[PATCH] tutorial: add programm to generate the drawing diagrams

Nis Martensen nis.martensen at web.de
Fri Aug 24 13:56:11 PDT 2007


---
 src/tutorial/draw.c |  375 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 375 insertions(+), 0 deletions(-)
 create mode 100644 src/tutorial/draw.c

diff --git a/src/tutorial/draw.c b/src/tutorial/draw.c
new file mode 100644
index 0000000..4452254
--- /dev/null
+++ b/src/tutorial/draw.c
@@ -0,0 +1,375 @@
+/*
+ * draw.c draws the images in the "Drawing with cairo" section as part
+ * of the the cairo tutorial
+ * Copyright (C) 2007  Nis Martensen
+ * Derived from draw.py
+ * <http://www.tortall.net/mu/wiki/CairoTutorial/draw.py?raw>
+ * Copyright (C) 2006-2007 Michael Urman
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <string.h>
+#include <math.h>
+#include <cairo.h>
+#include <cairo-svg.h>
+
+void diagram (char *name);
+void draw_diagram (char *name, cairo_t *cr);
+void draw_setsourcergba (cairo_t *cr);
+void draw_setsourcegradient (cairo_t *cr);
+void path_diagram (cairo_t *cr);
+void draw_path_curveto_hints (cairo_t *cr);
+void draw_path_moveto (cairo_t *cr);
+void draw_path_lineto (cairo_t *cr);
+void draw_path_arcto (cairo_t *cr);
+void draw_path_curveto (cairo_t *cr);
+void draw_path_close (cairo_t *cr);
+void draw_textextents (cairo_t *cr);
+
+int main ()
+{
+	diagram ("setsourcergba");
+	diagram ("setsourcegradient");
+	diagram ("path-moveto");
+	diagram ("path-lineto");
+	diagram ("path-arcto");
+	diagram ("path-curveto");
+	diagram ("path-close");
+	diagram ("textextents");
+
+	return 0;
+}
+
+void diagram (char *name)
+{
+	cairo_surface_t *surf;
+	cairo_t *cr;
+
+	double width=120, height=120;
+	double ux=2, uy=2;
+
+	char svg_filename[50];
+	char png_filename[50];
+	strcpy (svg_filename, name);
+	strcpy (png_filename, name);
+	strcat (svg_filename, ".svg");
+	strcat (png_filename, ".png");
+
+	surf = cairo_svg_surface_create (svg_filename, width, height);
+	cr = cairo_create (surf);
+
+	cairo_scale (cr, width, height);
+	cairo_set_line_width (cr, 0.01);
+
+	cairo_rectangle (cr, 0, 0, 1, 1);
+	cairo_set_source_rgb (cr, 1, 1, 1);
+	cairo_fill (cr);
+
+	draw_diagram (name, cr);
+
+	cairo_device_to_user_distance (cr, &ux, &uy);
+	if (ux < uy)
+		ux = uy;
+	cairo_set_line_width (cr, ux);
+	cairo_set_source_rgb (cr, 0, 0, 0);
+	cairo_rectangle (cr, 0, 0, 1, 1);
+	cairo_stroke (cr);
+
+	/* write output and clean up */
+	cairo_surface_write_to_png (surf, png_filename);
+	cairo_destroy (cr);
+	cairo_surface_destroy (surf);
+}
+
+void draw_diagram (char *name, cairo_t *cr)
+{
+	if (strcmp(name, "setsourcergba") == 0) {
+		draw_setsourcergba (cr);
+	} else if (strcmp(name, "setsourcegradient") == 0) {
+		draw_setsourcegradient (cr);
+	} else if (strcmp(name, "path-moveto") == 0) {
+		draw_path_moveto (cr);
+	} else if (strcmp(name, "path-lineto") == 0) {
+		draw_path_lineto (cr);
+	} else if (strcmp(name, "path-arcto") == 0) {
+		draw_path_arcto (cr);
+	} else if (strcmp(name, "path-curveto") == 0) {
+		draw_path_curveto_hints (cr);
+		draw_path_curveto (cr);
+	} else if (strcmp(name, "path-close") == 0) {
+		draw_path_close (cr);
+	} else if (strcmp(name, "textextents") == 0) {
+		draw_textextents (cr);
