This page contains samples of cairo's rendered output and the code snippets used to create them. The snippets are meant to be short, and easy to understand.
cairo_snippets, part of the cairo-demo module in cairo CVS, is
used to create these webpages. cairo_snippets serves as a testbed for
the rendered output of various cairo backends. The images rendered on
these webpages are created by the cairo_snippets_png program, which is
using cairo's software image backend.
The snippet environment, and the original snippets were originally created by Øyvind Kolås for a paper submitted to GUADEC 2004.
All of his original snippet code is considered to be part of the public domain.
arc
double xc = 128.0;
double yc = 128.0;
double radius = 100.0;
double angle1 = 45.0 * (M_PI/180.0); /* angles are specified */
double angle2 = 180.0 * (M_PI/180.0); /* in radians */
cairo_set_line_width (cr, 10.0);
cairo_arc (cr, xc, yc, radius, angle1, angle2);
cairo_stroke (cr);
/* draw helping lines */
cairo_set_source_rgba (cr, 1, 0.2, 0.2, 0.6);
cairo_set_line_width (cr, 6.0);
cairo_arc (cr, xc, yc, 10.0, 0, 2*M_PI);
cairo_fill (cr);
cairo_arc (cr, xc, yc, radius, angle1, angle1);
cairo_line_to (cr, xc, yc);
cairo_arc (cr, xc, yc, radius, angle2, angle2);
cairo_line_to (cr, xc, yc);
cairo_stroke (cr);
double xc = 128.0;
double yc = 128.0;
double radius = 100.0;
double angle1 = 45.0 * (M_PI/180.0); /* angles are specified */
double angle2 = 180.0 * (M_PI/180.0); /* in radians */
cairo_set_line_width (cr, 10.0);
cairo_arc_negative (cr, xc, yc, radius, angle1, angle2);
cairo_stroke (cr);
/* draw helping lines */
cairo_set_source_rgba (cr, 1, 0.2, 0.2, 0.6);
cairo_set_line_width (cr, 6.0);
cairo_arc (cr, xc, yc, 10.0, 0, 2*M_PI);
cairo_fill (cr);
cairo_arc (cr, xc, yc, radius, angle1, angle1);
cairo_line_to (cr, xc, yc);
cairo_arc (cr, xc, yc, radius, angle2, angle2);
cairo_line_to (cr, xc, yc);
cairo_stroke (cr);
cairo_arc (cr, 128.0, 128.0, 76.8, 0, 2 * M_PI);
cairo_clip (cr);
cairo_new_path (cr); /* current path is not
consumed by cairo_clip() */
cairo_rectangle (cr, 0, 0, 256, 256);
cairo_fill (cr);
cairo_set_source_rgb (cr, 0, 1, 0);
cairo_move_to (cr, 0, 0);
cairo_line_to (cr, 256, 256);
cairo_move_to (cr, 256, 0);
cairo_line_to (cr, 0, 256);
cairo_set_line_width (cr, 10.0);
cairo_stroke (cr);
int w, h;
cairo_surface_t *image;
cairo_arc (cr, 128.0, 128.0, 76.8, 0, 2*M_PI);
cairo_clip (cr);
cairo_new_path (cr); /* path not consumed by clip()*/
image = cairo_image_surface_create_from_png ("data/romedalen.png");
w = cairo_image_surface_get_width (image);
h = cairo_image_surface_get_height (image);
cairo_scale (cr, 256.0/w, 256.0/h);
cairo_set_source_surface (cr, image, 0, 0);
cairo_paint (cr);
cairo_surface_destroy (image);
/* a custom shape that could be wrapped in a function */
double x0 = 25.6, /* parameters like cairo_rectangle */
y0 = 25.6,
rect_width = 204.8,
rect_height = 204.8,
radius = 102.4; /* and an approximate curvature radius */
double x1,y1;
x1=x0+rect_width;
y1=y0+rect_height;
