Add support for calculating the position of the top controls in the cc layer.

cc/top_controls_manager.cc

+// Copyright 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "cc/top_controls_manager.h"
+
+#include <algorithm>
+
+#include "base/bind.h"
+#include "base/compiler_specific.h"
+#include "base/logging.h"
+#include "base/message_loop.h"
+#include "base/time.h"
+#include "cc/layer_tree_impl.h"
+#include "cc/top_controls_animation.h"
+#include "ui/gfx/transform.h"
+#include "ui/gfx/vector2d_f.h"
+
+namespace cc {
+namespace {
+static const float kShowHideThreshold = 0.75f;
+static const int64 kAutoHideDelayMs = 1500;

[jamesr, 2012/12/19 22:56:29]

I think the floating point constants will generate static initializers, which is
bad. check on that.

[Ted C, 2012/12/20 00:54:50]

thakis informed me that they do not, but he did point out that the statics are
unnecessary...which I removed.

+static const double kShowHideMaxDurationMs = 500;
+}
+
+// static
+scoped_ptr<TopControlsManager> TopControlsManager::Create(
+    TopControlsDelegate* delegate, float top_controls_height) {
+  return make_scoped_ptr(new TopControlsManager(delegate, top_controls_height));
+}
+
+TopControlsManager::TopControlsManager(TopControlsDelegate* delegate,
+                                       float top_controls_height)
+    : ALLOW_THIS_IN_INITIALIZER_LIST(weak_ptr_factory_(this)),
+      delegate_(delegate),
+      is_overlay_mode_(false),
+      top_controls_height_(top_controls_height),
+      controls_top_offset_(0),
+      content_top_offset_(top_controls_height),
+      top_controls_auto_hide_trigger_time_(-1),
+      previous_root_scroll_offset_(0.f),
+      scroll_readjustment_enabled_(false) {
+  CHECK(delegate_);
+}
+
+TopControlsManager::~TopControlsManager() {
+}
+
+void TopControlsManager::UpdateDrawPositions() {
+  if (!RootScrollLayer())
+    return;
+
+  // If the scroll position has changed underneath us (i.e. a javascript
+  // scroll), then simulate a scroll that covers the delta.
+  float scroll_total_y = RootScrollLayerTotalScrollY();
+  if (scroll_readjustment_enabled_
+      && scroll_total_y != previous_root_scroll_offset_) {
+    ScrollBy(gfx::Vector2dF(0, scroll_total_y - previous_root_scroll_offset_));
+    StartAnimationIfNecessary();
+    previous_root_scroll_offset_ = RootScrollLayerTotalScrollY();
+  }
+
+  float offset_top = is_overlay_mode_ ? 0 : content_top_offset_;
+
+  // The two layers that need to be transformed are the clip layer and root
+  // scrollbar layers, which are the only two children of the root layer.
+  LayerImpl* root_layer = delegate_->activeTree()->RootLayer();
+  for (size_t i = 0; i < root_layer->children().size(); ++i) {
+    LayerImpl* child_layer = root_layer->children()[i];
+    gfx::Transform transform;
+    transform.Translate(0, offset_top);
+    child_layer->setImplTransform(transform);
+  }
+
+  // TODO(tedchoc): Adjust fixed position layers as well.
+}
+
+void TopControlsManager::ScrollBegin() {
+  ResetAnimations();
+  scroll_readjustment_enabled_ = false;
+}
+
+gfx::Vector2dF TopControlsManager::ScrollBy(
+    const gfx::Vector2dF pending_delta) {
+  ResetAnimations();
+  return ScrollInternal(pending_delta);
+}
+
+gfx::Vector2dF TopControlsManager::ScrollInternal(
+    const gfx::Vector2dF pending_delta) {
+  float scroll_total_y = RootScrollLayerTotalScrollY();
+  float scroll_delta_y = pending_delta.y();
+
+  float previous_controls_offset = controls_top_offset_;
+  float previous_content_offset = content_top_offset_;
+  bool previous_was_overlay = is_overlay_mode_;
+
+  controls_top_offset_ -= scroll_delta_y;
+  controls_top_offset_ = std::min(
+      std::max(controls_top_offset_, -top_controls_height_), 0.f);
+
+  if (scroll_total_y > 0 || (scroll_total_y == 0
+      && content_top_offset_ < scroll_delta_y)) {
+    is_overlay_mode_ = true;
+    content_top_offset_ = 0;
+  } else if (scroll_total_y <= 0 && (scroll_delta_y < 0
