st/scroll-view: Make fade effect take ClutterMargin

Instead of taking just vertical/horizontal offsets, take a ClutterMargin
to allow us set the fade offsets on each direction specifically. Also,
handle negative values in margins, the fade effect will run in the negative
space left by the scrollview padding instead. Another difference now is
that areas outside the extents of the effect will be transparent, instead
of the effect ending abruptly past the given extents.

This will be used by the app grid, in order to selectively let see either
of next/prev pages while navigating.

While at it, fix code style issues in st_scroll_view_update_fade_effect(),
and clean up unused variables from the GLSL code.

Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1630>

diff --git a/js/ui/appDisplay.js b/js/ui/appDisplay.js
index c3958ae9ce83120b24c2dedcaa9618c11c8ba600..ca0f9d89d08a8145134345a9fcb785d496b9c3bc 100644 (file)
--- a/js/ui/appDisplay.js
+++ b/js/ui/appDisplay.js
@@ -264,7 +264,13 @@ var BaseAppView = GObject.registerClass({
                 return;
         }
 
-        this._scrollView.update_fade_effect(vOffset, hOffset);
+        this._scrollView.update_fade_effect(
+            new Clutter.Margin({
+                left: hOffset,
+                right: hOffset,
+                top: vOffset,
+                bottom: vOffset,
+            }));
     }
 
     _createGrid() {

diff --git a/src/st/st-scroll-view-fade.c b/src/st/st-scroll-view-fade.c
index a0bb85bda82fab513fa4b4584b4d2cced13c06f3..38d40ed651ec23b9b7d0d34e79c5616ebc7f2219 100644 (file)
--- a/src/st/st-scroll-view-fade.c
+++ b/src/st/st-scroll-view-fade.c
@@ -46,8 +46,7 @@ struct _StScrollViewFade
 
   guint fade_edges : 1;
 
-  float vfade_offset;
-  float hfade_offset;
+  ClutterMargin fade_margins;
 };
 
 G_DEFINE_TYPE (StScrollViewFade,
@@ -57,8 +56,7 @@ G_DEFINE_TYPE (StScrollViewFade,
 enum {
   PROP_0,
 
-  PROP_VFADE_OFFSET,
-  PROP_HFADE_OFFSET,
+  PROP_FADE_MARGINS,
   PROP_FADE_EDGES,
 
   N_PROPS
@@ -136,6 +134,15 @@ st_scroll_view_fade_paint_target (ClutterOffscreenEffect *effect,
   if (h_scroll_visible)
       fade_area_bottomright[1] -= clutter_actor_get_height (hscroll);
 
+  if (self->fade_margins.left < 0)
+    fade_area_topleft[0] -= ABS (self->fade_margins.left);
+  if (self->fade_margins.right < 0)
+    fade_area_bottomright[0] += ABS (self->fade_margins.right);
+  if (self->fade_margins.top < 0)
+    fade_area_topleft[1] -= ABS (self->fade_margins.top);
+  if (self->fade_margins.bottom < 0)
+    fade_area_bottomright[1] += ABS (self->fade_margins.bottom);
+
   st_adjustment_get_values (self->vadjustment, &value, &lower, &upper, NULL, NULL, &page_size);
   value = (value - lower) / (upper - page_size - lower);
   clutter_shader_effect_set_uniform (shader, "fade_edges_top", G_TYPE_INT, 1, self->fade_edges ? value >= 0.0 : value > 0.0);
@@ -146,8 +153,10 @@ st_scroll_view_fade_paint_target (ClutterOffscreenEffect *effect,
   clutter_shader_effect_set_uniform (shader, "fade_edges_left", G_TYPE_INT, 1, self->fade_edges ? value >= 0.0 : value > 0.0);
   clutter_shader_effect_set_uniform (shader, "fade_edges_right", G_TYPE_INT, 1, self->fade_edges ? value <= 1.0 : value < 1.0);
 
