add cairo

1 files changed, 178 insertions, 0 deletions

diff --git a/libs/cairo-1.16.0/test/line-width-scale.c b/libs/cairo-1.16.0/test/line-width-scale.c
new file mode 100644
index 0000000..037b887
--- /dev/null
+++ b/libs/cairo-1.16.0/test/line-width-scale.c
@@ -0,0 +1,178 @@
+/*
+ * Copyright © 2006 Red Hat, Inc.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without
+ * fee, provided that the above copyright notice appear in all copies
+ * and that both that copyright notice and this permission notice
+ * appear in supporting documentation, and that the name of
+ * Red Hat, Inc. not be used in advertising or publicity pertaining to
+ * distribution of the software without specific, written prior
+ * permission. Red Hat, Inc. makes no representations about the
+ * suitability of this software for any purpose.  It is provided "as
+ * is" without express or implied warranty.
+ *
+ * RED HAT, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL RED HAT, INC. BE LIABLE FOR ANY SPECIAL,
+ * INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER
+ * RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR
+ * IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Author: Carl D. Worth <cworth@cworth.org>
+ */
+
+#include "cairo-test.h"
+
+/* This test exercises the various interactions between
+ * cairo_set_line_width and cairo_scale. Specifically it shows how
+ * separate transformations can affect the pen for stroking compared
+ * to the path itself.
+ *
+ * This was inspired by an image by Maxim Shemanarev demonstrating the
+ * flexible-pipeline nature of his Antigrain Geometry project:
+ *
+ *	http://antigrain.com/tips/line_alignment/conv_order.gif
+ *
+ * It also uncovered some behavior in cairo that I found surprising.
+ * Namely, cairo_set_line_width was not transforming the width
+ * according the the current CTM, but instead delaying that
+ * transformation until the time of cairo_stroke.
+ *
+ * This delayed behavior was released in cairo 1.0 so we're going to
+ * document this as the way cairo_set_line_width works rather than
+ * considering this a bug.
+ */
+
+#define LINE_WIDTH 13
+#define SPLINE 50.0
+#define XSCALE  0.5
+#define YSCALE  2.0
+#define WIDTH (XSCALE * SPLINE * 6.0)
+#define HEIGHT (YSCALE * SPLINE * 2.0)
+
+static void
+spline_path (cairo_t *cr)
+{
+    cairo_save (cr);
+    {
+	cairo_move_to (cr,
+		       - SPLINE, 0);
+	cairo_curve_to (cr,
+			- SPLINE / 4, - SPLINE,
+			  SPLINE / 4,   SPLINE,
+			  SPLINE, 0);
+    }
+    cairo_restore (cr);
+}
+
+/* If we scale before setting the line width or creating the path,
+ * then obviously both will be scaled. */
+static void
+scale_then_set_line_width_and_stroke (cairo_t *cr)
+{
+    cairo_scale (cr, XSCALE, YSCALE);
+    cairo_set_line_width (cr, LINE_WIDTH);
+    spline_path (cr);
+    cairo_stroke (cr);
+}
+
+/* This is used to verify the results of
+ * scale_then_set_line_width_and_stroke.
+ *
+ * It uses save/restore pairs to isolate the scaling of the path and
+ * line_width and ensures that both are scaled.
+ */
+static void
+scale_path_and_line_width (cairo_t *cr)
+{
+    cairo_save (cr);
+    {
+	cairo_scale (cr, XSCALE, YSCALE);
+	spline_path (cr);
+    }
+    cairo_restore (cr);
+
+    cairo_save (cr);
+    {
+	cairo_scale (cr, XSCALE, YSCALE);
+	cairo_set_line_width (cr, LINE_WIDTH);
+	cairo_stroke (cr);
+    }
+    cairo_restore (cr);
+}
+
+/* This is the case that was surprising.
+ *
+ * Setting the line width before scaling doesn't change anything. The
+ * line width will be interpreted under the CTM in effect at the time
+ * of cairo_stroke, so the line width will be scaled as well as the
+ * path here.
+ */
+static void
+set_line_width_then_scale_and_stroke (cairo_t *cr)
+{
+    cairo_set_line_width (cr, LINE_WIDTH);
+    cairo_scale (cr, XSCALE, YSCALE);
+    spline_path (cr);
+    cairo_stroke (cr);
+}
+
+/* Here then is the way to achieve the alternate result.
+ *
+ * This uses save/restore pairs to isolate the scaling of the path and
+ * line_width and ensures that the path is scaled while the line width
+ * is not.
+ */
+static void
+scale_path_not_line_width (cairo_t *cr)
+{
+    cairo_save (cr);
+    {
+	cairo_scale (cr, XSCALE, YSCALE);
+	spline_path (cr);
+    }
+    cairo_restore (cr);
+
+    cairo_save (cr);
+    {
+	cairo_set_line_width (cr, LINE_WIDTH);
+	cairo_stroke (cr);
+    }
+    cairo_restore (cr);
+}
+
+static cairo_test_status_t
+draw (cairo_t *cr, int width, int height)
+{
+    int i;
+    void (* const figures[4]) (cairo_t *cr) = {
+	scale_then_set_line_width_and_stroke,
+	scale_path_and_line_width,
+	set_line_width_then_scale_and_stroke,
+	scale_path_not_line_width
+    };
+
+    cairo_set_source_rgb (cr, 1.0, 1.0, 1.0); /* white */
+    cairo_paint (cr);
+    cairo_set_source_rgb (cr, 0.0, 0.0, 0.0); /* black */
+
+    for (i = 0; i < 4; i++) {
+	cairo_save (cr);
+	cairo_translate (cr,
+			 WIDTH/4  + (i % 2) * WIDTH/2,
+			 HEIGHT/4 + (i / 2) * HEIGHT/2);
+	(figures[i]) (cr);
+	cairo_restore (cr);
+    }
+
+    return CAIRO_TEST_SUCCESS;
+}
+
+CAIRO_TEST (line_width_scale,
+	    "Tests interaction of cairo_set_line_width with cairo_scale",
+	    "stroke", /* keywords */
+	    NULL, /* requirements */
+	    WIDTH, HEIGHT,
+	    NULL, draw)