/* 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 #include #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; }