chrome/browser/ui/tabs/hover_tab_selector.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/browser/ui/tabs/hover_tab_selector.h"
   6
   7 #include "base/bind.h"
   8 #include "base/compiler_specific.h"
   9 #include "base/location.h"
  10 #include "base/single_thread_task_runner.h"
  11 #include "base/thread_task_runner_handle.h"
  12 #include "chrome/browser/ui/tabs/tab_strip_model.h"
  13
  14 HoverTabSelector::HoverTabSelector(
  15     TabStripModel* tab_strip_model)
  16     : tab_strip_model_(tab_strip_model),
  17       tab_transition_tab_index_(-1),
  18       weak_factory_(this) {
  19   DCHECK(tab_strip_model_);
  20 }
  21
  22 HoverTabSelector::~HoverTabSelector() {
  23 }
  24
  25 void HoverTabSelector::StartTabTransition(int index) {
  26   // If there is a transition underway already, only start a new
  27   // transition (canceling the old one) if the target tab differs.
  28   if (weak_factory_.HasWeakPtrs()) {
  29     if (index == tab_transition_tab_index_)
  30       return;
  31     CancelTabTransition();
  32   }
  33   // Start a new transition if the target isn't active already.
  34   if (index != tab_strip_model_->active_index()) {
  35     // The delay between beginning to hover over a tab and the transition
  36     // to that tab taking place.
  37     const base::TimeDelta kHoverTransitionDelay =
  38         base::TimeDelta::FromMilliseconds(500);
  39     tab_transition_tab_index_ = index;
  40     base::ThreadTaskRunnerHandle::Get()->PostDelayedTask(
  41         FROM_HERE, base::Bind(&HoverTabSelector::PerformTabTransition,
  42                               weak_factory_.GetWeakPtr()),
  43         kHoverTransitionDelay);
  44   }
  45 }
  46
  47 void HoverTabSelector::CancelTabTransition() {
  48   weak_factory_.InvalidateWeakPtrs();
  49 }
  50
  51 void HoverTabSelector::PerformTabTransition() {
  52   DCHECK(tab_transition_tab_index_ >= 0 &&
  53          tab_transition_tab_index_ < tab_strip_model_->count());
  54   tab_strip_model_->ActivateTabAt(tab_transition_tab_index_, true);
  55 }
  56