[gnome-shell] st-scroll-view-fade: Add horizontal fade support

[Adel Gadllah <agadllah src gnome org>]

commit fd4d64568736ce6f3503cae68c7dae03c7e94658
Author: Adel Gadllah <adel gadllah gmail com>
Date:   Wed Feb 8 18:47:23 2012 +0100

    st-scroll-view-fade: Add horizontal fade support
    
    St-scroll-view-fade only allowed adding a fade effect in the vertical
    direction; extend it so it can work horizontally too.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=613194

 data/theme/gnome-shell.css   |    5 ++
 src/st/st-scroll-view-fade.c |  150 +++++++++++++++++++++++++++++++++++-------
 src/st/st-scroll-view.c      |   46 +++++++------
 3 files changed, 157 insertions(+), 44 deletions(-)
---
diff --git a/data/theme/gnome-shell.css b/data/theme/gnome-shell.css
index 5001fd8..09229c5 100644
--- a/data/theme/gnome-shell.css
+++ b/data/theme/gnome-shell.css
@@ -44,6 +44,11 @@ StScrollView.vfade
     -st-vfade-offset: 68px;
 }
 
+StScrollView.hfade
+{
+    -st-hfade-offset: 68px;
+}
+
 StScrollView StScrollBar
 {
     min-width: 16px;
diff --git a/src/st/st-scroll-view-fade.c b/src/st/st-scroll-view-fade.c
index b9f250a..36d3640 100644
--- a/src/st/st-scroll-view-fade.c
+++ b/src/st/st-scroll-view-fade.c
@@ -43,6 +43,8 @@ static const gchar *fade_glsl_shader =
 "uniform float width;\n"
 "uniform float offset_bottom;\n"
 "uniform float offset_top;\n"
+"uniform float offset_right;\n"
+"uniform float offset_left;\n"
 /*
  * Used to pass the fade area to the shader
  *
@@ -61,11 +63,16 @@ static const gchar *fade_glsl_shader =
 " float x = width * cogl_tex_coord_in[0].x;\n"
 " float ratio = 1.0;\n"
 " float fade_bottom_start = fade_area[1][1] - offset_bottom;\n"
+" float fade_right_start = fade_area[1][0] - offset_right;\n"
 " float ratio_top = y / offset_top;\n"
 " float ratio_bottom = (fade_area[1][1] - y)/(fade_area[1][1] - fade_bottom_start);\n"
+" float ratio_left = x / offset_left;\n"
+" float ratio_right = (fade_area[1][0] - x)/(fade_area[1][0] - fade_right_start);\n"
 " bool in_scroll_area = fade_area[0][0] <= x && fade_area[1][0] >= x;\n"
 " bool fade_top = y < offset_top && in_scroll_area && (y >= fade_area[0][1]);\n"
 " bool fade_bottom = y > fade_bottom_start && in_scroll_area && (y <= fade_area[1][1]);\n"
+" bool fade_left = x < offset_left && in_scroll_area && (x >= fade_area[0][0]);\n"
+" bool fade_right = x > fade_right_start && in_scroll_area && (x <= fade_area[1][0]);\n"
 "\n"
 " if (fade_top) {\n"
 "  ratio *= ratio_top;\n"
@@ -75,6 +82,14 @@ static const gchar *fade_glsl_shader =
 "  ratio *= ratio_bottom;\n"
 " }\n"
 "\n"
+" if (fade_left) {\n"
+"  ratio *= ratio_left;\n"
+" }\n"
+"\n"
+" if (fade_right) {\n"
+"  ratio *= ratio_right;\n"
+" }\n"
+"\n"
 "  cogl_color_out = color * ratio;\n"
 "}";
 
@@ -94,12 +109,16 @@ struct _StScrollViewFade
   gint fade_area_uniform;
   gint offset_top_uniform;
   gint offset_bottom_uniform;
+  gint offset_left_uniform;
+  gint offset_right_uniform;
 
