Add configurable panel scroll volume with single OSD

NEWS

@@ -1,5 +1,7 @@
 ### mate-panel 1.29.0
 
+  * Add optional volume control by scrolling on empty panel space
+
 ### mate-panel 1.28.1
 
   * Build: require mate-desktop 1.28.2

configure.ac

@@ -73,6 +73,16 @@ PKG_CHECK_MODULES(PANEL, $GMODULE_ADD gdk-pixbuf-2.0 >= $GDK_PIXBUF_REQUIRED pan
 AC_SUBST(PANEL_CFLAGS)
 AC_SUBST(PANEL_LIBS)
 
+PKG_CHECK_MODULES(LIBPULSE, [libpulse libpulse-mainloop-glib], have_libpulse=yes, have_libpulse=no)
+AM_CONDITIONAL(HAVE_LIBPULSE, test "x$have_libpulse" = "xyes")
+if test "x$have_libpulse" = "xyes"; then
+	AC_DEFINE(HAVE_LIBPULSE, 1, [Define if libpulse is available])
+	PANEL_CFLAGS="$PANEL_CFLAGS $LIBPULSE_CFLAGS"
+	PANEL_LIBS="$PANEL_LIBS $LIBPULSE_LIBS"
+fi
+AC_SUBST(LIBPULSE_CFLAGS)
+AC_SUBST(LIBPULSE_LIBS)
+
 PKG_CHECK_MODULES(DCONF, dconf >= $DCONF_REQUIRED)
 
 PKG_CHECK_MODULES(LIBMATE_PANEL_APPLET, gtk+-3.0 >= $GTK_REQUIRED gio-2.0 >= $GLIB_REQUIRED gio-unix-2.0 >= $GLIB_REQUIRED)

data/org.mate.panel.gschema.xml.in

@@ -89,5 +89,26 @@
       <summary>Enable SNI support</summary>
       <description>If true, the panel provides support for SNI.</description>
     </key>
+    <key name="enable-scroll-volume" type="b">
+      <default>false</default>
+      <summary>Change volume by scrolling on empty panel space</summary>
+      <description>If true, scrolling on an unoccupied area of a panel changes the default audio output volume. Scrolling over an applet is left unchanged.</description>
+    </key>
+    <key name="volume-scroll-step" type="u">
+      <default>5</default>
+      <range min="1" max="20"/>
+      <summary>Volume scroll step</summary>
+      <description>Percentage points changed for each mouse wheel step.</description>
+    </key>
+    <key name="volume-scroll-osd" type="b">
+      <default>true</default>
+      <summary>Show volume on-screen display</summary>
+      <description>Show a single transient volume indicator when scrolling changes the volume.</description>
+    </key>
+    <key name="volume-scroll-feedback" type="b">
+      <default>true</default>
+      <summary>Play volume feedback</summary>
+      <description>Use the desktop bell as optional feedback when scrolling changes the volume.</description>
+    </key>
   </schema>
 </schemalist>

data/org.mate.panel.object.gschema.xml.in

@@ -20,6 +20,11 @@
       <summary>Object's position on the panel</summary>
       <description>The index of this panel object within the other objects with the same pack-type, from the left (or top if vertical) panel edge.</description>
     </key>
+    <key name="relative-to-edge" enum="org.mate.panel.PanelObjectEdgeRelativity">
+      <default>'start'</default>
+      <summary>Whether to interpret the position relative to the start, center or end of the panel</summary>
+      <description>The position of the object is interpreted relative to one edge of the panel. This key is compatible with newer MATE panel layouts.</description>
+    </key>
     <key name="position" type="i">
       <default>0</default>
       <summary>Object's position on the panel (deprecated)</summary>

mate-panel/Makefile.am

@@ -52,6 +52,7 @@ panel_sources = \
 	panel-multimonitor.c \
 	panel-a11y.c \
 	panel-bindings.c \
+	panel-volume.c \
 	panel-layout.c \
 	panel-profile.c \
 	panel-lockdown.c \
@@ -108,6 +109,7 @@ panel_headers = \
 	panel-multimonitor.h \
 	panel-a11y.h \
 	panel-bindings.h \
+	panel-volume.h \
 	panel-layout.h \
 	panel-profile.h \
 	panel-enums-gsettings.h \

mate-panel/meson.build

@@ -203,6 +203,7 @@ panel_sources = [
   'panel-multimonitor.c',
   'panel-a11y.c',
   'panel-bindings.c',
+  'panel-volume.c',
   'panel-layout.c',
   'panel-profile.c',
   'panel-lockdown.c',
@@ -243,6 +244,7 @@ panel_sources = [
   'panel-multimonitor.h',
   'panel-a11y.h',
   'panel-bindings.h',
+  'panel-volume.h',
   'panel-layout.h',
   'panel-profile.h',
   'panel-enums-gsettings.h',

mate-panel/panel-enums-gsettings.h

@@ -37,6 +37,15 @@ typedef enum {
 	PANEL_OBJECT_PACK_END    = 2
 } PanelObjectPackType;
 