-  clutter_shader_effect_set_uniform (shader, "vfade_offset", G_TYPE_FLOAT, 1, self->vfade_offset);
-  clutter_shader_effect_set_uniform (shader, "hfade_offset", G_TYPE_FLOAT, 1, self->hfade_offset);
+  clutter_shader_effect_set_uniform (shader, "fade_offset_top", G_TYPE_FLOAT, 1, ABS (self->fade_margins.top));
+  clutter_shader_effect_set_uniform (shader, "fade_offset_bottom", G_TYPE_FLOAT, 1, ABS (self->fade_margins.bottom));
+  clutter_shader_effect_set_uniform (shader, "fade_offset_left", G_TYPE_FLOAT, 1, ABS (self->fade_margins.left));
+  clutter_shader_effect_set_uniform (shader, "fade_offset_right", G_TYPE_FLOAT, 1, ABS (self->fade_margins.right));
   clutter_shader_effect_set_uniform (shader, "tex", G_TYPE_INT, 1, 0);
   clutter_shader_effect_set_uniform (shader, "height", G_TYPE_FLOAT, 1, clutter_actor_get_height (self->actor));
   clutter_shader_effect_set_uniform (shader, "width", G_TYPE_FLOAT, 1, clutter_actor_get_width (self->actor));
@@ -266,39 +275,21 @@ st_scroll_view_fade_dispose (GObject *gobject)
 }
 
 static void
-st_scroll_view_vfade_set_offset (StScrollViewFade *self,
-                                 float fade_offset)
-{
-  if (self->vfade_offset == fade_offset)
-    return;
-
-  g_object_freeze_notify (G_OBJECT (self));
-
-  self->vfade_offset = fade_offset;
-
-  if (self->actor != NULL)
-    clutter_actor_queue_redraw (self->actor);
-
-  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_VFADE_OFFSET]);
-  g_object_thaw_notify (G_OBJECT (self));
-}
-
-static void
-st_scroll_view_hfade_set_offset (StScrollViewFade *self,
-                                 float fade_offset)
+st_scroll_view_set_fade_margins (StScrollViewFade *self,
+                                 ClutterMargin    *fade_margins)
 {
-  if (self->hfade_offset == fade_offset)
+  if (self->fade_margins.left == fade_margins->left &&
+      self->fade_margins.right == fade_margins->right &&
+      self->fade_margins.top == fade_margins->top &&
+      self->fade_margins.bottom == fade_margins->bottom)
     return;
 
-  g_object_freeze_notify (G_OBJECT (self));
-
-  self->hfade_offset = fade_offset;
+  self->fade_margins = *fade_margins;
 
   if (self->actor != NULL)
     clutter_actor_queue_redraw (self->actor);
 
-  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_HFADE_OFFSET]);
-  g_object_thaw_notify (G_OBJECT (self));
+  g_object_notify_by_pspec (G_OBJECT (self), props[PROP_FADE_MARGINS]);
 }
 
 static void
@@ -329,11 +320,8 @@ st_scroll_view_fade_set_property (GObject *object,
 
   switch (prop_id)
     {
-    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));
+    case PROP_FADE_MARGINS:
+      st_scroll_view_set_fade_margins (self, g_value_get_boxed (value));
       break;
     case PROP_FADE_EDGES:
       st_scroll_view_fade_set_fade_edges (self, g_value_get_boolean (value));
@@ -354,11 +342,8 @@ st_scroll_view_fade_get_property (GObject *object,
 
   switch (prop_id)
     {
-    case PROP_HFADE_OFFSET:
-      g_value_set_float (value, self->hfade_offset);
-      break;
-    case PROP_VFADE_OFFSET:
-      g_value_set_float (value, self->vfade_offset);
+    case PROP_FADE_MARGINS:
+      g_value_set_boxed (value, &self->fade_margins);
       break;
     case PROP_FADE_EDGES:
       g_value_set_boolean (value, self->fade_edges);
@@ -391,29 +376,15 @@ st_scroll_view_fade_class_init (StScrollViewFadeClass *klass)
   offscreen_class->paint_target = st_scroll_view_fade_paint_target;
 
   /**
-   * StScrollViewFade:vfade-offset:
-   *
-   * The height of area which is faded at the top and bottom edges of the
-   * #StScrollViewFade.
-   */
-  props[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,
-                        ST_PARAM_READWRITE);
-
-  /**
-   * StScrollViewFade:hfade-offset:
+   * StScrollViewFade:fade-margins:
    *
-   * The height of area which is faded at the left and right edges of the
-   * #StScrollViewFade.
+   * The margins widths that are faded.
    */
-  props[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,
+  props[PROP_FADE_MARGINS] =
+    g_param_spec_boxed ("fade-margins",
+                        "Fade margins",
+                        "The margin widths that are faded",
+                        CLUTTER_TYPE_MARGIN,
                         ST_PARAM_READWRITE);
 
