[ADD] placeholder support on t-field

A placeholder is looked up:

1. in the field's options ("placeholder")
2. on the t-field node itself (@placeholder)
3. on the field's column (.placeholder)

The first one found is used as the @placeholder of the resulting node
(in-HTML), and displayed when the field is empty and unfocused.

If no placeholder is found, an empty field just gets a small padding
in order to be easier to see & focus.

bzr revid: xmo@openerp.com-20131218114901-xi3ye11x5pysq2a2

addons/website/models/ir_qweb.py

@@ -73,12 +73,21 @@ class Field(orm.AbstractModel):
 
     def attributes(self, cr, uid, field_name, record, options,
                    source_element, g_att, t_att, qweb_context, context=None):
+        if options is None: options = {}
         column = record._model._all_columns[field_name].column
+        attrs = [('data-oe-translate', 1 if column.translate else 0)]
+
+        placeholder = options.get('placeholder') \
+                   or source_element.getAttribute('placeholder') \
+                   or getattr(column, 'placeholder', None)
+        if placeholder:
+            attrs.append(('placeholder', placeholder))
+
         return itertools.chain(
             super(Field, self).attributes(cr, uid, field_name, record, options,
                                           source_element, g_att, t_att,
                                           qweb_context, context=context),
-            [('data-oe-translate', 1 if column.translate else 0)]
+            attrs
         )
 
     def value_from_string(self, value):

addons/website/static/src/css/editor.css

@@ -211,9 +211,15 @@ ul.oe_menu_editor .disclose {
 }
 
 .cke_widget_editable:empty:after {
-  content: " ";
+  opacity: 0.3;
   white-space: pre-wrap;
 }
+.cke_widget_editable:not([placeholder]):empty::after {
+  content: " ";
+}
+.cke_widget_editable[placeholder]:not(:focus):empty::after {
+  content: attr(placeholder);
+}
 
 .oe_carlos_danger {
   outline: 1px solid red !important;

addons/website/static/src/css/editor.sass

@@ -171,11 +171,20 @@ ul.oe_menu_editor
 // Breaks completely horribly crazy products listing page, so take it out.
 .cke_widget_wrapper
     position: static !important
+
 // prevent inline widgets from entirely disappearing when their (textual)
 // content is removed
-.cke_widget_editable:empty:after
-    content: " "
-    white-space: pre-wrap
+.cke_widget_editable
+    // basic config
+    &:empty:after
+        opacity: 0.3
+        white-space: pre-wrap
+    // no @placeholder -> just add some padding
+    &:not([placeholder]):empty::after
+        content: " "
+    // with placeholder and when not (yet) focused -> display placeholder
+    &[placeholder]:not(:focus):empty::after
+        content: attr(placeholder)
 
 .oe_carlos_danger
     outline: 1px solid red !important