Viewing file:  hypertext.c (9.09 KB) -rw-r--r--
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/* Text Widget/Hypertext
*
* Usually, tags modify the appearance of text in the view, e.g. making it
* bold or colored or underlined. But tags are not restricted to appearance.
* They can also affect the behavior of mouse and key presses, as this demo
* shows.
*/
#include <gtk/gtk.h>
#include <gdk/gdkkeysyms.h>
/* Inserts a piece of text into the buffer, giving it the usual
* appearance of a hyperlink in a web browser: blue and underlined.
* Additionally, attaches some data on the tag, to make it recognizable
* as a link.
*/
static void
insert_link (GtkTextBuffer *buffer,
GtkTextIter *iter,
gchar *text,
gint page)
{
GtkTextTag *tag;
tag = gtk_text_buffer_create_tag (buffer, NULL,
"foreground", "blue",
"underline", PANGO_UNDERLINE_SINGLE,
NULL);
g_object_set_data (G_OBJECT (tag), "page", GINT_TO_POINTER (page));
gtk_text_buffer_insert_with_tags (buffer, iter, text, -1, tag, NULL);
}
/* Fills the buffer with text and interspersed links. In any real
* hypertext app, this method would parse a file to identify the links.
*/
static void
show_page (GtkTextBuffer *buffer,
gint page)
{
GtkTextIter iter;
gtk_text_buffer_set_text (buffer, "", 0);
gtk_text_buffer_get_iter_at_offset (buffer, &iter, 0);
if (page == 1)
{
gtk_text_buffer_insert (buffer, &iter, "Some text to show that simple ", -1);
insert_link (buffer, &iter, "hypertext", 3);
gtk_text_buffer_insert (buffer, &iter, " can easily be realized with ", -1);
insert_link (buffer, &iter, "tags", 2);
gtk_text_buffer_insert (buffer, &iter, ".", -1);
}
else if (page == 2)
{
gtk_text_buffer_insert (buffer, &iter,
"A tag is an attribute that can be applied to some range of text. "
"For example, a tag might be called \"bold\" and make the text inside "
"the tag bold. However, the tag concept is more general than that; "
"tags don't have to affect appearance. They can instead affect the "
"behavior of mouse and key presses, \"lock\" a range of text so the "
"user can't edit it, or countless other things.\n", -1);
insert_link (buffer, &iter, "Go back", 1);
}
else if (page == 3)
{
GtkTextTag *tag;
tag = gtk_text_buffer_create_tag (buffer, NULL,
"weight", PANGO_WEIGHT_BOLD,
NULL);
gtk_text_buffer_insert_with_tags (buffer, &iter, "hypertext:\n", -1, tag, NULL);
gtk_text_buffer_insert (buffer, &iter,
"machine-readable text that is not sequential but is organized "
"so that related items of information are connected.\n", -1);
insert_link (buffer, &iter, "Go back", 1);
}
}
/* Looks at all tags covering the position of iter in the text view,
* and if one of them is a link, follow it by showing the page identified
* by the data attached to it.
*/
static void
follow_if_link (GtkWidget *text_view,
GtkTextIter *iter)
{
GSList *tags = NULL, *tagp = NULL;
tags = gtk_text_iter_get_tags (iter);
for (tagp = tags; tagp != NULL; tagp = tagp->next)
{
GtkTextTag *tag = tagp->data;
gint page = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (tag), "page"));
if (page != 0)
{
show_page (gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view)), page);
break;
}
}
if (tags)
g_slist_free (tags);
}
/* Links can be activated by pressing Enter.
*/
static gboolean
key_press_event (GtkWidget *text_view,
GdkEventKey *event)
{
GtkTextIter iter;
GtkTextBuffer *buffer;
switch (event->keyval)
{
case GDK_Return:
case GDK_KP_Enter:
buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view));
gtk_text_buffer_get_iter_at_mark (buffer, &iter,
gtk_text_buffer_get_insert (buffer));
follow_if_link (text_view, &iter);
break;
default:
break;
}
return FALSE;
}
/* Links can also be activated by clicking.
*/
static gboolean
event_after (GtkWidget *text_view,
GdkEvent *ev)
{
GtkTextIter start, end, iter;
GtkTextBuffer *buffer;
GdkEventButton *event;
gint x, y;
if (ev->type != GDK_BUTTON_RELEASE)
return FALSE;
event = (GdkEventButton *)ev;
if (event->button != 1)
return FALSE;
buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (text_view));
/* we shouldn't follow a link if the user has selected something */
gtk_text_buffer_get_selection_bounds (buffer, &start, &end);
if (gtk_text_iter_get_offset (&start) != gtk_text_iter_get_offset (&end))
return FALSE;
gtk_text_view_window_to_buffer_coords (GTK_TEXT_VIEW (text_view),
GTK_TEXT_WINDOW_WIDGET,
event->x, event->y, &x, &y);
gtk_text_view_get_iter_at_location (GTK_TEXT_VIEW (text_view), &iter, x, y);
follow_if_link (text_view, &iter);
return FALSE;
}
gboolean hovering_over_link = FALSE;
GdkCursor *hand_cursor = NULL;
GdkCursor *regular_cursor = NULL;
/* Looks at all tags covering the position (x, y) in the text view,
* and if one of them is a link, change the cursor to the "hands" cursor
* typically used by web browsers.
