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