add cairo

1 files changed, 306 insertions, 0 deletions

diff --git a/libs/cairo-1.16.0/src/cairo-line.c b/libs/cairo-1.16.0/src/cairo-line.c
new file mode 100644
index 0000000..dc00a9c
--- /dev/null
+++ b/libs/cairo-1.16.0/src/cairo-line.c
@@ -0,0 +1,306 @@
+/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
+/*
+ * Copyright © 2004 Carl Worth
+ * Copyright © 2006 Red Hat, Inc.
+ * Copyright © 2008 Chris Wilson
+ * Copyright © 2014 Intel Corporation
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it either under the terms of the GNU Lesser General Public
+ * License version 2.1 as published by the Free Software Foundation
+ * (the "LGPL") or, at your option, under the terms of the Mozilla
+ * Public License Version 1.1 (the "MPL"). If you do not alter this
+ * notice, a recipient may use your version of this file under either
+ * the MPL or the LGPL.
+ *
+ * You should have received a copy of the LGPL along with this library
+ * in the file COPYING-LGPL-2.1; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
+ * You should have received a copy of the MPL along with this library
+ * in the file COPYING-MPL-1.1
+ *
+ * The contents of this file are subject to the Mozilla Public License
+ * Version 1.1 (the "License"); you may not use this file except in
+ * compliance with the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
+ * OF ANY KIND, either express or implied. See the LGPL or the MPL for
+ * the specific language governing rights and limitations.
+ *
+ * The Original Code is the cairo graphics library.
+ *
+ * The Initial Developer of the Original Code is Keith Packard
+ *
+ * Contributor(s):
+ *	Carl D. Worth <cworth@cworth.org>
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ *
+ */
+
+#include "cairoint.h"
+
+#include "cairo-line-inline.h"
+#include "cairo-slope-private.h"
+
+static int
+line_compare_for_y_against_x (const cairo_line_t *a,
+			      int32_t y,
+			      int32_t x)
+{
+    int32_t adx, ady;
+    int32_t dx, dy;
+    cairo_int64_t L, R;
+
+    if (x < a->p1.x && x < a->p2.x)
+	return 1;
+    if (x > a->p1.x && x > a->p2.x)
+	return -1;
+
+    adx = a->p2.x - a->p1.x;
+    dx = x - a->p1.x;
+
+    if (adx == 0)
+	return -dx;
+    if (dx == 0 || (adx ^ dx) < 0)
+	return adx;
+
+    dy = y - a->p1.y;
+    ady = a->p2.y - a->p1.y;
+
+    L = _cairo_int32x32_64_mul (dy, adx);
+    R = _cairo_int32x32_64_mul (dx, ady);
+
+    return _cairo_int64_cmp (L, R);
+}
+
+/*
+ * We need to compare the x-coordinates of a pair of lines for a particular y,
+ * without loss of precision.
+ *
+ * The x-coordinate along an edge for a given y is:
+ *   X = A_x + (Y - A_y) * A_dx / A_dy
+ *
+ * So the inequality we wish to test is:
+ *   A_x + (Y - A_y) * A_dx / A_dy ∘ B_x + (Y - B_y) * B_dx / B_dy,
+ * where ∘ is our inequality operator.
+ *
+ * By construction, we know that A_dy and B_dy (and (Y - A_y), (Y - B_y)) are
+ * all positive, so we can rearrange it thus without causing a sign change:
+ *   A_dy * B_dy * (A_x - B_x) ∘ (Y - B_y) * B_dx * A_dy
+ *                                 - (Y - A_y) * A_dx * B_dy
+ *
+ * Given the assumption that all the deltas fit within 32 bits, we can compute
+ * this comparison directly using 128 bit arithmetic. For certain, but common,
+ * input we can reduce this down to a single 32 bit compare by inspecting the
+ * deltas.
+ *
+ * (And put the burden of the work on developing fast 128 bit ops, which are
+ * required throughout the tessellator.)
