simple_grid_layout.cc

// Copyright 2021 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/bubble/simple_grid_layout.h"

#include "ui/views/view.h"

namespace ash {

SimpleGridLayout::SimpleGridLayout(int column_count,
                                   int column_spacing,
                                   int row_spacing)
    : column_count_(column_count),
      column_spacing_(column_spacing),
      row_spacing_(row_spacing) {}

SimpleGridLayout::~SimpleGridLayout() = default;

views::ProposedLayout SimpleGridLayout::CalculateProposedLayout(
    const views::SizeBounds& size_bounds) const {
  views::ProposedLayout proposed_layout;

  if (size_bounds.is_fully_bounded()) {
    proposed_layout.host_size =
        gfx::Size(size_bounds.width().value(), size_bounds.height().value());
  } else {
    proposed_layout.host_size = CalculatePreferredSize();
  }

  gfx::Size size = GetChildPreferredSize();
  int row = 0;
  int col = 0;
  for (auto* child : host_view()->children()) {
    if (!IsChildIncludedInLayout(child))
      continue;

    int x = col * (column_spacing_ + size.width());
    int y = row * (row_spacing_ + size.height());
    proposed_layout.child_layouts.push_back(
        views::ChildLayout{child,
                           child->GetVisible(),
                           gfx::Rect(x, y, size.width(), size.height()),
                           {size.width(), size.height()}});

    ++col;
    if (col % column_count_ == 0) {
      ++row;
      col = 0;
    }
  }
  return proposed_layout;
}

void SimpleGridLayout::OnLayoutChanged() {
  LayoutManagerBase::OnLayoutChanged();
  cached_child_preferred_size_.reset();
  host_view()->SetPreferredSize(CalculatePreferredSize());
}

gfx::Size SimpleGridLayout::GetChildPreferredSize() const {
  if (cached_child_preferred_size_)
    return *cached_child_preferred_size_;

  if (!host_view()->children().size())
    return gfx::Size();

  cached_child_preferred_size_ = host_view()->children()[0]->GetPreferredSize();
  return *cached_child_preferred_size_;
}

gfx::Size SimpleGridLayout::CalculatePreferredSize() const {
  int total_children = 0;
  for (auto* child : host_view()->children()) {
    if (IsChildIncludedInLayout(child))
      ++total_children;
  }
  // Equivalent to `ceil(children().size() / column_count_)`.
  int number_of_rows = (total_children + column_count_ - 1) / column_count_;

  if (!number_of_rows)
    return gfx::Size();

  // `SimpleGridLayout` assumes all children have identical sizes.
  int child_height = GetChildPreferredSize().height();
  int child_width = GetChildPreferredSize().width();

  int height = (number_of_rows * (row_spacing_ + child_height)) - row_spacing_;
  int width =
      (column_count_ * (child_width + column_spacing_)) - column_spacing_;

  return gfx::Size(width, height);
}

}  // namespace ash