support gif frame brackets in filename when using streams too

index.js

@@ -42,6 +42,15 @@ function gm (source, height, color) {
 
   }
 
+  // parse out gif frame brackets from filename
+  // since stream doesn't use source path
+  // eg. "filename.gif[0]"
+  var frames;
+  if(frames = source.match(/(\[.+\])$/)) {
+    this.sourceFrames = source.substr(frames.index, frames[0].length);
+    source = source.substr(0, frames.index);
+  }
+
   this.source = source;
 }
 

lib/command.js

@@ -163,10 +163,12 @@ module.exports = function (proto) {
   }
 
   proto.args = function args () {
+    var source = (this.sourceStream ? "-" : this.source);
+    if(source && this.sourceFrames) source += this.sourceFrames;
     return [].concat(
                 'convert'
               , this._in
-              , this.sourceStream ? "-" : this.source
+              , source
               , this._out
               , this.outname || "-"
             ).filter(function(arg) { return !!arg });

test/gifFrame.js

@@ -0,0 +1,12 @@
+
+// gm - Copyright Aaron Heckmann <aaron.heckmann+github@gmail.com> (MIT Licensed)
+
+var fs = require('fs');
+
+module.exports = function (_, dir, finish, gm) {
+  
+  gm(dir + '/original.gif[0]')
+  .write(dir + '/gifFrame.jpg', function gifFrame (err){
+    finish(err);
+  });
+}

test/gifFrameStream.js

@@ -0,0 +1,12 @@
+
+// gm - Copyright Aaron Heckmann <aaron.heckmann+github@gmail.com> (MIT Licensed)
+
+var fs = require('fs');
+
+module.exports = function (_, dir, finish, gm) {
+  
+  gm(fs.createReadStream(dir + '/original.gif'), "original.gif[0]")
+  .write(dir + '/gifFrameStream.jpg', function gifFrame (err){
+    finish(err);
+  });
+}