+	}
+
+	if (strncmp(name, "path-", 5) == 0)
+		path_diagram (cr);
+}
+
+void draw_setsourcergba (cairo_t *cr)
+{
+	cairo_set_source_rgb (cr, 0, 0, 0);
+	cairo_move_to (cr, 0, 0);
+	cairo_line_to (cr, 1, 1);
+	cairo_move_to (cr, 1, 0);
+	cairo_line_to (cr, 0, 1);
+	cairo_set_line_width (cr, 0.2);
+	cairo_stroke (cr);
+
+	cairo_rectangle (cr, 0, 0, 0.5, 0.5);
+	cairo_set_source_rgba (cr, 1, 0, 0, 0.80);
+	cairo_fill (cr);
+
+	cairo_rectangle (cr, 0, 0.5, 0.5, 0.5);
+	cairo_set_source_rgba (cr, 0, 1, 0, 0.60);
+	cairo_fill (cr);
+
+	cairo_rectangle (cr, 0.5, 0, 0.5, 0.5);
+	cairo_set_source_rgba (cr, 0, 0, 1, 0.40);
+	cairo_fill (cr);
+}
+
+void draw_setsourcegradient (cairo_t *cr)
+{
+	int i, j;
+	cairo_pattern_t *radpat, *linpat;
+
+	radpat = cairo_pattern_create_radial (0.25, 0.25, 0.1, 0.5, 0.5, 0.5);
+	cairo_pattern_add_color_stop_rgb (radpat, 0, 1.0, 0.8, 0.8);
+	cairo_pattern_add_color_stop_rgb (radpat, 1, 0.9, 0.0, 0.0);
+
+	for (i = 1; i < 10; i++)
+		for (j = 1; j < 10; j++)
+			cairo_rectangle (cr, i / 10.0 - 0.04, j / 10.0 - 0.04,
+					 0.08, 0.08);
+	cairo_set_source (cr, radpat);
+	cairo_fill (cr);
+
+	linpat = cairo_pattern_create_linear (0.25, 0.35, 0.75, 0.65);
+	cairo_pattern_add_color_stop_rgba (linpat, 0.00, 1, 1, 1, 0);
+	cairo_pattern_add_color_stop_rgba (linpat, 0.25, 0, 1, 0, 0.5);
+	cairo_pattern_add_color_stop_rgba (linpat, 0.50, 1, 1, 1, 0);
+	cairo_pattern_add_color_stop_rgba (linpat, 0.75, 0, 0, 1, 0.5);
+	cairo_pattern_add_color_stop_rgba (linpat, 1.00, 1, 1, 1, 0);
+
+	cairo_rectangle (cr, 0.0, 0.0, 1, 1);
+	cairo_set_source (cr, linpat);
+	cairo_fill (cr);
+}
+
+void path_diagram (cairo_t *cr)
+{
+	cairo_path_t *path;
+	cairo_path_data_t *data;
+	double x, y, px = 3, py = 3;
+
+	path = cairo_copy_path_flat (cr);
+
+	cairo_device_to_user_distance (cr, &px, &py);
+	if (px < py)
+		px = py;
+	cairo_set_line_width (cr, px);
+	cairo_set_source_rgb (cr, 0, 0.6, 0);
+	cairo_stroke (cr);
+
+	if (path->num_data > 1) {
+		/*
+		 * Draw markers at the first and the last point of the
+		 * path, but only if the path is not closed.
+		 *
+		 * If the last path manipulation was a cairo_close(),
+		 * then we can detect this at the end of the path->data
+		 * array. The CLOSE_PATH element will be followed by a
+		 * MOVE_TO element (since cairo 1.2.4), so we need to
+		 * check position path->num_data - 3.
+		 *
+		 * More details can be found here:
+		 * <http://cairographics.org/manual/cairo-Paths.html#cairo-close-path>
+		 * <http://cairographics.org/manual/cairo-Paths.html#cairo-path-data-t>
+		 */
+		if (path->data[path->num_data-3].header.type != CAIRO_PATH_CLOSE_PATH) {
+			/* Get the first point in the path */
+			data = &path->data[0];
+			x = data[1].point.x;
+			y = data[1].point.y;
+
+			px = 5; py = 5;
+			cairo_device_to_user_distance (cr, &px, &py);
+			if (px < py)
+				px = py;
+
+			cairo_arc (cr, x, y, px, 0, 2*M_PI);
+			cairo_set_source_rgba (cr, 0.0, 0.6, 0.0, 0.5);
+			cairo_fill(cr);
+
+			/*
+			 * Because cairo_copy_path_flat() was used to
+			 * retrieve this path, there is no CURVE_TO
+			 * element, so the elements all have a length of
+			 * 2. The index of the last element must be
+			 * path->num_data - 2.