if (!rect_width || !rect_height)
return;
if (rect_width/2<radius) {
if (rect_height/2<radius) {
cairo_move_to (cr, x0, (y0 + y1)/2);
cairo_curve_to (cr, x0 ,y0, x0, y0, (x0 + x1)/2, y0);
cairo_curve_to (cr, x1, y0, x1, y0, x1, (y0 + y1)/2);
cairo_curve_to (cr, x1, y1, x1, y1, (x1 + x0)/2, y1);
cairo_curve_to (cr, x0, y1, x0, y1, x0, (y0 + y1)/2);
} else {
cairo_move_to (cr, x0, y0 + radius);
cairo_curve_to (cr, x0 ,y0, x0, y0, (x0 + x1)/2, y0);
cairo_curve_to (cr, x1, y0, x1, y0, x1, y0 + radius);
cairo_line_to (cr, x1 , y1 - radius);
cairo_curve_to (cr, x1, y1, x1, y1, (x1 + x0)/2, y1);
cairo_curve_to (cr, x0, y1, x0, y1, x0, y1- radius);
}
} else {
if (rect_height/2<radius) {
cairo_move_to (cr, x0, (y0 + y1)/2);
cairo_curve_to (cr, x0 , y0, x0 , y0, x0 + radius, y0);
cairo_line_to (cr, x1 - radius, y0);
cairo_curve_to (cr, x1, y0, x1, y0, x1, (y0 + y1)/2);
cairo_curve_to (cr, x1, y1, x1, y1, x1 - radius, y1);
cairo_line_to (cr, x0 + radius, y1);
cairo_curve_to (cr, x0, y1, x0, y1, x0, (y0 + y1)/2);
} else {
cairo_move_to (cr, x0, y0 + radius);
cairo_curve_to (cr, x0 , y0, x0 , y0, x0 + radius, y0);
cairo_line_to (cr, x1 - radius, y0);
cairo_curve_to (cr, x1, y0, x1, y0, x1, y0 + radius);
cairo_line_to (cr, x1 , y1 - radius);
cairo_curve_to (cr, x1, y1, x1, y1, x1 - radius, y1);
cairo_line_to (cr, x0 + radius, y1);
cairo_curve_to (cr, x0, y1, x0, y1, x0, y1- radius);
}
}
cairo_close_path (cr);
cairo_set_source_rgb (cr, 0.5, 0.5, 1);
cairo_fill_preserve (cr);
cairo_set_source_rgba (cr, 0.5, 0, 0, 0.5);
cairo_set_line_width (cr, 10.0);
cairo_stroke (cr);
double x=25.6, y=128.0;
double x1=102.4, y1=230.4,
x2=153.6, y2=25.6,
x3=230.4, y3=128.0;
cairo_move_to (cr, x, y);
cairo_curve_to (cr, x1, y1, x2, y2, x3, y3);
cairo_set_line_width (cr, 10.0);
cairo_stroke (cr);
cairo_set_source_rgba (cr, 1, 0.2, 0.2, 0.6);
cairo_set_line_width (cr, 6.0);
cairo_move_to (cr,x,y); cairo_line_to (cr,x1,y1);
cairo_move_to (cr,x2,y2); cairo_line_to (cr,x3,y3);
cairo_stroke (cr);
double dashes[] = {50.0, /* ink */
10.0, /* skip */
10.0, /* ink */
10.0 /* skip*/
};
int ndash = sizeof (dashes)/sizeof(dashes[0]);
double offset = -50.0;
cairo_set_dash (cr, dashes, ndash, offset);
cairo_set_line_width (cr, 10.0);
cairo_move_to (cr, 128.0, 25.6);
cairo_line_to (cr, 230.4, 230.4);
cairo_rel_line_to (cr, -102.4, 0.0);
cairo_curve_to (cr, 51.2, 230.4, 51.2, 128.0, 128.0, 128.0);
cairo_stroke (cr);
cairo_move_to (cr, 128.0, 25.6);
cairo_line_to (cr, 230.4, 230.4);
cairo_rel_line_to (cr, -102.4, 0.0);
cairo_curve_to (cr, 51.2, 230.4, 51.2, 128.0, 128.0, 128.0);
cairo_close_path (cr);
cairo_move_to (cr, 64.0, 25.6);
cairo_rel_line_to (cr, 51.2, 51.2);
cairo_rel_line_to (cr, -51.2, 51.2);
cairo_rel_line_to (cr, -51.2, -51.2);
cairo_close_path (cr);
cairo_set_line_width (cr, 10.0);
cairo_set_source_rgb (cr, 0, 0, 1);
cairo_fill_preserve (cr);
cairo_set_source_rgb (cr, 0, 0, 0);
cairo_stroke (cr);
cairo_set_line_width (cr, 6);
cairo_rectangle (cr, 12, 12, 232, 70);
cairo_new_sub_path (cr); cairo_arc (cr, 64, 64, 40, 0, 2*M_PI);
