Docs: changelog and credit for #3556

docs/api-resize.md

@@ -146,7 +146,8 @@ const scaleByHalf = await sharp(input)
 
 
 ## extend
-Extends/pads the edges of the image with the provided background colour.
+Extend / pad / extrude one or more edges of the image with either
+the provided background colour or pixels derived from the image.
 This operation will always occur after resizing and extraction, if any.
 
 
@@ -162,6 +163,7 @@ This operation will always occur after resizing and extraction, if any.
 | [extend.left] | <code>number</code> | <code>0</code> |  |
 | [extend.bottom] | <code>number</code> | <code>0</code> |  |
 | [extend.right] | <code>number</code> | <code>0</code> |  |
+| [extend.extendWith] | <code>String</code> | <code>&#x27;background&#x27;</code> | populate new pixels using this method, one of: background, copy, repeat, mirror. |
 | [extend.background] | <code>String</code> \| <code>Object</code> | <code>{r: 0, g: 0, b: 0, alpha: 1}</code> | background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency. |
 
 **Example**  
@@ -189,6 +191,16 @@ sharp(input)
   })
   ...
 ```
+**Example**  
+```js
+// Extrude image by 8 pixels to the right, mirroring existing right hand edge
+sharp(input)
+  .extend({
+    right: 8,
+    background: 'mirror'
+  })
+  ...
+```
 
 
 ## extract

docs/changelog.md

@@ -49,6 +49,10 @@ Requires libvips v8.14.0
   [#3548](https://github.com/lovell/sharp/pull/3548)
   [@kapouer](https://github.com/kapouer)
 
+* Add support to `extend` operation for `extendWith` to allow copy/mirror/repeat.
+  [#3556](https://github.com/lovell/sharp/pull/3556)
+  [@janaz](https://github.com/janaz)
+
 ## v0.31 - *eagle*
 
 Requires libvips v8.13.3

docs/humans.txt

@@ -266,3 +266,6 @@ GitHub: https://github.com/marcosc90
 
 Name: Emanuel Jöbstl
 GitHub: https://github.com/ejoebstl
+
+Name: Tomasz Janowski
+GitHub: https://github.com/janaz

lib/index.d.ts

@@ -755,7 +755,8 @@ declare namespace sharp {
         resize(options: ResizeOptions): Sharp;
 
         /**
-         * Extends/pads the edges of the image with either the provided background colour or pixels derived from the image.
+         * Extend / pad / extrude one or more edges of the image with either
+         * the provided background colour or pixels derived from the image.
          * This operation will always occur after resizing and extraction, if any.
          * @param extend single pixel count to add to all edges or an Object with per-edge counts
          * @throws {Error} Invalid parameters

lib/resize.js

@@ -334,7 +334,8 @@ function resize (width, height, options) {
 }
 
 /**
- * Extends/pads the edges of the image with the provided background colour.
+ * Extend / pad / extrude one or more edges of the image with either
+ * the provided background colour or pixels derived from the image.
  * This operation will always occur after resizing and extraction, if any.
  *
  * @example
@@ -360,11 +361,21 @@ function resize (width, height, options) {
  *   })
  *   ...
  *
+ * @example
+ * // Extrude image by 8 pixels to the right, mirroring existing right hand edge
+ * sharp(input)
+ *   .extend({
+ *     right: 8,
+ *     background: 'mirror'
+ *   })
+ *   ...
+ *
  * @param {(number|Object)} extend - single pixel count to add to all edges or an Object with per-edge counts
  * @param {number} [extend.top=0]
  * @param {number} [extend.left=0]
  * @param {number} [extend.bottom=0]
  * @param {number} [extend.right=0]
+ * @param {String} [extend.extendWith='background'] - populate new pixels using this method, one of: background, copy, repeat, mirror.
  * @param {String|Object} [extend.background={r: 0, g: 0, b: 0, alpha: 1}] - background colour, parsed by the [color](https://www.npmjs.org/package/color) module, defaults to black without transparency.
  * @returns {Sharp}
  * @throws {Error} Invalid parameters
@@ -409,7 +420,7 @@ function extend (extend) {
       if (is.string(extendWith[extend.extendWith])) {
         this.options.extendWith = extendWith[extend.extendWith];
       } else {
-        throw is.invalidParameterError('extendWith', 'valid value', extend.extendWith);
+        throw is.invalidParameterError('extendWith', 'one of: background, copy, repeat, mirror', extend.extendWith);
       }
     }
   } else {

test/unit/extend.js

@@ -147,7 +147,7 @@ describe('Extend', function () {
   it('invalid extendWith fails', () => {
     assert.throws(
       () => sharp().extend({ extendWith: 'invalid-value' }),
-      /Expected valid value for extendWith but received invalid-value of type string/
+      /Expected one of: background, copy, repeat, mirror for extendWith but received invalid-value of type string/
     );
   });
   it('can set all edges apart from right', () => {