root/ui/views/controls/scroll_view.cc

DEFINITIONS

1. OnNativeThemeChanged
2. SetThemeSpecificState
3. CheckScrollBounds
4. CheckScrollBounds
5. AdjustPosition
6. Viewport
7. Viewport
8. GetClassName
9. ScrollRectToVisible
10. ChildPreferredSizeChanged
11. hide_horizontal_scrollbar_
12. CreateScrollViewWithBorder
13. SetContents
14. SetHeader
15. GetVisibleRect
16. ClipHeightTo
17. GetScrollBarWidth
18. GetScrollBarHeight
19. SetHorizontalScrollBar
20. SetVerticalScrollBar
21. GetPreferredSize
22. GetHeightForWidth
23. Layout
24. OnKeyPressed
25. OnMouseWheel
26. OnMouseEntered
27. OnMouseExited
28. OnGestureEvent
29. GetClassName
30. ScrollToPosition
31. GetScrollIncrement
32. SetHeaderOrContents
33. ScrollContentsRegionToBeVisible
34. ComputeScrollBarsVisibility
35. SetControlVisibility
36. UpdateScrollBarPositions
37. GetPageScrollIncrement
38. GetLineScrollIncrement
39. GetRowInfo
40. row_height_
41. GetRowInfo

// 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 "ui/views/controls/scroll_view.h"

#include "base/logging.h"
#include "ui/events/event.h"
#include "ui/native_theme/native_theme.h"
#include "ui/views/border.h"
#include "ui/views/controls/scrollbar/native_scroll_bar.h"
#include "ui/views/widget/root_view.h"

namespace views {

const char ScrollView::kViewClassName[] = "ScrollView";

namespace {

// Subclass of ScrollView that resets the border when the theme changes.
class ScrollViewWithBorder : public views::ScrollView {
 public:
  ScrollViewWithBorder() {
    SetThemeSpecificState();
  }

  // View overrides;
  virtual void OnNativeThemeChanged(const ui::NativeTheme* theme) OVERRIDE {
    SetThemeSpecificState();
  }

 private:
  void SetThemeSpecificState() {
    SetBorder(Border::CreateSolidBorder(
        1,
        GetNativeTheme()->GetSystemColor(
            ui::NativeTheme::kColorId_UnfocusedBorderColor)));
  }

  DISALLOW_COPY_AND_ASSIGN(ScrollViewWithBorder);
};

// Returns the position for the view so that it isn't scrolled off the visible
// region.
int CheckScrollBounds(int viewport_size, int content_size, int current_pos) {
  int max = std::max(content_size - viewport_size, 0);
  if (current_pos < 0)
    return 0;
  if (current_pos > max)
    return max;
  return current_pos;
}

// Make sure the content is not scrolled out of bounds
void CheckScrollBounds(View* viewport, View* view) {
  if (!view)
    return;

  int x = CheckScrollBounds(viewport->width(), view->width(), -view->x());
  int y = CheckScrollBounds(viewport->height(), view->height(), -view->y());

  // This is no op if bounds are the same
  view->SetBounds(-x, -y, view->width(), view->height());
}

// Used by ScrollToPosition() to make sure the new position fits within the
// allowed scroll range.
int AdjustPosition(int current_position,
                   int new_position,
                   int content_size,
                   int viewport_size) {
  if (-current_position == new_position)
    return new_position;
  if (new_position < 0)
    return 0;
  const int max_position = std::max(0, content_size - viewport_size);
  return (new_position > max_position) ? max_position : new_position;
}

}  // namespace

// Viewport contains the contents View of the ScrollView.
class ScrollView::Viewport : public View {
 public:
  Viewport() {}
  virtual ~Viewport() {}

  virtual const char* GetClassName() const OVERRIDE {
    return "ScrollView::Viewport";
  }

  virtual void ScrollRectToVisible(const gfx::Rect& rect) OVERRIDE {
    if (!has_children() || !parent())
      return;

