Merge pull request #174 from cartuchogl/promises

Promisify async api on promises namespace

README.md

@@ -5,7 +5,7 @@
 Features
 
   * Native bindings to the C/C++ Magick++ library
-  * Async, sync, and stream API
+  * Async, sync, stream and promises API
   * Support for `convert`, `identify`, `composite`, and other utility functions
 
 [![Build Status](https://travis-ci.org/elad/node-imagemagick-native.png)](https://travis-ci.org/elad/node-imagemagick-native)
@@ -25,6 +25,7 @@ Table of contents
     * [`getConstPixels`](#getConstPixels)
     * [`quantumDepth`](#quantumDepth)
     * [`version`](#version)
+    * [Promises](#promises)
   * [Installation](#installation)
     * [Linux / Mac OS X](#installation-unix)
     * [Windows](#installation-windows)
@@ -363,6 +364,40 @@ ex: 16
 Return ImageMagick's version as string.  
 ex: '6.7.7'
 
+<a name="promises"></a>
+
+## Promises
+
+The namespace promises expose functions convert, composite and identify that returns a Promise.
+
+Examples:
+
+````js
+// convert
+imagemagick.promises.convert({ /* OPTIONS */ })
+  .then(function(buff) { /* Write buffer */ })
+  .catch(function(err) { /* log err */ })
+
+// ES8
+const buff = await imagemagick.promises.convert({ /* OPTIONS */ })
+
+// composite
+imagemagick.promises.composite({ /* OPTIONS */ })
+  .then(function(buff) { /* Write buffer */ })
+  .catch(function(err) { /* log err */ })
+
+// ES8
+const buff = await imagemagick.promises.composite({ /* OPTIONS */ })
+
+// identify
+imagemagick.promises.identify({ /* OPTIONS */ })
+  .then(function(info) { /* Write buffer */ })
+  .catch(function(err) { /* log err */ })
+
+// ES8
+const info = await imagemagick.promises.identify({ /* OPTIONS */ })
+````
+
 <a name='installation'></a>
 
 ## Installation

index.js

@@ -37,3 +37,22 @@ Convert.prototype._flush = function(done) {
 }
 
 module.exports.streams = { convert : Convert };
+
+function promisify(func) {
+  return function(options) {
+    return new Promise((resolve, reject) => {
+      func(options, function(err, buff) {
+        if (err) {
+          return reject(err);
+        }
+        resolve(buff);
+      });
+    });
+  };
+}
+
+module.exports.promises = {
+  convert: promisify(module.exports.convert),
+  identify: promisify(module.exports.identify),
+  composite: promisify(module.exports.composite),
+};

test/test.promises.js

@@ -0,0 +1,63 @@
+
+var test        = require('tap').test;
+var imagemagick = require('..');
+var debug       = 0;
+
+process.chdir(__dirname);
+
+function saveToFileIfDebug (buffer, file) {
+  if (debug) {
+    require('fs').writeFileSync( file, buffer, 'binary' );
+    console.log( 'wrote file: '+file );
+  }
+}
+
+test( 'promise convert', function (t) {
+  t.plan(1);
+  imagemagick.promises
+    .convert({
+      srcData: require('fs').readFileSync( 'test.png' ), // 58x66
+      width: 100,
+      height: 100,
+      filter: 'Lagrange',
+      quality: 80,
+      format: 'PNG',
+      debug: debug
+    })
+    .then(function(buffer) {
+      t.equal( Buffer.isBuffer(buffer), true, 'buffer is Buffer' );
+      saveToFileIfDebug( buffer, 'out.png-lagrange.png' );
+      t.end();
+    });
+});
+
+test( 'promise identify', function (t) {
+  t.plan(5);
+  imagemagick.promises
+    .identify({
+      srcData: require('fs').readFileSync( 'test.png' )
+    })
+    .then(function(info){
+      t.equal( info.width, 58, 'width is 58' );
+      t.equal( info.height, 66, 'height is 66' );
+      t.equal( info.depth, 8, 'depth is 8' );
+      t.equal( info.format, 'PNG', 'format is PNG' );
+      t.equal( info.exif.orientation, 0, 'orientation doesnt exist' );
+      t.end();
+    });
+});
+
+test( 'promise composite', function (t) {
+  t.plan(1);
+  imagemagick.promises
+    .composite({
+      srcData: require('fs').readFileSync( 'test.quantizeColors.png' ),
+      compositeData: require('fs').readFileSync('test.png'),
+      debug: debug
+    })
+    .then(function(buffer){
+      t.equal( Buffer.isBuffer(buffer), true, 'buffer is Buffer' );
+      saveToFileIfDebug( buffer, 'out.composite-async.png' );
+      t.end();
+    });
+});