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diff --git a/libs/cairo-1.16.0/test/degenerate-pen.c b/libs/cairo-1.16.0/test/degenerate-pen.c
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+/*
+ * Copyright © 2007 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Author: Carl D. Worth <cworth@cworth.org>
+ */
+
+#include "cairo-test.h"
+
+#define SIZE   20
+#define PAD    5
+#define WIDTH  (PAD + 3 * (PAD + SIZE) + PAD)
+#define HEIGHT (PAD + SIZE + PAD)
+
+/* We're demonstrating here a bug originally reported by Benjamin Otte
+ * on the cairo mailing list here, (after he ran into this problem
+ * with various flash animations):
+ *
+ *	[cairo] Assertion `i < pen->num_vertices' failed in 1.4.10
+ *	https://lists.cairographics.org/archives/cairo/2007-August/011282.html
+ *
+ * The problem shows up with an extreme transformation matrix that
+ * collapses the pen to a single line, (which means that
+ * _cairo_slope_compare cannot handle adjacent vertices in the pen
+ * since they have parallel slope).
+ *
+ * This test case tests degenerate pens in several directions and uses
+ * round caps to force the stroking code to attempt to walk around the
+ * pen doing slope comparisons.
+ */
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    cairo_set_source_rgb (cr, 1, 1, 1);
+    cairo_paint (cr);
+
+    cairo_set_source_rgb (cr, 0, 0, 0);
+    cairo_set_line_join (cr, CAIRO_LINE_JOIN_ROUND);
+
+    cairo_translate (cr, PAD, PAD);
+
+    /* First compress the pen to a vertical line. */
+    cairo_rectangle (cr, 0, 0, SIZE, SIZE);
+    cairo_curve_to (cr, SIZE / 2, 0, SIZE, SIZE / 2, SIZE, SIZE);
+    cairo_save (cr);
+    {
+	cairo_scale (cr, 0.000001, 1.0);
+	cairo_stroke (cr);
+    }
+    cairo_restore (cr);
+
+    cairo_translate (cr, PAD + SIZE, 0);
+
+    /* Then compress the pen to a horizontal line. */
+    cairo_rectangle (cr, 0, 0, SIZE, SIZE);
+    cairo_curve_to (cr, SIZE / 2, 0, SIZE, SIZE / 2, SIZE, SIZE);
+    cairo_save (cr);
+    {
+	cairo_scale (cr, 1.0, 0.000001);
+	cairo_stroke (cr);
+    }
+    cairo_restore (cr);
+
+    cairo_translate (cr, PAD + SIZE, 0);
+
+    /* Finally a line at an angle. */
+    cairo_rectangle (cr, 0, 0, SIZE, SIZE);
+    cairo_curve_to (cr, SIZE / 2, 0, SIZE, SIZE / 2, SIZE, SIZE);
+    cairo_save (cr);
+    {
+	cairo_rotate (cr, M_PI / 4.0);
+	cairo_scale (cr, 0.000001, 1.0);
+	cairo_stroke (cr);
+    }
+    cairo_restore (cr);
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (degenerate_pen,
+	    "Test round joins with a pen that's transformed to a line",
+	    "degenerate", /* keywords */
+	    NULL, /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, draw)