    View* contents = child_at(0);
    gfx::Rect scroll_rect(rect);
    scroll_rect.Offset(-contents->x(), -contents->y());
    static_cast<ScrollView*>(parent())->ScrollContentsRegionToBeVisible(
        scroll_rect);
  }

  virtual void ChildPreferredSizeChanged(View* child) OVERRIDE {
    if (parent())
      parent()->Layout();
  }

 private:
  DISALLOW_COPY_AND_ASSIGN(Viewport);
};

ScrollView::ScrollView()
    : contents_(NULL),
      contents_viewport_(new Viewport()),
      header_(NULL),
      header_viewport_(new Viewport()),
      horiz_sb_(new NativeScrollBar(true)),
      vert_sb_(new NativeScrollBar(false)),
      resize_corner_(NULL),
      min_height_(-1),
      max_height_(-1),
      hide_horizontal_scrollbar_(false) {
  set_notify_enter_exit_on_child(true);

  AddChildView(contents_viewport_);
  AddChildView(header_viewport_);

  // Don't add the scrollbars as children until we discover we need them
  // (ShowOrHideScrollBar).
  horiz_sb_->SetVisible(false);
  horiz_sb_->set_controller(this);
  vert_sb_->SetVisible(false);
  vert_sb_->set_controller(this);
  if (resize_corner_)
    resize_corner_->SetVisible(false);
}

ScrollView::~ScrollView() {
  // The scrollbars may not have been added, delete them to ensure they get
  // deleted.
  delete horiz_sb_;
  delete vert_sb_;

  if (resize_corner_ && !resize_corner_->parent())
    delete resize_corner_;
}

// static
ScrollView* ScrollView::CreateScrollViewWithBorder() {
  return new ScrollViewWithBorder();
}

void ScrollView::SetContents(View* a_view) {
  SetHeaderOrContents(contents_viewport_, a_view, &contents_);
}

void ScrollView::SetHeader(View* header) {
  SetHeaderOrContents(header_viewport_, header, &header_);
}

gfx::Rect ScrollView::GetVisibleRect() const {
  if (!contents_)
    return gfx::Rect();
  return gfx::Rect(-contents_->x(), -contents_->y(),
                   contents_viewport_->width(), contents_viewport_->height());
}

void ScrollView::ClipHeightTo(int min_height, int max_height) {
  min_height_ = min_height;
  max_height_ = max_height;
}

int ScrollView::GetScrollBarWidth() const {
  return vert_sb_ ? vert_sb_->GetLayoutSize() : 0;
}

int ScrollView::GetScrollBarHeight() const {
  return horiz_sb_ ? horiz_sb_->GetLayoutSize() : 0;
}

void ScrollView::SetHorizontalScrollBar(ScrollBar* horiz_sb) {
  DCHECK(horiz_sb);
  horiz_sb->SetVisible(horiz_sb_->visible());
  delete horiz_sb_;
  horiz_sb->set_controller(this);
  horiz_sb_ = horiz_sb;
}

void ScrollView::SetVerticalScrollBar(ScrollBar* vert_sb) {
  DCHECK(vert_sb);
  vert_sb->SetVisible(vert_sb_->visible());
  delete vert_sb_;
  vert_sb->set_controller(this);
  vert_sb_ = vert_sb;
}

gfx::Size ScrollView::GetPreferredSize() {
  if (!is_bounded())
    return View::GetPreferredSize();

  gfx::Size size = contents()->GetPreferredSize();
  size.SetToMax(gfx::Size(size.width(), min_height_));
  size.SetToMin(gfx::Size(size.width(), max_height_));
  gfx::Insets insets = GetInsets();
  size.Enlarge(insets.width(), insets.height());
  return size;
}

int ScrollView::GetHeightForWidth(int width) {
  if (!is_bounded())
    return View::GetHeightForWidth(width);

