From 6d08bcab0d2821365a2ffd955cbbb07270565664 Mon Sep 17 00:00:00 2001
From: Behdad Esfahbod <behdad@behdad.org>
Date: Fri, 27 Sep 2013 14:36:51 -0400
Subject: Bug 685167 - migrate docs to no-tmpl flavour
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Patch from Rafał Mużyło.
---
 pango/pangocairo-render.c | 133 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)

(limited to 'pango/pangocairo-render.c')

diff --git a/pango/pangocairo-render.c b/pango/pangocairo-render.c
index 48743444..03a2811a 100644
--- a/pango/pangocairo-render.c
+++ b/pango/pangocairo-render.c
@@ -19,6 +19,139 @@
  * Boston, MA 02111-1307, USA.
  */
 
+/**
+ * SECTION:pangocairo
+ * @short_description:Rendering with the Cairo backend
+ * @title:Cairo Rendering
+ *
+ * The <ulink url="http://cairographics.org">Cairo library</ulink> is a
+ * vector graphics library with a powerful rendering model. It has such
+ * features as anti-aliased primitives, alpha-compositing, and
+ * gradients. Multiple backends for Cairo are available, to allow
+ * rendering to images, to PDF files, and to the screen on X and on other
+ * windowing systems. The functions in this section allow using Pango
+ * to render to Cairo surfaces.
+ *
+ * Using Pango with Cairo is straightforward. A #PangoContext created
+ * with pango_cairo_font_map_create_context() can be used on any
+ * Cairo context (cairo_t), but needs to be updated to match the
+ * current transformation matrix and target surface of the Cairo context
+ * using pango_cairo_update_context(). The convenience functions
+ * pango_cairo_create_layout() and pango_cairo_update_layout() handle
+ * the common case where the program doesn't need to manipulate the
+ * properties of the #PangoContext.
+ *
+ * When you get the metrics of a layout or of a piece of a layout using
+ * functions such as pango_layout_get_extents(), the reported metrics
+ * are in user-space coordinates. If a piece of text is 10 units long,
+ * and you call cairo_scale (cr, 2.0), it still is more-or-less 10
+ * units long. However, the results will be affected by hinting
+ * (that is, the process of adjusting the text to look good on the
+ * pixel grid), so you shouldn't assume they are completely independent
+ * of the current transformation matrix. Note that the basic metrics
+ * functions in Pango report results in integer Pango units. To get
+ * to the floating point units used in Cairo divide by %PANGO_SCALE.
+ *
+ * <example id="rotated-example">
+ * <title>Using Pango with Cairo</title>
+ *  <programlisting>
+ * #include <math.h>
+ * #include <pango/pangocairo.h>
+ *
+ * static void
+ * draw_text (cairo_t *cr)
+ * {
+ * #define RADIUS 150
+ * #define N_WORDS 10
+ * #define FONT "Sans Bold 27"
+ *
+ *   PangoLayout *layout;
+ *   PangoFontDescription *desc;
+ *   int i;
+ *
+ *   /&ast; Center coordinates on the middle of the region we are drawing
+ *    &ast;/
+ *   cairo_translate (cr, RADIUS, RADIUS);
+ *
+ *   /&ast; Create a PangoLayout, set the font and text &ast;/
+ *   layout = pango_cairo_create_layout (cr);
+ *
+ *   pango_layout_set_text (layout, "Text", -1);
+ *   desc = pango_font_description_from_string (FONT);
+ *   pango_layout_set_font_description (layout, desc);
+ *   pango_font_description_free (desc);
+ *
+ *   /&ast; Draw the layout N_WORDS times in a circle &ast;/
+ *   for (i = 0; i &lt; N_WORDS; i++)
+ *     {
+ *       int width, height;
+ *       double angle = (360. * i) / N_WORDS;
+ *       double red;
+ *
+ *       cairo_save (cr);
+ *
+ *       /&ast; Gradient from red at angle == 60 to blue at angle == 240 &ast;/
+ *       red   = (1 + cos ((angle - 60) * G_PI / 180.)) / 2;
+ *       cairo_set_source_rgb (cr, red, 0, 1.0 - red);
+ *
+ *       cairo_rotate (cr, angle * G_PI / 180.);
+ *
+ *       /&ast; Inform Pango to re-layout the text with the new transformation &ast;/
+ *       pango_cairo_update_layout (cr, layout);
+ *
+ *       pango_layout_get_size (layout, &amp;width, &amp;height);
+ *       cairo_move_to (cr, - ((double)width / PANGO_SCALE) / 2, - RADIUS);
+ *       pango_cairo_show_layout (cr, layout);
+ *
+ *       cairo_restore (cr);
+ *     }
+ *
+ *   /&ast; free the layout object &ast;/
+ *   g_object_unref (layout);
+ * }
+ *
+ * int main (int argc, char **argv)
+ * {
+ *   cairo_t *cr;
+ *   char *filename;
+ *   cairo_status_t status;
+ *   cairo_surface_t *surface;
+ *
+ *   if (argc != 2)
+ *     {
+ *       g_printerr ("Usage: cairosimple OUTPUT_FILENAME\n");
+ *       return 1;
+ *     }
+ *
+ *      filename = argv[1];
+ *
+ *   surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
+ *                                         2 * RADIUS, 2 * RADIUS);
+ *   cr = cairo_create (surface);
+ *
+ *   cairo_set_source_rgb (cr, 1.0, 1.0, 1.0);
+ *   cairo_paint (cr);
+ *   draw_text (cr);
+ *   cairo_destroy (cr);
+ *
+ *   status = cairo_surface_write_to_png (surface, filename);
+ *   cairo_surface_destroy (surface);
+ *
+ *   if (status != CAIRO_STATUS_SUCCESS)
+ *     {
+ *       g_printerr ("Could not save png to '%s'\n", filename);
+ *       return 1;
+ *     }
+ *
+ *   return 0;
+ * }
+ * </programlisting>
+ * </example>
+ * <figure id="rotated-example-output">
+ *   <title>Output of <xref linkend="rotated-example"/></title>
+ *   <graphic fileref="rotated-text.png" format="PNG"/>
+ * </figure>
+ */
 #include "config.h"
 
 #include <math.h>
-- 
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