   StAdjustment *vadjustment;
+  StAdjustment *hadjustment;
 
   guint is_attached : 1;
 
-  float fade_offset;
+  float vfade_offset;
+  float hfade_offset;
 };
 
 struct _StScrollViewFadeClass
@@ -114,7 +133,8 @@ G_DEFINE_TYPE (StScrollViewFade,
 enum {
   PROP_0,
 
-  PROP_FADE_OFFSET,
+  PROP_VFADE_OFFSET,
+  PROP_HFADE_OFFSET
 };
 
 static gboolean
@@ -159,6 +179,10 @@ st_scroll_view_fade_pre_paint (ClutterEffect *effect)
         cogl_program_get_uniform_location (self->program, "offset_top");
       self->offset_bottom_uniform =
         cogl_program_get_uniform_location (self->program, "offset_bottom");
+      self->offset_left_uniform =
+        cogl_program_get_uniform_location (self->program, "offset_left");
+      self->offset_right_uniform =
+        cogl_program_get_uniform_location (self->program, "offset_right");
     }
 
   parent_class = CLUTTER_EFFECT_CLASS (st_scroll_view_fade_parent_class);
@@ -241,18 +265,34 @@ st_scroll_view_fade_paint_target (ClutterOffscreenEffect *effect)
 
   if (self->offset_top_uniform > -1) {
     if (value > lower + 0.1)
-      cogl_program_set_uniform_1f (self->program, self->offset_top_uniform, self->fade_offset);
+      cogl_program_set_uniform_1f (self->program, self->offset_top_uniform, self->vfade_offset);
     else
       cogl_program_set_uniform_1f (self->program, self->offset_top_uniform, 0.0f);
   }
 
   if (self->offset_bottom_uniform > -1) {
     if (value < upper - page_size - 0.1)
-      cogl_program_set_uniform_1f (self->program, self->offset_bottom_uniform, self->fade_offset);
+      cogl_program_set_uniform_1f (self->program, self->offset_bottom_uniform, self->vfade_offset);
     else
       cogl_program_set_uniform_1f (self->program, self->offset_bottom_uniform, 0.0f);
   }
 
+  st_adjustment_get_values (self->hadjustment, &value, &lower, &upper, NULL, NULL, &page_size);
+
+  if (self->offset_left_uniform > -1) {
+    if (value > lower + 0.1)
+      cogl_program_set_uniform_1f (self->program, self->offset_left_uniform, self->hfade_offset);
+    else
+      cogl_program_set_uniform_1f (self->program, self->offset_left_uniform, 0.0f);
+  }
+
+  if (self->offset_right_uniform > -1) {
+    if (value < upper - page_size - 0.1)
+      cogl_program_set_uniform_1f (self->program, self->offset_right_uniform, self->hfade_offset);
+    else
+      cogl_program_set_uniform_1f (self->program, self->offset_right_uniform, 0.0f);
+  }
+
   if (self->tex_uniform > -1)
     cogl_program_set_uniform_1i (self->program, self->tex_uniform, 0);
   if (self->height_uniform > -1)
@@ -271,15 +311,22 @@ out:
 }
 
 static void
-on_vadjustment_changed (StAdjustment *adjustment,
-                        ClutterEffect *effect)
+on_adjustment_changed (StAdjustment *adjustment,
+                       ClutterEffect *effect)
 {
   gdouble value, lower, upper, page_size;
   gboolean needs_fade;
+  StScrollViewFade *self = ST_SCROLL_VIEW_FADE (effect);
 
-  st_adjustment_get_values (adjustment, &value, &lower, &upper, NULL, NULL, &page_size);
+  st_adjustment_get_values (self->vadjustment, &value, &lower, &upper, NULL, NULL, &page_size);
   needs_fade = (value > lower + 0.1) || (value < upper - page_size - 0.1);
 
