[FIX] product_multi_image: Do not resize large image to small/medium

when saved from single image

product_multi_image/models/product_template.py

@@ -3,7 +3,7 @@
 # © 2015 Antiun Ingeniería S.L. - Jairo Llopis
 # License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
 
-from odoo import fields, models
+from odoo import api, fields, models
 
 
 class ProductTemplate(models.Model):
@@ -22,3 +22,30 @@ class ProductTemplate(models.Model):
         related='image_main_small',
         store=False,
     )
+
+    @api.multi
+    def write(self, vals):
+        if set(['image', 'image_medium', 'image_small']) & set(vals.keys()):
+            # medium/small image is saved as large
+            # on load image will be medium/small resized on the fly
+            if 'image' in vals:
+                pass
+            elif 'image_medium' in vals:
+                vals['image'] = vals['image_medium']
+                del vals['image_medium']
+            elif 'image_small' in vals:
+                vals['image'] = vals['image_small']
+                del vals['image_small']
+        return super(ProductTemplate, self).write(vals)
+
+    @api.multi
+    def _set_multi_image_main_medium(self):
+        # on save product module resizes large image to medium
+        # medium image should not overwrite the large
+        pass
+
+    @api.multi
+    def _set_multi_image_main_small(self):
+        # on save product module resizes large image to small
+        # small image should not overwrite the large
+        pass