[IMP] website: ir_qweb - add lazyloading by default on img

closes odoo/odoo#55945

Signed-off-by: Jérémy Kersten (jke) <jke@openerp.com>

addons/website/models/ir_qweb.py

@@ -50,6 +50,9 @@ class QWeb(models.AbstractModel):
 
         atts = super(QWeb, self)._post_processing_att(tagName, atts, options)
 
+        if tagName == 'img' and 'loading' not in atts:
+            atts['loading'] = 'lazy'  # default is auto
+
         if options.get('inherit_branding') or options.get('rendering_bundle') or \
            options.get('edit_translations') or options.get('debug') or (request and request.session.debug):
             return atts

addons/website/tests/test_qweb.py

@@ -50,15 +50,15 @@ class TestQweb(TransactionCaseWithUserDemo):
         <script type="text/javascript" src="http://test.cdn%(js)s"></script>
     </head>
     <body>
-        <img src="http://test.external.link/img.png"/>
-        <img src="http://test.cdn/website/static/img.png"/>
+        <img src="http://test.external.link/img.png" loading="lazy"/>
+        <img src="http://test.cdn/website/static/img.png" loading="lazy"/>
         <a href="http://test.external.link/link">x</a>
         <a href="http://test.cdn/web/content/local_link">x</a>
         <span style="background-image: url('http://test.cdn/web/image/2')">xxx</span>
         <div widget="html"><span class="toto">
-                span<span class="fa"></span><img src="http://test.cdn/web/image/1">
+                span<span class="fa"></span><img src="http://test.cdn/web/image/1" loading="lazy">
             </span></div>
-        <div widget="image"><img src="http://test.cdn/web/image/res.users/%(user_id)s/image_1920/%(filename)s" class="img img-fluid" alt="%(alt)s"/></div>
+        <div widget="image"><img src="http://test.cdn/web/image/res.users/%(user_id)s/image_1920/%(filename)s" class="img img-fluid" alt="%(alt)s" loading="lazy"/></div>
     </body>
 </html>""" % {
             "js": attachments[0].url,