Minor refactoring of window resize code. I wasn't too happy with

ash/wm/default_window_resizer.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 "ash/wm/window_resizer.h"
+#include "ash/wm/default_window_resizer.h"
 
 #include "ash/shell.h"
 #include "ash/wm/root_window_event_filter.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/root_window.h"
 #include "ui/aura/window.h"
 #include "ui/aura/window_delegate.h"
 #include "ui/base/hit_test.h"
 #include "ui/base/ui_base_types.h"
 #include "ui/gfx/compositor/scoped_layer_animation_settings.h"
 #include "ui/gfx/screen.h"
 
 namespace ash {
 
-namespace {
-
-int GetPositionChangeDirectionForWindowComponent(int window_component) {
-  int pos_change_direction = WindowResizer::kBoundsChangeDirection_None;
-  switch (window_component) {
-    case HTTOPLEFT:
-    case HTBOTTOMRIGHT:
-    case HTGROWBOX:
-    case HTCAPTION:
-      pos_change_direction |=
-          WindowResizer::kBoundsChangeDirection_Horizontal |
-          WindowResizer::kBoundsChangeDirection_Vertical;
-      break;
-    case HTTOP:
-    case HTTOPRIGHT:
-    case HTBOTTOM:
-      pos_change_direction |= WindowResizer::kBoundsChangeDirection_Vertical;
-      break;
-    case HTBOTTOMLEFT:
-    case HTRIGHT:
-    case HTLEFT:
-      pos_change_direction |= WindowResizer::kBoundsChangeDirection_Horizontal;
-      break;
-    default:
-      break;
-  }
-  return pos_change_direction;
-}
-
-int GetSizeChangeDirectionForWindowComponent(int window_component) {
-  int size_change_direction = WindowResizer::kBoundsChangeDirection_None;
-  switch (window_component) {
-    case HTTOPLEFT:
-    case HTTOPRIGHT:
-    case HTBOTTOMLEFT:
-    case HTBOTTOMRIGHT:
-    case HTGROWBOX:
-    case HTCAPTION:
-      size_change_direction |=
-          WindowResizer::kBoundsChangeDirection_Horizontal |
-          WindowResizer::kBoundsChangeDirection_Vertical;
-      break;
-    case HTTOP:
-    case HTBOTTOM:
-      size_change_direction |= WindowResizer::kBoundsChangeDirection_Vertical;
-      break;
-    case HTRIGHT:
-    case HTLEFT:
-      size_change_direction |= WindowResizer::kBoundsChangeDirection_Horizontal;
-      break;
-    default:
-      break;
-  }
-  return size_change_direction;
-}
-
-// Returns true for resize components along the right edge, where a drag in
-// positive x will make the window larger.
-bool IsRightEdge(int window_component) {
-  return window_component == HTTOPRIGHT ||
-      window_component == HTRIGHT ||
-      window_component == HTBOTTOMRIGHT ||
-      window_component == HTGROWBOX;
-}
-
-// Returns true for resize components in along the bottom edge, where a drag
-// in positive y will make the window larger.
-bool IsBottomEdge(int window_component) {
-  return window_component == HTBOTTOMLEFT ||
-      window_component == HTBOTTOM ||
-      window_component == HTBOTTOMRIGHT ||
-      window_component == HTGROWBOX;
-}
-
-// Returns the closest location to |location| that is aligned to fall on
-// increments of |grid_size|.
-int AlignToGridRoundUp(int location, int grid_size) {
-  if (grid_size <= 1 || location % grid_size == 0)
-    return location;
-  return (location / grid_size + 1) * grid_size;
-}
-
-gfx::Point ConvertPointToParent(aura::Window* window,
-                                const gfx::Point& point) {
-  gfx::Point result(point);
-  aura::Window::ConvertPointToWindow(window, window->parent(), &result);
-  return result;
-}
-
-}  // namespace
-
-// static
-const int WindowResizer::kBoundsChange_None = 0;
-// static
-const int WindowResizer::kBoundsChange_Repositions = 1;
-// static
-const int WindowResizer::kBoundsChange_Resizes = 2;
-
-// static
-const int WindowResizer::kBoundsChangeDirection_None = 0;
-// static
-const int WindowResizer::kBoundsChangeDirection_Horizontal = 1;
-// static
-const int WindowResizer::kBoundsChangeDirection_Vertical = 2;
-
-WindowResizer::WindowResizer(aura::Window* window,
-                             const gfx::Point& location,
-                             int window_component,
-                             int grid_size)
-    : window_(window),
-      initial_bounds_(window->bounds()),
-      initial_location_in_parent_(ConvertPointToParent(window, location)),
-      window_component_(window_component),
-      bounds_change_(GetBoundsChangeForWindowComponent(window_component_)),
-      position_change_direction_(
-          GetPositionChangeDirectionForWindowComponent(window_component_)),
-      size_change_direction_(
-          GetSizeChangeDirectionForWindowComponent(window_component_)),
-      is_resizable_(bounds_change_ != kBoundsChangeDirection_None),
-      grid_size_(grid_size),
-      did_move_or_resize_(false),
-      root_filter_(NULL) {
-  if (is_resizable_) {
-    root_filter_ = Shell::GetInstance()->root_filter();
-    if (root_filter_)
-      root_filter_->LockCursor();
-  }
-}
-
-WindowResizer::~WindowResizer() {
+DefaultWindowResizer::~DefaultWindowResizer() {
   if (root_filter_)
     root_filter_->UnlockCursor();
 }
 
