[IMP] test_themes: (re)add preview to website (themes) switcher

Commit [1] moved the website switcher from the frontend to the backend
and in doing so re-factored it into an OWL component.

Initially, this refactoring broke the theme preview from the previous
widget. This commit re-introduces those previews.

[1]: https://github.com/odoo/design-themes/commit/163a8b6fae0d6709d61af81550d1ad77dfe311c9

task-2687506

closes odoo/design-themes#573

Signed-off-by: Romain Derie (rde) <rde@odoo.com>
Co-authored-by: Younn Olivier <yol@odoo.com>
Co-authored-by: Romain Derie <rde@odoo.com>

test_themes/models/__init__.py

@@ -2,5 +2,4 @@
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
 from . import ir_http
-from . import ir_qweb
 from . import website

test_themes/models/ir_qweb.py

@@ -1,28 +0,0 @@
-# -*- coding: utf-8 -*-
-# Part of Odoo. See LICENSE file for full copyright and licensing details.
-
-from odoo import api, models
-from odoo.http import request
-
-
-class IrQWeb(models.AbstractModel):
-    _inherit = "ir.qweb"
-
-    def _prepare_frontend_environment(self, values):
-        irQweb = super()._prepare_frontend_environment(values)
-
-        if 'multi_website_websites' in values:
-            websites_themes = self.env['website'].get_test_themes_websites()
-
-            for multi_website_website in values['multi_website_websites']:
-                website_id = multi_website_website['website_id']
-                website = websites_themes.filtered(lambda website: website.id == website_id)
-                theme_img = None
-                if website:
-                    # prefetched by get_test_themes_websites
-                    image_ids = website.theme_id.sudo().image_ids
-                    if image_ids:
-                        theme_img = f"<img src='/web/image/{image_ids[0].id}' width='150'/>"
-                multi_website_website['theme_img'] = theme_img
-
-        return irQweb

test_themes/models/website.py

@@ -1,12 +1,20 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from odoo import models
+from odoo import api, models
 
 
 class Website(models.Model):
     _inherit = 'website'
 
+    @api.model
+    def get_test_themes_websites_theme_preview(self):
+        websites_themes = self.env['website'].get_test_themes_websites()
+        return {
+            website.id: f"/web/image/{website.theme_id.sudo().image_ids[0].id}"
+            for website in websites_themes.filtered(lambda w: w.theme_id.sudo().image_ids)
+        }
+
     def get_test_themes_websites(self):
         website_imd_ids = self.env['ir.model.data'].sudo().search([
             ('module', '=', 'test_themes'),