   /**
@@ -434,8 +405,12 @@ st_scroll_view_fade_class_init (StScrollViewFadeClass *klass)
 static void
 st_scroll_view_fade_init (StScrollViewFade *self)
 {
-  self->vfade_offset = DEFAULT_FADE_OFFSET;
-  self->hfade_offset = DEFAULT_FADE_OFFSET;
+  self->fade_margins = (ClutterMargin) {
+    DEFAULT_FADE_OFFSET,
+    DEFAULT_FADE_OFFSET,
+    DEFAULT_FADE_OFFSET,
+    DEFAULT_FADE_OFFSET,
+  };
 }
 
 /**

diff --git a/src/st/st-scroll-view-fade.glsl b/src/st/st-scroll-view-fade.glsl
index e3f1a259f36c020a8df15e252943a9232a24ac26..264f3bcd7228e757fd92aa206d93b54bd7592fb6 100644 (file)
--- a/src/st/st-scroll-view-fade.glsl
+++ b/src/st/st-scroll-view-fade.glsl
@@ -20,8 +20,10 @@
 uniform sampler2D tex;
 uniform float height;
 uniform float width;
-uniform float vfade_offset;
-uniform float hfade_offset;
+uniform float fade_offset_top;
+uniform float fade_offset_bottom;
+uniform float fade_offset_left;
+uniform float fade_offset_right;
 uniform bool  fade_edges_top;
 uniform bool  fade_edges_right;
 uniform bool  fade_edges_bottom;
@@ -37,23 +39,19 @@ void main ()
     float y = height * cogl_tex_coord_in[0].y;
     float x = width * cogl_tex_coord_in[0].x;
 
-    /*
-     * We cannot just return here due to a bug in llvmpipe see:
-     * https://bugzilla.freedesktop.org/show_bug.cgi?id=62357
-     */
     if (x > fade_area_topleft[0] && x < fade_area_bottomright[0] &&
-        y > fade_area_topleft[1] && y < fade_area_bottomright[1]) {
+        y > fade_area_topleft[1] && y < fade_area_bottomright[1])
+    {
         float ratio = 1.0;
-        float fade_top_start = fade_area_topleft[1] + vfade_offset;
-        float fade_left_start = fade_area_topleft[0] + hfade_offset;
-        float fade_bottom_start = fade_area_bottomright[1] - vfade_offset;
-        float fade_right_start = fade_area_bottomright[0] - hfade_offset;
-        bool fade_top = y < vfade_offset && fade_edges_top;
+        float fade_top_start = fade_area_topleft[1] + fade_offset_top;
+        float fade_left_start = fade_area_topleft[0] + fade_offset_left;
+        float fade_bottom_start = fade_area_bottomright[1] - fade_offset_bottom;
+        float fade_right_start = fade_area_bottomright[0] - fade_offset_right;
+        bool fade_top = y < fade_top_start && fade_edges_top;
         bool fade_bottom = y > fade_bottom_start && fade_edges_bottom;
         bool fade_left = x < fade_left_start && fade_edges_left;
         bool fade_right = x > fade_right_start && fade_edges_right;
 
-        float vfade_scale = height / vfade_offset;
         if (fade_top) {
             ratio *= (fade_area_topleft[1] - y) / (fade_area_topleft[1] - fade_top_start);
         }
@@ -62,7 +60,6 @@ void main ()
             ratio *= (fade_area_bottomright[1] - y) / (fade_area_bottomright[1] - fade_bottom_start);
         }
 