 // static
-int WindowResizer::GetBoundsChangeForWindowComponent(int component) {
-  int bounds_change = WindowResizer::kBoundsChange_None;
-  switch (component) {
-    case HTTOPLEFT:
-    case HTTOP:
-    case HTTOPRIGHT:
-    case HTLEFT:
-    case HTBOTTOMLEFT:
-      bounds_change |= WindowResizer::kBoundsChange_Repositions |
-                      WindowResizer::kBoundsChange_Resizes;
-      break;
-    case HTCAPTION:
-      bounds_change |= WindowResizer::kBoundsChange_Repositions;
-      break;
-    case HTRIGHT:
-    case HTBOTTOMRIGHT:
-    case HTBOTTOM:
-    case HTGROWBOX:
-      bounds_change |= WindowResizer::kBoundsChange_Resizes;
-      break;
-    default:
-      break;
-  }
-  return bounds_change;
+DefaultWindowResizer*
+DefaultWindowResizer::Create(aura::Window* window,
+                             const gfx::Point& location,
+                             int window_component,
+                             int grid_size) {
+  Details details(window, location, window_component, grid_size);
+  return details.is_resizable ? new DefaultWindowResizer(details) : NULL;
 }
 
-// static
-int WindowResizer::AlignToGrid(int location, int grid_size) {
-  if (grid_size <= 1 || location % grid_size == 0)
-    return location;
-  return floor(static_cast<float>(location) / static_cast<float>(grid_size) +
-               .5f) * grid_size;
-}
-
-void WindowResizer::Drag(const gfx::Point& location) {
-  gfx::Rect bounds = GetBoundsForDrag(location);
-  if (bounds != window_->bounds()) {
+void DefaultWindowResizer::Drag(const gfx::Point& location) {
+  gfx::Rect bounds(CalculateBoundsForDrag(details_, location));
+  if (bounds != details_.window->bounds()) {
     did_move_or_resize_ = true;
-    window_->SetBounds(bounds);
+    details_.window->SetBounds(bounds);
   }
 }
 
-void WindowResizer::CompleteDrag() {
-  if (grid_size_ <= 1 || !did_move_or_resize_)
+void DefaultWindowResizer::CompleteDrag() {
+  if (details_.grid_size <= 1 || !did_move_or_resize_)
     return;
-  gfx::Rect new_bounds(GetFinalBounds());
-  if (new_bounds == window_->bounds())
+  gfx::Rect new_bounds(AdjustBoundsToGrid(details_));
+  if (new_bounds == details_.window->bounds())
     return;
 
-  if (new_bounds.size() != window_->bounds().size()) {
+  if (new_bounds.size() != details_.window->bounds().size()) {
     // Don't attempt to animate a size change.
-    window_->SetBounds(new_bounds);
+    details_.window->SetBounds(new_bounds);
     return;
   }
 
   ui::ScopedLayerAnimationSettings scoped_setter(
-      window_->layer()->GetAnimator());
+      details_.window->layer()->GetAnimator());
   // Use a small duration since the grid is small.
   scoped_setter.SetTransitionDuration(base::TimeDelta::FromMilliseconds(100));
-  window_->SetBounds(new_bounds);
+  details_.window->SetBounds(new_bounds);
 }
 
-void WindowResizer::RevertDrag() {
+void DefaultWindowResizer::RevertDrag() {
   if (!did_move_or_resize_)
     return;
 
-  window_->SetBounds(initial_bounds_);
+  details_.window->SetBounds(details_.initial_bounds);
 }
 
