Fix #49: Division by 0 on dashed or dotted border smaller than one do…

…t/dash.
Kozea · Mar 18, 2013 · 408b7d6 · 408b7d6
1 parent 4c04bcd
commit 408b7d6
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Showing 2 changed files with 22 additions and 2 deletions.
diff --git a/weasyprint/draw.py b/weasyprint/draw.py
@@ -469,12 +469,12 @@ def draw_border_segment(context, enable_hinting, style, width, color, side,
                 if context.user_to_device_distance(width, 0)[0] > 3:
                     # Round so that dash is a divisor of length,
                     # but not in the dots are too small.
-                    dash = length / round(length / dash)
+                    dash = length / max(1, round(length / dash))
                 context.set_line_cap(cairo.LINE_CAP_ROUND)
                 context.set_dash([0, dash])
             else:  # dashed
                 # Round so that 2*dash is a divisor of length
-                dash = length / (2 * round(length / (2 * dash)))
+                dash = length / (2 * max(1, round(length / (2 * dash))))
                 context.set_dash([dash])
             # Stroke along the line in === above, as wide as the border
             context.move_to(x1, y1)

diff --git a/weasyprint/tests/test_draw.py b/weasyprint/tests/test_draw.py
@@ -1588,6 +1588,26 @@ def test_outlines():
     return test_borders(margin='20px', prop='outline')
 
 
+@assert_no_logs
+def test_small_borders():
+    # Regression test for ZeroDivisionError on dashed or dotted borders
+    # smaller than a dash/dot.
+    # https://github.com/Kozea/WeasyPrint/issues/49
+
+    # Do not test the exact rendering of earch border style but at least
+    # check that they do not do the same.
+    assert_different_renderings(50, 50, [('small_border_%s'  % border_style, '''
+        <style>
+            @page { size: 50px 50px }
+            html { background: #fff }
+            body { margin: 5px; height: 0; border: 10px %s blue }
+        </style>
+        <body>''' % border_style)
+        for border_style in ['none', 'solid', 'dashed', 'dotted']
+    ])
+
+
+
 @assert_no_logs
 def test_margin_boxes():
     """Test the rendering of margin boxes"""