path-bounder: Simplify code

If the path extents are tight, all the extents computations and
approximations become trivial except for the stroke extents.

1 files changed, 56 insertions, 193 deletions

diff --git a/src/cairo-path-bounds.c b/src/cairo-path-bounds.c
index 9cfc56d3b..d17d9a207 100644
--- a/src/cairo-path-bounds.c
+++ b/src/cairo-path-bounds.c
@@ -1,3 +1,4 @@
+/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
 /* cairo - a vector graphics library with display and print output
  *
  * Copyright © 2003 University of Southern California
@@ -35,48 +36,16 @@
  */
 
 #include "cairoint.h"
+#include "cairo-box-private.h"
 #include "cairo-path-fixed-private.h"
 
-typedef struct cairo_path_bounder {
-    cairo_point_t current_point;
-    cairo_bool_t has_initial_point;
-    cairo_bool_t has_point;
 
+typedef struct _cairo_path_bounder {
+    cairo_point_t current_point;
+    cairo_bool_t has_extents;
     cairo_box_t extents;
 } cairo_path_bounder_t;
 
-static void
-_cairo_path_bounder_init (cairo_path_bounder_t *bounder)
-{
-    bounder->has_initial_point = FALSE;
-    bounder->has_point = FALSE;
-}
-
-static void
-_cairo_path_bounder_add_point (cairo_path_bounder_t *bounder,
-			       const cairo_point_t *point)
-{
-    if (bounder->has_point) {
-	if (point->x < bounder->extents.p1.x)
-	    bounder->extents.p1.x = point->x;
-
-	if (point->y < bounder->extents.p1.y)
-	    bounder->extents.p1.y = point->y;
-
-	if (point->x > bounder->extents.p2.x)
-	    bounder->extents.p2.x = point->x;
-
-	if (point->y > bounder->extents.p2.y)
-	    bounder->extents.p2.y = point->y;
-    } else {
-	bounder->extents.p1.x = point->x;
-	bounder->extents.p1.y = point->y;
-	bounder->extents.p2.x = point->x;
-	bounder->extents.p2.y = point->y;
-	bounder->has_point = TRUE;
-    }
-}
-
 static cairo_status_t
 _cairo_path_bounder_move_to (void *closure,
 			     const cairo_point_t *point)
@@ -84,7 +53,13 @@ _cairo_path_bounder_move_to (void *closure,
     cairo_path_bounder_t *bounder = closure;
 
     bounder->current_point = *point;
-    bounder->has_initial_point = TRUE;
+
+    if (likely (bounder->has_extents)) {
+	_cairo_box_add_point (&bounder->extents, point);
+    } else {
+	bounder->has_extents = TRUE;
+	_cairo_box_set (&bounder->extents, point, point);
+    }
 
     return CAIRO_STATUS_SUCCESS;
 }
@@ -95,13 +70,8 @@ _cairo_path_bounder_line_to (void *closure,
 {
     cairo_path_bounder_t *bounder = closure;
 
-    if (bounder->has_initial_point) {
-	_cairo_path_bounder_add_point (bounder, &bounder->current_point);
-	bounder->has_initial_point = FALSE;
-    }
-
-    _cairo_path_bounder_add_point (bounder, point);
     bounder->current_point = *point;
+    _cairo_box_add_point (&bounder->extents, point);
 
     return CAIRO_STATUS_SUCCESS;
 }
@@ -114,25 +84,12 @@ _cairo_path_bounder_curve_to (void *closure,
 {
     cairo_path_bounder_t *bounder = closure;
 
-    /* If the bbox of the control points is entirely inside, then we
-     * do not need to further evaluate the spline.
-     */
-    if (! bounder->has_point ||
-	b->x < bounder->extents.p1.x || b->x > bounder->extents.p2.x ||
-	b->y < bounder->extents.p1.y || b->y > bounder->extents.p2.y ||
-	c->x < bounder->extents.p1.x || c->x > bounder->extents.p2.x ||
-	c->y < bounder->extents.p1.y || c->y > bounder->extents.p2.y ||
-	d->x < bounder->extents.p1.x || d->x > bounder->extents.p2.x ||
-	d->y < bounder->extents.p1.y || d->y > bounder->extents.p2.y)
-    {
-	return _cairo_spline_bound (_cairo_path_bounder_line_to, bounder,
-				    &bounder->current_point, b, c, d);
-    }
-    else
-    {
-	/* All control points are within the current extents. */
-	return CAIRO_STATUS_SUCCESS;
-    }
+    _cairo_box_add_curve_to (&bounder->extents,
+			     &bounder->current_point,
+			     b, c, d);
+    bounder->current_point = *d;
+
+    return CAIRO_STATUS_SUCCESS;
 }
 
 static cairo_status_t
@@ -141,53 +98,40 @@ _cairo_path_bounder_close_path (void *closure)
     return CAIRO_STATUS_SUCCESS;
 }
 