+  if (!needs_fade)
+    {
+      st_adjustment_get_values (self->hadjustment, &value, &lower, &upper, NULL, NULL, &page_size);
+      needs_fade = (value > lower + 0.1) || (value < upper - page_size - 0.1);
+    }
+
   clutter_actor_meta_set_enabled (CLUTTER_ACTOR_META (effect), needs_fade);
 }
 
@@ -301,22 +348,37 @@ st_scroll_view_fade_set_actor (ClutterActorMeta *meta,
   if (self->vadjustment)
     {
       g_signal_handlers_disconnect_by_func (self->vadjustment,
-                                            (gpointer)on_vadjustment_changed,
+                                            (gpointer)on_adjustment_changed,
                                             self);
       self->vadjustment = NULL;
     }
 
+  if (self->hadjustment)
+    {
+      g_signal_handlers_disconnect_by_func (self->hadjustment,
+                                            (gpointer)on_adjustment_changed,
+                                            self);
+      self->hadjustment = NULL;
+    }
+
+
   if (actor)
     {
         StScrollView *scroll_view = ST_SCROLL_VIEW (actor);
         StScrollBar *vscroll = ST_SCROLL_BAR (st_scroll_view_get_vscroll_bar (scroll_view));
+        StScrollBar *hscroll = ST_SCROLL_BAR (st_scroll_view_get_hscroll_bar (scroll_view));
         self->vadjustment = ST_ADJUSTMENT (st_scroll_bar_get_adjustment (vscroll));
+        self->hadjustment = ST_ADJUSTMENT (st_scroll_bar_get_adjustment (hscroll));
 
         g_signal_connect (self->vadjustment, "changed",
-                          G_CALLBACK (on_vadjustment_changed),
+                          G_CALLBACK (on_adjustment_changed),
                           self);
 
-        on_vadjustment_changed (self->vadjustment, CLUTTER_EFFECT (self));
+        g_signal_connect (self->hadjustment, "changed",
+                          G_CALLBACK (on_adjustment_changed),
+                          self);
+
+        on_adjustment_changed (NULL, CLUTTER_EFFECT (self));
     }
 
   parent = CLUTTER_ACTOR_META_CLASS (st_scroll_view_fade_parent_class);
@@ -342,31 +404,57 @@ st_scroll_view_fade_dispose (GObject *gobject)
   if (self->vadjustment)
     {
       g_signal_handlers_disconnect_by_func (self->vadjustment,
-                                            (gpointer)on_vadjustment_changed,
+                                            (gpointer)on_adjustment_changed,
                                             self);
       self->vadjustment = NULL;
     }
 
+  if (self->hadjustment)
+    {
+      g_signal_handlers_disconnect_by_func (self->hadjustment,
+                                            (gpointer)on_adjustment_changed,
+                                            self);
+      self->hadjustment = NULL;
+    }
+
   self->actor = NULL;
 
   G_OBJECT_CLASS (st_scroll_view_fade_parent_class)->dispose (gobject);
 }
 
 static void
-st_scroll_view_fade_set_offset (StScrollViewFade *self,
-                                float fade_offset)
+st_scroll_view_vfade_set_offset (StScrollViewFade *self,
+                                 float fade_offset)
 {
-  if (self->fade_offset == fade_offset)
+  if (self->vfade_offset == fade_offset)
     return;
 
   g_object_freeze_notify (G_OBJECT (self));
 
-  self->fade_offset = fade_offset;
+  self->vfade_offset = fade_offset;
 
   if (self->actor != NULL)
     clutter_actor_queue_redraw (self->actor);
 
