Set page background origin to margin box when attachment is fixed

Fix #1993.
Kozea · Nov 9, 2023 · 3b6f826 · 3b6f826
1 parent bc0798b
commit 3b6f826
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Showing 2 changed files with 43 additions and 1 deletion.
diff --git a/tests/draw/test_background.py b/tests/draw/test_background.py
@@ -1052,6 +1052,42 @@ def test_background_size_clip(assert_pixels):
       <body>''')
 
 
+@assert_no_logs
+def test_page_background_fixed(assert_pixels):
+    # Regression test for https://github.com/Kozea/WeasyPrint/issues/1993
+    assert_pixels('''
+        RBBB
+        BBBB
+        BBBB
+        BBBB
+    ''', '''
+      <style>
+         @page { size: 4px; margin: 1px;
+                 background: url(pattern.png) red;
+                 background-attachment: fixed; }
+      </style>
+      <body>''')
+
+
+@assert_no_logs
+def test_page_background_fixed_bleed(assert_pixels):
+    # Regression test for https://github.com/Kozea/WeasyPrint/issues/1993
+    assert_pixels('''
+        RRRRRR
+        RRBBBR
+        RBBBBR
+        RBBBBR
+        RBBBBR
+        RRRRRR
+    ''', '''
+      <style>
+         @page { size: 4px; margin: 1px; bleed: 1px;
+                 background: url(pattern.png) no-repeat red;
+                 background-attachment: fixed; }
+      </style>
+      <body>''')
+
+
 @assert_no_logs
 def test_bleed_background_size_clip(assert_pixels):
     # Regression test for https://github.com/Kozea/WeasyPrint/issues/1943

diff --git a/weasyprint/layout/background.py b/weasyprint/layout/background.py
@@ -137,7 +137,13 @@ def layout_background_layer(box, page, resolution, image, size, clip, repeat,
 
     if attachment == 'fixed':
         # Initial containing block
-        positioning_area = box_rectangle(page, 'content-box')
+        if isinstance(box, boxes.PageBox):
+            # […] if background-attachment is fixed then the image is
+            # positioned relative to the page box including its margins […].
+            # https://drafts.csswg.org/css-page/#painting
+            positioning_area = (0, 0, box.margin_width(), box.margin_height())
+        else:
+            positioning_area = box_rectangle(page, 'content-box')
     else:
         positioning_area = box_rectangle(box, origin)