+ *
+ * See the similar discussion for _slope_compare().
+ */
+static int
+lines_compare_x_for_y_general (const cairo_line_t *a,
+			       const cairo_line_t *b,
+			       int32_t y)
+{
+    /* XXX: We're assuming here that dx and dy will still fit in 32
+     * bits. That's not true in general as there could be overflow. We
+     * should prevent that before the tessellation algorithm
+     * begins.
+     */
+    int32_t dx = 0;
+    int32_t adx = 0, ady = 0;
+    int32_t bdx = 0, bdy = 0;
+    enum {
+       HAVE_NONE    = 0x0,
+       HAVE_DX      = 0x1,
+       HAVE_ADX     = 0x2,
+       HAVE_DX_ADX  = HAVE_DX | HAVE_ADX,
+       HAVE_BDX     = 0x4,
+       HAVE_DX_BDX  = HAVE_DX | HAVE_BDX,
+       HAVE_ADX_BDX = HAVE_ADX | HAVE_BDX,
+       HAVE_ALL     = HAVE_DX | HAVE_ADX | HAVE_BDX
+    } have_dx_adx_bdx = HAVE_ALL;
+
+    ady = a->p2.y - a->p1.y;
+    adx = a->p2.x - a->p1.x;
+    if (adx == 0)
+	have_dx_adx_bdx &= ~HAVE_ADX;
+
+    bdy = b->p2.y - b->p1.y;
+    bdx = b->p2.x - b->p1.x;
+    if (bdx == 0)
+	have_dx_adx_bdx &= ~HAVE_BDX;
+
+    dx = a->p1.x - b->p1.x;
+    if (dx == 0)
+	have_dx_adx_bdx &= ~HAVE_DX;
+
+#define L _cairo_int64x32_128_mul (_cairo_int32x32_64_mul (ady, bdy), dx)
+#define A _cairo_int64x32_128_mul (_cairo_int32x32_64_mul (adx, bdy), y - a->p1.y)
+#define B _cairo_int64x32_128_mul (_cairo_int32x32_64_mul (bdx, ady), y - b->p1.y)
+    switch (have_dx_adx_bdx) {
+    default:
+    case HAVE_NONE:
+	return 0;
+    case HAVE_DX:
+	/* A_dy * B_dy * (A_x - B_x) ∘ 0 */
+	return dx; /* ady * bdy is positive definite */
+    case HAVE_ADX:
+	/* 0 ∘  - (Y - A_y) * A_dx * B_dy */
+	return adx; /* bdy * (y - a->top.y) is positive definite */
+    case HAVE_BDX:
+	/* 0 ∘ (Y - B_y) * B_dx * A_dy */
+	return -bdx; /* ady * (y - b->top.y) is positive definite */
+    case HAVE_ADX_BDX:
+	/*  0 ∘ (Y - B_y) * B_dx * A_dy - (Y - A_y) * A_dx * B_dy */
+	if ((adx ^ bdx) < 0) {
+	    return adx;
+	} else if (a->p1.y == b->p1.y) { /* common origin */
+	    cairo_int64_t adx_bdy, bdx_ady;
+
+	    /* ∴ A_dx * B_dy ∘ B_dx * A_dy */
+
+	    adx_bdy = _cairo_int32x32_64_mul (adx, bdy);
+	    bdx_ady = _cairo_int32x32_64_mul (bdx, ady);
+
+	    return _cairo_int64_cmp (adx_bdy, bdx_ady);
+	} else
+	    return _cairo_int128_cmp (A, B);
+    case HAVE_DX_ADX:
+	/* A_dy * (A_x - B_x) ∘ - (Y - A_y) * A_dx */
+	if ((-adx ^ dx) < 0) {
+	    return dx;
+	} else {
+	    cairo_int64_t ady_dx, dy_adx;
+
+	    ady_dx = _cairo_int32x32_64_mul (ady, dx);
+	    dy_adx = _cairo_int32x32_64_mul (a->p1.y - y, adx);
+
+	    return _cairo_int64_cmp (ady_dx, dy_adx);
+	}
+    case HAVE_DX_BDX:
