Merge branch 'dev' of https://github.com/artf/grapesjs into dev

src/asset_manager/config/config.js

@@ -100,5 +100,14 @@ export default {
   modalTitle: 'Select Image',
 
   //Default placeholder for input
-  inputPlaceholder: 'http://path/to/the/image.jpg'
+  inputPlaceholder: 'http://path/to/the/image.jpg',
+
+  //method called before upload, on return false upload is canceled.
+  // @example
+  // beforeUpload: (files) => {
+  //   // logic...
+  //   var stopUpload = true;
+  //   if(stopUpload) return false;
+  // }
+  beforeUpload: null
 };

src/asset_manager/view/FileUploader.js

@@ -108,6 +108,11 @@ export default Backbone.View.extend(
     uploadFile(e, clb) {
       const files = e.dataTransfer ? e.dataTransfer.files : e.target.files;
       const { config } = this;
+      const { beforeUpload } = config;
+
+      const beforeUploadResponse = beforeUpload && beforeUpload(files);
+      if (beforeUploadResponse === false) return;
+
       const body = new FormData();
       const { params, customFetch } = config;