forked from AuroraMiddleware/gtk
docs: Move documentation to inline comments: gdkpango
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Javier Jardón
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docs/reference/gdk/tmpl/.gitignore
vendored
1
docs/reference/gdk/tmpl/.gitignore
vendored
@ -9,6 +9,7 @@ gdkscreen.sgml
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gdktesting.sgml
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general.sgml
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keys.sgml
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pango_interaction.sgml
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pixbufs.sgml
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regions.sgml
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windows.sgml
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@ -1,158 +0,0 @@
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<!-- ##### SECTION Title ##### -->
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Pango Interaction
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<!-- ##### SECTION Short_Description ##### -->
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Using Pango in GDK
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<!-- ##### SECTION Long_Description ##### -->
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<para>
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Pango is the text layout system used by GDK and GTK+. The functions
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and types in this section are used to obtain clip regions for
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#PangoLayouts, and to get #PangoContexts that can be used with
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GDK.
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</para>
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<para>
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Creating a #PangoLayout object is the first step in rendering text,
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and requires getting a handle to a #PangoContext. For GTK+ programs,
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you'll usually want to use gtk_widget_get_pango_context(), or
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gtk_widget_create_pango_layout(), rather than using the lowlevel
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gdk_pango_context_get_for_screen(). Once you have a #PangoLayout, you
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can set the text and attributes of it with Pango functions like
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pango_layout_set_text() and get its size with pango_layout_get_size().
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(Note that Pango uses a fixed point system internally, so converting
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between Pango units and pixels using <link
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linkend="PANGO-SCALE-CAPS">PANGO_SCALE</link> or the PANGO_PIXELS() macro.)
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</para>
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<para>
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Rendering a Pango layout is done most simply with pango_cairo_show_layout();
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you can also draw pieces of the layout with pango_cairo_show_layout_line().
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</para>
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<example id="rotated-example">
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<title>Draw transformed text with Pango and cairo</title>
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<!-- Note that this example is basically the same as
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demos/gtk-demo/rotated_text.c -->
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<programlisting>
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#define RADIUS 100
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#define N_WORDS 10
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#define FONT "Sans Bold 18"
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PangoContext *context;
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PangoLayout *layout;
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PangoFontDescription *desc;
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double radius;
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int width, height;
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int i;
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/* Set up a transformation matrix so that the user space coordinates for
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* where we are drawing are [-RADIUS, RADIUS], [-RADIUS, RADIUS]
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* We first center, then change the scale */
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width = gdk_window_get_width (window);
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height = gdk_window_get_height (window);
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radius = MIN (width, height) / 2.;
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cairo_translate (cr,
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radius + (width - 2 * radius) / 2,
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radius + (height - 2 * radius) / 2);
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cairo_scale (cr, radius / RADIUS, radius / RADIUS);
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/* Create a PangoLayout, set the font and text */
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context = gdk_pango_context_get_for_screen (screen);
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layout = pango_layout_new (context);
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pango_layout_set_text (layout, "Text", -1);
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desc = pango_font_description_from_string (FONT);
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pango_layout_set_font_description (layout, desc);
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pango_font_description_free (desc);
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/* Draw the layout N_WORDS times in a circle */
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for (i = 0; i < N_WORDS; i++)
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{
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double red, green, blue;
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double angle = 2 * G_PI * i / n_words;
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cairo_save (cr);
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/* Gradient from red at angle == 60 to blue at angle == 300 */
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red = (1 + cos (angle - 60)) / 2;
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green = 0;
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blue = 1 - red;
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cairo_set_source_rgb (cr, red, green, blue);
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cairo_rotate (cr, angle);
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/* Inform Pango to re-layout the text with the new transformation matrix */
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pango_cairo_update_layout (cr, layout);
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pango_layout_get_size (layout, &width, &height);
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cairo_move_to (cr, - width / 2 / PANGO_SCALE, - DEFAULT_TEXT_RADIUS);
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pango_cairo_show_layout (cr, layout);
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cairo_restore (cr);
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}
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g_object_unref (layout);
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g_object_unref (context);
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</programlisting>
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</example>
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<figure>
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<title>Output of <xref linkend="rotated-example"/></title>
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<graphic fileref="rotated-text.png" format="PNG"/>
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</figure>
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<!-- ##### SECTION See_Also ##### -->
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<para>
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</para>
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<!-- ##### SECTION Stability_Level ##### -->
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<!-- ##### SECTION Image ##### -->
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<!-- ##### FUNCTION gdk_pango_layout_get_clip_region ##### -->
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<para>
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</para>
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@layout:
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@x_origin:
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@y_origin:
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@index_ranges:
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@n_ranges:
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@Returns:
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<!-- ##### FUNCTION gdk_pango_layout_line_get_clip_region ##### -->
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<para>
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</para>
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@line:
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@x_origin:
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@y_origin:
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@index_ranges:
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@n_ranges:
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@Returns:
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<!-- ##### FUNCTION gdk_pango_context_get ##### -->
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<para>
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</para>
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@void:
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@Returns:
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<!-- ##### FUNCTION gdk_pango_context_get_for_screen ##### -->
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<para>
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</para>
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@screen:
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@Returns:
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@ -27,6 +27,105 @@
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#include <math.h>
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#include <pango/pangocairo.h>
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/**
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* SECTION:pango_interaction
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* @Short_description: Using Pango in GDK
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* @Title: Pango Interaction
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*
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* Pango is the text layout system used by GDK and GTK+. The functions
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* and types in this section are used to obtain clip regions for
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* #PangoLayouts, and to get #PangoContexts that can be used with
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* GDK.