  gfx::Insets insets = GetInsets();
  width = std::max(0, width - insets.width());
  int height = contents()->GetHeightForWidth(width) + insets.height();
  return std::min(std::max(height, min_height_), max_height_);
}

void ScrollView::Layout() {
  if (is_bounded()) {
    int content_width = width();
    int content_height = contents()->GetHeightForWidth(content_width);
    if (content_height > height()) {
      content_width = std::max(content_width - GetScrollBarWidth(), 0);
      content_height = contents()->GetHeightForWidth(content_width);
    }
    if (contents()->bounds().size() != gfx::Size(content_width, content_height))
      contents()->SetBounds(0, 0, content_width, content_height);
  }

  // Most views will want to auto-fit the available space. Most of them want to
  // use all available width (without overflowing) and only overflow in
  // height. Examples are HistoryView, MostVisitedView, DownloadTabView, etc.
  // Other views want to fit in both ways. An example is PrintView. To make both
  // happy, assume a vertical scrollbar but no horizontal scrollbar. To override
  // this default behavior, the inner view has to calculate the available space,
  // used ComputeScrollBarsVisibility() to use the same calculation that is done
  // here and sets its bound to fit within.
  gfx::Rect viewport_bounds = GetContentsBounds();
  const int contents_x = viewport_bounds.x();
  const int contents_y = viewport_bounds.y();
  if (viewport_bounds.IsEmpty()) {
    // There's nothing to layout.
    return;
  }

  const int header_height =
      std::min(viewport_bounds.height(),
               header_ ? header_->GetPreferredSize().height() : 0);
  viewport_bounds.set_height(
      std::max(0, viewport_bounds.height() - header_height));
  viewport_bounds.set_y(viewport_bounds.y() + header_height);
  // viewport_size is the total client space available.
  gfx::Size viewport_size = viewport_bounds.size();
  // Assumes a vertical scrollbar since most of the current views are designed
  // for this.
  int horiz_sb_height = GetScrollBarHeight();
  int vert_sb_width = GetScrollBarWidth();
  viewport_bounds.set_width(viewport_bounds.width() - vert_sb_width);
  // Update the bounds right now so the inner views can fit in it.
  contents_viewport_->SetBoundsRect(viewport_bounds);

  // Give |contents_| a chance to update its bounds if it depends on the
  // viewport.
  if (contents_)
    contents_->Layout();

  bool should_layout_contents = false;
  bool horiz_sb_required = false;
  bool vert_sb_required = false;
  if (contents_) {
    gfx::Size content_size = contents_->size();
    ComputeScrollBarsVisibility(viewport_size,
                                content_size,
                                &horiz_sb_required,
                                &vert_sb_required);
  }
  bool resize_corner_required = resize_corner_ && horiz_sb_required &&
                                vert_sb_required;
  // Take action.
  SetControlVisibility(horiz_sb_, horiz_sb_required);
  SetControlVisibility(vert_sb_, vert_sb_required);
  SetControlVisibility(resize_corner_, resize_corner_required);

  // Non-default.
  if (horiz_sb_required) {
    viewport_bounds.set_height(
        std::max(0, viewport_bounds.height() - horiz_sb_height));
    should_layout_contents = true;
  }
  // Default.
  if (!vert_sb_required) {
    viewport_bounds.set_width(viewport_bounds.width() + vert_sb_width);
    should_layout_contents = true;
  }

  if (horiz_sb_required) {
    int height_offset = horiz_sb_->GetContentOverlapSize();
    horiz_sb_->SetBounds(0,
                         viewport_bounds.bottom() - height_offset,
                         viewport_bounds.right(),
                         horiz_sb_height + height_offset);
  }
  if (vert_sb_required) {
    int width_offset = vert_sb_->GetContentOverlapSize();
    vert_sb_->SetBounds(viewport_bounds.right() - width_offset,
                        0,
                        vert_sb_width + width_offset,
                        viewport_bounds.bottom());
  }
  if (resize_corner_required) {
    // Show the resize corner.
    resize_corner_->SetBounds(viewport_bounds.right(),
                              viewport_bounds.bottom(),
                              vert_sb_width,
                              horiz_sb_height);
  }