+			 */
+			data = &path->data[path->num_data-2];
+			x = data[1].point.x;
+			y = data[1].point.y;
+			cairo_arc (cr, x, y, px, 0, 2*M_PI);
+			cairo_set_source_rgba (cr, 0.0, 0.0, 0.75, 0.5);
+			cairo_fill (cr);
+		}
+	}
+
+	cairo_path_destroy (path);
+}
+
+void draw_path_curveto_hints (cairo_t *cr)
+{
+	double px = 3, py = 3;
+	cairo_save (cr);
+	cairo_device_to_user_distance (cr, &px, &py);
+	if (px < py)
+		px = py;
+	cairo_set_source_rgba (cr, 0.5, 0, 0, 0.5);
+
+	cairo_new_sub_path (cr);
+	cairo_arc (cr, 0.5, 0.625, px, 0, 2*M_PI);
+	cairo_fill (cr);
+	cairo_arc (cr, 0.5, 0.875, px, 0, 2*M_PI);
+	cairo_fill (cr);
+
+	px = 2; py = 2;
+	cairo_device_to_user_distance (cr, &px, &py);
+	if (px < py)
+		px = py;
+	cairo_set_line_width (cr, px);
+	cairo_set_source_rgba (cr, 0.5, 0, 0, 0.25);
+
+	cairo_move_to (cr, 0.25, 0.75);
+	cairo_rel_line_to (cr, 0.25, 0.125);
+	cairo_stroke (cr);
+
+	cairo_move_to (cr, 0.75, 0.75);
+	cairo_rel_line_to (cr, -0.25, -0.125);
+	cairo_stroke (cr);
+
+	cairo_restore (cr);
+}
+
+void draw_path_moveto (cairo_t *cr)
+{
+	cairo_set_line_width (cr, 0.1);
+	cairo_set_source_rgb (cr, 0, 0, 0);
+
+	cairo_move_to (cr, 0.25, 0.25);
+}
+
+void draw_path_lineto (cairo_t *cr)
+{
+	draw_path_moveto (cr);
+
+	cairo_line_to (cr, 0.5, 0.375);
+	cairo_rel_line_to (cr, 0.25, -0.125);
+}
+
+void draw_path_arcto (cairo_t *cr)
+{
+	draw_path_lineto (cr);
+
+	cairo_arc (cr, 0.5, 0.5, 0.25 * sqrt(2), -0.25 * M_PI, 0.25 * M_PI);
+}
+
+void draw_path_curveto (cairo_t *cr)
+{
+	draw_path_arcto (cr);
+
+	cairo_rel_curve_to (cr, -0.25, -0.125, -0.25, 0.125, -0.5, 0);
+}
+
+void draw_path_close (cairo_t *cr)
+{
+	draw_path_curveto (cr);
+
+	cairo_close_path (cr);
+}
+
+void draw_textextents (cairo_t *cr)
+{
+	double x, y, px, ux=1, uy=1, dashlength;
+	char text[]="joy";
+	cairo_font_extents_t fe;
+	cairo_text_extents_t te;
+
+	cairo_set_font_size (cr, 0.5);
+
+	/* Drawing code goes here */
+	cairo_set_source_rgb (cr, 0.0, 0.0, 0.0);
+	cairo_select_font_face (cr, "Georgia",
+			CAIRO_FONT_SLANT_NORMAL, CAIRO_FONT_WEIGHT_BOLD);
+	cairo_font_extents (cr, &fe);
+
+	cairo_device_to_user_distance (cr, &ux, &uy);
+	if (ux > uy)
+		px = ux;
+	else
+		px = uy;
+	cairo_font_extents (cr, &fe);
+	cairo_text_extents (cr, text, &te);
+	x = 0.5 - te.x_bearing - te.width / 2;
+	y = 0.5 - fe.descent + fe.height / 2;
+
+	/* baseline, descent, ascent, height */
+	cairo_set_line_width (cr, 4*px);
+	dashlength = 9*px;
+	cairo_set_dash (cr, &dashlength, 1, 0);
+	cairo_set_source_rgba (cr, 0, 0.6, 0, 0.5);
+	cairo_move_to (cr, x + te.x_bearing, y);
+	cairo_rel_line_to (cr, te.width, 0);
+	cairo_move_to (cr, x + te.x_bearing, y + fe.descent);
+	cairo_rel_line_to (cr, te.width, 0);
+	cairo_move_to (cr, x + te.x_bearing, y - fe.ascent);
+	cairo_rel_line_to (cr, te.width, 0);
+	cairo_move_to (cr, x + te.x_bearing, y - fe.height);
+	cairo_rel_line_to (cr, te.width, 0);
+	cairo_stroke (cr);
+
+	/* extents: width & height */
+	cairo_set_source_rgba (cr, 0, 0, 0.75, 0.5);
+	cairo_set_line_width (cr, px);
+	dashlength = 3*px;
+	cairo_set_dash (cr, &dashlength, 1, 0);
+	cairo_rectangle (cr, x + te.x_bearing, y + te.y_bearing, te.width, te.height);
+	cairo_stroke (cr);
+
+	/* text */
+	cairo_move_to (cr, x, y);
+	cairo_set_source_rgb (cr, 0, 0, 0);
+	cairo_show_text (cr, text);
+
+	/* bearing */
+	cairo_set_dash (cr, NULL, 0, 0);
+	cairo_set_line_width (cr, 2 * px);
+	cairo_set_source_rgba (cr, 0, 0, 0.75, 0.5);
+	cairo_move_to (cr, x, y);
+	cairo_rel_line_to (cr, te.x_bearing, te.y_bearing);
+	cairo_stroke (cr);
+
+	/* text's advance */
+	cairo_set_source_rgba (cr, 0, 0, 0.75, 0.5);
+	cairo_arc (cr, x + te.x_advance, y + te.y_advance, 5 * px, 0, 2 * M_PI);
+	cairo_fill (cr);
+
+	/* reference point */
+	cairo_arc (cr, x, y, 5 * px, 0, 2 * M_PI);
+	cairo_set_source_rgba (cr, 0.75, 0, 0, 0.5);
+	cairo_fill (cr);
+}
-- 
1.5.3.rc6.17.g1911


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