-/* This computes the extents of all the points in the path, not those of
- * the damage area (i.e it does not consider winding and it only inspects
- * the control points of the curves, not the flattened path).
- */
+cairo_bool_t
+_cairo_path_bounder_extents (const cairo_path_fixed_t *path,
+			     cairo_box_t *extents)
+{
+    cairo_path_bounder_t bounder;
+    cairo_status_t status;
+
+    bounder.has_extents = FALSE;
+    status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
+					  _cairo_path_bounder_move_to,
+					  _cairo_path_bounder_line_to,
+					  _cairo_path_bounder_curve_to,
+					  _cairo_path_bounder_close_path,
+					  &bounder);
+    assert (!status);
+
+    if (bounder.has_extents)
+	*extents = bounder.extents;
+
+    return bounder.has_extents;
+}
+
 void
 _cairo_path_fixed_approximate_clip_extents (const cairo_path_fixed_t *path,
 					    cairo_rectangle_int_t *extents)
 {
-    if (path->extents.p1.x < path->extents.p2.x) {
-	_cairo_box_round_to_rectangle (&path->extents, extents);
-    } else {
-	extents->x = extents->y = 0;
-	extents->width = extents->height = 0;
-    }
+    _cairo_path_fixed_approximate_fill_extents (path, extents);
 }
 
-/* A slightly better approximation than above - we actually decompose the
- * Bezier, but we continue to ignore winding.
- */
 void
 _cairo_path_fixed_approximate_fill_extents (const cairo_path_fixed_t *path,
 					    cairo_rectangle_int_t *extents)
 {
-    cairo_path_bounder_t bounder;
-    cairo_status_t status;
-
-    if (! path->has_curve_to) {
-	bounder.extents = path->extents;
-	bounder.has_point = path->extents.p1.x < path->extents.p2.x;
-    } else {
-	_cairo_path_bounder_init (&bounder);
-
-	status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
-					      _cairo_path_bounder_move_to,
-					      _cairo_path_bounder_line_to,
-					      _cairo_path_bounder_curve_to,
-					      _cairo_path_bounder_close_path,
-					      &bounder);
-	assert (status == CAIRO_STATUS_SUCCESS);
-    }
-
-    if (bounder.has_point) {
-	_cairo_box_round_to_rectangle (&bounder.extents, extents);
-    } else {
-	extents->x = extents->y = 0;
-	extents->width = extents->height = 0;
-    }
+    _cairo_path_fixed_fill_extents (path, CAIRO_FILL_RULE_WINDING, 0, extents);
 }
 