+	/* B_dy * (A_x - B_x) ∘ (Y - B_y) * B_dx */
+	if ((bdx ^ dx) < 0) {
+	    return dx;
+	} else {
+	    cairo_int64_t bdy_dx, dy_bdx;
+
+	    bdy_dx = _cairo_int32x32_64_mul (bdy, dx);
+	    dy_bdx = _cairo_int32x32_64_mul (y - b->p1.y, bdx);
+
+	    return _cairo_int64_cmp (bdy_dx, dy_bdx);
+	}
+    case HAVE_ALL:
+	/* XXX try comparing (a->p2.x - b->p2.x) et al */
+	return _cairo_int128_cmp (L, _cairo_int128_sub (B, A));
+    }
+#undef B
+#undef A
+#undef L
+}
+
+static int
+lines_compare_x_for_y (const cairo_line_t *a,
+		       const cairo_line_t *b,
+		       int32_t y)
+{
+    /* If the sweep-line is currently on an end-point of a line,
+     * then we know its precise x value (and considering that we often need to
+     * compare events at end-points, this happens frequently enough to warrant
+     * special casing).
+     */
+    enum {
+       HAVE_NEITHER = 0x0,
+       HAVE_AX      = 0x1,
+       HAVE_BX      = 0x2,
+       HAVE_BOTH    = HAVE_AX | HAVE_BX
+    } have_ax_bx = HAVE_BOTH;
+    int32_t ax = 0, bx = 0;
+
+    if (y == a->p1.y)
+	ax = a->p1.x;
+    else if (y == a->p2.y)
+	ax = a->p2.x;
+    else
+	have_ax_bx &= ~HAVE_AX;
+
+    if (y == b->p1.y)
+	bx = b->p1.x;
+    else if (y == b->p2.y)
+	bx = b->p2.x;
+    else
+	have_ax_bx &= ~HAVE_BX;
+
+    switch (have_ax_bx) {
+    default:
+    case HAVE_NEITHER:
+	return lines_compare_x_for_y_general (a, b, y);
+    case HAVE_AX:
+	return -line_compare_for_y_against_x (b, y, ax);
+    case HAVE_BX:
+	return line_compare_for_y_against_x (a, y, bx);
+    case HAVE_BOTH:
+	return ax - bx;
+    }
+}
+
+static int bbox_compare (const cairo_line_t *a,
+			 const cairo_line_t *b)
+{
+    int32_t amin, amax;
+    int32_t bmin, bmax;
+
+    if (a->p1.x < a->p2.x) {
+	amin = a->p1.x;
+	amax = a->p2.x;
+    } else {
+	amin = a->p2.x;
+	amax = a->p1.x;
+    }
+
+    if (b->p1.x < b->p2.x) {
+	bmin = b->p1.x;
+	bmax = b->p2.x;
+    } else {
+	bmin = b->p2.x;
+	bmax = b->p1.x;
+    }
+
+    if (amax < bmin)
+	return -1;
+
+    if (amin > bmax)
+	return +1;
+
+    return 0;
+}
+
+int cairo_lines_compare_at_y (const cairo_line_t *a,
+			      const cairo_line_t *b,
+			      int y)
+{
+    cairo_slope_t sa, sb;
+    int ret;
+
+    if (cairo_lines_equal (a, b))
+	return 0;
+
+    /* Don't bother solving for abscissa if the edges' bounding boxes
+     * can be used to order them.
+     */
+    ret = bbox_compare (a, b);
+    if (ret)
+	return ret;
+
+    ret = lines_compare_x_for_y (a, b, y);
+    if (ret)
+	return ret;
+
+    _cairo_slope_init (&sa, &a->p1, &a->p2);
+    _cairo_slope_init (&sb, &b->p1, &b->p2);
+
+    return _cairo_slope_compare (&sb, &sa);
+}