cairo_new_sub_path (cr); cairo_arc_negative (cr, 192, 64, 40, 0, -2*M_PI);
cairo_set_fill_rule (cr, CAIRO_FILL_RULE_EVEN_ODD);
cairo_set_source_rgb (cr, 0, 0.7, 0); cairo_fill_preserve (cr);
cairo_set_source_rgb (cr, 0, 0, 0); cairo_stroke (cr);
cairo_translate (cr, 0, 128);
cairo_rectangle (cr, 12, 12, 232, 70);
cairo_new_sub_path (cr); cairo_arc (cr, 64, 64, 40, 0, 2*M_PI);
cairo_new_sub_path (cr); cairo_arc_negative (cr, 192, 64, 40, 0, -2*M_PI);
cairo_set_fill_rule (cr, CAIRO_FILL_RULE_WINDING);
cairo_set_source_rgb (cr, 0, 0, 0.9); cairo_fill_preserve (cr);
cairo_set_source_rgb (cr, 0, 0, 0); cairo_stroke (cr);
cairo_pattern_t *pat;
pat = cairo_pattern_create_linear (0.0, 0.0, 0.0, 256.0);
cairo_pattern_add_color_stop_rgba (pat, 1, 0, 0, 0, 1);
cairo_pattern_add_color_stop_rgba (pat, 0, 1, 1, 1, 1);
cairo_rectangle (cr, 0, 0, 256, 256);
cairo_set_source (cr, pat);
cairo_fill (cr);
cairo_pattern_destroy (pat);
pat = cairo_pattern_create_radial (115.2, 102.4, 25.6,
102.4, 102.4, 128.0);
cairo_pattern_add_color_stop_rgba (pat, 0, 1, 1, 1, 1);
cairo_pattern_add_color_stop_rgba (pat, 1, 0, 0, 0, 1);
cairo_set_source (cr, pat);
cairo_arc (cr, 128.0, 128.0, 76.8, 0, 2 * M_PI);
cairo_fill (cr);
cairo_pattern_destroy (pat);
int w, h;
cairo_surface_t *image;
image = cairo_image_surface_create_from_png ("data/romedalen.png");
w = cairo_image_surface_get_width (image);
h = cairo_image_surface_get_height (image);
cairo_translate (cr, 128.0, 128.0);
cairo_rotate (cr, 45* M_PI/180);
cairo_scale (cr, 256.0/w, 256.0/h);
cairo_translate (cr, -0.5*w, -0.5*h);
cairo_set_source_surface (cr, image, 0, 0);
cairo_paint (cr);
cairo_surface_destroy (image);
int w, h;
cairo_surface_t *image;
cairo_pattern_t *pattern;
cairo_matrix_t matrix;
image = cairo_image_surface_create_from_png ("data/romedalen.png");
w = cairo_image_surface_get_width (image);
h = cairo_image_surface_get_height (image);
pattern = cairo_pattern_create_for_surface (image);
cairo_pattern_set_extend (pattern, CAIRO_EXTEND_REPEAT);
cairo_translate (cr, 128.0, 128.0);
cairo_rotate (cr, M_PI / 4);
cairo_scale (cr, 1 / sqrt (2), 1 / sqrt (2));
cairo_translate (cr, -128.0, -128.0);
cairo_matrix_init_scale (&matrix, w/256.0 * 5.0, h/256.0 * 5.0);
cairo_pattern_set_matrix (pattern, &matrix);
cairo_set_source (cr, pattern);
cairo_rectangle (cr, 0, 0, 256.0, 256.0);
cairo_fill (cr);
cairo_pattern_destroy (pattern);
cairo_surface_destroy (image);
cairo_move_to (cr, 50.0, 75.0);
cairo_line_to (cr, 200.0, 75.0);
cairo_move_to (cr, 50.0, 125.0);
cairo_line_to (cr, 200.0, 125.0);
cairo_move_to (cr, 50.0, 175.0);
cairo_line_to (cr, 200.0, 175.0);
cairo_set_line_width (cr, 30.0);
cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
cairo_stroke (cr);
cairo_set_line_width (cr, 30.0);
cairo_set_line_cap (cr, CAIRO_LINE_CAP_BUTT); /* default */
cairo_move_to (cr, 64.0, 50.0); cairo_line_to (cr, 64.0, 200.0);
cairo_stroke (cr);
cairo_set_line_cap (cr, CAIRO_LINE_CAP_ROUND);
cairo_move_to (cr, 128.0, 50.0); cairo_line_to (cr, 128.0, 200.0);
