Merge pull request #318 from mathoudebine/feature/detect-theme-change…

…s-on-pr

.github/workflows/themes-screenshot-on-pr.yml

@@ -53,11 +53,19 @@ jobs:
 
             # Rename screen capture
             cp screencap.png "screenshot-$theme.png"
+
+            # Compare with original theme preview to detect changes, generate a diff
+            python3 tools/compare-images.py "screenshot-$theme.png" "$dir/preview.png" "diff-$theme.png"
+            if [ -f "diff-$theme.png" ]; then
+              echo "::warning::$theme theme rendering has changed, check if it is intentional or a side-effect. A diff is included in the job artifacts."
+            fi
           fi
         done
 
     - name: Archive screenshots
       uses: actions/upload-artifact@v3
       with:
         name: themes-screenshots
-        path: screenshot-*.png
+        path: |
+          screenshot-*.png
+          diff-*.png

tools/compare-images.py

@@ -0,0 +1,34 @@
+#!/usr/bin/env python
+# turing-smart-screen-python - a Python system monitor and library for USB-C displays like Turing Smart Screen or XuanFang
+# https://github.com/mathoudebine/turing-smart-screen-python/
+
+# Copyright (C) 2021-2023  Matthieu Houdebine (mathoudebine)
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+# compare-images.py: Run by GitHub actions on new PR, to compare theme renderings and generate a diff if it has changed
+
+import sys
+
+from PIL import Image, ImageChops
+
+im1 = Image.open(sys.argv[1]).convert('RGB')
+im2 = Image.open(sys.argv[2]).convert('RGB')
+
+if list(im1.getdata()) == list(im2.getdata()):
+    print("The 2 pictures are visually identical")
+else:
+    print("The 2 pictures are different!")
+    diff = ImageChops.difference(im1, im2)
+    diff.save(sys.argv[3])