flexbox.cpp

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// Copyright 2020 Arthur Sonzogni. All rights reserved.
// 本源代码的使用受 MIT 许可协议的约束，该协议可在 LICENSE 文件中找到。
#include <algorithm>  // for min, max
#include <cstddef>    // for size_t
#include <memory>  // for __shared_ptr_access, shared_ptr, allocator_traits<>::value_type, make_shared
#include <tuple>   // for ignore
#include <utility>  // for move, swap
#include <vector>   // for vector
 
#include "ftxui/dom/elements.hpp"  // for Element, Elements, flexbox, hflow, vflow
#include "ftxui/dom/flexbox_config.hpp"  // for FlexboxConfig, FlexboxConfig::Direction, FlexboxConfig::Direction::Column, FlexboxConfig::AlignContent, FlexboxConfig::Direction::ColumnInversed, FlexboxConfig::Direction::Row, FlexboxConfig::JustifyContent, FlexboxConfig::Wrap, FlexboxConfig::AlignContent::FlexStart, FlexboxConfig::Direction::RowInversed, FlexboxConfig::JustifyContent::FlexStart, FlexboxConfig::Wrap::Wrap
#include "ftxui/dom/flexbox_helper.hpp"  // for Block, Global, Compute
#include "ftxui/dom/node.hpp"            // for Node, Elements, Node::Status
#include "ftxui/dom/requirement.hpp"     // for Requirement
#include "ftxui/dom/selection.hpp"       // for Selection
#include "ftxui/screen/box.hpp"          // for Box
 
namespace ftxui {
 
namespace {
void Normalize(FlexboxConfig::Direction& direction) {
  switch (direction) {
    case FlexboxConfig::Direction::Row:
    case FlexboxConfig::Direction::RowInversed: {
      direction = FlexboxConfig::Direction::Row;
    } break;
    case FlexboxConfig::Direction::Column:
    case FlexboxConfig::Direction::ColumnInversed: {
      direction = FlexboxConfig::Direction::Column;
    } break;
  }
}
 
void Normalize(FlexboxConfig::AlignContent& align_content) {
  align_content = FlexboxConfig::AlignContent::FlexStart;
}
 
void Normalize(FlexboxConfig::JustifyContent& justify_content) {
  justify_content = FlexboxConfig::JustifyContent::FlexStart;
}
 
void Normalize(FlexboxConfig::Wrap& wrap) {
  wrap = FlexboxConfig::Wrap::Wrap;
}
 
FlexboxConfig Normalize(FlexboxConfig config) {
  Normalize(config.direction);
  Normalize(config.wrap);
  Normalize(config.justify_content);
  Normalize(config.align_content);
  return config;
}
 
class Flexbox : public Node {
 public:
  Flexbox(Elements children, FlexboxConfig config)
      : Node(std::move(children)),
        config_(config),
        config_normalized_(Normalize(config)) {
    requirement_.flex_grow_x = 1;
    requirement_.flex_grow_y = 0;
 
    if (IsColumnOriented()) {
      std::swap(requirement_.flex_grow_x, requirement_.flex_grow_y);
    }
  }
 
  bool IsColumnOriented() const {
    return config_.direction == FlexboxConfig::Direction::Column ||
           config_.direction == FlexboxConfig::Direction::ColumnInversed;
  }
 
  void Layout(flexbox_helper::Global& global,
              bool compute_requirement = false) {
    global.blocks.reserve(children_.size());
    for (auto& child : children_) {
      flexbox_helper::Block block;
      block.min_size_x = child->requirement().min_x;
      block.min_size_y = child->requirement().min_y;
      if (!compute_requirement) {
        block.flex_grow_x = child->requirement().flex_grow_x;
        block.flex_grow_y = child->requirement().flex_grow_y;
        block.flex_shrink_x = child->requirement().flex_shrink_x;
        block.flex_shrink_y = child->requirement().flex_shrink_y;
      }
      global.blocks.push_back(block);
    }
 
    flexbox_helper::Compute(global);
  }
 
  void ComputeRequirement() override {
    requirement_ = Requirement{};
    for (auto& child : children_) {
      child->ComputeRequirement();
    }
    global_ = flexbox_helper::Global();
    global_.config = config_normalized_;
    if (IsColumnOriented()) {
      global_.size_x = 100000;  // NOLINT
      global_.size_y = asked_;
    } else {
      global_.size_x = asked_;
      global_.size_y = 100000;  // NOLINT
    }
    Layout(global_, true);
 
    if (global_.blocks.empty()) {
      return;
    }
 
    // Compute the union of all the blocks:
    Box box;
    box.x_min = global_.blocks[0].x;
    box.y_min = global_.blocks[0].y;
    box.x_max = global_.blocks[0].x + global_.blocks[0].dim_x;
    box.y_max = global_.blocks[0].y + global_.blocks[0].dim_y;
    for (auto& b : global_.blocks) {
      box.x_min = std::min(box.x_min, b.x);
      box.y_min = std::min(box.y_min, b.y);
      box.x_max = std::max(box.x_max, b.x + b.dim_x);
      box.y_max = std::max(box.y_max, b.y + b.dim_y);
    }
    requirement_.min_x = box.x_max - box.x_min;
    requirement_.min_y = box.y_max - box.y_min;
 
