[libwnck] pager: Add wnck_pager_set_scroll_mode

[Alberts Muktupāvels <muktupavels src gnome org>]

commit b7bacc30da3091fb78a6aba4e9bcdd2be19ef598
Author: Simon Steinbeiss <simon steinbeiss elfenbeinturm at>
Date:   Sun Aug 18 18:00:58 2019 +0200

    pager: Add wnck_pager_set_scroll_mode
    
    There are two scroll modes: the default 2d scroll mode is essentially
    only useful for touchpads, because mice cannot scroll horizontally, so
    scrolling up/down to get to the next workspace will get users confused.
    By setting the scroll_mode to 1 users get a simple way of scrolling
    through workspaces, irrespective of the number of rows the pager sets.
    
    https://gitlab.gnome.org/GNOME/libwnck/issues/134
    Fixes: #134

 doc/libwnck-sections.txt |   2 +
 libwnck/pager.c          | 180 ++++++++++++++++++++++++++++++-----------------
 libwnck/pager.h          |  18 +++++
 libwnck/test-pager.c     |  12 +++-
 4 files changed, 147 insertions(+), 65 deletions(-)
---
diff --git a/doc/libwnck-sections.txt b/doc/libwnck-sections.txt
index a4de2f6..6fb1139 100644
--- a/doc/libwnck-sections.txt
+++ b/doc/libwnck-sections.txt
@@ -244,6 +244,8 @@ wnck_pager_set_orientation
 wnck_pager_set_n_rows
 WnckPagerDisplayMode
 wnck_pager_set_display_mode
+WnckPagerScrollMode
+wnck_pager_set_scroll_mode
 wnck_pager_set_show_all
 wnck_pager_set_shadow_type
 <SUBSECTION Private>
diff --git a/libwnck/pager.c b/libwnck/pager.c
index a0921ae..f75bdd8 100644
--- a/libwnck/pager.c
+++ b/libwnck/pager.c
@@ -65,6 +65,7 @@ struct _WnckPagerPrivate
 
   int n_rows; /* really columns for vertical orientation */
   WnckPagerDisplayMode display_mode;
+  WnckPagerScrollMode scroll_mode;
   gboolean show_all_workspaces;
   GtkShadowType shadow_type;
   gboolean wrap_on_scroll;
@@ -212,6 +213,7 @@ wnck_pager_init (WnckPager *pager)
 
   pager->priv->n_rows = 1;
   pager->priv->display_mode = WNCK_PAGER_DISPLAY_CONTENT;
+  pager->priv->scroll_mode = WNCK_PAGER_SCROLL_2D;
   pager->priv->show_all_workspaces = TRUE;
   pager->priv->shadow_type = GTK_SHADOW_NONE;
   pager->priv->wrap_on_scroll = FALSE;
@@ -2078,73 +2080,103 @@ wnck_pager_scroll_event (GtkWidget      *widget,
         }
     }
 
