data, $post_id, $size );
+            // Sort the array by size if we have more than one candidate.
+            if ( 1 < count( $candidates ) ) {
+                ksort( $candidates );
             }
-        }
-    }
-
-    if ( is_array($size) || empty($size) || empty($imagedata['sizes'][$size]) )
+
+            $data = array_shift( $candidates );
+        /*
+         * When the size requested is smaller than the thumbnail dimensions, we
+         * fall back to the thumbnail size to maintain backwards compatibility with
+         * pre 4.6 versions of WordPress.
+         */
+        } elseif ( ! empty( $imagedata['sizes']['thumbnail'] ) && $imagedata['sizes']['thumbnail']['width'] >= $size[0] && $imagedata['sizes']['thumbnail']['width'] >= $size[1] ) {
+            $data = $imagedata['sizes']['thumbnail'];
+        } else {
+            return false;
+        }
+
+        // Constrain the width and height attributes to the requested values.
+        list( $data['width'], $data['height'] ) = image_constrain_size_for_editor( $data['width'], $data['height'], $size );
+
+    } elseif ( ! empty( $imagedata['sizes'][ $size ] ) ) {
+        $data = $imagedata['sizes'][ $size ];
+    }
+
+    // If we still don't have a match at this point, return false.
+    if ( empty( $data ) ) {
         return false;
-
-    $data = $imagedata['sizes'][$size];
+    }
+
     // include the full filesystem path of the intermediate file
     if ( empty($data['path']) && !empty($data['file']) ) {
@@ -1093 +1132 @@
         }
 
-        /**
-         * To check for varying crops, we calculate the expected size of the smaller
-         * image if the larger were constrained by the width of the smaller and then
-         * see if it matches what we're expecting.
-         */
-        if ( $image_width > $image['width'] ) {
-            $constrained_size = wp_constrain_dimensions( $image_width, $image_height, $image['width'] );
-            $expected_size = array( $image['width'], $image['height'] );
-        } else {
-            $constrained_size = wp_constrain_dimensions( $image['width'], $image['height'], $image_width );
-            $expected_size = array( $image_width, $image_height );
-        }
-
         // If the image dimensions are within 1px of the expected size, use it.
-        if ( abs( $constrained_size[0] - $expected_size[0] ) <= 1 && abs( $constrained_size[1] - $expected_size[1] ) <= 1 ) {
+        if ( wp_image_matches_ratio( $image_width, $image_height, $image['width'], $image['height'] ) ) {
             // Add the URL, descriptor, and value to the sources array to be returned.
             $source = array(

trunk/tests/phpunit/tests/image/intermediate_size.php

@@ -225 +225 @@
         $this->assertTrue( strpos( $image['file'], $width . 'x' . $height ) > 0 );
     }
+
+    /**
+     * @ticket 34384
+     */
+    public function test_get_intermediate_size_with_small_size_array() {
+        // Add a hard cropped size that matches the aspect ratio we're going to test.
+        add_image_size( 'test-size', 200, 100, true );
+
+        $file = DIR_TESTDATA . '/images/waffles.jpg';
+        $id = $this->_make_attachment( $file, 0 );
+
+        // Request a size by array that doesn't exist and is smaller than the 'thumbnail'
+        $image = image_get_intermediate_size( $id, array( 50, 25 ) );
+
+        // We should get the 'test-size' file and not the thumbnail.
+        $this->assertTrue( strpos( $image['file'], '200x100' ) > 0 );
+    }
+
+    /**
+     * @ticket 34384
+     */
+    public function test_get_intermediate_size_with_small_size_array_fallback() {
+        $file = DIR_TESTDATA . '/images/waffles.jpg';
+        $id = $this->_make_attachment( $file, 0 );
+
+        $original = wp_get_attachment_metadata( $id );
+        $thumbnail_file = $original['sizes']['thumbnail']['file'];
+
+        // Request a size by array that doesn't exist and is smaller than the 'thumbnail'
+        $image = image_get_intermediate_size( $id, array( 50, 25 ) );
+
+        // We should get the 'thumbnail' file as a fallback.
+        $this->assertSame( $image['file'], $thumbnail_file );
+    }
 }