cairo_stroke (cr);
cairo_set_line_cap (cr, CAIRO_LINE_CAP_SQUARE);
cairo_move_to (cr, 192.0, 50.0); cairo_line_to (cr, 192.0, 200.0);
cairo_stroke (cr);
/* draw helping lines */
cairo_set_source_rgb (cr, 1, 0.2, 0.2);
cairo_set_line_width (cr, 2.56);
cairo_move_to (cr, 64.0, 50.0); cairo_line_to (cr, 64.0, 200.0);
cairo_move_to (cr, 128.0, 50.0); cairo_line_to (cr, 128.0, 200.0);
cairo_move_to (cr, 192.0, 50.0); cairo_line_to (cr, 192.0, 200.0);
cairo_stroke (cr);
cairo_set_line_width (cr, 40.96);
cairo_move_to (cr, 76.8, 84.48);
cairo_rel_line_to (cr, 51.2, -51.2);
cairo_rel_line_to (cr, 51.2, 51.2);
cairo_set_line_join (cr, CAIRO_LINE_JOIN_MITER); /* default */
cairo_stroke (cr);
cairo_move_to (cr, 76.8, 161.28);
cairo_rel_line_to (cr, 51.2, -51.2);
cairo_rel_line_to (cr, 51.2, 51.2);
cairo_set_line_join (cr, CAIRO_LINE_JOIN_BEVEL);
cairo_stroke (cr);
cairo_move_to (cr, 76.8, 238.08);
cairo_rel_line_to (cr, 51.2, -51.2);
cairo_rel_line_to (cr, 51.2, 51.2);
cairo_set_line_join (cr, CAIRO_LINE_JOIN_ROUND);
cairo_stroke (cr);
cairo_select_font_face (cr, "Sans", CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_BOLD);
cairo_set_font_size (cr, 90.0);
cairo_move_to (cr, 10.0, 135.0);
cairo_show_text (cr, "Hello");
cairo_move_to (cr, 70.0, 165.0);
cairo_text_path (cr, "void");
cairo_set_source_rgb (cr, 0.5, 0.5, 1);
cairo_fill_preserve (cr);
cairo_set_source_rgb (cr, 0, 0, 0);
cairo_set_line_width (cr, 2.56);
cairo_stroke (cr);
/* draw helping lines */
cairo_set_source_rgba (cr, 1, 0.2, 0.2, 0.6);
cairo_arc (cr, 10.0, 135.0, 5.12, 0, 2*M_PI);
cairo_close_path (cr);
cairo_arc (cr, 70.0, 165.0, 5.12, 0, 2*M_PI);
cairo_fill (cr);
cairo_text_extents_t extents;
const char *utf8 = "cairo";
double x,y;
cairo_select_font_face (cr, "Sans",
CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_NORMAL);
cairo_set_font_size (cr, 52.0);
cairo_text_extents (cr, utf8, &extents);
x = 128.0-(extents.width/2 + extents.x_bearing);
y = 128.0-(extents.height/2 + extents.y_bearing);
cairo_move_to (cr, x, y);
cairo_show_text (cr, utf8);
/* draw helping lines */
cairo_set_source_rgba (cr, 1, 0.2, 0.2, 0.6);
cairo_set_line_width (cr, 6.0);
cairo_arc (cr, x, y, 10.0, 0, 2*M_PI);
cairo_fill (cr);
cairo_move_to (cr, 128.0, 0);
cairo_rel_line_to (cr, 0, 256);
cairo_move_to (cr, 0, 128.0);
cairo_rel_line_to (cr, 256, 0);
cairo_stroke (cr);
cairo_text_extents_t extents;
const char *utf8 = "cairo";
double x,y;
cairo_select_font_face (cr, "Sans",
CAIRO_FONT_SLANT_NORMAL,
CAIRO_FONT_WEIGHT_NORMAL);
cairo_set_font_size (cr, 100.0);
cairo_text_extents (cr, utf8, &extents);
x=25.0;
y=150.0;
cairo_move_to (cr, x,y);
cairo_show_text (cr, utf8);
/* draw helping lines */
cairo_set_source_rgba (cr, 1, 0.2, 0.2, 0.6);
cairo_set_line_width (cr, 6.0);
cairo_arc (cr, x, y, 10.0, 0, 2*M_PI);
cairo_fill (cr);
cairo_move_to (cr, x,y);
cairo_rel_line_to (cr, 0, -extents.height);
cairo_rel_line_to (cr, extents.width, 0);
cairo_rel_line_to (cr, extents.x_bearing, -extents.y_bearing);
cairo_stroke (cr);