LIL-319. Fix course preview img

apps/course/templates/course/_items.html

@@ -1,3 +1,4 @@
+{% load thumbnail %}
 {% load static %}
 {% load data_liked from data_liked %}
 
@@ -8,9 +9,11 @@
 >
 <a class="courses__preview" href="{% if course.status == 0 %}{% url 'course_edit' course.id %}{% else %}{% url 'course' course.id %}?next={{ request.get_full_path }}{% endif %}">
   {% if course.cover %}
-  <img width="300px" height="170px" class="courses__pic" src="{{ course.cover.image.url }}"/>
+  {% thumbnail course.cover.image "300x170" crop="center" as im %}
+  <img class="courses__pic" src="{{ im.url }}" width="{{ im.width }}" height="{{ im.height }}"/>
+  {% endthumbnail %}
   {% else %}
-  <img width="300px" height="170px" class="courses__pic" src="{% static 'img/no_cover.png' %}"/>
+  <img class="courses__pic" src="{% static 'img/no_cover.png' %}" width="300px" height="170px"/>
   {% endif %}
   <div class="courses__view">Подробнее</div>
   {% if course.is_featured %}
@@ -86,4 +89,4 @@
       </div>
     </div>
   </div>
-</div>
+</div>