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*
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* Creating a #PangoLayout object is the first step in rendering text,
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* and requires getting a handle to a #PangoContext. For GTK+ programs,
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* you'll usually want to use gtk_widget_get_pango_context(), or
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* gtk_widget_create_pango_layout(), rather than using the lowlevel
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* gdk_pango_context_get_for_screen(). Once you have a #PangoLayout, you
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* can set the text and attributes of it with Pango functions like
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* pango_layout_set_text() and get its size with pango_layout_get_size().
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* (Note that Pango uses a fixed point system internally, so converting
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* between Pango units and pixels using <link
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* linkend="PANGO-SCALE-CAPS">PANGO_SCALE</link> or the PANGO_PIXELS() macro.)
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*
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* Rendering a Pango layout is done most simply with pango_cairo_show_layout();
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* you can also draw pieces of the layout with pango_cairo_show_layout_line().
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* <example id="rotated-example">
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* <title>Draw transformed text with Pango and cairo</title>
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* <!-- Note that this example is basically the same as
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* demos/gtk-demo/rotated_text.c -->
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* <programlisting>
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* #define RADIUS 100
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* #define N_WORDS 10
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* #define FONT "Sans Bold 18"
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*
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* PangoContext *context;
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* PangoLayout *layout;
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* PangoFontDescription *desc;
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*
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* double radius;
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* int width, height;
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* int i;
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*
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* /<!---->* Set up a transformation matrix so that the user space coordinates for
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* * where we are drawing are [-RADIUS, RADIUS], [-RADIUS, RADIUS]
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* * We first center, then change the scale *<!---->/
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*
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* width = gdk_window_get_width (window);
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* height = gdk_window_get_height (window);
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* radius = MIN (width, height) / 2.;
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*
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* cairo_translate (cr,
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* radius + (width - 2 * radius) / 2,
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* radius + (height - 2 * radius) / 2);
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* cairo_scale (cr, radius / RADIUS, radius / RADIUS);
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*
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* /<!---->* Create a PangoLayout, set the font and text *<!---->/
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* context = gdk_pango_context_get_for_screen (screen);
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* layout = pango_layout_new (context);
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* pango_layout_set_text (layout, "Text", -1);
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* desc = pango_font_description_from_string (FONT);
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* pango_layout_set_font_description (layout, desc);
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* pango_font_description_free (desc);
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*
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* /<!---->* Draw the layout N_WORDS times in a circle *<!---->/
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* for (i = 0; i < N_WORDS; i++)
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* {
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* double red, green, blue;
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* double angle = 2 * G_PI * i / n_words;
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*
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* cairo_save (cr);
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*
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* /<!---->* Gradient from red at angle == 60 to blue at angle == 300 *<!---->/
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* red = (1 + cos (angle - 60)) / 2;
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* green = 0;
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* blue = 1 - red;
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*
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* cairo_set_source_rgb (cr, red, green, blue);
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* cairo_rotate (cr, angle);
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*
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* /<!---->* Inform Pango to re-layout the text with the new transformation matrix *<!---->/
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* pango_cairo_update_layout (cr, layout);
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*
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* pango_layout_get_size (layout, &width, &height);
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*
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* cairo_move_to (cr, - width / 2 / PANGO_SCALE, - DEFAULT_TEXT_RADIUS);
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* pango_cairo_show_layout (cr, layout);
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*
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* cairo_restore (cr);
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* }
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*
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* g_object_unref (layout);
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* g_object_unref (context);
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* </programlisting>
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* </example>
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* <figure>
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* <title>Output of <xref linkend="rotated-example"/></title>
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* <graphic fileref="rotated-text.png" format="PNG"/>
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* </figure>
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*/
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/* Get a clip region to draw only part of a layout. index_ranges
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* contains alternating range starts/stops. The region is the
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* region which contains the given ranges, i.e. if you draw with the
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