Add a property to configure the scroll speed

By default, it is set to zero which gives the current behaviour of
moving the buffer by a function of the number of visible rows.

https://bugzilla.redhat.com/show_bug.cgi?id=1103380

6 files changed, 71 insertions, 1 deletions

diff --git a/doc/reference/vte-sections.txt b/doc/reference/vte-sections.txt
index 9b34536c..b67f3957 100644
--- a/doc/reference/vte-sections.txt
+++ b/doc/reference/vte-sections.txt
@@ -44,6 +44,7 @@ vte_terminal_set_cursor_shape
 vte_terminal_get_cursor_shape
 vte_terminal_get_cursor_blink_mode
 vte_terminal_set_cursor_blink_mode
+vte_terminal_set_scroll_speed
 vte_terminal_set_scrollback_lines
 vte_terminal_set_font
 vte_terminal_get_font
diff --git a/src/vte.cc b/src/vte.cc
index f3b86643..c1b1e508 100644
--- a/src/vte.cc
+++ b/src/vte.cc
@@ -9899,6 +9899,7 @@ void
 VteTerminalPrivate::widget_scroll(GdkEventScroll *event)
 {
 	gdouble delta_x, delta_y;
+	gdouble scroll_speed;
 	gdouble v;
 	gint cnt, i;
 	int button;
@@ -9952,7 +9953,13 @@ VteTerminalPrivate::widget_scroll(GdkEventScroll *event)
 		return;
 	}
 
-	v = MAX (1., ceil (gtk_adjustment_get_page_increment (m_vadjustment) / 10.));
+	if (m_scroll_speed == 0) {
+		scroll_speed = ceil (gtk_adjustment_get_page_increment (m_vadjustment) / 10.);
+	} else {
+		scroll_speed = m_scroll_speed;
+	}
+
+	v = MAX (1., scroll_speed);
 	_vte_debug_print(VTE_DEBUG_EVENTS,
 			"Scroll speed is %d lines per non-smooth scroll unit\n",
 			(int) v);
@@ -10190,6 +10197,16 @@ VteTerminalPrivate::decscusr_cursor_shape()
 }
 
 bool
+VteTerminalPrivate::set_scroll_speed(unsigned int scroll_speed)
+{
+        if (scroll_speed == m_scroll_speed)
+                return false;
+
+        m_scroll_speed = scroll_speed;
+        return true;
+}
+
+bool
 VteTerminalPrivate::set_scrollback_lines(long lines)
 {
         glong low, high, next;
diff --git a/src/vte/vteterminal.h b/src/vte/vteterminal.h
index b3c6978f..befde68c 100644
--- a/src/vte/vteterminal.h
+++ b/src/vte/vteterminal.h
@@ -275,6 +275,10 @@ void vte_terminal_set_cursor_shape(VteTerminal *terminal,
 _VTE_PUBLIC
 VteCursorShape vte_terminal_get_cursor_shape(VteTerminal *terminal) _VTE_GNUC_NONNULL(1);
 
+_VTE_PUBLIC
+void vte_terminal_set_scroll_speed(VteTerminal *terminal,
+                                   guint scroll_speed) _VTE_GNUC_NONNULL(1);
+
 /* Set the number of scrollback lines, above or at an internal minimum. */
 _VTE_PUBLIC
 void vte_terminal_set_scrollback_lines(VteTerminal *terminal,
diff --git a/src/vtegtk.cc b/src/vtegtk.cc
index 4ccc4ff9..2b98eb8a 100644
--- a/src/vtegtk.cc
+++ b/src/vtegtk.cc
@@ -481,6 +481,9 @@ vte_terminal_get_property (GObject *object,
                 case PROP_REWRAP_ON_RESIZE:
                         g_value_set_boolean (value, vte_terminal_get_rewrap_on_resize (terminal));
                         break;
+                case PROP_SCROLL_SPEED:
+                        g_value_set_uint (value, impl->m_scroll_speed);
+                        break;
                 case PROP_SCROLLBACK_LINES:
                         g_value_set_uint (value, impl->m_scrollback_lines);
                         break;
@@ -570,6 +573,9 @@ vte_terminal_set_property (GObject *object,
                 case PROP_REWRAP_ON_RESIZE:
                         vte_terminal_set_rewrap_on_resize (terminal, g_value_get_boolean (value));
                         break;
+                case PROP_SCROLL_SPEED:
+                        vte_terminal_set_scroll_speed (terminal, g_value_get_uint (value));
+                        break;
                 case PROP_SCROLLBACK_LINES:
                         vte_terminal_set_scrollback_lines (terminal, g_value_get_uint (value));
                         break;
@@ -1467,6 +1473,21 @@ vte_terminal_class_init(VteTerminalClass *klass)
                                       (GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | G_PARAM_EXPLICIT_NOTIFY));
 