  // Update to the real client size with the visible scrollbars.
  contents_viewport_->SetBoundsRect(viewport_bounds);
  if (should_layout_contents && contents_)
    contents_->Layout();

  header_viewport_->SetBounds(contents_x, contents_y,
                              viewport_bounds.width(), header_height);
  if (header_)
    header_->Layout();

  CheckScrollBounds(header_viewport_, header_);
  CheckScrollBounds(contents_viewport_, contents_);
  SchedulePaint();
  UpdateScrollBarPositions();
}

bool ScrollView::OnKeyPressed(const ui::KeyEvent& event) {
  bool processed = false;

  // Give vertical scrollbar priority
  if (vert_sb_->visible())
    processed = vert_sb_->OnKeyPressed(event);

  if (!processed && horiz_sb_->visible())
    processed = horiz_sb_->OnKeyPressed(event);

  return processed;
}

bool ScrollView::OnMouseWheel(const ui::MouseWheelEvent& e) {
  bool processed = false;
  // Give vertical scrollbar priority
  if (vert_sb_->visible())
    processed = vert_sb_->OnMouseWheel(e);

  if (!processed && horiz_sb_->visible())
    processed = horiz_sb_->OnMouseWheel(e);

  return processed;
}

void ScrollView::OnMouseEntered(const ui::MouseEvent& event) {
  if (horiz_sb_)
    horiz_sb_->OnMouseEnteredScrollView(event);
  if (vert_sb_)
    vert_sb_->OnMouseEnteredScrollView(event);
}

void ScrollView::OnMouseExited(const ui::MouseEvent& event) {
  if (horiz_sb_)
    horiz_sb_->OnMouseExitedScrollView(event);
  if (vert_sb_)
    vert_sb_->OnMouseExitedScrollView(event);
}

void ScrollView::OnGestureEvent(ui::GestureEvent* event) {
  // If the event happened on one of the scrollbars, then those events are
  // sent directly to the scrollbars. Otherwise, only scroll events are sent to
  // the scrollbars.
  bool scroll_event = event->type() == ui::ET_GESTURE_SCROLL_UPDATE ||
                      event->type() == ui::ET_GESTURE_SCROLL_BEGIN ||
                      event->type() == ui::ET_GESTURE_SCROLL_END ||
                      event->type() == ui::ET_SCROLL_FLING_START;

  if (vert_sb_->visible()) {
    if (vert_sb_->bounds().Contains(event->location()) || scroll_event)
      vert_sb_->OnGestureEvent(event);
  }
  if (!event->handled() && horiz_sb_->visible()) {
    if (horiz_sb_->bounds().Contains(event->location()) || scroll_event)
      horiz_sb_->OnGestureEvent(event);
  }
}

const char* ScrollView::GetClassName() const {
  return kViewClassName;
}

void ScrollView::ScrollToPosition(ScrollBar* source, int position) {
  if (!contents_)
    return;

  if (source == horiz_sb_ && horiz_sb_->visible()) {
    position = AdjustPosition(contents_->x(), position, contents_->width(),
                              contents_viewport_->width());
    if (-contents_->x() == position)
      return;
    contents_->SetX(-position);
    if (header_) {
      header_->SetX(-position);
      header_->SchedulePaintInRect(header_->GetVisibleBounds());
    }
  } else if (source == vert_sb_ && vert_sb_->visible()) {
    position = AdjustPosition(contents_->y(), position, contents_->height(),
                              contents_viewport_->height());
    if (-contents_->y() == position)
      return;
    contents_->SetY(-position);
  }
  contents_->SchedulePaintInRect(contents_->GetVisibleBounds());
}

