diff options
| -rw-r--r-- | ChangeLog | 6 | ||||
| -rw-r--r-- | examples/cairotwisted.c | 76 |
2 files changed, 75 insertions, 7 deletions
@@ -1,3 +1,9 @@ +2007-10-20 Behdad Esfahbod <behdad@gnome.org> + + * examples/cairotwisted.c (curve_length): Implement bezier curve + length function that flattens the curve and sum the length of straight + lines approximating it. + 2007-10-15 Behdad Esfahbod <behdad@gnome.org> Bug 483600 – Leak of font family name in diff --git a/examples/cairotwisted.c b/examples/cairotwisted.c index 93fa5164..180cd447 100644 --- a/examples/cairotwisted.c +++ b/examples/cairotwisted.c @@ -20,6 +20,54 @@ two_points_distance (cairo_path_data_t *a, cairo_path_data_t *b) return sqrt (dx * dx + dy * dy); } +static double +curve_length (double x0, double y0, + double x1, double y1, + double x2, double y2, + double x3, double y3) +{ + cairo_surface_t *surface; + cairo_t *cr; + cairo_path_t *path; + cairo_path_data_t *data, current_point; + int i; + double length; + + surface = cairo_image_surface_create (CAIRO_FORMAT_A8, 0, 0); + cr = cairo_create (surface); + cairo_surface_destroy (surface); + + cairo_move_to (cr, x0, y0); + cairo_curve_to (cr, x1, y1, x2, y2, x3, y3); + + length = 0; + path = cairo_copy_path_flat (cr); + for (i=0; i < path->num_data; i += path->data[i].header.length) { + data = &path->data[i]; + switch (data->header.type) { + + case CAIRO_PATH_MOVE_TO: + current_point = data[1]; + break; + + case CAIRO_PATH_LINE_TO: + length += two_points_distance (¤t_point, &data[1]); + current_point = data[1]; + break; + + default: + case CAIRO_PATH_CURVE_TO: + case CAIRO_PATH_CLOSE_PATH: + g_assert_not_reached (); + } + } + cairo_path_destroy (path); + + cairo_destroy (cr); + + return length; +} + typedef double parametrization_t; static parametrization_t * @@ -43,20 +91,22 @@ parametrize_path (cairo_path_t *path) current_point = data[1]; break; case CAIRO_PATH_CURVE_TO: - /* + /* naive curve-length, treating bezier as three line segments: + parametrization[i] = two_points_distance (¤t_point, &data[1]) + + two_points_distance (&data[1], &data[2]) + + two_points_distance (&data[2], &data[3]); + */ parametrization[i] = curve_length (current_point.point.x, current_point.point.x, data[1].point.x, data[1].point.y, data[2].point.x, data[2].point.y, data[3].point.x, data[3].point.y); - */ - parametrization[i] = two_points_distance (¤t_point, &data[1]); - parametrization[i] += two_points_distance (&data[1], &data[2]); - parametrization[i] += two_points_distance (&data[2], &data[3]); current_point = data[3]; break; case CAIRO_PATH_CLOSE_PATH: break; + default: + g_assert_not_reached (); } } @@ -96,6 +146,8 @@ _fancy_cairo_stroke (cairo_t *cr, cairo_bool_t preserve) break; case CAIRO_PATH_CLOSE_PATH: break; + default: + g_assert_not_reached (); } } cairo_stroke (cr); @@ -125,6 +177,8 @@ _fancy_cairo_stroke (cairo_t *cr, cairo_bool_t preserve) case CAIRO_PATH_CLOSE_PATH: cairo_rel_line_to (cr, 0, 0); break; + default: + g_assert_not_reached (); } } cairo_rel_line_to (cr, 0, 0); @@ -148,6 +202,8 @@ _fancy_cairo_stroke (cairo_t *cr, cairo_bool_t preserve) case CAIRO_PATH_CLOSE_PATH: cairo_close_path (cr); break; + default: + g_assert_not_reached (); } } cairo_stroke (cr); @@ -192,6 +248,8 @@ transform_path (cairo_path_t *path, transform_point_func_t f, void *closure) break; case CAIRO_PATH_CLOSE_PATH: break; + default: + g_assert_not_reached (); } } } @@ -229,6 +287,8 @@ point_on_path (parametrized_path_t *param, break; case CAIRO_PATH_CLOSE_PATH: break; + default: + g_assert_not_reached (); } } data = &path->data[i]; @@ -282,6 +342,8 @@ point_on_path (parametrized_path_t *param, break; case CAIRO_PATH_CLOSE_PATH: break; + default: + g_assert_not_reached (); } } @@ -357,10 +419,10 @@ draw_twisted (cairo_t *cr, cairo_save (cr); /* Decrease tolerance a bit, since it's going to be magnified */ - cairo_set_tolerance (cr, 0.05); + cairo_set_tolerance (cr, 0.1); path = cairo_copy_path_flat (cr); - /*path = cairo_copy_path (cr);*/ +/*path = cairo_copy_path (cr);*/ cairo_new_path (cr); |