/* 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 heard using cairo drawing operations instead of the Unicode heart
* character.
*/
#include <gtk/gtk.h>
#include <string.h>
static GtkWidget *window = NULL;
#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);
switch (GPOINTER_TO_UINT (attr->data))
{
case 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);
}
break;
}
if (!do_path) {
cairo_set_source_rgb (cr, 1., 0., 0.);
cairo_fill (cr);
}
}
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 gboolean
rotated_text_expose_event (GtkWidget *widget,
GdkEventExpose *event,
gpointer data)
{
#define RADIUS 150
#define N_WORDS 5
#define FONT "Serif 18"
PangoContext *context;
PangoLayout *layout;
PangoFontDescription *desc;
cairo_t *cr;
cairo_pattern_t *pattern;
PangoAttrList *attrs;
GtkAllocation allocation;
int width, height;
double device_radius;
int i;
gtk_widget_get_allocation (widget, &allocation);
width = allocation.width;
height = allocation.height;
/* 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. */
cr = gdk_cairo_create (gtk_widget_get_window (widget));
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 (widget);
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 width, 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, &width, &height);
cairo_move_to (cr, - 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);
cairo_destroy (cr);
return FALSE;
}
GtkWidget *
do_rotated_text (GtkWidget *do_widget)
{
if (!window)
{
GtkWidget *box;
GtkWidget *drawing_area;
GtkWidget *label;
PangoLayout *layout;
PangoAttrList *attrs;
const GdkColor white = { 0, 0xffff, 0xffff, 0xffff };
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_screen (GTK_WINDOW (window),
gtk_widget_get_screen (do_widget));
gtk_window_set_title (GTK_WINDOW (window), "Rotated Text");
gtk_window_set_default_size (GTK_WINDOW (window), 4 * RADIUS, 2 * RADIUS);
g_signal_connect (window, "destroy", G_CALLBACK (gtk_widget_destroyed), &window);
box = gtk_hbox_new (TRUE, 0);
gtk_container_add (GTK_CONTAINER (window), box);
/* Add a drawing area */
drawing_area = gtk_drawing_area_new ();
gtk_container_add (GTK_CONTAINER (box), drawing_area);
/* This overrides the background color from the theme */
gtk_widget_modify_bg (drawing_area, GTK_STATE_NORMAL, &white);
g_signal_connect (drawing_area, "expose-event",
G_CALLBACK (rotated_text_expose_event), NULL);
/* And a label */
label = gtk_label_new (text);
gtk_container_add (GTK_CONTAINER (box), label);
gtk_label_set_angle (GTK_LABEL (label), 45);
/* 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_all (window);
}
else
{
gtk_widget_destroy (window);
window = NULL;
}
return window;
}