+/* Position relative to an edge of the panel.  This is the schema key used
+ * by newer MATE panel layouts; keep it separate from pack-type so older
+ * layouts remain compatible. */
+typedef enum {
+	PANEL_OBJECT_EDGE_START  = 0,
+	PANEL_OBJECT_EDGE_CENTER = 1,
+	PANEL_OBJECT_EDGE_END    = 2
+} PanelObjectEdgeRelativity;
+
 typedef enum { /*< flags=0 >*/
 	PANEL_ORIENTATION_TOP    = 1 << 0,
 	PANEL_ORIENTATION_RIGHT  = 1 << 1,

mate-panel/panel-profile.c

@@ -1317,9 +1317,11 @@ panel_profile_load_object (char *id)
 	char                *toplevel_id;
 	int                  position;
 	PanelObjectPackType  pack_type;
+	PanelObjectEdgeRelativity relative_to_edge;
 	int                  pack_index;
 	gboolean             right_stick;
 	gboolean             locked;
+	GVariant            *relative_to_edge_value;
 	GSettings           *settings;
 
 	object_path = g_strdup_printf (PANEL_OBJECT_PATH "%s/", id);
@@ -1329,14 +1331,36 @@ panel_profile_load_object (char *id)
 	position = g_settings_get_int (settings, PANEL_OBJECT_POSITION_KEY);
 	toplevel_id = g_settings_get_string (settings, PANEL_OBJECT_TOPLEVEL_ID_KEY);
 	pack_type = g_settings_get_enum (settings, PANEL_OBJECT_PACK_TYPE_KEY);
+	relative_to_edge_value = g_settings_get_user_value (settings, PANEL_OBJECT_RELATIVE_TO_EDGE_KEY);
+	relative_to_edge = relative_to_edge_value != NULL ?
+		g_settings_get_enum (settings, PANEL_OBJECT_RELATIVE_TO_EDGE_KEY) :
+		PANEL_OBJECT_EDGE_START;
 	pack_index = g_settings_get_int (settings, PANEL_OBJECT_PACK_INDEX_KEY);
 	right_stick = g_settings_get_boolean (settings, PANEL_OBJECT_PANEL_RIGHT_STICK_KEY);
 	locked = g_settings_get_boolean (settings, PANEL_OBJECT_LOCKED_KEY);
 
-	/* If pack-type is still at the default value ('start') but right-stick
-	 * is set, then map right-stick to PACK_END so the comparator sorts
-	 * correctly. */
-	if (pack_type == PANEL_OBJECT_PACK_START && right_stick)
+	/* Newer MATE panel layouts store the zone in relative-to-edge, while
+	 * older layouts use pack-type (or the deprecated panel-right-stick).
+	 * Only override pack-type when relative-to-edge has an explicit user
+	 * value, so old layouts keep their pack-type setting. */
+	if (relative_to_edge_value != NULL) {
+		switch (relative_to_edge) {
+			case PANEL_OBJECT_EDGE_CENTER:
+				pack_type = PANEL_OBJECT_PACK_CENTER;
+				break;
+			case PANEL_OBJECT_EDGE_END:
+				pack_type = PANEL_OBJECT_PACK_END;
+				break;
+			case PANEL_OBJECT_EDGE_START:
+			default:
+				pack_type = PANEL_OBJECT_PACK_START;
+				break;
+		}
+	}
+
+	/* If relative-to-edge is at its default ('start') but right-stick is
+	 * set, map right-stick to PACK_END for old configurations. */
+	if (relative_to_edge_value == NULL && right_stick)
 		pack_type = PANEL_OBJECT_PACK_END;
 
 	mate_panel_applet_queue_applet_to_load (id,
@@ -1349,6 +1373,8 @@ panel_profile_load_object (char *id)
 
 	g_free (toplevel_id);
 	g_free (object_path);
+	if (relative_to_edge_value != NULL)
+		g_variant_unref (relative_to_edge_value);
 	g_object_unref (settings);
 }
 

mate-panel/panel-schemas.h

@@ -16,6 +16,10 @@
 #define PANEL_LOCKED_DOWN_KEY         "locked-down"
 #define PANEL_DISABLE_FORCE_QUIT_KEY  "disable-force-quit"
 #define PANEL_DISABLED_APPLETS_KEY    "disabled-applets"
+#define PANEL_ENABLE_SCROLL_VOLUME_KEY "enable-scroll-volume"
+#define PANEL_VOLUME_SCROLL_STEP_KEY   "volume-scroll-step"
+#define PANEL_VOLUME_SCROLL_OSD_KEY     "volume-scroll-osd"
+#define PANEL_VOLUME_SCROLL_FEEDBACK_KEY "volume-scroll-feedback"
 
