Attempt 3 at a better touch tabstrip. There is still a bunch to do,

chrome/browser/ui/views/tabs/touch_tab_strip_layout.cc

+// Copyright (c) 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 "chrome/browser/ui/views/tabs/touch_tab_strip_layout.h"
+
+#include <stdio.h>
+
+#include "base/logging.h"
+#include "base/string_number_conversions.h"
+
+TouchTabStripLayout::TouchTabStripLayout(const gfx::Size& size,
+                                         int padding,
+                                         int stacked_padding,
+                                         int max_stacked_count,
+                                         views::ViewModel* view_model)
+    : size_(size),
+      padding_(padding),
+      stacked_padding_(stacked_padding),
+      max_stacked_count_(max_stacked_count),
+      view_model_(view_model),
+      x_(0),
+      width_(0),
+      mini_tab_count_(0),
+      active_index_(-1) {
+}
+
+TouchTabStripLayout::~TouchTabStripLayout() {
+}
+
+void TouchTabStripLayout::SetXAndMiniCount(int x, int mini_tab_count) {
+  x_ = x;
+  mini_tab_count_ = mini_tab_count;
+  SetIdealBoundsAt(active_index(), ConstrainActiveX(ideal_x(active_index())));
+  LayoutByTabOffsetAfter(active_index());
+  LayoutByTabOffsetBefore(active_index());
+}
+
+void TouchTabStripLayout::SetWidth(int width) {
+  if (width_ == width)
+    return;
+
+  width_ = width;
+  if (!requires_stacking()) {
+    ResetToIdealState();
+    return;
+  }
+  SetActiveBoundsAndLayoutFromActiveTab();
+}
+
+void TouchTabStripLayout::SetActiveIndex(int index) {
+  int old = active_index();
+  active_index_ = index;
+  if (old == active_index() || !requires_stacking())
+    return;
+  SetIdealBoundsAt(active_index(), ConstrainActiveX(ideal_x(active_index())));
+  LayoutByTabOffsetBefore(active_index());
+  LayoutByTabOffsetAfter(active_index());
+  AdjustStackedTabs();
+}
+
+void TouchTabStripLayout::DragActiveTab(int delta) {
+  if (delta == 0 && !requires_stacking())
+    return;
+  int initial_x = ideal_x(active_index());
+  // If we're at a particular edge and start dragging, reset to ideal state.
+  if ((delta > 0 && initial_x == GetMinX(active_index())) ||
+      (delta < 0 && initial_x == GetMaxX(active_index()))) {
+    ResetToIdealState();
+  }
+  int x = delta > 0 ?
+      std::min(initial_x + delta, GetMaxX(active_index())) :
+      std::max(initial_x + delta, GetMinX(active_index()));
+  if (x != initial_x) {
+    SetIdealBoundsAt(active_index(), x);
+    LayoutByTabOffsetAfter(active_index());
+    LayoutByTabOffsetBefore(active_index());
+    delta -= (x - initial_x);
+  }
+  if (delta > 0)
+    ExpandTabsBefore(active_index(), delta);
+  else if (delta < 0)
+    ExpandTabsAfter(active_index(), -delta);
+  AdjustStackedTabs();
+}
+
+void TouchTabStripLayout::AddTab(int index,
+                                 int add_types,
+                                 int start_x) {
+  if (add_types & kAddTypeActive)
+    active_index_ = index;
+  else if (active_index_ >= index)
+    active_index_++;
+  if (add_types & kAddTypeMini)
+    mini_tab_count_++;
+  x_ = start_x;
+  if (!requires_stacking() || normal_tab_count() <= 1) {
+    ResetToIdealState();
+    return;
+  }
+  int active_x = (index + 1 == tab_count()) ?
+      width_ - size_.width() : ideal_x(index + 1);
+  SetIdealBoundsAt(active_index(), ConstrainActiveX(active_x));
+  LayoutByTabOffsetAfter(active_index());
+  LayoutByTabOffsetBefore(active_index());
+  AdjustStackedTabs();
+}
+
+void TouchTabStripLayout::RemoveTab(int index, int start_x, int old_x) {
+  if (index == active_index_)
+    active_index_ = std::min(active_index_, tab_count() - 1);
+  else if (index > active_index_)
+    active_index_--;
+  bool removed_mini_tab = index < mini_tab_count_;
+  if (removed_mini_tab) {
+    mini_tab_count_--;
+    DCHECK_GE(mini_tab_count_, 0);
+  }
+  int delta = start_x - x_;
+  x_ = start_x;
+  if (!requires_stacking()) {
+    ResetToIdealState();
+    return;
+  }
+  if (removed_mini_tab) {
+    for (int i = mini_tab_count_; i < tab_count(); ++i)
+      SetIdealBoundsAt(i, ideal_x(i) + delta);
+  }
+  SetActiveBoundsAndLayoutFromActiveTab();
+  AdjustStackedTabs();
+}
+
+void TouchTabStripLayout::MoveTab(int from,
+                                  int to,
+                                  int new_active_index,
+                                  int start_x,
+                                  int mini_tab_count) {
+  x_ = start_x;
+  mini_tab_count_ = mini_tab_count;
+  active_index_ = new_active_index;
+  SetIdealBoundsAt(active_index(), ConstrainActiveX(ideal_x(active_index())));
+  LayoutByTabOffsetAfter(active_index());
+  LayoutByTabOffsetBefore(active_index());
+  AdjustStackedTabs();
+}
+
+void TouchTabStripLayout::Reset(int x,
+                                int width,
+                                int mini_tab_count,
+                                int active_index) {
+  x_ = x;
+  width_ = width;
+  mini_tab_count_ = mini_tab_count;
+  active_index_ = active_index;
+  ResetToIdealState();
+}
+
+void TouchTabStripLayout::ResetToIdealState() {
+  if (tab_count() == mini_tab_count_)
+    return;
+
+  if (!requires_stacking()) {
+    SetIdealBoundsAt(mini_tab_count_, x_);
+    LayoutByTabOffsetAfter(mini_tab_count_);
+    return;
+  }
+
+  if (normal_tab_count() == 1) {
+    // TODO: might want to shrink the tab here.