+      || (scroll_delta_y > 0 && content_top_offset_ > 0))) {
+    is_overlay_mode_ = false;
+    content_top_offset_ -= scroll_delta_y;
+  }
+  content_top_offset_ = std::max(
+      std::min(content_top_offset_,
+               controls_top_offset_ + top_controls_height_), 0.f);
+
+  gfx::Vector2dF applied_delta;
+  if (!previous_was_overlay)
+    applied_delta.set_y(previous_content_offset - content_top_offset_);
+
+  if (is_overlay_mode_ != previous_was_overlay
+      || previous_controls_offset != controls_top_offset_
+      || previous_content_offset != content_top_offset_) {
+    delegate_->setNeedsRedraw();
+    delegate_->setNeedsUpdateDrawProperties();
+  }
+
+  return pending_delta - applied_delta;
+}
+
+void TopControlsManager::ScrollEnd() {
+  StartAnimationIfNecessary();
+  previous_root_scroll_offset_ = RootScrollLayerTotalScrollY();
+  scroll_readjustment_enabled_ = true;
+}
+
+void TopControlsManager::Animate(base::TimeTicks monotonic_time) {
+  if (!top_controls_animation_ || !RootScrollLayer())
+    return;
+
+  double time = (monotonic_time - base::TimeTicks()).InSecondsF();
+  float new_offset =
+      top_controls_animation_->ScrollOffsetAtTime(monotonic_time);
+  gfx::Vector2dF scroll_vector(0.f, -(new_offset - controls_top_offset_));
+  ScrollInternal(scroll_vector);
+  delegate_->setNeedsRedraw();
+
+  if (top_controls_animation_->IsAnimationCompleteAtTime(monotonic_time)) {
+    top_controls_animation_.reset();
+    StartAnimationIfNecessary();
+  }
+}
+
+void TopControlsManager::ResetAnimations() {
+  if (top_controls_animation_)
+    top_controls_animation_.reset();
+  top_controls_auto_hide_trigger_time_ = -1;
+}
+
+LayerImpl* TopControlsManager::RootScrollLayer() {
+  return delegate_->activeTree()->root_scroll_layer();
+}
+
+float TopControlsManager::RootScrollLayerTotalScrollY() {
+  LayerImpl* layer = RootScrollLayer();
+  if (!layer)
+    return 0;
+  gfx::Vector2dF scroll_total = layer->scrollOffset() + layer->scrollDelta();
+  return scroll_total.y();
+}
+
+void TopControlsManager::StartAnimationIfNecessary() {
+  if (!is_overlay_mode_)
+    return;
+
+  float scroll_total_y = RootScrollLayerTotalScrollY();
+
+  if (controls_top_offset_ != 0
+      && controls_top_offset_ != -top_controls_height_) {
+    top_controls_animation_ = TopControlsAnimation::Create(
+        controls_top_offset_,
+        top_controls_height_,
+        base::TimeTicks::Now(),
+        base::TimeDelta::FromMilliseconds(kShowHideMaxDurationMs));
+    top_controls_animation_->SetDirection(
+        controls_top_offset_ >= -(top_controls_height_ * kShowHideThreshold));
+    delegate_->setNeedsRedraw();
+  } else if (controls_top_offset_ == 0 && scroll_total_y != 0) {
+    MessageLoop* loop = MessageLoop::current();
+    DCHECK(loop);
+    if (loop) {
+      int64 trigger_time = top_controls_auto_hide_trigger_time_ =
+          (base::TimeTicks::Now() - base::TimeTicks()).InMilliseconds();
+      loop->PostDelayedTask(
+          FROM_HERE,
+          base::Bind(&TopControlsManager::StartAutoHideAnimation,
+                     weak_ptr_factory_.GetWeakPtr(), trigger_time),

[jamesr, 2012/12/19 22:56:29]

a WeakPtrFactory seems like overkill for this - check out base/timer.h. I think
you want a OneShotTimer. it'll take care of auto-cancellation on destruction

[Ted C, 2012/12/20 00:42:39]

Awesome...didn't know about this.  Done

+          base::TimeDelta::FromMilliseconds(kAutoHideDelayMs));
+    }
+  }
+}
+
+void TopControlsManager::StartAutoHideAnimation(int64 triggered_time) {
+  if (triggered_time != top_controls_auto_hide_trigger_time_)
+    return;
+
+  top_controls_animation_ = TopControlsAnimation::Create(
+      controls_top_offset_,
+      top_controls_height_,
+      base::TimeTicks::Now(),
+      base::TimeDelta::FromMilliseconds(kShowHideMaxDurationMs));
+  top_controls_animation_->SetDirection(false);
+  delegate_->setNeedsRedraw();
+}
+
+}  // namespace cc