[Fixes #4881] Improve initial generate thumbnail quality

 - Fix pep8 issues

geonode/geoserver/helpers.py

@@ -1909,6 +1909,19 @@ def _render_thumbnail(req_body, width=240, height=180):
     try:
         req, content = http_client.post(
             url, data=data, headers=headers)
+        # Optimize the Thumbnail size and resolution
+        from PIL import Image
+        from io import BytesIO
+        content_data = BytesIO(content)
+        im = Image.open(content_data)
+        im_width, im_height = im.size
+        right = min(width, im_width)
+        bottom = min(height, im_height)
+        size = right, bottom
+        im.thumbnail(size, Image.ANTIALIAS)
+        imgByteArr = BytesIO()
+        im.save(imgByteArr, format='JPEG')
+        content = imgByteArr.getvalue()
     except BaseException as e:
         logger.warning('Error generating thumbnail')
         logger.exception(e)

geonode/utils.py

@@ -345,7 +345,7 @@ def zoom(mapPx, worldPx, fraction):
     latZoom = zoom(float(height), WORLD_DIM['height'], latFraction)
     lngZoom = zoom(float(width), WORLD_DIM['width'], lngFraction)
     ratio = float(max(width, height)) / float(min(width, height))
-    z_offset = 0 if ratio >= 1.5 else -1
+    z_offset = 0 if ratio >= 2 else -1
     zoom = int(max(latZoom, lngZoom) + z_offset)
     zoom = 0 if zoom > ZOOM_MAX else zoom
     return max(zoom, 0)