[gtk+] HC theme: implement scroll overshoot

[Jakub Steiner <jimmac src gnome org>]

commit fb4073a60aae5cb58d9a86c86263a8c91615a1aa
Author: Jakub Steiner <jimmac gmail com>
Date:   Mon Dec 1 12:33:23 2014 +0100

    HC theme: implement scroll overshoot
    
    https://bugzilla.gnome.org/show_bug.cgi?id=740876

 gtk/theme/HighContrast/_common.scss  |   20 +++++++++
 gtk/theme/HighContrast/_drawing.scss |   79 ++++++++++++++++++++++++++++++++++
 gtk/theme/HighContrast/gtk.css       |   65 ++++++++++++++++++++++++++++
 3 files changed, 164 insertions(+), 0 deletions(-)
---
diff --git a/gtk/theme/HighContrast/_common.scss b/gtk/theme/HighContrast/_common.scss
index 149c7f0..57b5b96 100644
--- a/gtk/theme/HighContrast/_common.scss
+++ b/gtk/theme/HighContrast/_common.scss
@@ -123,6 +123,26 @@
   background-color: transparentize($selected_bg_color,0.8);
 }
 
+// This is used by GtkScrolledWindow, when content is touch-dragged past boundaries.
+.overshoot {
+  &.top {
+    @include overshoot(top);
+    &:backdrop { @include overshoot(top, backdrop); }
+  }
+  &.bottom {
+    @include overshoot(bottom);
+    &:backdrop { @include overshoot(bottom, backdrop); }
+  }
+  &.left {
+    @include overshoot(left);
+    &:backdrop { @include overshoot(left, backdrop); }
+  }
+  &.right {
+    @include overshoot(right);
+    &:backdrop { @include overshoot(right, backdrop); }
+  }
+}
+
 GtkLabel {
   &:selected,
   &:selected:focus,
diff --git a/gtk/theme/HighContrast/_drawing.scss b/gtk/theme/HighContrast/_drawing.scss
index 1db956b..d9e3b36 100644
--- a/gtk/theme/HighContrast/_drawing.scss
+++ b/gtk/theme/HighContrast/_drawing.scss
@@ -280,3 +280,82 @@ $widget_edge: 0 1px $borders_edge; //outer hilight "used" on
   }
 
 }
+
+ mixin overshoot($p, $t:normal, $c:$fg_color) {
+//
+// overshoot
+//
+// $p: position
+// $t: type
+// $c: base color
+//
+// possible $p values:
+// top, bottom, right, left
+//
+// possible $t values:
+// normal, backdrop
+//
+
+  $_small_gradient_length: 5%;
+  $_big_gradient_length: 100%;
+
+  $_position: center top;
+  $_small_gradient_size: 100% $_small_gradient_length;
+  $_big_gradient_size: 100% $_big_gradient_length;
+
+  @if $p==bottom {
+    $_position: center bottom;
+    $_linear_gradient_direction: to top; 
+  }
+
+  @else if $p==right {
+    $_position: right center;
+    $_small_gradient_size: $_small_gradient_length 100%;
+    $_big_gradient_size: $_big_gradient_length 100%;
+  }
+
+  @else if $p==left {
+    $_position: left center;
+    $_small_gradient_size: $_small_gradient_length 100%;
+    $_big_gradient_size: $_big_gradient_length 100%;
+  }
+  
+  $_small_gradient_color: $c;
+  $_big_gradient_color: $c;
+
+  @if $c==$fg_color {
+    $_small_gradient_color: darken($borders_color, 50%);
+    $_big_gradient_color: $fg_color;
+
+    @if $t==backdrop { $_small_gradient_color: $backdrop_borders_color; }
+  }
+
+  $_small_gradient: -gtk-gradient(radial,
+                                  $_position, 0,
+                                  $_position, 0.5,
+                                  to($_small_gradient_color),
+                                  to(transparentize($_small_gradient_color, 1)));
+
+  $_big_gradient: -gtk-gradient(radial,
+                                $_position, 0,
+                                $_position, 0.6,
+                                from(transparentize($_big_gradient_color, 0.5)),
+                                to(transparentize($_big_gradient_color, 1)));
+
+  @if $t==normal {
+    background-image: $_small_gradient, $_big_gradient;
+    background-size: $_small_gradient_size, $_big_gradient_size;
+  }
+
+  @else if $t==backdrop {
+    background-image: $_small_gradient;
+    background-size: $_small_gradient_size;
+  }
+
+  background-repeat: no-repeat;
+  background-position: $_position;
+
+  background-color: transparent; // reset some properties to be sure to not inherit them somehow
+  border: none;                  //
+  box-shadow: none;              //
+}
diff --git a/gtk/theme/HighContrast/gtk.css b/gtk/theme/HighContrast/gtk.css
index c964eb2..690b402 100644
--- a/gtk/theme/HighContrast/gtk.css
+++ b/gtk/theme/HighContrast/gtk.css
@@ -109,6 +109,71 @@
   border: 1px solid #000;
   background-color: rgba(0, 0, 0, 0.2); }
 
