Windows docking should get triggered by pressing against the screen edge

ash/wm/workspace/snap_sizer.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/workspace/snap_sizer.h"
 
 #include <cmath>
 
+#include "ash/ash_switches.h"
+#include "ash/launcher/launcher.h"
 #include "ash/screen_ash.h"
+#include "ash/shell.h"
+#include "ash/shell_window_ids.h"
+#include "ash/wm/dock/docked_window_layout_manager.h"
 #include "ash/wm/property_util.h"
+#include "ash/wm/window_properties.h"
 #include "ash/wm/window_resizer.h"
 #include "ash/wm/window_util.h"
+#include "base/command_line.h"
 #include "ui/aura/window.h"
 #include "ui/gfx/screen.h"
 
 namespace ash {
 namespace internal {
 
 namespace {
 
 // A list of ideal window width in pixel which will be used to populate the
 // |usable_width_| list.
 const int kIdealWidth[] = { 1280, 1024, 768, 640 };
 
 // Windows are initially snapped to the size in |usable_width_| at index 0.
 // The index into |usable_width_| is changed if any of the following happen:
 // . The user stops moving the mouse for |kDelayBeforeIncreaseMS| and then
 //   moves the mouse again.
 // . The mouse moves |kPixelsBeforeAdjust| horizontal pixels.
 // . The mouse is against the edge of the screen and the mouse is moved
 //   |kMovesBeforeAdjust| times.
 const int kDelayBeforeIncreaseMS = 500;
 const int kMovesBeforeAdjust = 25;
 const int kPixelsBeforeAdjust = 100;
 
 // When the smallest resolution does not fit on the screen, we take this
 // fraction of the available space.
 const int kMinimumScreenPercent = 90;
 
 // Create the list of possible width for the current screen configuration:
-// Fill the |usable_width_| list with items from |kIdealWidth| which fit on
-// the screen and supplement it with the 'half of screen' size. Furthermore,
-// add an entry for 90% of the screen size if it is smaller then the biggest
-// value in the |kIdealWidth| list (to get a step between the values).
-std::vector<int> BuildIdealWidthList(aura::Window* window) {
+// Returns a list that for windows that can be snapped (|allow_snap| set)
+// includes items from |kIdealWidth| which fit on the screen and supplement it
+// with the 'half of screen' size. Furthermore, add an entry for 90% of the
+// screen size if it is smaller then the biggest value in the |kIdealWidth|
+// list (to get a step between the values).
+// When a window can be docked (|allow_dock| set) a zero-width is added as the
+// last value to facilitate showing a docking guide.
+std::vector<int> BuildIdealWidthList(aura::Window* window,

[sky, 2013/09/11 19:38:40]

allow_snap is effectively should this function do anything. Such checks should
be at the call site, not the function itself.

[varkha, 2013/09/11 20:02:10]

What about the docking guide (allow_dock)? There are three cases here - the
returned list may contain tiling sequence, docking zero marker or both. This
will be changed with https://codereview.chromium.org/23471004/ so let me rebase
to that and see what is left of this. I would like to leave the ownership of the
tiling or docking guide in this class and transition between those as if they
were part of the same sequence. On the other hand CanDockWindow can be moved
elsewhere.

[varkha, 2013/09/12 19:49:23]

I have removed docking state updates from the SnapSizer so this change is no
longer necessary. The only thing that I am adding here is ability to query this
class if the snapping sequence has been exhausted.

+                                     bool allow_snap,
+                                     bool allow_dock) {
   std::vector<int> ideal_width_list;
-  gfx::Rect work_area(ScreenAsh::GetDisplayWorkAreaBoundsInParent(window));
-  int half_size = work_area.width() / 2;
-  int maximum_width = (kMinimumScreenPercent * work_area.width()) / 100;
-  for (size_t i = 0; i < arraysize(kIdealWidth); i++) {
-    if (maximum_width >= kIdealWidth[i]) {
-      if (i && !ideal_width_list.size() && maximum_width != kIdealWidth[i])
-        ideal_width_list.push_back(maximum_width);
-      if (half_size > kIdealWidth[i])
-        ideal_width_list.push_back(half_size);
-      if (half_size >= kIdealWidth[i])
-        half_size = 0;
-      ideal_width_list.push_back(kIdealWidth[i]);
+  if (allow_snap) {
+    gfx::Rect work_area(ScreenAsh::GetDisplayWorkAreaBoundsInParent(window));
+    int half_size = work_area.width() / 2;
+    int maximum_width = (kMinimumScreenPercent * work_area.width()) / 100;
+    for (size_t i = 0; i < arraysize(kIdealWidth); i++) {
+      if (maximum_width >= kIdealWidth[i]) {
+        if (i && !ideal_width_list.size() && maximum_width != kIdealWidth[i])
+          ideal_width_list.push_back(maximum_width);
+        if (half_size > kIdealWidth[i])
+          ideal_width_list.push_back(half_size);
+        if (half_size >= kIdealWidth[i])
+          half_size = 0;
+        ideal_width_list.push_back(kIdealWidth[i]);
+      }
     }
+    if (half_size)
+      ideal_width_list.push_back(half_size);
   }
-  if (half_size)
-    ideal_width_list.push_back(half_size);
+  if (allow_dock)
+    ideal_width_list.push_back(0);
 
