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/* Pango/Rotated Text
*
* This demo shows how to use PangoCairo to draw rotated and transformed
* text. The right pane shows a rotated GtkLabel widget.
*
* In both cases, a custom PangoCairo shape renderer is installed to draw
* a red heart using cairo drawing operations instead of the Unicode heart
* character.
*/
#include <gtk/gtk.h>
#include <string.h>
#define HEART "♥"
const char text[] = "I ♥ GTK";
static void
fancy_shape_renderer (cairo_t *cr,
PangoAttrShape *attr,
gboolean do_path,
gpointer data)
{
double x, y;
cairo_get_current_point (cr, &x, &y);
cairo_translate (cr, x, y);
cairo_scale (cr,
(double) attr->ink_rect.width / PANGO_SCALE,
(double) attr->ink_rect.height / PANGO_SCALE);
if (GPOINTER_TO_UINT (attr->data) == 0x2665) /* U+2665 BLACK HEART SUIT */
{
cairo_move_to (cr, .5, .0);
cairo_line_to (cr, .9, -.4);
cairo_curve_to (cr, 1.1, -.8, .5, -.9, .5, -.5);
cairo_curve_to (cr, .5, -.9, -.1, -.8, .1, -.4);
cairo_close_path (cr);
}
if (!do_path)
{
cairo_set_source_rgb (cr, 1., 0., 0.);
cairo_fill (cr);
}
}
static PangoAttrList *
create_fancy_attr_list_for_layout (PangoLayout *layout)
{
PangoAttrList *attrs;
PangoFontMetrics *metrics;
int ascent;
PangoRectangle ink_rect, logical_rect;
const char *p;
/* Get font metrics and prepare fancy shape size */
metrics = pango_context_get_metrics (pango_layout_get_context (layout),
pango_layout_get_font_description (layout),
NULL);
ascent = pango_font_metrics_get_ascent (metrics);
logical_rect.x = 0;
logical_rect.width = ascent;
logical_rect.y = -ascent;
logical_rect.height = ascent;
ink_rect = logical_rect;
pango_font_metrics_unref (metrics);
/* Set fancy shape attributes for all hearts */
attrs = pango_attr_list_new ();
for (p = text; (p = strstr (p, HEART)); p += strlen (HEART))
{
PangoAttribute *attr;
attr = pango_attr_shape_new_with_data (&ink_rect,
&logical_rect,
GUINT_TO_POINTER (g_utf8_get_char (p)),
NULL, NULL);
attr->start_index = p - text;
attr->end_index = attr->start_index + strlen (HEART);
pango_attr_list_insert (attrs, attr);
}
return attrs;
}
static void
rotated_text_draw (GtkDrawingArea *da,
cairo_t *cr,
int width,
int height,
gpointer data)
{
#define RADIUS 150
#define N_WORDS 5
#define FONT "Serif 18"
PangoContext *context;
PangoLayout *layout;
PangoFontDescription *desc;
cairo_pattern_t *pattern;
PangoAttrList *attrs;
double device_radius;
int i;
/* Create a cairo context and set up a transformation matrix so that the user
* space coordinates for the centered square where we draw are [-RADIUS, RADIUS],
* [-RADIUS, RADIUS].
* We first center, then change the scale. */
device_radius = MIN (width, height) / 2.;
cairo_translate (cr,
device_radius + (width - 2 * device_radius) / 2,
device_radius + (height - 2 * device_radius) / 2);
cairo_scale (cr, device_radius / RADIUS, device_radius / RADIUS);
/* Create and a subtle gradient source and use it. */
pattern = cairo_pattern_create_linear (-RADIUS, -RADIUS, RADIUS, RADIUS);
cairo_pattern_add_color_stop_rgb (pattern, 0., .5, .0, .0);
cairo_pattern_add_color_stop_rgb (pattern, 1., .0, .0, .5);
cairo_set_source (cr, pattern);
/* Create a PangoContext and set up our shape renderer */
context = gtk_widget_create_pango_context (GTK_WIDGET (da));
pango_cairo_context_set_shape_renderer (context,
fancy_shape_renderer,
NULL, NULL);
/* Create a PangoLayout, set the text, font, and attributes */
layout = pango_layout_new (context);
pango_layout_set_text (layout, text, -1);
desc = pango_font_description_from_string (FONT);
pango_layout_set_font_description (layout, desc);
attrs = create_fancy_attr_list_for_layout (layout);
pango_layout_set_attributes (layout, attrs);
pango_attr_list_unref (attrs);
/* Draw the layout N_WORDS times in a circle */
for (i = 0; i < N_WORDS; i++)
{
int layout_width, layout_height;
/* Inform Pango to re-layout the text with the new transformation matrix */
pango_cairo_update_layout (cr, layout);
pango_layout_get_pixel_size (layout, &layout_width, &layout_height);
cairo_move_to (cr, - layout_width / 2, - RADIUS * .9);
pango_cairo_show_layout (cr, layout);
/* Rotate for the next turn */
cairo_rotate (cr, G_PI*2 / N_WORDS);
}
/* free the objects we created */
pango_font_description_free (desc);
g_object_unref (layout);
g_object_unref (context);
cairo_pattern_destroy (pattern);
}
GtkWidget *
do_rotated_text (GtkWidget *do_widget)
{
static GtkWidget *window = NULL;
if (!window)
{
GtkWidget *box;
GtkWidget *drawing_area;
GtkWidget *label;
PangoLayout *layout;
PangoAttrList *attrs;
window = gtk_window_new ();
gtk_window_set_display (GTK_WINDOW (window),
gtk_widget_get_display (do_widget));
gtk_window_set_title (GTK_WINDOW (window), "Rotated Text");
gtk_window_set_default_size (GTK_WINDOW (window), 4 * RADIUS, 2 * RADIUS);
g_object_add_weak_pointer (G_OBJECT (window), (gpointer *)&window);
box = gtk_box_new (GTK_ORIENTATION_HORIZONTAL, 0);
gtk_box_set_homogeneous (GTK_BOX (box), TRUE);
gtk_window_set_child (GTK_WINDOW (window), box);
/* Add a drawing area */
drawing_area = gtk_drawing_area_new ();
gtk_box_append (GTK_BOX (box), drawing_area);
gtk_widget_add_css_class (drawing_area, "view");
gtk_drawing_area_set_draw_func (GTK_DRAWING_AREA (drawing_area),
rotated_text_draw,
NULL, NULL);
/* And a label */
label = gtk_label_new (text);
gtk_box_append (GTK_BOX (box), label);
/* Set up fancy stuff on the label */
layout = gtk_label_get_layout (GTK_LABEL (label));
pango_cairo_context_set_shape_renderer (pango_layout_get_context (layout),
fancy_shape_renderer,
NULL, NULL);
attrs = create_fancy_attr_list_for_layout (layout);
gtk_label_set_attributes (GTK_LABEL (label), attrs);
pango_attr_list_unref (attrs);
}
if (!gtk_widget_get_visible (window))
gtk_widget_show (window);
else
gtk_window_destroy (GTK_WINDOW (window));
return window;
}
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