Add toFormat convenience method #137

README.md

@@ -197,7 +197,7 @@ sharp('input.gif')
   .resize(200, 300)
   .background({r: 0, g: 0, b: 0, a: 0})
   .embed()
-  .webp()
+  .toFormat(sharp.format.webp)
   .toBuffer(function(err, outputBuffer) {
     if (err) {
       throw err;
@@ -211,7 +211,7 @@ sharp('input.gif')
 sharp(inputBuffer)
   .resize(200, 200)
   .max()
-  .jpeg()
+  .toFormat('jpeg')
   .toBuffer().then(function(outputBuffer) {
     // outputBuffer contains JPEG image data no wider than 200 pixels and no higher
     // than 200 pixels regardless of the inputBuffer image dimensions
@@ -415,6 +415,13 @@ The number of channels depends on the input image and selected options.
 * 3 channels for colour images without alpha transparency, with bytes ordered \[red, green, blue, red, green, blue, etc.\]).
 * 4 channels for colour images with alpha transparency, with bytes ordered \[red, green, blue, alpha, red, green, blue, alpha, etc.\].
 
+#### toFormat(format)
+
+Convenience method for the above output format methods, where `format` is either:
+
+* an attribute of the `sharp.format` Object e.g. `sharp.format.jpeg`, or
+* a String containing `jpeg`, `png`, `webp` or `raw`.
+
 #### quality(quality)
 
 The output quality to use for lossy JPEG, WebP and TIFF output formats. The default quality is `80`.

index.js

@@ -435,25 +435,40 @@ Sharp.prototype.toFile = function(output, callback) {
   return this;
 };
 
+/*
+  Write output to a Buffer
+*/
 Sharp.prototype.toBuffer = function(callback) {
   return this._sharp(callback);
 };
 
+/*
+  Force JPEG output
+*/
 Sharp.prototype.jpeg = function() {
   this.options.output = '__jpeg';
   return this;
 };
 
+/*
+  Force PNG output
+*/
 Sharp.prototype.png = function() {
   this.options.output = '__png';
   return this;
 };
 
+/*
+  Force WebP output
+*/
 Sharp.prototype.webp = function() {
   this.options.output = '__webp';
   return this;
 };
 
+/*
+  Force raw, uint8 output
+*/
 Sharp.prototype.raw = function() {
   if (semver.gte(libvipsVersion, '7.42.0')) {
     this.options.output = '__raw';
@@ -463,6 +478,23 @@ Sharp.prototype.raw = function() {
   return this;
 };
 
+/*
+  Force output to a given format
+*/
+module.exports.format = {'jpeg': 'jpeg', 'png': 'png', 'webp': 'webp', 'raw': 'raw'};
+Sharp.prototype.toFormat = function(format) {
+  if (
+    typeof format === 'string' &&
+    typeof module.exports.format[format] === 'string' &&
+    typeof this[format] === 'function'
+  ) {
+    this[format]();
+  } else {
+    throw new Error('Unsupported format ' + format);
+  }
+  return this;
+};
+
 /*
   Used by a Writable Stream to notify that it is ready for data
 */

package.json

@@ -34,10 +34,10 @@
     "vips"
   ],
   "dependencies": {
-    "bluebird": "^2.9.7",
+    "bluebird": "^2.9.8",
     "color": "^0.7.3",
     "nan": "^1.6.2",
-    "semver": "^4.2.0"
+    "semver": "^4.2.2"
   },
   "devDependencies": {
     "mocha": "^2.1.0",

test/unit/io.js

@@ -135,10 +135,11 @@ describe('Input/output', function() {
     readableButNotAnImage.pipe(writable);
   });
 
-  it('Sequential read', function(done) {
+  it('Sequential read, force JPEG', function(done) {
     sharp(fixtures.inputJpg)
       .sequentialRead()
       .resize(320, 240)
+      .toFormat(sharp.format.jpeg)
       .toBuffer(function(err, data, info) {
         if (err) throw err;
         assert.strictEqual(true, data.length > 0);
@@ -150,10 +151,11 @@ describe('Input/output', function() {
       });
   });
 
-  it('Not sequential read', function(done) {
+  it('Not sequential read, force JPEG', function(done) {
     sharp(fixtures.inputJpg)
       .sequentialRead(false)
       .resize(320, 240)
+      .toFormat('jpeg')
       .toBuffer(function(err, data, info) {
         if (err) throw err;
         assert.strictEqual(true, data.length > 0);
@@ -292,6 +294,30 @@ describe('Input/output', function() {
       });
   });
 
+  it('WebP output', function(done) {
+    sharp(fixtures.inputJpg)
+      .resize(320, 240)
+      .toFormat(sharp.format.webp)
+      .toBuffer(function(err, data, info) {
+        if (err) throw err;
+        assert.strictEqual(true, data.length > 0);
+        assert.strictEqual('webp', info.format);
+        assert.strictEqual(320, info.width);
+        assert.strictEqual(240, info.height);
+        done();
+      });
+  });
+
+  it('Invalid output format', function(done) {
+    var isValid = false;
+    try {
+      sharp().toFormat('zoinks');
+      isValid = true;
+    } catch (e) {}
+    assert(!isValid);
+    done();
+  });
+
   it('File input with corrupt header fails gracefully', function(done) {
     sharp(fixtures.inputJpgWithCorruptHeader)
       .toBuffer(function(err) {
@@ -436,7 +462,7 @@ describe('Input/output', function() {
   it('Convert SVG, if supported, to PNG', function(done) {
     sharp(fixtures.inputSvg)
       .resize(100, 100)
-      .png()
+      .toFormat('png')
       .toFile(fixtures.path('output.svg.png'), function(err, info) {
         if (err) {
           assert.strictEqual('Input file is of an unsupported image format', err.message);
@@ -453,7 +479,7 @@ describe('Input/output', function() {
   it('Convert PSD to PNG', function(done) {
     sharp(fixtures.inputPsd)
       .resize(320, 240)
-      .png()
+      .toFormat(sharp.format.png)
       .toFile(fixtures.path('output.psd.png'), function(err, info) {
         if (err) throw err;
         assert.strictEqual(true, info.size > 0);
@@ -501,7 +527,7 @@ describe('Input/output', function() {
       it('3 channel colour image without transparency', function(done) {
         sharp(fixtures.inputJpg)
           .resize(32, 24)
-          .raw()
+          .toFormat('raw')
           .toBuffer(function(err, data, info) {
             assert.strictEqual(32 * 24 * 3, info.size);
             assert.strictEqual(data.length, info.size);
@@ -514,7 +540,7 @@ describe('Input/output', function() {
       it('4 channel colour image with transparency', function(done) {
         sharp(fixtures.inputPngWithTransparency)
           .resize(32, 24)
-          .raw()
+          .toFormat(sharp.format.raw)
           .toBuffer(function(err, data, info) {
             assert.strictEqual(32 * 24 * 4, info.size);
             assert.strictEqual(data.length, info.size);