   return ideal_width_list;
 }
 
 }  // namespace
 
 SnapSizer::SnapSizer(aura::Window* window,
                      const gfx::Point& start,
                      Edge edge,
                      InputType input_type)
     : window_(window),
       edge_(edge),
       time_last_update_(base::TimeTicks::Now()),
       size_index_(0),
       resize_disabled_(false),
       num_moves_since_adjust_(0),
       last_adjust_x_(start.x()),
       last_update_x_(start.x()),
       start_x_(start.x()),
-      input_type_(input_type),
-      usable_width_(BuildIdealWidthList(window)) {
+      input_type_(input_type) {
+  aura::Window* dock_container = Shell::GetContainer(
+      window_->GetRootWindow(), kShellWindowId_DockedContainer);
+  dock_layout_ = static_cast<DockedWindowLayoutManager*>(
+      dock_container->layout_manager());
+  bool allow_dock =
+      input_type_ == internal::SnapSizer::WORKSPACE_DRAG_INPUT &&
+      CanDockWindow(window_, edge_);
+  bool allow_snap = !allow_dock ||
+      (wm::CanSnapWindow(window_) &&
+       !dock_layout_->is_dragged_window_docked() &&
+       window->bounds().width() > DockedWindowLayoutManager::kMaxDockWidth);
+  usable_width_ = BuildIdealWidthList(window, allow_snap, allow_dock);
   DCHECK(!usable_width_.empty());
+  UpdateDockedState();
   target_bounds_ = GetTargetBounds();
 }
 
 SnapSizer::~SnapSizer() {
+  // Normally when a drag is completed CompleteDrag will be called making
+  // the following a no-op. updating state is necessary when a window gets
+  // snapped in and out during the drag.
+  if (dock_layout_->is_dragged_window_docked())
+    dock_layout_->UndockDraggedWindow();
 }
 
 void SnapSizer::SnapWindow(aura::Window* window, SnapSizer::Edge edge) {
   if (!wm::CanSnapWindow(window))
     return;
   internal::SnapSizer sizer(window, gfx::Point(), edge,
       internal::SnapSizer::OTHER_INPUT);
   if (wm::IsWindowFullscreen(window) || wm::IsWindowMaximized(window)) {
     // Before we can set the bounds we need to restore the window.
     // Restoring the window will set the window to its restored bounds.
@@ skipping 30 matching lines @@
             std::min(pixels_before_adjust,
                      (workspace_bounds.width() - start_x_) / 10);
       }
     }
     if (std::abs(location.x() - last_adjust_x_) >= pixels_before_adjust ||
         (along_edge && num_moves_since_adjust_ >= kMovesBeforeAdjust)) {
       ChangeBounds(location.x(),
                    CalculateIncrement(location.x(), last_adjust_x_));
     }
   }
+  UpdateDockedState();
   last_update_x_ = location.x();
   time_last_update_ = base::TimeTicks::Now();
 }
 
 gfx::Rect SnapSizer::GetSnapBounds(const gfx::Rect& bounds) {
   int current = 0;
   if (!resize_disabled_) {
     for (current = usable_width_.size() - 1; current >= 0; current--) {
       gfx::Rect target = GetTargetBoundsForSize(current);
       if (target == bounds) {
         ++current;
         break;
       }
     }
   }
   return GetTargetBoundsForSize(current % usable_width_.size());
 }
 
 void SnapSizer::SelectDefaultSizeAndDisableResize() {
   resize_disabled_ = true;
   size_index_ = 0;
+  UpdateDockedState();
   target_bounds_ = GetTargetBounds();
 }
 
