libvips
diff --git a/‎src/Image.php
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Lines changed: 45 additions & 0 deletions
diff --git a/‎tests/new.php
Lines changed: 14 additions & 0 deletions b/‎tests/new.php
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@@ -374,6 +374,44 @@
  * If you want to avoid the copies, you'll need to call drawing operations
  * yourself.
  *
+ * # Thumbnailing
+ *
+ * The thumbnailing functionality is implemented by `Vips\Image::thumbnail` and
+ * `Vips\Image::thumbnail_buffer` (which thumbnails an image held as a string).
+ *
+ * You could write:
+ * ```php
+ * $filename = 'image.jpg';
+ * $image->writeToFile('my-thumbnail.jpg');
+ * ```
+ *
+ * # Resample
+ *
+ * There are three types of operation in this section.
+ *
+ * First, `->affine()` applies an affine transform to an image.
+ * This is any sort of 2D transform which preserves straight lines;
+ * so any combination of stretch, sheer, rotate and translate.
+ * You supply an interpolator for it to use to generate pixels
+ * (@see Image::newInterpolator()). It will not produce good results for
+ * very large shrinks: you'll see aliasing.
+ *
+ * `->reduce()` is like `->affine()`, but it can only shrink images,
+ * it can't enlarge, rotate, or skew.
+ * It's very fast and uses an adaptive kernel (@see Kernel for possible values)
+ * for interpolation. Again, it will give poor results for large size reductions.
+ *
+ * `->shrink()` is a fast block shrinker. It can quickly reduce images by large
+ * integer factors. It will give poor results for small size reductions:
+ * again, you'll see aliasing.
+ *
+ * Next, `->resize()` specialises in the common task of image reduce and enlarge.
+ * It strings together combinations of `->shrink()`, `->reduce()`, `->affine()`
+ * and others to implement a general, high-quality image resizer.
+ *
+ * Finally, `->mapim()` can apply arbitrary 2D image transforms to an image.
+ *
  * # Expansions
  *
  * Some vips operators take an enum to select an action, for example
@@ -817,6 +855,13 @@ public static function newFromArray(
      * Make an interpolator from a name.
      *
      * @param string $name Name of the interpolator.
+     * Possible interpolators are:
+     *  - `'nearest'`: Use nearest neighbour interpolation.
+     *  - `'bicubic'`: Use bicubic interpolation.
+     *  - `'bilinear'`: Use bilinear interpolation (the default).
+     *  - `'nohalo'`: Use Nohalo interpolation.
+     *  - `'lbb'`: Use LBB interpolation.
+     *  - `'vsqbs'`: Use the VSQBS interpolation.
      *
      * @return resource|null The interpolator, or null on error.
      */
 
@@ -91,6 +91,20 @@ public function testVipsCopyMemory()
         $this->assertEquals($image1->avg(), $image2->avg());
     }
 
+    public function testVipsNewInterpolator()
+    {
+        $filename = dirname(__FILE__) . '/images/img_0076.jpg';
+        $image1 = Vips\Image::newFromFile($filename);
+        $interp = Vips\Image::newInterpolator('bicubic');
+        $image2 = $image1->affine([2, 0, 0, 2], ['interpolate' => $interp]);
+
+        $widthInput = $image1->width;
+        $widthOutput = $image2->width;
+
+        $this->assertNotNull($interp);
+        $this->assertEquals($widthInput * 2, $widthOutput);
+    }
+
 }
 
 /*