ImportImage (#264)

* not working yet...

* fixed basic functioning!

* working! now on to blending

src/modules/ImportImage/Module.js

@@ -0,0 +1,68 @@
+/*
+ * Import Image module; this fetches a given remote or local image via URL 
+ * or data-url, and overwrites the current one. It saves the original as 
+ * step.metadata.input for use in future modules such as blending.
+ * TODO: we could accept an operation for blending like "screen" or "overlay",
+ * or a function with blend(r1,g1,b1,a1,r2,g2,b2,a2), OR we could simply allow
+ * subsequent modules to do this blending and keep this one simple. 
+ */
+module.exports = function ImportImageModule(options, UI) {
+
+  options = options || {};
+  options.imageUrl = options.imageUrl || "/examples/images/monarch.png";
+
+  var output,
+      imgObj = new Image();
+
+  // Tell the UI that a step has been added
+  UI.onSetup(options.step); // we should get UI to return the image thumbnail so we can attach our own UI extensions
+
+  // add our custom in-module html ui:
+  if (options.step.inBrowser) {
+    var ui = require('./Ui.js')(options.step, UI);
+    ui.setup();
+  }
+
+  // This function is caled everytime the step has to be redrawn
+  function draw(input,callback) {
+
+    // Tell the UI that the step has been triggered
+    UI.onDraw(options.step);
+    var step = this;
+
+    step.metadata = step.metadata || {};
+    // TODO: develop a standard API method for saving each input state,
+    // for reference in future steps (for blending, for example)
+    step.metadata.input = input;
+
+    function onLoad() {
+
+      // This output is accessible to Image Sequencer
+      step.output = {
+        src: imgObj.src,
+        format: options.format
+      }
+
+      // This output is accessible to the UI
+      options.step.output = imgObj.src;
+ 
+      // Tell the UI that the step has been drawn
+      UI.onComplete(options.step);
+
+      // Tell Image Sequencer that step has been drawn
+      callback();
+    }
+
+    options.format = require('../../util/GetFormat')(options.imageUrl);
+    imgObj.onload = onLoad;
+    imgObj.src = options.imageUrl;
+
+  }
+
+  return {
+    options: options,
+    draw: draw,
+    output: output,
+    UI: UI
+  }
+}