Detect image type from buffer

lib/obtain.js

@@ -43,6 +43,19 @@
                     callback(null, new Image(source, type.width, type.height, (numChannels % 2 === 0)));
                 } else if (typeof type === 'string') {
                     // it's an encoded image
+                    opener = getOpener(type);
+                    opener(source, function(err, pixelsBuf, width, height, channels, trans) {
+                        callback(err, err ? null : new Image(pixelsBuf, width, height, trans));
+                    });
+                } else if (!type) {
+                    //No type passed, auto resolve type from buffer
+                    var resolvedType = require('file-type')(source);
+
+                    //Faulty buffers or unresolved types will return null.
+                    if (resolvedType === null) throw Error('Failed to auto resolve buffer type.');  
+
+                    type = resolvedType.ext;
+
                     opener = getOpener(type);
                     opener(source, function(err, pixelsBuf, width, height, channels, trans) {
                         callback(err, err ? null : new Image(pixelsBuf, width, height, trans));

package.json

@@ -5,7 +5,8 @@
   "dependencies": {
     "async": "~0.9.0",
     "decree": "0.0.6",
-    "nan": "~1.4.1"
+    "nan": "~1.4.1",
+    "file-type": "~2.0.1"
   },
   "scripts": {
     "install": "node-gyp rebuild",

tests/00.argsValidation/001.open.js

@@ -58,8 +58,8 @@ describe('lwip.open arguments validation', function() {
         });
 
         describe('without type', function() {
-            it('should throw an error', function() {
-                lwip.open.bind(lwip, buffer, function() {}).should.throwError();
+            it('should succeed', function() {
+                lwip.open.bind(lwip, buffer, function() {}).should.not.throw();
             });
         });
         describe('with invalid type', function() {
@@ -69,6 +69,17 @@ describe('lwip.open arguments validation', function() {
         });
 
     });
+
+    describe('invalid buffer', function() {
+
+        var buffer = new Buffer("I'm not an image at all!", "utf-8");
+
+        describe('without type', function() {
+            it('should throw an error', function() {
+                lwip.open.bind(lwip, buffer, function() {}).should.throw(/Failed to auto resolve buffer type/);
+            });
+        });
+    });
 
     describe('pixelbuffer', function() {