-  switch (absolute_direction)
+  if (pager->priv->scroll_mode == WNCK_PAGER_SCROLL_2D)
     {
-      case GDK_SCROLL_DOWN:
-        if (index + n_columns < n_workspaces)
-          {
-            index += n_columns;
-          }
-        else if (wrap_workspaces && index == n_workspaces - 1)
-          {
-            index = 0;
-          }
-        else if ((index < n_workspaces - 1 &&
-                  index + in_last_row != n_workspaces - 1) ||
-                 (index == n_workspaces - 1 &&
-                  in_last_row != 0))
-          {
-            index = (index % n_columns) + 1;
-          }
-        break;
-
-      case GDK_SCROLL_RIGHT:
-        if (index < n_workspaces - 1)
-          {
-            index++;
-          }
-        else if (wrap_workspaces)
-          {
-            index = 0;
-          }
-        break;
-
-      case GDK_SCROLL_UP:
-        if (index - n_columns >= 0)
-          {
-            index -= n_columns;
-          }
-        else if (index > 0)
-          {
-            index = ((pager->priv->n_rows - 1) * n_columns) + (index % n_columns) - 1;
-          }
-        else if (wrap_workspaces)
-          {
-            index = n_workspaces - 1;
-          }
-
-        if (index >= n_workspaces)
-          {
-            index -= n_columns;
-          }
-        break;
-
-      case GDK_SCROLL_LEFT:
-        if (index > 0)
-          {
-            index--;
-          }
-        else if (wrap_workspaces)
+      switch (absolute_direction)
+        {
+          case GDK_SCROLL_DOWN:
+            if (index + n_columns < n_workspaces)
+              {
+                index += n_columns;
+              }
+            else if (wrap_workspaces && index == n_workspaces - 1)
+              {
+                index = 0;
+              }
+            else if ((index < n_workspaces - 1 &&
+                      index + in_last_row != n_workspaces - 1) ||
+                     (index == n_workspaces - 1 &&
+                      in_last_row != 0))
+              {
+                index = (index % n_columns) + 1;
+              }
+            break;
+          case GDK_SCROLL_RIGHT:
+            if (index < n_workspaces - 1)
+              {
+                index++;
+              }
+            else if (wrap_workspaces)
+              {
+                index = 0;
+              }
+            break;
+          case GDK_SCROLL_UP:
+            if (index - n_columns >= 0)
+              {
+                index -= n_columns;
+              }
+            else if (index > 0)
+              {
+                index = ((pager->priv->n_rows - 1) * n_columns) + (index % n_columns) - 1;
+              }
+            else if (wrap_workspaces)
+              {
+                index = n_workspaces - 1;
+              }
+            if (index >= n_workspaces)
+              {
+                index -= n_columns;
+              }
+            break;
+          case GDK_SCROLL_LEFT:
+            if (index > 0)
+              {
+                index--;
+              }
+            else if (wrap_workspaces)
+              {
+                index = n_workspaces - 1;
+              }
+            break;
+          case GDK_SCROLL_SMOOTH:
+          default:
+            g_assert_not_reached ();
+            break;
+        }
+      }
+    else
+      {
+        switch (absolute_direction)
           {
-            index = n_workspaces - 1;
+            case GDK_SCROLL_UP:
+            case GDK_SCROLL_LEFT:
+              if (index > 0)
+                {
+                  index--;
+                }
+              else if (wrap_workspaces)
+                {
+                  index = n_workspaces - 1;
+                }
+              break;
+            case GDK_SCROLL_DOWN:
+            case GDK_SCROLL_RIGHT:
+              if (index < n_workspaces - 1)
+                {
+                  index++;
+                }
+              else if (wrap_workspaces)
+                {
+                  index = 0;
+                }
+              break;
+            case GDK_SCROLL_SMOOTH:
+            default:
+              g_assert_not_reached ();
+              break;
           }
-        break;
-
-      case GDK_SCROLL_SMOOTH:
-      default:
-        g_assert_not_reached ();
-        break;
-    }
+      }
 
   space = wnck_screen_get_workspace (pager->priv->screen, index);
   wnck_workspace_activate (space, event->time);
@@ -2396,6 +2428,26 @@ wnck_pager_set_display_mode (WnckPager            *pager,
   gtk_widget_queue_resize (GTK_WIDGET (pager));
 }
 
+/**
+ * wnck_pager_set_scroll_mode:
+ * @pager: a #WnckPager.
+ * @scroll_mode: a scroll mode.
+ *
+ * Sets @pager to react to input device scrolling in one of the
+ * available scroll modes.
+ */
+void
+wnck_pager_set_scroll_mode (WnckPager           *pager,
+                            WnckPagerScrollMode  scroll_mode)
+{
+  g_return_if_fail (WNCK_IS_PAGER (pager));
+
+  if (pager->priv->scroll_mode == scroll_mode)
+    return;
+
+  pager->priv->scroll_mode = scroll_mode;
+}
+
 /**
  * wnck_pager_set_show_all:
  * @pager: a #WnckPager.
diff --git a/libwnck/pager.h b/libwnck/pager.h
index 5a43d05..aaa667c 100644
--- a/libwnck/pager.h
+++ b/libwnck/pager.h
@@ -80,6 +80,22 @@ typedef enum {
   WNCK_PAGER_DISPLAY_CONTENT
 } WnckPagerDisplayMode;
 
+/**
+ * WnckPagerScrollMode:
+ * @WNCK_PAGER_SCROLL_2D: given that the workspaces are set up in multiple rows,
+ * scrolling on the #WnckPager will cycle through the workspaces as if on a
+ * 2-dimensional map. Example cycling order with 2 rows and 4 workspaces: 1 3 2 4.
+ * @WNCK_PAGER_SCROLL_1D: the #WnckPager will always cycle workspaces in a linear
+ * manner, irrespective of how many rows are configured. (Hint: Better for mice)
+ * Example cycling order with 2 rows and 4 workspaces: 1 2 3 4.
+ *
+ * Mode defining in which order scrolling on a #WnckPager will cycle through workspaces.
+ */
+typedef enum {
+  WNCK_PAGER_SCROLL_2D,
+  WNCK_PAGER_SCROLL_1D
+} WnckPagerScrollMode;
+
 GType      wnck_pager_get_type           (void) G_GNUC_CONST;
 