-gfx::Rect WindowResizer::GetBoundsForDrag(const gfx::Point& location) {
-  if (!is_resizable())
-    return window_->bounds();
-
-  // Dragging a window moves the local coordinate frame, so do arithmetic
-  // in the parent coordinate frame.
-  gfx::Point event_location_in_parent(location);
-  aura::Window::ConvertPointToWindow(window_, window_->parent(),
-                                     &event_location_in_parent);
-  int delta_x = event_location_in_parent.x() - initial_location_in_parent_.x();
-  int delta_y = event_location_in_parent.y() - initial_location_in_parent_.y();
-
-  // The minimize size constraint may limit how much we change the window
-  // position.  For example, dragging the left edge to the right should stop
-  // repositioning the window when the minimize size is reached.
-  gfx::Size size = GetSizeForDrag(&delta_x, &delta_y);
-  gfx::Point origin = GetOriginForDrag(delta_x, delta_y);
-
-  gfx::Rect new_bounds(origin, size);
-  // Update bottom edge to stay in the work area when we are resizing
-  // by dragging the bottome edge or corners.
-  if (bounds_change_ & kBoundsChange_Resizes &&
-      origin.y() == window_->bounds().y()) {
-    gfx::Rect work_area = gfx::Screen::GetMonitorWorkAreaNearestWindow(window_);
-    if (new_bounds.bottom() > work_area.bottom())
-      new_bounds.Inset(0, 0, 0,
-                       new_bounds.bottom() - work_area.bottom());
-  }
-  if (bounds_change_ & kBoundsChange_Resizes &&
-      bounds_change_ & kBoundsChange_Repositions && new_bounds.y() < 0) {
-    int delta = new_bounds.y();
-    new_bounds.set_y(0);
-    new_bounds.set_height(new_bounds.height() + delta);
-  }
-  return new_bounds;
-}
-
-gfx::Rect WindowResizer::GetFinalBounds() {
-  const gfx::Rect& bounds(window_->bounds());
-  int x = AlignToGrid(bounds.x(), grid_size_);
-  int y = AlignToGrid(bounds.y(), grid_size_);
-  return gfx::Rect(x, y, bounds.width(), bounds.height());
-}
-
-gfx::Point WindowResizer::GetOriginForDrag(
-    int delta_x,
-    int delta_y) const {
-  gfx::Point origin = initial_bounds_.origin();
-  if (bounds_change_ & kBoundsChange_Repositions) {
-    int pos_change_direction =
-        GetPositionChangeDirectionForWindowComponent(window_component_);
-    if (pos_change_direction & kBoundsChangeDirection_Horizontal)
-      origin.Offset(delta_x, 0);
-    if (pos_change_direction & kBoundsChangeDirection_Vertical)
-      origin.Offset(0, delta_y);
-  }
-  return origin;
-}
-
-gfx::Size WindowResizer::GetSizeForDrag(
-    int* delta_x,
-    int* delta_y) const {
-  gfx::Size size = initial_bounds_.size();
-  if (bounds_change_ & kBoundsChange_Resizes) {
-    gfx::Size min_size = window_->delegate()->GetMinimumSize();
-    min_size.set_width(AlignToGridRoundUp(min_size.width(), grid_size_));
-    min_size.set_height(AlignToGridRoundUp(min_size.height(), grid_size_));
-    size.SetSize(GetWidthForDrag(min_size.width(), delta_x),
-                 GetHeightForDrag(min_size.height(), delta_y));
-  }
-  return size;
-}
-
-int WindowResizer::GetWidthForDrag(int min_width, int* delta_x) const {
-  int width = initial_bounds_.width();
-  if (size_change_direction_ & kBoundsChangeDirection_Horizontal) {
-    // Along the right edge, positive delta_x increases the window size.
-    int x_multiplier = IsRightEdge(window_component_) ? 1 : -1;
-    width += x_multiplier * (*delta_x);
-    int adjusted_width = AlignToGrid(width, grid_size_);
-    if (adjusted_width != width) {
-      *delta_x += -x_multiplier * (width - adjusted_width);
-      width = adjusted_width;
-    }
-
-    // Ensure we don't shrink past the minimum width and clamp delta_x
-    // for the window origin computation.
-    if (width < min_width) {
-      width = min_width;
-      *delta_x = -x_multiplier * (initial_bounds_.width() - min_width);
-    }
-
-    // And don't let the window go bigger than the monitor.
-    int max_width =
-        gfx::Screen::GetMonitorAreaNearestWindow(window_).width();
-    if (width > max_width) {
-      width = max_width;
-      *delta_x = -x_multiplier * (initial_bounds_.width() - max_width);
-    }
-  }
-  return width;
-}
-
-int WindowResizer::GetHeightForDrag(int min_height, int* delta_y) const {
-  int height = initial_bounds_.height();
-  if (size_change_direction_ & kBoundsChangeDirection_Vertical) {
-    // Along the bottom edge, positive delta_y increases the window size.
-    int y_multiplier = IsBottomEdge(window_component_) ? 1 : -1;
-    height += y_multiplier * (*delta_y);
-    int adjusted_height = AlignToGrid(height, grid_size_);
-    if (height != adjusted_height) {
-      *delta_y += -y_multiplier * (height - adjusted_height);
-      height = adjusted_height;
-    }
-
-    // Ensure we don't shrink past the minimum height and clamp delta_y
-    // for the window origin computation.
-    if (height < min_height) {
-      height = min_height;
-      *delta_y = -y_multiplier * (initial_bounds_.height() - min_height);
-    }
-
-    // And don't let the window go bigger than the monitor.
-    int max_height = gfx::Screen::GetMonitorAreaNearestWindow(window_).height();
-    if (height > max_height) {
-      height = max_height;
-      *delta_y = -y_multiplier * (initial_bounds_.height() - max_height);
-    }
-  }
-  return height;
+DefaultWindowResizer::DefaultWindowResizer(const Details& details)
+    : details_(details),
+      did_move_or_resize_(false),
+      root_filter_(NULL) {
+  DCHECK(details_.is_resizable);
+  root_filter_ = Shell::GetInstance()->root_filter();
+  if (root_filter_)
+    root_filter_->LockCursor();
 }
 
 }  // namespace aura