*/
static void
set_cursor_if_appropriate (GtkTextView *text_view,
gint x,
gint y)
{
GSList *tags = NULL, *tagp = NULL;
GtkTextBuffer *buffer;
GtkTextIter iter;
gboolean hovering = FALSE;
buffer = gtk_text_view_get_buffer (text_view);
gtk_text_view_get_iter_at_location (text_view, &iter, x, y);
tags = gtk_text_iter_get_tags (&iter);
for (tagp = tags; tagp != NULL; tagp = tagp->next)
{
GtkTextTag *tag = tagp->data;
gint page = GPOINTER_TO_INT (g_object_get_data (G_OBJECT (tag), "page"));
if (page != 0)
{
hovering = TRUE;
break;
}
}
if (hovering != hovering_over_link)
{
hovering_over_link = hovering;
if (hovering_over_link)
gdk_window_set_cursor (gtk_text_view_get_window (text_view, GTK_TEXT_WINDOW_TEXT), hand_cursor);
else
gdk_window_set_cursor (gtk_text_view_get_window (text_view, GTK_TEXT_WINDOW_TEXT), regular_cursor);
}
if (tags)
g_slist_free (tags);
}
/* Update the cursor image if the pointer moved.
*/
static gboolean
motion_notify_event (GtkWidget *text_view,
GdkEventMotion *event)
{
gint x, y;
gtk_text_view_window_to_buffer_coords (GTK_TEXT_VIEW (text_view),
GTK_TEXT_WINDOW_WIDGET,
event->x, event->y, &x, &y);
set_cursor_if_appropriate (GTK_TEXT_VIEW (text_view), x, y);
gdk_window_get_pointer (text_view->window, NULL, NULL, NULL);
return FALSE;
}
/* Also update the cursor image if the window becomes visible
* (e.g. when a window covering it got iconified).
*/
static gboolean
visibility_notify_event (GtkWidget *text_view,
GdkEventVisibility *event)
{
gint wx, wy, bx, by;
gdk_window_get_pointer (text_view->window, &wx, &wy, NULL);
gtk_text_view_window_to_buffer_coords (GTK_TEXT_VIEW (text_view),
GTK_TEXT_WINDOW_WIDGET,
wx, wy, &bx, &by);
set_cursor_if_appropriate (GTK_TEXT_VIEW (text_view), bx, by);
return FALSE;
}
GtkWidget *
do_hypertext (GtkWidget *do_widget)
{
static GtkWidget *window = NULL;
if (!window)
{
GtkWidget *view;
GtkWidget *sw;
GtkTextBuffer *buffer;
hand_cursor = gdk_cursor_new (GDK_HAND2);
regular_cursor = gdk_cursor_new (GDK_XTERM);
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_screen (GTK_WINDOW (window),
gtk_widget_get_screen (do_widget));
gtk_window_set_default_size (GTK_WINDOW (window),
450, 450);
g_signal_connect (window, "destroy",
G_CALLBACK (gtk_widget_destroyed), &window);
gtk_window_set_title (GTK_WINDOW (window), "Hypertext");
gtk_container_set_border_width (GTK_CONTAINER (window), 0);
view = gtk_text_view_new ();
gtk_text_view_set_wrap_mode (GTK_TEXT_VIEW (view), GTK_WRAP_WORD);
g_signal_connect (view, "key-press-event",
G_CALLBACK (key_press_event), NULL);
g_signal_connect (view, "event-after",
G_CALLBACK (event_after), NULL);
g_signal_connect (view, "motion-notify-event",
G_CALLBACK (motion_notify_event), NULL);
g_signal_connect (view, "visibility-notify-event",
G_CALLBACK (visibility_notify_event), NULL);
buffer = gtk_text_view_get_buffer (GTK_TEXT_VIEW (view));
sw = gtk_scrolled_window_new (NULL, NULL);
gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (sw),
GTK_POLICY_AUTOMATIC,
GTK_POLICY_AUTOMATIC);
gtk_container_add (GTK_CONTAINER (window), sw);
gtk_container_add (GTK_CONTAINER (sw), view);
show_page (buffer, 1);
gtk_widget_show_all (sw);
}
if (!GTK_WIDGET_VISIBLE (window))
{
gtk_widget_show (window);
}
else
{
gtk_widget_destroy (window);
window = NULL;
}
return window;
}
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