 gfx::Rect SnapSizer::GetTargetBoundsForSize(size_t size_index) const {
   gfx::Rect work_area(ScreenAsh::GetDisplayWorkAreaBoundsInParent(window_));
   int y = work_area.y();
   // We don't align to the bottom of the grid as the launcher may not
   // necessarily align to the grid (happens when auto-hidden).
   int max_y = work_area.bottom();
   int width = 0;
   if (resize_disabled_) {
     // Make sure that we keep the size of the window smaller then a certain
     // fraction of the screen space.
     int minimum_size = (kMinimumScreenPercent * work_area.width()) / 100;
     width = std::max(std::min(minimum_size, 1024), work_area.width() / 2);
   } else {
     DCHECK(size_index < usable_width_.size());
     width = usable_width_[size_index];
   }
 
+  if (width == 0) {
+    return ScreenAsh::ConvertRectFromScreen(window_->parent(),
+                                            dock_layout_->dragged_bounds());
+  }
+
   if (edge_ == LEFT_EDGE) {
     int x = work_area.x();
     int mid_x = x + width;
     return gfx::Rect(x, y, mid_x - x, max_y - y);
   }
   int max_x = work_area.right();
   int x = max_x - width;
   return gfx::Rect(x , y, max_x - x, max_y - y);
 }
 
+bool SnapSizer::ShouldDockWindow() const {
+  // TODO(varkha): use dedicated state.
+  return (usable_width_[size_index_] == 0);
+}
+
+// static
+bool SnapSizer::CanDockWindow(aura::Window* window, SnapSizer::Edge edge) {
+  if (!CommandLine::ForCurrentProcess()->HasSwitch(
+      switches::kAshEnableDockedWindows)) {
+    return false;
+  }
+  // Cannot dock on the other size from an existing dock.
+  aura::Window* dock_container = Shell::GetContainer(
+      window->GetRootWindow(), kShellWindowId_DockedContainer);
+  DockedWindowLayoutManager* dock_layout =
+      static_cast<DockedWindowLayoutManager*>(dock_container->layout_manager());
+  const DockedAlignment alignment = dock_layout->CalculateAlignment();
+  if ((edge == LEFT_EDGE && alignment == DOCKED_ALIGNMENT_RIGHT) ||
+      (edge == RIGHT_EDGE && alignment == DOCKED_ALIGNMENT_LEFT)) {
+    return false;
+  }
+
+  // Do not allow docking on the same side as launcher shelf.
+  Launcher* shelf = Launcher::ForWindow(window);
+  if (shelf &&
+      ((edge == LEFT_EDGE && shelf->alignment() == SHELF_ALIGNMENT_LEFT) ||
+       (edge == RIGHT_EDGE && shelf->alignment() == SHELF_ALIGNMENT_RIGHT))) {
+    return false;
+  }
+  return true;
+}
+
 int SnapSizer::CalculateIncrement(int x, int reference_x) const {
   if (AlongEdge(x))
     return 1;
   if (x == reference_x)
     return 0;
   if (edge_ == LEFT_EDGE) {
     if (x < reference_x)
       return 1;
     return -1;
   }
@@ skipping 12 matching lines @@
   }
   num_moves_since_adjust_ = 0;
   last_adjust_x_ = x;
 }
 
 gfx::Rect SnapSizer::GetTargetBounds() const {
   return GetTargetBoundsForSize(size_index_);
 }
 
 bool SnapSizer::AlongEdge(int x) const {
-  gfx::Rect area(ScreenAsh::GetDisplayBoundsInParent(window_));
+  gfx::Rect area(ScreenAsh::GetDisplayWorkAreaBoundsInParent(window_));
   return (x <= area.x()) || (x >= area.right() - 1);
 }
 
+void SnapSizer::UpdateDockedState() {
+  if (ShouldDockWindow() &&
+      dock_layout_->GetAlignmentOfWindow(window_) != DOCKED_ALIGNMENT_NONE) {
+    if (!dock_layout_->is_dragged_window_docked())
+      dock_layout_->DockDraggedWindow(window_);
+    target_bounds_ = GetTargetBounds();
+  } else {
+    if (dock_layout_->is_dragged_window_docked())
+      dock_layout_->UndockDraggedWindow();
+  }
+}
+
 }  // namespace internal
 }  // namespace ash