int ScrollView::GetScrollIncrement(ScrollBar* source, bool is_page,
                                   bool is_positive) {
  bool is_horizontal = source->IsHorizontal();
  int amount = 0;
  if (contents_) {
    if (is_page) {
      amount = contents_->GetPageScrollIncrement(
          this, is_horizontal, is_positive);
    } else {
      amount = contents_->GetLineScrollIncrement(
          this, is_horizontal, is_positive);
    }
    if (amount > 0)
      return amount;
  }
  // No view, or the view didn't return a valid amount.
  if (is_page) {
    return is_horizontal ? contents_viewport_->width() :
                           contents_viewport_->height();
  }
  return is_horizontal ? contents_viewport_->width() / 5 :
                         contents_viewport_->height() / 5;
}

void ScrollView::SetHeaderOrContents(View* parent,
                                     View* new_view,
                                     View** member) {
  if (*member == new_view)
    return;

  delete *member;
  *member = new_view;
  if (*member)
    parent->AddChildView(*member);
  Layout();
}

void ScrollView::ScrollContentsRegionToBeVisible(const gfx::Rect& rect) {
  if (!contents_ || (!horiz_sb_->visible() && !vert_sb_->visible()))
    return;

  // Figure out the maximums for this scroll view.
  const int contents_max_x =
      std::max(contents_viewport_->width(), contents_->width());
  const int contents_max_y =
      std::max(contents_viewport_->height(), contents_->height());

  // Make sure x and y are within the bounds of [0,contents_max_*].
  int x = std::max(0, std::min(contents_max_x, rect.x()));
  int y = std::max(0, std::min(contents_max_y, rect.y()));

  // Figure out how far and down the rectangle will go taking width
  // and height into account.  This will be "clipped" by the viewport.
  const int max_x = std::min(contents_max_x,
      x + std::min(rect.width(), contents_viewport_->width()));
  const int max_y = std::min(contents_max_y,
      y + std::min(rect.height(), contents_viewport_->height()));

  // See if the rect is already visible. Note the width is (max_x - x)
  // and the height is (max_y - y) to take into account the clipping of
  // either viewport or the content size.
  const gfx::Rect vis_rect = GetVisibleRect();
  if (vis_rect.Contains(gfx::Rect(x, y, max_x - x, max_y - y)))
    return;

  // Shift contents_'s X and Y so that the region is visible. If we
  // need to shift up or left from where we currently are then we need
  // to get it so that the content appears in the upper/left
  // corner. This is done by setting the offset to -X or -Y.  For down
  // or right shifts we need to make sure it appears in the
  // lower/right corner. This is calculated by taking max_x or max_y
  // and scaling it back by the size of the viewport.
  const int new_x =
      (vis_rect.x() > x) ? x : std::max(0, max_x - contents_viewport_->width());
  const int new_y =
      (vis_rect.y() > y) ? y : std::max(0, max_y -
                                        contents_viewport_->height());

  contents_->SetX(-new_x);
  if (header_)
    header_->SetX(-new_x);
  contents_->SetY(-new_y);
  UpdateScrollBarPositions();
}

void ScrollView::ComputeScrollBarsVisibility(const gfx::Size& vp_size,
                                             const gfx::Size& content_size,
                                             bool* horiz_is_shown,
                                             bool* vert_is_shown) const {
  // Try to fit both ways first, then try vertical bar only, then horizontal
  // bar only, then defaults to both shown.
  if (content_size.width() <= vp_size.width() &&
      content_size.height() <= vp_size.height()) {
    *horiz_is_shown = false;
    *vert_is_shown = false;
  } else if (content_size.width() <= vp_size.width() - GetScrollBarWidth()) {
    *horiz_is_shown = false;
    *vert_is_shown = true;
  } else if (content_size.height() <= vp_size.height() - GetScrollBarHeight()) {
    *horiz_is_shown = true;
    *vert_is_shown = false;
  } else {
    *horiz_is_shown = true;
    *vert_is_shown = true;
  }

