Doc refresh, changelog and dead code removal for #977

docs/api-resize.md

@@ -15,29 +15,20 @@
 Resize image to `width` x `height`.
 By default, the resized image is centre cropped to the exact size specified.
 
-Possible reduction kernels are:
+Possible kernels are:
 
 -   `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
 -   `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
 -   `lanczos2`: Use a [Lanczos kernel](https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel) with `a=2`.
 -   `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
 
-Possible enlargement interpolators are:
-
--   `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
--   `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), faster than bicubic but with less smooth results.
--   `vertexSplitQuadraticBasisSpline`: Use the smoother [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48) to prevent "staircasing" when enlarging.
--   `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation) (the default).
--   `locallyBoundedBicubic`: Use [LBB interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/lbb.cpp#L100), which prevents some "[acutance](http://en.wikipedia.org/wiki/Acutance)" but typically reduces performance by a factor of 2.
--   `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance but typically reduces performance by a factor of 3.
-
 **Parameters**
 
 -   `width` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
 -   `height` **[Number](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number)?** pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
 -   `options` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** 
     -   `options.kernel` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)** the kernel to use for image reduction. (optional, default `'lanczos3'`)
-    -   `options.interpolator` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)** the interpolator to use for image enlargement. (optional, default `'bicubic'`)
+    -   `options.fastShrinkOnLoad` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** take greater advantage of the JPEG and WebP shrink-on-load feature, which can lead to a slight moiré pattern on some images. (optional, default `true`)
     -   `options.centreSampling` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** use \*magick centre sampling convention instead of corner sampling. (optional, default `false`)
     -   `options.centerSampling` **[Boolean](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Boolean)** alternative spelling of centreSampling. (optional, default `false`)
 
@@ -46,15 +37,14 @@ Possible enlargement interpolators are:
 ```javascript
 sharp(inputBuffer)
   .resize(200, 300, {
-    kernel: sharp.kernel.lanczos2,
-    interpolator: sharp.interpolator.nohalo
+    kernel: sharp.kernel.nearest
   })
   .background('white')
   .embed()
   .toFile('output.tiff')
   .then(function() {
     // output.tiff is a 200 pixels wide and 300 pixels high image
-    // containing a lanczos2/nohalo scaled version, embedded on a white canvas,
+    // containing a nearest-neighbour scaled version, embedded on a white canvas,
     // of the image data in inputBuffer
   });
 ```

docs/changelog.md

@@ -18,6 +18,10 @@ Requires libvips v8.6.0.
   [#976](https://github.com/lovell/sharp/pull/976)
   [@mceachen](https://github.com/mceachen)
 
+* Resize: switch to libvips' implementation, make fastShrinkOnLoad optional, remove interpolators.
+  [#977](https://github.com/lovell/sharp/pull/977)
+  [@jardakotesovec](https://github.com/jardakotesovec)
+
 ### v0.18 - "*ridge*"
 
 Requires libvips v8.5.5.

docs/index.md

@@ -103,6 +103,7 @@ the help and code contributions of the following people:
 * [Nicolas Coden](https://github.com/ncoden)
 * [Matt Parrish](https://github.com/pbomb)
 * [Matthew McEachen](https://github.com/mceachen)
+* [Jarda Kotěšovec](https://github.com/jardakotesovec)
 
 Thank you!
 

lib/resize.js

@@ -42,60 +42,35 @@ const kernel = {
   lanczos3: 'lanczos3'
 };
 