-  g_object_notify (G_OBJECT (self), "fade-offset");
+  g_object_notify (G_OBJECT (self), "vfade-offset");
+  g_object_thaw_notify (G_OBJECT (self));
+}
+
+static void
+st_scroll_view_hfade_set_offset (StScrollViewFade *self,
+                                 float fade_offset)
+{
+  if (self->hfade_offset == fade_offset)
+    return;
+
+  g_object_freeze_notify (G_OBJECT (self));
+
+  self->hfade_offset = fade_offset;
+
+  if (self->actor != NULL)
+    clutter_actor_queue_redraw (self->actor);
+
+  g_object_notify (G_OBJECT (self), "hfade-offset");
   g_object_thaw_notify (G_OBJECT (self));
 }
 
@@ -380,8 +468,11 @@ st_scroll_view_fade_set_property (GObject *object,
 
   switch (prop_id)
     {
-    case PROP_FADE_OFFSET:
-      st_scroll_view_fade_set_offset (self, g_value_get_float (value));
+    case PROP_VFADE_OFFSET:
+      st_scroll_view_vfade_set_offset (self, g_value_get_float (value));
+      break;
+    case PROP_HFADE_OFFSET:
+      st_scroll_view_hfade_set_offset (self, g_value_get_float (value));
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -399,8 +490,11 @@ st_scroll_view_fade_get_property (GObject *object,
 
   switch (prop_id)
     {
-    case PROP_FADE_OFFSET:
-      g_value_set_float (value, self->fade_offset);
+    case PROP_HFADE_OFFSET:
+      g_value_set_float (value, self->vfade_offset);
+      break;
+    case PROP_VFADE_OFFSET:
+      g_value_set_float (value, self->hfade_offset);
       break;
     default:
       G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
@@ -429,12 +523,19 @@ st_scroll_view_fade_class_init (StScrollViewFadeClass *klass)
   offscreen_class->paint_target = st_scroll_view_fade_paint_target;
 
   g_object_class_install_property (gobject_class,
-                                   PROP_FADE_OFFSET,
-                                   g_param_spec_float ("fade-offset",
-                                                       "Fade Offset",
+                                   PROP_VFADE_OFFSET,
+                                   g_param_spec_float ("vfade-offset",
+                                                       "Vertical Fade Offset",
                                                        "The height of the area which is faded at the edge",
                                                        0.f, G_MAXFLOAT, DEFAULT_FADE_OFFSET,
                                                        G_PARAM_READWRITE));
+  g_object_class_install_property (gobject_class,
+                                   PROP_HFADE_OFFSET,
+                                   g_param_spec_float ("hfade-offset",
+                                                       "Horizontal Fade Offset",
+                                                       "The width of the area which is faded at the edge",
+                                                       0.f, G_MAXFLOAT, DEFAULT_FADE_OFFSET,
+                                                       G_PARAM_READWRITE));
 
 }
 
@@ -472,7 +573,8 @@ st_scroll_view_fade_init (StScrollViewFade *self)
   self->fade_area_uniform = -1;
   self->offset_top_uniform = -1;
   self->offset_bottom_uniform = -1;
-  self->fade_offset = DEFAULT_FADE_OFFSET;
+  self->vfade_offset = DEFAULT_FADE_OFFSET;
+  self->hfade_offset = DEFAULT_FADE_OFFSET;
 
   if (shader != COGL_INVALID_HANDLE)
     cogl_handle_ref (self->shader);
diff --git a/src/st/st-scroll-view.c b/src/st/st-scroll-view.c
index cca7f0b..b19022c 100644
--- a/src/st/st-scroll-view.c
+++ b/src/st/st-scroll-view.c
@@ -96,7 +96,7 @@ struct _StScrollViewPrivate
   gfloat        row_size;
   gfloat        column_size;
 
-  StScrollViewFade *vfade_effect;
+  StScrollViewFade *fade_effect;
 
   gboolean      row_size_set : 1;
   gboolean      column_size_set : 1;
@@ -154,38 +154,43 @@ st_scroll_view_get_property (GObject    *object,
 }
 