+    SetIdealBoundsAt(mini_tab_count_, 0);
+    return;
+  }
+
+  int available_width = width_ - x_;
+  int leading_count = active_index() - mini_tab_count_;
+  int trailing_count = tab_count() - active_index();
+  if (width_for_count(leading_count + 1) + max_stacked_width() <
+      available_width) {
+    SetIdealBoundsAt(mini_tab_count_, x_);
+    LayoutByTabOffsetAfter(mini_tab_count_);
+  } else if (width_for_count(trailing_count) + max_stacked_width() <
+             available_width) {
+    SetIdealBoundsAt(tab_count() - 1, width_ - size_.width());
+    LayoutByTabOffsetBefore(tab_count() - 1);
+  } else {
+    int index = active_index();
+    do {
+      int stacked_padding = stacked_padding_for_count(index - mini_tab_count_);
+      SetIdealBoundsAt(index, x_ + stacked_padding);
+      LayoutByTabOffsetAfter(index);
+      LayoutByTabOffsetBefore(index);
+      index--;
+    } while (index >= mini_tab_count_ && ideal_x(mini_tab_count_) != x_ &&
+             ideal_x(tab_count() - 1) != width_ - size_.width());
+  }
+  AdjustStackedTabs();
+}
+
+int TouchTabStripLayout::ConstrainActiveX(int x) const {
+  return std::min(GetMaxX(active_index()),
+                  std::max(GetMinX(active_index()), x));
+}
+
+void TouchTabStripLayout::SetActiveBoundsAndLayoutFromActiveTab() {
+  int x = ConstrainActiveX(ideal_x(active_index()));
+  SetIdealBoundsAt(active_index(), x);
+  LayoutUsingCurrentBefore(active_index());
+  LayoutUsingCurrentAfter(active_index());
+  AdjustStackedTabs();
+}
+
+void TouchTabStripLayout::LayoutByTabOffsetAfter(int index) {
+  for (int i = index + 1; i < tab_count(); ++i) {
+    int max_x = width_ - size_.width() -
+        stacked_padding_for_count(tab_count() - i - 1);
+    int x = std::min(max_x,
+                     view_model_->ideal_bounds(i - 1).x() + tab_offset());
+    SetIdealBoundsAt(i, x);
+  }
+}
+
+void TouchTabStripLayout::LayoutByTabOffsetBefore(int index) {
+  for (int i = index - 1; i >= mini_tab_count_; --i) {
+    int min_x = x_ + stacked_padding_for_count(i - mini_tab_count_);
+    int x = std::max(min_x, ideal_x(i + 1) - (tab_offset()));
+    SetIdealBoundsAt(i, x);
+  }
+}
+
+void TouchTabStripLayout::LayoutUsingCurrentAfter(int index) {
+  for (int i = index + 1; i < tab_count(); ++i) {
+    int min_x = width_ - width_for_count(tab_count() - i);
+    int x = std::max(min_x,
+                     std::min(ideal_x(i), ideal_x(i - 1) + tab_offset()));
+    x = std::min(GetMaxX(i), x);
+    SetIdealBoundsAt(i, x);
+  }
+}
+
+void TouchTabStripLayout::LayoutUsingCurrentBefore(int index) {
+  for (int i = index - 1; i >= mini_tab_count_; --i) {
+    int max_x = x_ + width_for_count(i - mini_tab_count_);
+    SetIdealBoundsAt(
+        i, std::min(max_x,
+                    std::max(ideal_x(i), ideal_x(i + 1) - tab_offset())));
+  }
+}
+
+void TouchTabStripLayout::ExpandTabsBefore(int index, int delta) {
+  if (index == mini_tab_count_ + 1)
+    return;  // Nothing to expand.
+
+  for (int i = index - 1; i > mini_tab_count_ && delta > 0; --i) {
+    int to_resize = std::min(delta, GetMaxXCompressed(i) - ideal_x(i));
+    if (to_resize <= 0)
+      continue;
+    SetIdealBoundsAt(i, ideal_x(i) + to_resize);
+    delta -= to_resize;
+    LayoutByTabOffsetBefore(i);
+  }
+}
+
+void TouchTabStripLayout::ExpandTabsAfter(int index, int delta) {
+  if (index == tab_count() - 1)
+    return;  // Nothing to expand.