 void
@@ -196,25 +140,9 @@ _cairo_path_fixed_fill_extents (const cairo_path_fixed_t	*path,
 				double			 tolerance,
 				cairo_rectangle_int_t	*extents)
 {
-    cairo_path_bounder_t bounder;
-    cairo_status_t status;
-
-    if (! path->has_curve_to) {
-	bounder.extents = path->extents;
-	bounder.has_point = path->extents.p1.x < path->extents.p2.x;
-    } else {
-	_cairo_path_bounder_init (&bounder);
-
-	status = _cairo_path_fixed_interpret_flat (path, CAIRO_DIRECTION_FORWARD,
-						   _cairo_path_bounder_move_to,
-						   _cairo_path_bounder_line_to,
-						   _cairo_path_bounder_close_path,
-						   &bounder, tolerance);
-	assert (status == CAIRO_STATUS_SUCCESS);
-    }
-
-    if (bounder.has_point) {
-	_cairo_box_round_to_rectangle (&bounder.extents, extents);
+    if (path->extents.p1.x < path->extents.p2.x &&
+	path->extents.p1.y < path->extents.p2.y) {
+	_cairo_box_round_to_rectangle (&path->extents, extents);
     } else {
 	extents->x = extents->y = 0;
 	extents->width = extents->height = 0;
@@ -228,65 +156,18 @@ _cairo_path_fixed_approximate_stroke_extents (const cairo_path_fixed_t *path,
 					      const cairo_matrix_t *ctm,
 					      cairo_rectangle_int_t *extents)
 {
-    cairo_path_bounder_t bounder;
-    cairo_status_t status;
-
-    if (! path->has_curve_to) {
-	bounder.extents = path->extents;
-
-	/* include trailing move-to for degenerate segments */
-	if (path->needs_move_to) {
-	    const cairo_point_t *point = &path->current_point;
-
-	    if (point->x < bounder.extents.p1.x)
-		bounder.extents.p1.x = point->x;
-	    if (point->y < bounder.extents.p1.y)
-		bounder.extents.p1.y = point->y;
-
-	    if (point->x > bounder.extents.p2.x)
-		bounder.extents.p2.x = point->x;
-	    if (point->y > bounder.extents.p2.y)
-		bounder.extents.p2.y = point->y;
-	}
-
-	bounder.has_point = bounder.extents.p1.x <= bounder.extents.p2.x;
-	bounder.has_initial_point = FALSE;
-    } else {
-	_cairo_path_bounder_init (&bounder);
-
-	status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
-					      _cairo_path_bounder_move_to,
-					      _cairo_path_bounder_line_to,
-					      _cairo_path_bounder_curve_to,
-					      _cairo_path_bounder_close_path,
-					      &bounder);
-	assert (status == CAIRO_STATUS_SUCCESS);
-    }
-
-    if (bounder.has_point) {
-	double dx, dy;
-
-	_cairo_stroke_style_max_distance_from_path (style, ctm, &dx, &dy);
-
-	bounder.extents.p1.x -= _cairo_fixed_from_double (dx);
-	bounder.extents.p2.x += _cairo_fixed_from_double (dx);
-	bounder.extents.p1.y -= _cairo_fixed_from_double (dy);
-	bounder.extents.p2.y += _cairo_fixed_from_double (dy);
-
-	_cairo_box_round_to_rectangle (&bounder.extents, extents);
-    } else if (bounder.has_initial_point) {
+    if (path->has_extents) {
+	cairo_box_t box_extents;
 	double dx, dy;
 
-	/* accommodate capping of degenerate paths */
-
+	box_extents = path->extents;
 	_cairo_stroke_style_max_distance_from_path (style, ctm, &dx, &dy);
+	box_extents.p1.x -= _cairo_fixed_from_double (dx);
+	box_extents.p1.y -= _cairo_fixed_from_double (dy);
+	box_extents.p2.x += _cairo_fixed_from_double (dx);
+	box_extents.p2.y += _cairo_fixed_from_double (dy);
 
-	bounder.extents.p1.x = bounder.current_point.x - _cairo_fixed_from_double (dx);
-	bounder.extents.p2.x = bounder.current_point.x + _cairo_fixed_from_double (dx);
-	bounder.extents.p1.y = bounder.current_point.y - _cairo_fixed_from_double (dy);
-	bounder.extents.p2.y = bounder.current_point.y + _cairo_fixed_from_double (dy);
-
-	_cairo_box_round_to_rectangle (&bounder.extents, extents);
+	_cairo_box_round_to_rectangle (&box_extents, extents);
     } else {
 	extents->x = extents->y = 0;
 	extents->width = extents->height = 0;
@@ -326,24 +207,6 @@ cairo_bool_t
 _cairo_path_fixed_extents (const cairo_path_fixed_t *path,
 			   cairo_box_t *box)
 {
-    cairo_path_bounder_t bounder;
-    cairo_status_t status;
-
-    if (! path->has_curve_to) {
-	*box = path->extents;
-	return path->has_extents;
-    }
-
-    _cairo_path_bounder_init (&bounder);
-
-    status = _cairo_path_fixed_interpret (path, CAIRO_DIRECTION_FORWARD,
-					  _cairo_path_bounder_move_to,
-					  _cairo_path_bounder_line_to,
-					  _cairo_path_bounder_curve_to,
-					  _cairo_path_bounder_close_path,
-					  &bounder);
-    assert (status == CAIRO_STATUS_SUCCESS);
-
-    *box = bounder.extents;
-    return bounder.has_point;
+    *box = path->extents;
+    return path->has_extents;
 }