  if (hide_horizontal_scrollbar_)
    *horiz_is_shown = false;
}

// Make sure that a single scrollbar is created and visible as needed
void ScrollView::SetControlVisibility(View* control, bool should_show) {
  if (!control)
    return;
  if (should_show) {
    if (!control->visible()) {
      AddChildView(control);
      control->SetVisible(true);
    }
  } else {
    RemoveChildView(control);
    control->SetVisible(false);
  }
}

void ScrollView::UpdateScrollBarPositions() {
  if (!contents_)
    return;

  if (horiz_sb_->visible()) {
    int vw = contents_viewport_->width();
    int cw = contents_->width();
    int origin = contents_->x();
    horiz_sb_->Update(vw, cw, -origin);
  }
  if (vert_sb_->visible()) {
    int vh = contents_viewport_->height();
    int ch = contents_->height();
    int origin = contents_->y();
    vert_sb_->Update(vh, ch, -origin);
  }
}

// VariableRowHeightScrollHelper ----------------------------------------------

VariableRowHeightScrollHelper::VariableRowHeightScrollHelper(
    Controller* controller) : controller_(controller) {
}

VariableRowHeightScrollHelper::~VariableRowHeightScrollHelper() {
}

int VariableRowHeightScrollHelper::GetPageScrollIncrement(
    ScrollView* scroll_view, bool is_horizontal, bool is_positive) {
  if (is_horizontal)
    return 0;
  // y coordinate is most likely negative.
  int y = abs(scroll_view->contents()->y());
  int vis_height = scroll_view->contents()->parent()->height();
  if (is_positive) {
    // Align the bottom most row to the top of the view.
    int bottom = std::min(scroll_view->contents()->height() - 1,
                          y + vis_height);
    RowInfo bottom_row_info = GetRowInfo(bottom);
    // If 0, ScrollView will provide a default value.
    return std::max(0, bottom_row_info.origin - y);
  } else {
    // Align the row on the previous page to to the top of the view.
    int last_page_y = y - vis_height;
    RowInfo last_page_info = GetRowInfo(std::max(0, last_page_y));
    if (last_page_y != last_page_info.origin)
      return std::max(0, y - last_page_info.origin - last_page_info.height);
    return std::max(0, y - last_page_info.origin);
  }
}

int VariableRowHeightScrollHelper::GetLineScrollIncrement(
    ScrollView* scroll_view, bool is_horizontal, bool is_positive) {
  if (is_horizontal)
    return 0;
  // y coordinate is most likely negative.
  int y = abs(scroll_view->contents()->y());
  RowInfo row = GetRowInfo(y);
  if (is_positive) {
    return row.height - (y - row.origin);
  } else if (y == row.origin) {
    row = GetRowInfo(std::max(0, row.origin - 1));
    return y - row.origin;
  } else {
    return y - row.origin;
  }
}

VariableRowHeightScrollHelper::RowInfo
    VariableRowHeightScrollHelper::GetRowInfo(int y) {
  return controller_->GetRowInfo(y);
}

// FixedRowHeightScrollHelper -----------------------------------------------

FixedRowHeightScrollHelper::FixedRowHeightScrollHelper(int top_margin,
                                                       int row_height)
    : VariableRowHeightScrollHelper(NULL),
      top_margin_(top_margin),
      row_height_(row_height) {
  DCHECK_GT(row_height, 0);
}

VariableRowHeightScrollHelper::RowInfo
    FixedRowHeightScrollHelper::GetRowInfo(int y) {
  if (y < top_margin_)
    return RowInfo(0, top_margin_);
  return RowInfo((y - top_margin_) / row_height_ * row_height_ + top_margin_,
                 row_height_);
}

}  // namespace views