[IMP] base,web: add image_url widget support in qweb.

The new "image_url" widget logic provides the ability to provide static image
links in Char fields instead of duplicating the image file in database (+ filestore)
through an Image field (& ir_attachment).

This commits implements the frontend qweb logic for this widget, following the logic
of the existing "image" qweb widget.

addons/web/models/ir_qweb.py

@@ -21,20 +21,12 @@ class Image(models.AbstractModel):
     _description = 'Qweb Field Image'
     _inherit = 'ir.qweb.field.image'
 
-    @api.model
-    def record_to_html(self, record, field_name, options):
-        assert options['tagName'] != 'img',\
-            "Oddly enough, the root tag of an image field can not be img. " \
-            "That is because the image goes into the tag, or it gets the " \
-            "hose again."
-
-        if options.get('qweb_img_raw_data', False):
-            return super(Image, self).record_to_html(record, field_name, options)
-
-        aclasses = ['img', 'img-fluid'] if options.get('qweb_img_responsive', True) else ['img']
-        aclasses += options.get('class', '').split()
-        classes = ' '.join(map(escape, aclasses))
+    def _get_src_urls(self, record, field_name, options):
+        """Considering the rendering options, returns the src and data-zoom-image urls.
 
+        :return: src, src_zoom urls
+        :rtype: tuple
+        """
         max_size = None
         if options.get('resize'):
             max_size = options.get('resize')
@@ -56,6 +48,30 @@ class Image(models.AbstractModel):
 
         src = '/web/image/%s/%s/%s%s/%s?unique=%s' % (record._name, record.id, options.get('preview_image', field_name), max_size, url_quote(filename), sha)
 
+        src_zoom = None
+        if options.get('zoom') and getattr(record, options['zoom'], None):
+            src_zoom = '/web/image/%s/%s/%s%s/%s?unique=%s' % (record._name, record.id, options['zoom'], max_size, url_quote(filename), sha)
+        elif options.get('zoom'):
+            src_zoom = options['zoom']
+
+        return src, src_zoom
+
+    @api.model
+    def record_to_html(self, record, field_name, options):
+        assert options['tagName'] != 'img',\
+            "Oddly enough, the root tag of an image field can not be img. " \
+            "That is because the image goes into the tag, or it gets the " \
+            "hose again."
+
+        if options.get('qweb_img_raw_data', False):
+            return super(Image, self).record_to_html(record, field_name, options)
+
+        aclasses = ['img', 'img-fluid'] if options.get('qweb_img_responsive', True) else ['img']
+        aclasses += options.get('class', '').split()
+        classes = ' '.join(map(escape, aclasses))
+
+        src, src_zoom = self._get_src_urls(record, field_name, options)
+
         if options.get('alt-field') and getattr(record, options['alt-field'], None):
             alt = escape(record[options['alt-field']])
         elif options.get('alt'):
@@ -63,12 +79,6 @@ class Image(models.AbstractModel):
         else:
             alt = escape(record.display_name)
 
-        src_zoom = None
-        if options.get('zoom') and getattr(record, options['zoom'], None):
-            src_zoom = '/web/image/%s/%s/%s%s/%s?unique=%s' % (record._name, record.id, options['zoom'], max_size, url_quote(filename), sha)
-        elif options.get('zoom'):
-            src_zoom = options['zoom']
-
         itemprop = None
         if options.get('itemprop'):
             itemprop = options['itemprop']
@@ -96,3 +106,11 @@ class Image(models.AbstractModel):
         img.append('/>')
 
         return u''.join(img)
+
+class ImageUrlConverter(models.AbstractModel):
+    _description = 'Qweb Field Image'
+    _inherit = 'ir.qweb.field.image_url'
+
+    def _get_src_urls(self, record, field_name, options):
+        image_url = record[options.get('preview_image', field_name)]
+        return image_url, options.get("zoom", None)

odoo/addons/base/models/ir_qweb_fields.py

@@ -385,6 +385,17 @@ class ImageConverter(models.AbstractModel):
 
         return u'<img src="data:%s;base64,%s">' % (Image.MIME[image.format], value.decode('ascii'))
 
+class ImageUrlConverter(models.AbstractModel):
+    """ ``image_url`` widget rendering, inserts an image tag in the
+    document.
+    """
+    _name = 'ir.qweb.field.image_url'
+    _description = 'Qweb Field Image'
+    _inherit = 'ir.qweb.field.image'
+
+    @api.model
+    def value_to_html(self, value, options):
+        return u'<img src="%s">' % (value)
 
 class MonetaryConverter(models.AbstractModel):
     """ ``monetary`` converter, has a mandatory option