-        float hfade_scale = width / hfade_offset;
         if (fade_left) {
             ratio *= (fade_area_topleft[0] - x) / (fade_area_topleft[0] - fade_left_start);
         }
@@ -72,5 +69,7 @@ void main ()
         }
 
         cogl_color_out *= ratio;
+    } else {
+        cogl_color_out *= 0;
     }
 }

diff --git a/src/st/st-scroll-view.c b/src/st/st-scroll-view.c
index 0cf48adafc4fa768dcec00d6cd1196c6ea0fd462..3b9711ea216f3b5539e9751aacced22e9ea51fd9 100644 (file)
--- a/src/st/st-scroll-view.c
+++ b/src/st/st-scroll-view.c
@@ -164,42 +164,41 @@ st_scroll_view_get_property (GObject    *object,
 /**
  * st_scroll_view_update_fade_effect:
  * @scroll: a #StScrollView
- * @vfade_offset: The length of the vertical fade effect, in pixels.
- * @hfade_offset: The length of the horizontal fade effect, in pixels.
+ * @fade_margins: a #ClutterMargin defining the vertical fade effects, in pixels.
  *
- * Sets the height of the fade area area in pixels. A value of 0
+ * Sets the fade effects in all four edges of the view. A value of 0
  * disables the effect.
  */
 void
-st_scroll_view_update_fade_effect (StScrollView *scroll,
-                                   float         vfade_offset,
-                                   float         hfade_offset)
+st_scroll_view_update_fade_effect (StScrollView  *scroll,
+                                   ClutterMargin *fade_margins)
 {
   StScrollViewPrivate *priv = ST_SCROLL_VIEW (scroll)->priv;
 
-  /* A fade amount of more than 0 enables the effect. */
-  if (vfade_offset > 0. || hfade_offset > 0.)
+  /* A fade amount of other than 0 enables the effect. */
+  if (fade_margins->left != 0. || fade_margins->right != 0. ||
+      fade_margins->top != 0. || fade_margins->bottom != 0.)
     {
-      if (priv->fade_effect == NULL) {
-        priv->fade_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 (scroll), "fade",
-                                            CLUTTER_EFFECT (priv->fade_effect));
-      }
+          clutter_actor_add_effect_with_name (CLUTTER_ACTOR (scroll), "fade",
+                                              CLUTTER_EFFECT (priv->fade_effect));
+        }
 
       g_object_set (priv->fade_effect,
-                    "vfade-offset", vfade_offset,
-                    NULL);
-      g_object_set (priv->fade_effect,
-                    "hfade-offset", hfade_offset,
+                    "fade-margins", fade_margins,
                     NULL);
     }
    else
     {
-      if (priv->fade_effect != NULL) {
-        clutter_actor_remove_effect (CLUTTER_ACTOR (scroll), CLUTTER_EFFECT (priv->fade_effect));
-        priv->fade_effect = NULL;
-      }
+      if (priv->fade_effect != NULL)
+        {
+          clutter_actor_remove_effect (CLUTTER_ACTOR (scroll),
+                                       CLUTTER_EFFECT (priv->fade_effect));
+          priv->fade_effect = NULL;
+        }
     }
 
   clutter_actor_queue_redraw (CLUTTER_ACTOR (scroll));
@@ -744,7 +743,13 @@ st_scroll_view_style_changed (StWidget *widget)
   StThemeNode *theme_node = st_widget_get_theme_node (widget);
   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_scroll_view_update_fade_effect (self,
+                                     &(ClutterMargin) {
+                                       .top = vfade_offset,
+                                       .bottom = vfade_offset,
+                                       .left = hfade_offset,
+                                       .right = hfade_offset,
+                                     });
 
   st_widget_style_changed (ST_WIDGET (priv->hscroll));
   st_widget_style_changed (ST_WIDGET (priv->vscroll));

diff --git a/src/st/st-scroll-view.h b/src/st/st-scroll-view.h
index 2f2c31d6c925cd54d3176cde4075b2ca66712482..e2acaca2f599c9b3a9eafe067c8e2897e9e7d193 100644 (file)
--- a/src/st/st-scroll-view.h
+++ b/src/st/st-scroll-view.h
@@ -82,9 +82,8 @@ gboolean      st_scroll_view_get_overlay_scrollbars (StScrollView *scroll);
 void          st_scroll_view_set_policy          (StScrollView   *scroll,
                                                   StPolicyType    hscroll,
                                                   StPolicyType    vscroll);
-void          st_scroll_view_update_fade_effect  (StScrollView *scroll,
-                                                  float vfade_offset,
-                                                  float hfade_offset);
+void          st_scroll_view_update_fade_effect  (StScrollView  *scroll,
+                                                  ClutterMargin *fade_margins);
 
 G_END_DECLS