+
+  for (int i = index + 1; i < tab_count() - 1 && delta > 0; ++i) {
+    int to_resize = std::min(ideal_x(i) - GetMinXCompressed(i), delta);
+    if (to_resize <= 0)
+      continue;
+    SetIdealBoundsAt(i, ideal_x(i) - to_resize);
+    delta -= to_resize;
+    LayoutByTabOffsetAfter(i);
+  }
+}
+
+void TouchTabStripLayout::AdjustStackedTabs() {
+  if (!requires_stacking() || mini_tab_count_ == tab_count())
+    return;
+
+  AdjustLeadingStackedTabs();
+  AdjustTrailingStackedTabs();
+}
+
+void TouchTabStripLayout::AdjustLeadingStackedTabs() {
+  int index = mini_tab_count_ + 1;
+  while (index < active_index() &&
+         ideal_x(index) - ideal_x(index - 1) <= stacked_padding_ &&
+         ideal_x(index) <= x_ + max_stacked_width()) {
+    index++;
+  }
+  if (ideal_x(index) - ideal_x(index - 1) <= stacked_padding_ &&
+      ideal_x(index) <= x_ + max_stacked_width()) {
+    index++;
+  }
+  if (index <= mini_tab_count_ + max_stacked_count_ - 1)
+    return;
+  int max_stacked = index;
+  int x = x_;
+  index = mini_tab_count_;
+  for (; index < max_stacked - max_stacked_count_ - 1; ++index)
+    SetIdealBoundsAt(index, x);
+  for (; index < max_stacked; ++index, x += stacked_padding_)
+    SetIdealBoundsAt(index, x);
+}
+
+void TouchTabStripLayout::AdjustTrailingStackedTabs() {
+  int index = tab_count() - 1;
+  int max_stacked_x = width_ - size_.width() - max_stacked_width();
+  while (index > active_index() &&
+         ideal_x(index) - ideal_x(index - 1) <= stacked_padding_ &&
+         ideal_x(index - 1) >= max_stacked_x) {
+    index--;
+  }
+  if (ideal_x(index) - ideal_x(index - 1) <= stacked_padding_ &&
+      ideal_x(index - 1) >= max_stacked_x) {
+    index--;
+  }
+  if (index >= tab_count() - max_stacked_count_)
+    return;
+  int first_stacked = index;
+  int x = width_ - size_.width() -
+      std::min(tab_count() - first_stacked, max_stacked_count_) *
+      stacked_padding_;
+  for (; index < first_stacked + max_stacked_count_;
+       ++index, x += stacked_padding_) {
+    SetIdealBoundsAt(index, x);
+  }
+  for (; index < tab_count(); ++index)
+    SetIdealBoundsAt(index, x);
+}
+
+void TouchTabStripLayout::SetIdealBoundsAt(int index, int x) {
+  view_model_->set_ideal_bounds(index, gfx::Rect(gfx::Point(x, 0), size_));
+}
+
+int TouchTabStripLayout::GetMinX(int index) const {
+  int leading_count = index - mini_tab_count_;
+  int trailing_count = tab_count() - index;
+  return std::max(x_ + stacked_padding_for_count(leading_count),
+                  width_ - width_for_count(trailing_count));
+}
+
+int TouchTabStripLayout::GetMaxX(int index) const {
+  int leading_count = index - mini_tab_count_;
+  int trailing_count = tab_count() - index - 1;
+  int trailing_offset = stacked_padding_for_count(trailing_count);
+  int leading_size = width_for_count(leading_count) + x_;
+  if (leading_count > 0)
+    leading_size += padding_;
+  return std::min(width_ - trailing_offset - size_.width(), leading_size);
+}
+
+int TouchTabStripLayout::GetMaxXCompressed(int index) const {
+  DCHECK_LT(index, active_index());
+  DCHECK_GT(index, mini_tab_count_);
+  int trailing = active_index() - index;
+  return std::min(
+      x_ + width_for_count(index - mini_tab_count_) + padding_,
+      ideal_x(active_index()) - stacked_padding_for_count(trailing));
+}
+
+int TouchTabStripLayout::GetMinXCompressed(int index) const {
+  DCHECK_GT(index, active_index());
+  return std::max(
+      width_ - width_for_count(tab_count() - index),
+      ideal_x(active_index()) +
+          stacked_padding_for_count(index - active_index()));
+
+}
+
+#if !defined(NDEBUG)
+std::string TouchTabStripLayout::BoundsString() const {
+  std::string result;
+  for (int i = 0; i < view_model_->view_size(); ++i) {
+    if (!result.empty())
+      result += " ";
+    if (i == active_index())
+      result += "[";
+    result += base::IntToString(view_model_->ideal_bounds(i).x());
+    if (i == active_index())
+      result += "]";
+  }
+  return result;
+}
+#endif