gm().stream() now returns a stream #155

lib/command.js

@@ -8,6 +8,7 @@ var spawn = require('child_process').spawn;
 var utils = require('./utils');
 var debug = require('debug')('gm');
 var series = require('array-series');
+var through = require('through');
 
 /**
  * Error messaging.
@@ -89,17 +90,27 @@ module.exports = function (proto) {
   }
 
   /**
-   * Execute the command and return stdin and stderr ReadableStreams providing the image data.
+   * Execute the command and return stdin and stderr
+   * ReadableStreams providing the image data.
+   * If no callback is passed, a "through" stream will be returned,
+   * and stdout will be piped through, otherwise the error will be passed.
    *
-   * @param {Function} callback
-   * @return {Object} gm
+   * @param {String} format (optional)
+   * @param {Function} callback (optional)
+   * @return {Stream}
    */
 
   proto.stream = function stream (format, callback) {
     if (!callback) callback = format, format = null;
 
+    var throughStream;
+
     if ("function" !== typeof callback) {
-      throw new TypeError("gm().stream() expects a callback function")
+      throughStream = through()
+      callback = function (err, stdout, stderr) {
+        if (err) throughStream.emit('error', err);
+        else stdout.pipe(throughStream);
+      }
     }
 
     if (format) {
@@ -112,6 +123,8 @@ module.exports = function (proto) {
       if (err) return callback(err);
       return self._spawn(self.args(), false, callback);
     });
+
+    return throughStream
   }
 
   /**

package.json

@@ -20,6 +20,7 @@
 , "dependencies": {
       "debug": "0.7.0",
       "array-series": "~0.1.0",
-      "array-parallel": "~0.1.0"
+      "array-parallel": "~0.1.0",
+      "through": "~2.3.1"
   }
 }

test/streamOut.js

@@ -6,11 +6,26 @@ module.exports = function (gm, dir, finish, GM) {
   if (!GM.integration)
     return finish();
 
-  gm
-  .stream(function streamOut (err, stdout, stderr) {
+  withCallback(function (err) {
     if (err) return finish(err);
-    stdout.pipe(fs.createWriteStream(dir + '/streamOut.jpg'));
-    stdout.on('error', finish);
-    stdout.on('close', finish);
+
+    withoutCallback(finish);
   });
+
+  function withCallback(done) {
+    gm
+    .stream(function streamOut (err, stdout, stderr) {
+      if (err) return done(err);
+      stdout.pipe(fs.createWriteStream(dir + '/streamOut.png'));
+      stdout.on('error', done);
+      stdout.on('close', done);
+    });
+  }
+
+  function withoutCallback(done) {
+    var stream = gm.stream()
+    stream.on('error', done)
+    stream.pipe(fs.createWriteStream(dir + '/streamOut2.png'))
+    stream.on('end', done)
+  }
 }

test/streamOutFormat.js

@@ -3,6 +3,7 @@ var assert = require('assert')
 var fs = require('fs');
 
 module.exports = function (gm, dir, finish, GM) {
+  /*
   assert.throws(function () {
     gm.stream()
   }, /expects a callback/);
@@ -10,15 +11,31 @@ module.exports = function (gm, dir, finish, GM) {
   assert.throws(function () {
     gm.stream('PNG')
   }, /expects a callback/);
+  */
 
   if (!GM.integration)
     return finish();
 
-  gm
-  .stream('PNG', function streamOut (err, stdout, stderr) {
+  withCallback(function (err) {
     if (err) return finish(err);
-    stdout.pipe(fs.createWriteStream(dir + '/streamOut.png'));
-    stdout.on('error', finish);
-    stdout.on('close', finish);
+
+    withoutCallback(finish);
   });
+
+  function withCallback(done) {
+    gm
+    .stream('PNG', function streamOut (err, stdout, stderr) {
+      if (err) return done(err);
+      stdout.pipe(fs.createWriteStream(dir + '/streamOut.png'));
+      stdout.on('error', done);
+      stdout.on('close', done);
+    });
+  }
+
+  function withoutCallback(done) {
+    var stream = gm.stream('PNG')
+    stream.on('error', done)
+    stream.pipe(fs.createWriteStream(dir + '/streamOut2.png'))
+    stream.on('end', done)
+  }
 }