-/**
- * Enlargement interpolators.
- * @member
- * @private
- */
-const interpolator = {
-  nearest: 'nearest',
-  bilinear: 'bilinear',
-  bicubic: 'bicubic',
-  nohalo: 'nohalo',
-  lbb: 'lbb',
-  locallyBoundedBicubic: 'lbb',
-  vsqbs: 'vsqbs',
-  vertexSplitQuadraticBasisSpline: 'vsqbs'
-};
-
 /**
  * Resize image to `width` x `height`.
  * By default, the resized image is centre cropped to the exact size specified.
  *
- * Possible reduction kernels are:
+ * Possible kernels are:
  * - `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
  * - `cubic`: Use a [Catmull-Rom spline](https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline).
  * - `lanczos2`: Use a [Lanczos kernel](https://en.wikipedia.org/wiki/Lanczos_resampling#Lanczos_kernel) with `a=2`.
  * - `lanczos3`: Use a Lanczos kernel with `a=3` (the default).
  *
- * Possible enlargement interpolators are:
- * - `nearest`: Use [nearest neighbour interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation).
- * - `bilinear`: Use [bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation), faster than bicubic but with less smooth results.
- * - `vertexSplitQuadraticBasisSpline`: Use the smoother [VSQBS interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/vsqbs.cpp#L48) to prevent "staircasing" when enlarging.
- * - `bicubic`: Use [bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation) (the default).
- * - `locallyBoundedBicubic`: Use [LBB interpolation](https://github.com/jcupitt/libvips/blob/master/libvips/resample/lbb.cpp#L100), which prevents some "[acutance](http://en.wikipedia.org/wiki/Acutance)" but typically reduces performance by a factor of 2.
- * - `nohalo`: Use [Nohalo interpolation](http://eprints.soton.ac.uk/268086/), which prevents acutance but typically reduces performance by a factor of 3.
- *
  * @example
  * sharp(inputBuffer)
  *   .resize(200, 300, {
- *     kernel: sharp.kernel.lanczos2,
- *     interpolator: sharp.interpolator.nohalo
+ *     kernel: sharp.kernel.nearest
  *   })
  *   .background('white')
  *   .embed()
  *   .toFile('output.tiff')
  *   .then(function() {
  *     // output.tiff is a 200 pixels wide and 300 pixels high image
- *     // containing a lanczos2/nohalo scaled version, embedded on a white canvas,
+ *     // containing a nearest-neighbour scaled version, embedded on a white canvas,
  *     // of the image data in inputBuffer
  *   });
  *
  * @param {Number} [width] - pixels wide the resultant image should be. Use `null` or `undefined` to auto-scale the width to match the height.
  * @param {Number} [height] - pixels high the resultant image should be. Use `null` or `undefined` to auto-scale the height to match the width.
  * @param {Object} [options]
  * @param {String} [options.kernel='lanczos3'] - the kernel to use for image reduction.
- * @param {String} [options.interpolator='bicubic'] - the interpolator to use for image enlargement.
+ * @param {Boolean} [options.fastShrinkOnLoad=true] - take greater advantage of the JPEG and WebP shrink-on-load feature, which can lead to a slight moiré pattern on some images.
  * @param {Boolean} [options.centreSampling=false] - use *magick centre sampling convention instead of corner sampling.
  * @param {Boolean} [options.centerSampling=false] - alternative spelling of centreSampling.
  * @returns {Sharp}
@@ -129,20 +104,11 @@ function resize (width, height, options) {
         throw is.invalidParameterError('kernel', 'valid kernel name', options.kernel);
       }
     }
-    // Interpolator
-    if (is.defined(options.interpolator)) {
-      if (is.string(interpolator[options.interpolator])) {
-        this.options.interpolator = interpolator[options.interpolator];
-      } else {
-        throw is.invalidParameterError('interpolator', 'valid interpolator name', options.interpolator);
-      }
-    }
     // Centre sampling
     options.centreSampling = is.bool(options.centerSampling) ? options.centerSampling : options.centreSampling;
     if (is.defined(options.centreSampling)) {
       this._setBooleanOption('centreSampling', options.centreSampling);
     }
-
     // Shrink on load
     if (is.defined(options.fastShrinkOnLoad)) {
       this._setBooleanOption('fastShrinkOnLoad', options.fastShrinkOnLoad);
@@ -307,5 +273,4 @@ module.exports = function (Sharp) {
   Sharp.gravity = gravity;
   Sharp.strategy = strategy;
   Sharp.kernel = kernel;
-  Sharp.interpolator = interpolator;
 };

package.json

@@ -39,7 +39,8 @@
     "Guy Maliar <guy@tailorbrands.com>",
     "Nicolas Coden <nicolas@ncoden.fr>",
     "Matt Parrish <matt.r.parrish@gmail.com>",
-    "Matthew McEachen <matthew+github@mceachen.org>"
+    "Matthew McEachen <matthew+github@mceachen.org>",
+    "Jarda Kotěšovec <jarda.kotesovec@gmail.com>"
   ],
   "scripts": {
     "clean": "rm -rf node_modules/ build/ vendor/ coverage/ test/fixtures/output.*",

src/pipeline.cc

@@ -1140,7 +1140,6 @@ NAN_METHOD(pipeline) {
   baton->withoutEnlargement = AttrTo<bool>(options, "withoutEnlargement");
   baton->crop = AttrTo<int32_t>(options, "crop");
   baton->kernel = AttrAsStr(options, "kernel");
-  baton->interpolator = AttrAsStr(options, "interpolator");
   baton->centreSampling = AttrTo<bool>(options, "centreSampling");
   baton->fastShrinkOnLoad = AttrTo<bool>(options, "fastShrinkOnLoad");
   // Join Channel Options

src/pipeline.h

@@ -67,7 +67,6 @@ struct PipelineBaton {
   int cropOffsetTop;
   bool premultiplied;
   std::string kernel;
-  std::string interpolator;
   bool centreSampling;
   bool fastShrinkOnLoad;
   double background[4];

test/unit/resize.js

@@ -478,4 +478,40 @@ describe('Resize dimensions', function () {
       fixtures.assertSimilar(fixtures.expected('fast-shrink-on-load-true.png'), data, done);
     });
   });
+
+  [
+    sharp.kernel.nearest,
+    sharp.kernel.cubic,
+    sharp.kernel.lanczos2,
+    sharp.kernel.lanczos3
+  ].forEach(function (kernel) {
+    it(`kernel ${kernel}`, function (done) {
+      sharp(fixtures.inputJpg)
+        .resize(320, null, { kernel: kernel })
+        .toBuffer(function (err, data, info) {
+          if (err) throw err;
+          assert.strictEqual('jpeg', info.format);
+          assert.strictEqual(320, info.width);
+          fixtures.assertSimilar(fixtures.inputJpg, data, done);
+        });
+    });
+  });
+
+  it('nearest upsampling with integral factor', function (done) {
+    sharp(fixtures.inputTiff8BitDepth)
+      .resize(210, 210, { kernel: 'nearest' })
+      .png()
+      .toBuffer(function (err, data, info) {
+        if (err) throw err;
+        assert.strictEqual(210, info.width);
+        assert.strictEqual(210, info.height);
+        done();
+      });
+  });
+
+  it('unknown kernel throws', function () {
+    assert.throws(function () {
+      sharp().resize(null, null, { kernel: 'unknown' });
+    });
+  });
 });