 /**
- * st_scroll_view_update_vfade_effect:
+ * st_scroll_view_update_fade_effect:
  * @self: a #StScrollView
- * @fade_offset: The length of the fade effect, in pixels.
+ * @vfade_offset: The length of the veritcal fade effect, in pixels.
+ * @hfade_offset: The length of the horizontal fade effect, in pixels.
  *
  * Sets the height of the fade area area in pixels. A value of 0
  * disables the effect.
  */
 static void
-st_scroll_view_update_vfade_effect (StScrollView *self,
-                                    float fade_offset)
+st_scroll_view_update_fade_effect (StScrollView *self,
+                                   float vfade_offset,
+                                   float hfade_offset)
 {
   StScrollViewPrivate *priv = ST_SCROLL_VIEW (self)->priv;
 
   /* A fade amount of more than 0 enables the effect. */
-  if (fade_offset > 0.)
+  if (vfade_offset > 0. || hfade_offset > 0.)
     {
-      if (priv->vfade_effect == NULL) {
-        priv->vfade_effect = g_object_new (ST_TYPE_SCROLL_VIEW_FADE, NULL);
+      if (priv->fade_effect == NULL) {
+        priv->fade_effect = g_object_new (ST_TYPE_SCROLL_VIEW_FADE, NULL);
 
-        clutter_actor_add_effect_with_name (CLUTTER_ACTOR (self), "vfade",
-                                            CLUTTER_EFFECT (priv->vfade_effect));
+        clutter_actor_add_effect_with_name (CLUTTER_ACTOR (self), "fade",
+                                            CLUTTER_EFFECT (priv->fade_effect));
       }
 
-      g_object_set (priv->vfade_effect,
-                    "fade-offset", fade_offset,
+      g_object_set (priv->fade_effect,
+                    "vfade-offset", vfade_offset,
+                    NULL);
+      g_object_set (priv->fade_effect,
+                    "hfade-offset", hfade_offset,
                     NULL);
     }
    else
     {
-      if (priv->vfade_effect != NULL) {
-        clutter_actor_remove_effect (CLUTTER_ACTOR (self), CLUTTER_EFFECT (priv->vfade_effect));
-        priv->vfade_effect = NULL;
+      if (priv->fade_effect != NULL) {
+        clutter_actor_remove_effect (CLUTTER_ACTOR (self), CLUTTER_EFFECT (priv->fade_effect));
+        priv->fade_effect = NULL;
       }
     }
 
@@ -227,10 +232,10 @@ st_scroll_view_dispose (GObject *object)
 {
   StScrollViewPrivate *priv = ST_SCROLL_VIEW (object)->priv;
 
-  if (priv->vfade_effect)
+  if (priv->fade_effect)
     {
-      clutter_actor_remove_effect (CLUTTER_ACTOR (object), CLUTTER_EFFECT (priv->vfade_effect));
-      priv->vfade_effect = NULL;
+      clutter_actor_remove_effect (CLUTTER_ACTOR (object), CLUTTER_EFFECT (priv->fade_effect));
+      priv->fade_effect = NULL;
     }
 
   if (priv->vscroll)
@@ -668,8 +673,9 @@ st_scroll_view_style_changed (StWidget *widget)
   StScrollViewPrivate *priv = self->priv;
 
   StThemeNode *theme_node = st_widget_get_theme_node (widget);
-  gdouble fade_offset = st_theme_node_get_length (theme_node, "-st-vfade-offset");
-  st_scroll_view_update_vfade_effect (self, fade_offset);
+  gdouble vfade_offset = st_theme_node_get_length (theme_node, "-st-vfade-offset");
+  gdouble hfade_offset = st_theme_node_get_length (theme_node, "-st-hfade-offset");
+  st_scroll_view_update_fade_effect (self, vfade_offset, hfade_offset);
 
   st_widget_style_changed (ST_WIDGET (priv->hscroll));
   st_widget_style_changed (ST_WIDGET (priv->vscroll));