emulation: Implement DECSET 1004

Add support for xterm's DECSET 1004 to enable focus tracking.
This sends CSI I on focus in, and CSI O on focus out.

Contrary to xterm, vte disables the focus tracking on reset, and when
focus tracking is enabled, immediately sends a focus in or focus out, so
that clients always have an accurate value.

4 files changed, 44 insertions, 0 deletions

diff --git a/src/vte-private.h b/src/vte-private.h
index 736520aa..d8fb11a8 100644
--- a/src/vte-private.h
+++ b/src/vte-private.h
@@ -93,6 +93,8 @@ void _vte_terminal_set_color_internal(VteTerminal *terminal,
                                       int source,
                                       const PangoColor *color);
 
+void _vte_terminal_feed_focus_event(VteTerminal *terminal, gboolean in);
+
 void _vte_terminal_inline_error_message(VteTerminal *terminal, const char *format, ...) G_GNUC_PRINTF(2,3);
 
 VteRowData *_vte_terminal_ring_insert (VteTerminal *terminal, glong position, gboolean fill);
diff --git a/src/vte.cc b/src/vte.cc
index 5b70bd1b..3ddcee55 100644
--- a/src/vte.cc
+++ b/src/vte.cc
@@ -5656,6 +5656,25 @@ vte_terminal_send_mouse_button_internal(VteTerminal *terminal,
 	vte_terminal_feed_mouse_event(terminal, button, FALSE /* not drag */, is_release, col, row);
 }
 
+void
+_vte_terminal_feed_focus_event(VteTerminal *terminal,
+                               gboolean in)
+{
+        char buf[8];
+        gsize len;
+
+        len = g_snprintf(buf, sizeof(buf), _VTE_CAP_CSI "%c", in ? 'I' : 'O');
+        vte_terminal_feed_child_binary(terminal, (guint8 *)buf, len);
+}
+
+static void
+vte_terminal_feed_focus_event_internal(VteTerminal *terminal,
+                                       gboolean in)
+{
+        if (terminal->pvt->focus_tracking_mode)
+                _vte_terminal_feed_focus_event(terminal, in);
+}
+
 /*
  * vte_terminal_maybe_send_mouse_button:
  * @terminal:
@@ -7630,6 +7649,7 @@ vte_terminal_focus_in(GtkWidget *widget, GdkEventFocus *event)
 		gtk_im_context_focus_in(terminal->pvt->im_context);
 		_vte_invalidate_cursor_once(terminal, FALSE);
 		_vte_terminal_set_pointer_visible(terminal, TRUE);
+                vte_terminal_feed_focus_event_internal(terminal, TRUE);
 	}
 
 	return FALSE;
@@ -7646,6 +7666,8 @@ vte_terminal_focus_out(GtkWidget *widget, GdkEventFocus *event)
 	/* We only have an IM context when we're realized, and there's not much
 	 * point to painting ourselves if we don't have a window. */
 	if (gtk_widget_get_realized (widget)) {
+                vte_terminal_feed_focus_event_internal(terminal, FALSE);
+
 		_vte_terminal_maybe_end_selection (terminal);
 
 		gtk_im_context_focus_out(terminal->pvt->im_context);
@@ -12279,6 +12301,8 @@ vte_terminal_reset(VteTerminal *terminal,
 	pvt->mouse_xterm_extension = FALSE;
 	pvt->mouse_urxvt_extension = FALSE;
 	pvt->mouse_smooth_scroll_delta = 0.;
+        /* Reset focus tracking. xterm doesn't, but that makes no sense */
+        pvt->focus_tracking_mode = FALSE;
 	/* Clear modifiers. */
 	pvt->modifiers = 0;
 	/* Reset miscellaneous stuff. */
diff --git a/src/vteinternal.hh b/src/vteinternal.hh
index 4eeeddbc..04d8104b 100644
--- a/src/vteinternal.hh
+++ b/src/vteinternal.hh
@@ -311,6 +311,8 @@ public:
 	gboolean mouse_urxvt_extension;
 	double mouse_smooth_scroll_delta;
 
+        gboolean focus_tracking_mode;
+
 	/* State variables for handling match checks. */
 	char *match_contents;
 	GArray *match_attributes;
diff --git a/src/vteseq.cc b/src/vteseq.cc
index ffb00f68..af27ff5e 100644
--- a/src/vteseq.cc
+++ b/src/vteseq.cc
@@ -601,6 +601,16 @@ vte_reset_mouse_smooth_scroll_delta(VteTerminal *terminal,
 	terminal->pvt->mouse_smooth_scroll_delta = 0.;
 }
 
+static void
+vte_set_focus_tracking_mode(VteTerminal *terminal,
+                            GValueArray *params)
+{
+        /* We immediately send the terminal a focus event, since otherwise
+         * it has no way to know the current status.
+         */
+        _vte_terminal_feed_focus_event(terminal, gtk_widget_has_focus(&terminal->widget));
+}
+
 struct decset_t {
         gint16 setting;
         /* offset in VteTerminalPrivate (> 0) or VteScreen (< 0) */
@@ -732,6 +742,12 @@ vte_sequence_handler_decset_internal(VteTerminal *terminal,
 		 (MOUSE_TRACKING_ALL_MOTION_TRACKING),
 		 vte_reset_mouse_smooth_scroll_delta,
 		 vte_reset_mouse_smooth_scroll_delta,},
+		/* 1004: Focus tracking. */
+		{1004, PRIV_OFFSET(focus_tracking_mode), 0, 0,
+		 FALSE,
+		 TRUE,
+                 NULL,
+                 vte_set_focus_tracking_mode,},
 		/* 1006: Extended mouse coordinates. */
 		{1006, PRIV_OFFSET(mouse_xterm_extension), 0, 0,
 		 FALSE,