[Android] Suppress overscroll for unscrollable axes in the browser

content/browser/android/overscroll_glow.cc

Index: content/browser/android/overscroll_glow.cc
diff --git a/content/browser/android/overscroll_glow.cc b/content/browser/android/overscroll_glow.cc
index 0aa00e04ac6ad8d8addf8875fa1952befd04963a..c20787164316ccf05be7b4a3f1a75d4e5bcf0096 100644
--- a/content/browser/android/overscroll_glow.cc
+++ b/content/browser/android/overscroll_glow.cc
@@ -77,7 +77,11 @@ gfx::SizeF ComputeSize(OverscrollGlow::Edge edge,
 }  // namespace
 
 OverscrollGlow::OverscrollGlow(OverscrollGlowClient* client)
-    : client_(client), edge_offsets_(), initialized_(false) {
+    : client_(client),
+      edge_offsets_(),
+      initialized_(false),
+      allow_horizontal_overscroll_(true),
+      allow_vertical_overscroll_(true) {
   DCHECK(client);
 }
 
@@ -116,12 +120,21 @@ bool OverscrollGlow::OnOverscrolled(base::TimeTicks current_time,
           const gfx::Vector2dF& accumulated_overscroll,
           gfx::Vector2dF overscroll_delta,
           gfx::Vector2dF velocity,
-          const gfx::Vector2dF& displacement) {
+          const gfx::Vector2dF& overscroll_location) {
   // The size of the glow determines the relative effect of the inputs; an
   // empty-sized effect is effectively disabled.
   if (viewport_size_.IsEmpty())
     return false;
 
+  if (!allow_horizontal_overscroll_) {
+    overscroll_delta.set_x(0);
+    velocity.set_x(0);
+  }
+  if (!allow_vertical_overscroll_) {
+    overscroll_delta.set_y(0);
+    velocity.set_y(0);
+  }
+
   // Ignore sufficiently small values that won't meaningfuly affect animation.
   overscroll_delta = ZeroSmallComponents(overscroll_delta);
   if (overscroll_delta.IsZero()) {
@@ -143,7 +156,7 @@ bool OverscrollGlow::OnOverscrolled(base::TimeTicks current_time,
   if (!velocity.IsZero())
     Absorb(current_time, velocity, x_overscroll_started, y_overscroll_started);
   else
-    Pull(current_time, overscroll_delta, displacement);
+    Pull(current_time, overscroll_delta, overscroll_location);
 
   return CheckNeedsAnimate();
 }
@@ -180,6 +193,12 @@ void OverscrollGlow::OnFrameUpdated(
                                                viewport_size.height();
   edge_offsets_[OverscrollGlow::EDGE_RIGHT] =
       content_size.width() - content_scroll_offset.x() - viewport_size.width();
+
+  // Disallow overscroll on unscrollable axes, matching platform behavior.
+  allow_horizontal_overscroll_ =
+      std::ceil(viewport_size_.width()) < content_size.width();
+  allow_vertical_overscroll_ =
+      std::ceil(viewport_size_.height()) < content_size.height();

[tdresser, 2015/07/10 18:41:30]

We don't need an epsilon check here?

[jdduke (slow), 2015/07/10 19:12:50]

This is the logic we had before the check got moved to the renderer (see
https://codereview.chromium.org/230223006/diff/40001/content/browser/renderer...).
I can switch it to an epsilon check if you like.

 }
 
 bool OverscrollGlow::CheckNeedsAnimate() {
@@ -246,8 +265,8 @@ void OverscrollGlow::Pull(base::TimeTicks current_time,
       min(overscroll_pull.x(), 0.f),  // Left
       max(overscroll_pull.y(), 0.f),  // Bottom
       max(overscroll_pull.x(), 0.f)   // Right
-  };
-
+  }

[tdresser, 2015/07/10 18:41:30]

Fix ;

[jdduke (slow), 2015/07/10 19:12:50]

Whoops, done.

+;
   gfx::Vector2dF displacement =
       gfx::ScaleVector2d(overscroll_location, inv_width, inv_height);
   displacement.set_x(max(0.f, min(1.f, displacement.x())));