 #define PANEL_TOPLEVEL_SCHEMA                "org.mate.panel.toplevel"
 #define PANEL_TOPLEVEL_NAME_KEY              "name"
@@ -47,6 +51,7 @@
 #define PANEL_OBJECT_TOPLEVEL_ID_KEY         "toplevel-id"
 #define PANEL_OBJECT_PACK_TYPE_KEY           "pack-type"
 #define PANEL_OBJECT_PACK_INDEX_KEY          "pack-index"
+#define PANEL_OBJECT_RELATIVE_TO_EDGE_KEY    "relative-to-edge"
 #define PANEL_OBJECT_POSITION_KEY            "position"
 #define PANEL_OBJECT_PANEL_RIGHT_STICK_KEY   "panel-right-stick"
 #define PANEL_OBJECT_LOCKED_KEY              "locked"

mate-panel/panel-toplevel.c

@@ -52,6 +52,7 @@
 #include "panel-config-global.h"
 #include "panel-lockdown.h"
 #include "panel-schemas.h"
+#include "panel-volume.h"
 
 #ifdef HAVE_X11
 #include "xstuff.h"
@@ -3483,6 +3484,73 @@ panel_toplevel_button_release_event (GtkWidget      *widget,
 	return TRUE;
 }
 
+static gboolean
+panel_toplevel_scroll_is_on_empty_space (PanelToplevel  *toplevel,
+                                         GdkEventScroll *event)
+{
+	GtkWidget *event_widget = NULL;
+	GtkAllocation panel_allocation;
+	GtkAllocation applet_allocation;
+	GList *list;
+	gint x;
+	gint y;
+
+	/* The panel widget has its own GDK window, so the event can arrive at the
+	 * toplevel even when the pointer is over the panel widget.  Translate the
+	 * event coordinates to the panel widget and hit-test its applets. */
+	gdk_window_get_user_data (event->window, (gpointer) &event_widget);
+	if (!GTK_IS_WIDGET (event_widget))
+		return FALSE;
+
+	if (!gtk_widget_translate_coordinates (event_widget,
+	                                       GTK_WIDGET (toplevel->priv->panel_widget),
+	                                       event->x, event->y, &x, &y))
+		return FALSE;
+
+	panel_allocation = (GtkAllocation) { 0, 0,
+		gtk_widget_get_allocated_width (GTK_WIDGET (toplevel->priv->panel_widget)),
+		gtk_widget_get_allocated_height (GTK_WIDGET (toplevel->priv->panel_widget)) };
+	if (x < panel_allocation.x || y < panel_allocation.y ||
+	    x >= panel_allocation.x + panel_allocation.width ||
+	    y >= panel_allocation.y + panel_allocation.height)
+		return FALSE;
+
+	for (list = toplevel->priv->panel_widget->applet_list;
+	     list != NULL;
+	     list = list->next) {
+		AppletData *applet_data = list->data;
+
+		gtk_widget_get_allocation (applet_data->applet, &applet_allocation);
+		if (x >= applet_allocation.x &&
+		    x < applet_allocation.x + applet_allocation.width &&
+		    y >= applet_allocation.y &&
+		    y < applet_allocation.y + applet_allocation.height)
+			return FALSE;
+	}
+
+	return TRUE;
+}
+
+static gboolean
+panel_toplevel_scroll_event (GtkWidget      *widget,
+				      GdkEventScroll *event)
+{
+	PanelToplevel *toplevel = PANEL_TOPLEVEL (widget);
+
+	if (event->direction == GDK_SCROLL_UP ||
+	    event->direction == GDK_SCROLL_DOWN ||
+	    event->direction == GDK_SCROLL_SMOOTH) {
+		if (panel_toplevel_scroll_is_on_empty_space (toplevel, event) &&
+		    panel_volume_handle_scroll (event))
+			return TRUE;
+	}
+
+	if (GTK_WIDGET_CLASS (panel_toplevel_parent_class)->scroll_event)
+		return GTK_WIDGET_CLASS (panel_toplevel_parent_class)->scroll_event (widget, event);
+
+	return FALSE;
+}
+
 static gboolean
 panel_toplevel_configure_event (GtkWidget	  *widget,
 				GdkEventConfigure *event)
@@ -4364,6 +4432,7 @@ panel_toplevel_class_init (PanelToplevelClass *klass)
 	widget_class->configure_event      = panel_toplevel_configure_event;
 	widget_class->key_press_event      = panel_toplevel_key_press_event;
 	widget_class->motion_notify_event  = panel_toplevel_motion_notify_event;
+	widget_class->scroll_event        = panel_toplevel_scroll_event;
 	widget_class->enter_notify_event   = panel_toplevel_enter_notify_event;
 	widget_class->leave_notify_event   = panel_toplevel_leave_notify_event;
 	widget_class->screen_changed       = panel_toplevel_screen_changed;
@@ -4864,6 +4933,7 @@ panel_toplevel_init (PanelToplevel *toplevel)
 	gtk_widget_add_events (widget,
 			       GDK_BUTTON_PRESS_MASK |
 			       GDK_BUTTON_RELEASE_MASK |
+			       GDK_SCROLL_MASK |
 			       GDK_POINTER_MOTION_MASK |
 			       GDK_ENTER_NOTIFY_MASK |
 			       GDK_LEAVE_NOTIFY_MASK);