    // Find the selection:
    for (size_t i = 0; i < children_.size(); ++i) {
      if (requirement_.focused.Prefer(children_[i]->requirement().focused)) {
        requirement_.focused = children_[i]->requirement().focused;
        // Shift |focused.box| according to its position inside this component:
        auto& b = global_.blocks[i];
        requirement_.focused.box.Shift(b.x, b.y);
        requirement_.focused.box =
            Box::Intersection(requirement_.focused.box, box);
      }
    }
  }
 
  void SetBox(Box box) override {
    Node::SetBox(box);
 
    const int asked_previous = asked_;
    asked_ = std::min(asked_, IsColumnOriented() ? box.y_max - box.y_min + 1
                                                 : box.x_max - box.x_min + 1);
    need_iteration_ = (asked_ != asked_previous);
 
    flexbox_helper::Global global;
    global.config = config_;
    global.size_x = box.x_max - box.x_min + 1;
    global.size_y = box.y_max - box.y_min + 1;
    Layout(global);
 
    for (size_t i = 0; i < children_.size(); ++i) {
      auto& child = children_[i];
      auto& b = global.blocks[i];
 
      Box children_box;
      children_box.x_min = box.x_min + b.x;
      children_box.y_min = box.y_min + b.y;
      children_box.x_max = box.x_min + b.x + b.dim_x - 1;
      children_box.y_max = box.y_min + b.y + b.dim_y - 1;
 
      const Box intersection = Box::Intersection(children_box, box);
      child->SetBox(intersection);
 
      need_iteration_ |= (intersection != children_box);
    }
  }
 
  void Select(Selection& selection) override {
    // If this Node box_ doesn't intersect with the selection, then no
    // selection.
    if (Box::Intersection(selection.GetBox(), box_).IsEmpty()) {
      return;
    }
 
    Selection selection_lines = IsColumnOriented()
                                    ? selection.SaturateVertical(box_)
                                    : selection.SaturateHorizontal(box_);
 
    size_t i = 0;
    for (auto& line : global_.lines) {
      Box box;
      box.x_min = box_.x_min + line.x;
      box.x_max = box_.x_min + line.x + line.dim_x - 1;
      box.y_min = box_.y_min + line.y;
      box.y_max = box_.y_min + line.y + line.dim_y - 1;
 
      // If the line box doesn't intersect with the selection, then no
      // selection.
      if (Box::Intersection(selection.GetBox(), box).IsEmpty()) {
        continue;
      }
 
      Selection selection_line = IsColumnOriented()
                                     ? selection_lines.SaturateHorizontal(box)
                                     : selection_lines.SaturateVertical(box);
 
      for (auto& block : line.blocks) {
        std::ignore = block;
        children_[i]->Select(selection_line);
        i++;
      }
    }
  }
 
  void Check(Status* status) override {
    for (auto& child : children_) {
      child->Check(status);
    }
 
    if (status->iteration == 0) {
      asked_ = 6000;  // NOLINT
      need_iteration_ = true;
    }
 
    status->need_iteration |= need_iteration_;
  }
 
  int asked_ = 6000;  // NOLINT
  bool need_iteration_ = true;
  const FlexboxConfig config_;
  const FlexboxConfig config_normalized_;
  flexbox_helper::Global global_;
};
 
}  // namespace
 
/// @brief 一个容器，用于在行/列中显示元素，并且在填满时能够换行到下一列/行。
/// @param children 容器中的元素
/// @param config 选项
/// @return 容器。
///
/// #### Example
///
/// ```cpp
/// flexbox({
///   text("element 1"),
///   text("element 2"),
///   text("element 3"),
/// }, FlexboxConfig()
///      .Set(FlexboxConfig::Direction::Column)
///      .Set(FlexboxConfig::Wrap::WrapInversed)
///      .SetGapMainAxis(1)
///      .SetGapCrossAxis(1)
/// )
/// ```
Element flexbox(Elements children, FlexboxConfig config) {
  return std::make_shared<Flexbox>(std::move(children), config);
}
 
/// @brief 一个容器，用于从左到右在行中显示元素。当填满时，它会在下方开始新的一行。
/// @param children 容器中的元素
/// @return 容器。
///
/// #### Example
///
/// ```cpp
/// hflow({
///   text("element 1"),
///   text("element 2"),
///   text("element 3"),
/// });
/// ```
Element hflow(Elements children) {
  return flexbox(std::move(children), FlexboxConfig());
}
 
/// @brief 一个容器，用于从上到下在行中显示元素。当填满时，它会在右侧开始新的一列。
/// @param children 容器中的元素
/// @return 容器。
///
/// #### Example
///
/// ```cpp
/// vflow({
///   text("element 1"),
///   text("element 2"),
///   text("element 3"),
/// });
/// ```
Element vflow(Elements children) {
  return flexbox(std::move(children),
                 FlexboxConfig().Set(FlexboxConfig::Direction::Column));
}
 
}  // namespace ftxui