 GtkWidget* wnck_pager_new                (void);
@@ -90,6 +106,8 @@ gboolean   wnck_pager_set_n_rows         (WnckPager            *pager,
                                           int                   n_rows);
 void       wnck_pager_set_display_mode   (WnckPager            *pager,
                                           WnckPagerDisplayMode  mode);
+void       wnck_pager_set_scroll_mode    (WnckPager            *pager,
+                                          WnckPagerScrollMode   scroll_mode);
 void       wnck_pager_set_show_all       (WnckPager            *pager,
                                           gboolean              show_all_workspaces);
 void       wnck_pager_set_shadow_type    (WnckPager            *pager,
diff --git a/libwnck/test-pager.c b/libwnck/test-pager.c
index 316b13a..d60b047 100644
--- a/libwnck/test-pager.c
+++ b/libwnck/test-pager.c
@@ -7,6 +7,7 @@ static int n_rows = 1;
 static gboolean only_current = FALSE;
 static gboolean rtl = FALSE;
 static gboolean show_name = FALSE;
+static gboolean simple_scrolling = FALSE;
 static gboolean vertical = FALSE;
 static gboolean wrap_on_scroll = FALSE;
 
@@ -15,6 +16,7 @@ static GOptionEntry entries[] = {
        {"only-current", 'c', 0, G_OPTION_ARG_NONE, &only_current, "Only show current workspace", NULL},
        {"rtl", 'r', 0, G_OPTION_ARG_NONE, &rtl, "Use RTL as default direction", NULL},
        {"show-name", 's', 0, G_OPTION_ARG_NONE, &show_name, "Show workspace names instead of workspace 
contents", NULL},
+       {"simple-scrolling", 'd', 0, G_OPTION_ARG_NONE, &simple_scrolling, "Use the simple 1d scroll mode", 
NULL},
        {"vertical-orientation", 'v', 0, G_OPTION_ARG_NONE, &vertical, "Use a vertical orientation", NULL},
        {"wrap-on-scroll", 'w', 0, G_OPTION_ARG_NONE, &wrap_on_scroll, "Wrap on scrolling over borders", 
NULL},
        {NULL }
@@ -24,6 +26,7 @@ static void
 create_pager_window (GtkOrientation       orientation,
                      gboolean             show_all,
                      WnckPagerDisplayMode mode,
+                     WnckPagerScrollMode  scroll_mode,
                      int                  rows,
                      gboolean             wrap)
 {
@@ -51,6 +54,7 @@ create_pager_window (GtkOrientation       orientation,
 
   wnck_pager_set_show_all (WNCK_PAGER (pager), show_all);
   wnck_pager_set_display_mode (WNCK_PAGER (pager), mode);
+  wnck_pager_set_scroll_mode (WNCK_PAGER (pager), scroll_mode);
   wnck_pager_set_orientation (WNCK_PAGER (pager), orientation);
   wnck_pager_set_n_rows (WNCK_PAGER (pager), rows);
   wnck_pager_set_shadow_type (WNCK_PAGER (pager), GTK_SHADOW_IN);
@@ -67,6 +71,7 @@ main (int argc, char **argv)
   GOptionContext *ctxt;
   GtkOrientation  orientation;
   WnckPagerDisplayMode mode;
+  WnckPagerScrollMode scroll_mode;
   WnckScreen *screen;
 
   ctxt = g_option_context_new ("");
@@ -96,7 +101,12 @@ main (int argc, char **argv)
   else
          mode = WNCK_PAGER_DISPLAY_CONTENT;
 
-  create_pager_window (orientation, !only_current, mode, n_rows, wrap_on_scroll);
+  if (simple_scrolling)
+         scroll_mode = WNCK_PAGER_SCROLL_1D;
+  else
+         scroll_mode = WNCK_PAGER_SCROLL_2D;
+
+  create_pager_window (orientation, !only_current, mode, scroll_mode, n_rows, wrap_on_scroll);
 
   gtk_main ();