         /**
+         * VteTerminal:scroll-speed:
+         *
+         * The number of lines by which the buffer is moved when
+         * scrolling with a mouse wheel on top of the terminal
+         * Setting it to zero will cause the buffer to be moved by an
+         * amount depending on the number of visible rows the widget
+         * can display.
+         */
+        pspecs[PROP_SCROLL_SPEED] =
+                g_param_spec_uint ("scroll-speed", NULL, NULL,
+                                   0, G_MAXUINT,
+                                   0,
+                                   (GParamFlags) (G_PARAM_READWRITE | G_PARAM_STATIC_STRINGS | G_PARAM_EXPLICIT_NOTIFY));
+
+        /**
          * VteTerminal:scrollback-lines:
          *
          * The length of the scrollback buffer used by the terminal.  The size of
@@ -3810,6 +3831,30 @@ vte_terminal_get_row_count(VteTerminal *terminal)
 }
 
 /**
+ * vte_terminal_set_scroll_speed:
+ * @terminal: a #VteTerminal
+ * @scroll_speed: move the buffer by this number of lines while scrolling
+ *
+ * Sets the number of lines by which the buffer is moved when
+ * scrolling with a mouse wheel. Setting it to zero will cause the
+ * buffer to be moved by an amount depending on the number of visible
+ * rows the widget can display.
+ */
+void
+vte_terminal_set_scroll_speed(VteTerminal *terminal, guint scroll_speed)
+{
+        g_return_if_fail(VTE_IS_TERMINAL(terminal));
+
+        GObject *object = G_OBJECT(terminal);
+        g_object_freeze_notify(object);
+
+        if (IMPL(terminal)->set_scroll_speed(scroll_speed))
+                g_object_notify_by_pspec(object, pspecs[PROP_SCROLL_SPEED]);
+
+        g_object_thaw_notify(object);
+}
+
+/**
  * vte_terminal_set_scrollback_lines:
  * @terminal: a #VteTerminal
  * @lines: the length of the history buffer
diff --git a/src/vtegtk.hh b/src/vtegtk.hh
index 07c714e6..5a6c9382 100644
--- a/src/vtegtk.hh
+++ b/src/vtegtk.hh
@@ -83,6 +83,7 @@ enum {
         PROP_MOUSE_POINTER_AUTOHIDE,
         PROP_PTY,
         PROP_REWRAP_ON_RESIZE,
+        PROP_SCROLL_SPEED,
         PROP_SCROLLBACK_LINES,
         PROP_SCROLL_ON_KEYSTROKE,
         PROP_SCROLL_ON_OUTPUT,
diff --git a/src/vteinternal.hh b/src/vteinternal.hh
index f7faa7a5..137987ac 100644
--- a/src/vteinternal.hh
+++ b/src/vteinternal.hh
@@ -385,6 +385,7 @@ public:
         gboolean m_scroll_on_output;
         gboolean m_scroll_on_keystroke;
         gboolean m_alternate_screen_scroll;
+        guint m_scroll_speed;
         vte::grid::row_t m_scrollback_lines;
 
         /* Restricted scrolling */
@@ -1112,6 +1113,7 @@ public:
         bool set_mouse_autohide(bool autohide);
         bool set_pty(VtePty *pty);
         bool set_rewrap_on_resize(bool rewrap);
+        bool set_scroll_speed(unsigned int scroll_speed);
         bool set_scrollback_lines(long lines);
         bool set_scroll_on_keystroke(bool scroll);
         bool set_scroll_on_output(bool scroll);