+.overshoot.top {
+  background-image: -gtk-gradient(radial, center top, 0, center top, 0.5, to(black), to(transparent)), 
-gtk-gradient(radial, center top, 0, center top, 0.6, from(rgba(0, 0, 0, 0.5)), to(transparent));
+  background-size: 100% 5%, 100% 100%;
+  background-repeat: no-repeat;
+  background-position: center top;
+  background-color: transparent;
+  border: none;
+  box-shadow: none; }
+  .overshoot.top:backdrop {
+    background-image: -gtk-gradient(radial, center top, 0, center top, 0.5, to(#8b8b8b), to(rgba(139, 139, 
139, 0)));
+    background-size: 100% 5%;
+    background-repeat: no-repeat;
+    background-position: center top;
+    background-color: transparent;
+    border: none;
+    box-shadow: none; }
+.overshoot.bottom {
+  background-image: -gtk-gradient(radial, center bottom, 0, center bottom, 0.5, to(black), to(transparent)), 
-gtk-gradient(radial, center bottom, 0, center bottom, 0.6, from(rgba(0, 0, 0, 0.5)), to(transparent));
+  background-size: 100% 5%, 100% 100%;
+  background-repeat: no-repeat;
+  background-position: center bottom;
+  background-color: transparent;
+  border: none;
+  box-shadow: none; }
+  .overshoot.bottom:backdrop {
+    background-image: -gtk-gradient(radial, center bottom, 0, center bottom, 0.5, to(#8b8b8b), to(rgba(139, 
139, 139, 0)));
+    background-size: 100% 5%;
+    background-repeat: no-repeat;
+    background-position: center bottom;
+    background-color: transparent;
+    border: none;
+    box-shadow: none; }
+.overshoot.left {
+  background-image: -gtk-gradient(radial, left center, 0, left center, 0.5, to(black), to(transparent)), 
-gtk-gradient(radial, left center, 0, left center, 0.6, from(rgba(0, 0, 0, 0.5)), to(transparent));
+  background-size: 5% 100%, 100% 100%;
+  background-repeat: no-repeat;
+  background-position: left center;
+  background-color: transparent;
+  border: none;
+  box-shadow: none; }
+  .overshoot.left:backdrop {
+    background-image: -gtk-gradient(radial, left center, 0, left center, 0.5, to(#8b8b8b), to(rgba(139, 139, 
139, 0)));
+    background-size: 5% 100%;
+    background-repeat: no-repeat;
+    background-position: left center;
+    background-color: transparent;
+    border: none;
+    box-shadow: none; }
+.overshoot.right {
+  background-image: -gtk-gradient(radial, right center, 0, right center, 0.5, to(black), to(transparent)), 
-gtk-gradient(radial, right center, 0, right center, 0.6, from(rgba(0, 0, 0, 0.5)), to(transparent));
+  background-size: 5% 100%, 100% 100%;
+  background-repeat: no-repeat;
+  background-position: right center;
+  background-color: transparent;
+  border: none;
+  box-shadow: none; }
+  .overshoot.right:backdrop {
+    background-image: -gtk-gradient(radial, right center, 0, right center, 0.5, to(#8b8b8b), to(rgba(139, 
139, 139, 0)));
+    background-size: 5% 100%;
+    background-repeat: no-repeat;
+    background-position: right center;
+    background-color: transparent;
+    border: none;
+    box-shadow: none; }
+
 /*********************
  * Spinner Animation *
  *********************/