Make it clear when there's no change (fixes #52)

Author: danvk

webdiff/static/css/style.css

@@ -118,3 +118,17 @@ ul.file-list {
 table .side-a, table .side-b {
   background: url(/static/img/trans_bg.gif);
 }
+
+.no-changes {
+  background-color: rgb(252, 248, 227);
+  border: 1px solid rgb(245, 231, 158);
+  border-radius: 4px;
+  color: rgb(138, 109, 59);
+  text-align: center;
+  padding: 5px 5px;
+  margin-bottom: 10px;
+}
+
+.image-diff .no-changes {
+  margin-top: 10px;
+}

webdiff/static/js/components.jsx

@@ -252,13 +252,32 @@ var DiffView = React.createClass({
   }
 });
 
+// A "no changes" sign which only appears when applicable.
+var NoChanges = React.createClass({
+  propTypes: {
+    filePair: React.PropTypes.object.isRequired
+  },
+  render: function() {
+    if (this.props.filePair.no_changes) {
+      return <div className="no-changes">(No Changes)</div>;
+    } else {
+      return null;
+    }
+  }
+});
+
 // A side-by-side diff of source code.
 var CodeDiff = React.createClass({
   propTypes: {
     filePair: React.PropTypes.object.isRequired
   },
   render: function() {
-    return <div key={this.props.filePair.idx}>Loading&hellip;</div>;
+    return (
+      <div style={{display: 'table'}}>
+        <NoChanges filePair={this.props.filePair} />
+        <div ref="codediff" key={this.props.filePair.idx}>Loading&hellip;</div>
+      </div>
+    );
   },
   renderDiff: function() {
     // Either side can be empty (i.e. an add or a delete), in which case
@@ -274,7 +293,7 @@ var CodeDiff = React.createClass({
     $.when(beforeDeferred, afterDeferred).done((before, after) => {
       if (!this.isMounted()) return;
       // Call out to codediff.js to construct the side-by-side diff.
-      $(this.getDOMNode()).empty().append(
+      $(this.refs.codediff.getDOMNode()).empty().append(
           renderDiff(pair.a, pair.b, before[0], after[0]));
     })
     .fail((e) => alert("Unable to get diff!"));
@@ -333,6 +352,7 @@ var ImageDiff = React.createClass({
         <label htmlFor="shrink-to-fit"> Shrink to fit</label>
       </div>
       <div className={'image-diff ' + mode}>
+        <NoChanges filePair={this.props.filePair} />
         {image}
       </div>
     </div>;

webdiff/util.py

@@ -76,13 +76,19 @@ def _convert_to_pair_objects(pairs):
 
 
 def _annotate_file_pair(d, a_dir, b_dir):
+    a_path = os.path.join(a_dir, d['a']) if d['a'] else None
+    b_path = os.path.join(b_dir, d['b']) if d['b'] else None
+
     # Attach image metadata if applicable.
     if is_image_diff(d):
         d['is_image_diff'] = True
-        if d['a']: d['image_a'] = _image_metadata(os.path.join(a_dir, d['a']))
-        if d['b']: d['image_b'] = _image_metadata(os.path.join(b_dir, d['b']))
+        if d['a']: d['image_a'] = _image_metadata(a_path)
+        if d['b']: d['image_b'] = _image_metadata(b_path)
 
-    # TODO: diffstats
+    if a_path and b_path:
+        d['no_changes'] = _are_files_identical(a_path, b_path)
+    else:
+        d['no_changes'] = False
 
 
 def annotate_file_pairs(file_pairs, a_dir, b_dir):
@@ -97,7 +103,7 @@ def annotate_file_pairs(file_pairs, a_dir, b_dir):
 
 def find_moves(diff, a_dir, b_dir):
     def hash(d, path):
-        return hashlib.sha512(open(os.path.join(d, path)).read()).digest()
+        return _contentHash(os.path.join(d, path))
 
     out = copy.deepcopy(diff)
     add_delete_pairs = defaultdict(lambda: [None,None])
@@ -144,6 +150,24 @@ def is_image(path):
     return False
 
 
+hash_cache = {}
+def _contentHash(path):
+    global hash_cache
+    if path in hash_cache:
+        return hash_cache[path]
+    sha = hashlib.sha512(open(path).read()).digest()
+    hash_cache[path] = sha
+    return sha
+
+
+def _are_files_identical(path1, path2):
+    # Check if anything has changed.
+    # Compare lengths & then checksums.
+    if os.path.getsize(path1) != os.path.getsize(path2):
+        return False
+    return _contentHash(path1) == _contentHash(path2) 
+
+
 def _image_metadata(path):
     md = { 'num_bytes': os.path.getsize(path) }
     try: