path: root/libs/litehtml/src/line_box.cpp

#include "html.h"
#include "line_box.h"
#include "element.h"
#include "render_item.h"
#include <algorithm>

//////////////////////////////////////////////////////////////////////////////////////////

litehtml::line_box_item::~line_box_item() = default;

void litehtml::line_box_item::place_to(int x, int y)
{
	m_element->pos().x = x + m_element->content_offset_left();
	m_element->pos().y = y + m_element->content_offset_top();
}

litehtml::position& litehtml::line_box_item::pos()
{
	return m_element->pos();
}


int litehtml::line_box_item::width() const
{
	return m_element->width();
}

int litehtml::line_box_item::top() const
{
	return m_element->top();
}

int litehtml::line_box_item::bottom() const
{
	return m_element->bottom();
}

int litehtml::line_box_item::right() const
{
	return m_element->right();
}

int litehtml::line_box_item::left() const
{
	return m_element->left();
}

int litehtml::line_box_item::height() const
{
	return m_element->height();
}

//////////////////////////////////////////////////////////////////////////////////////////

litehtml::lbi_start::lbi_start(const std::shared_ptr<render_item>& element) : line_box_item(element)
{
	m_pos.height = m_element->src_el()->css().get_font_metrics().height;
	m_pos.width = m_element->content_offset_left();
}

litehtml::lbi_start::~lbi_start() = default;

void litehtml::lbi_start::place_to(int x, int y)
{
	m_pos.x = x + m_element->content_offset_left();
	m_pos.y = y;
}

int litehtml::lbi_start::width() const
{
	return m_pos.width;
}

int litehtml::lbi_start::top() const
{
	return m_pos.y;
}

int litehtml::lbi_start::bottom() const
{
	return m_pos.y + m_pos.height;
}

int litehtml::lbi_start::right() const
{
	return m_pos.x;
}

int litehtml::lbi_start::left() const
{
	return m_pos.x - m_element->content_offset_left();
}

int litehtml::lbi_start::height() const
{
	return m_pos.height;
}

//////////////////////////////////////////////////////////////////////////////////////////

litehtml::lbi_end::lbi_end(const std::shared_ptr<render_item>& element) : lbi_start(element)
{
	m_pos.height = m_element->src_el()->css().get_font_metrics().height;
	m_pos.width = m_element->content_offset_right();
}

litehtml::lbi_end::~lbi_end() = default;

void litehtml::lbi_end::place_to(int x, int y)
{
	m_pos.x = x;
	m_pos.y = y;
}

int litehtml::lbi_end::right() const
{
	return m_pos.x + m_pos.width;
}

int litehtml::lbi_end::left() const
{
	return m_pos.x;
}

//////////////////////////////////////////////////////////////////////////////////////////

litehtml::lbi_continue::lbi_continue(const std::shared_ptr<render_item>& element) : lbi_start(element)
{
	m_pos.height = m_element->src_el()->css().get_font_metrics().height;
	m_pos.width = 0;
}

litehtml::lbi_continue::~lbi_continue() = default;

void litehtml::lbi_continue::place_to(int x, int y)
{
	m_pos.x = x;
	m_pos.y = y;
}

int litehtml::lbi_continue::right() const
{
	return m_pos.x;
}

int litehtml::lbi_continue::left() const
{
	return m_pos.x;
}

int litehtml::lbi_continue::width() const
{
	return 0;
}

//////////////////////////////////////////////////////////////////////////////////////////

void litehtml::line_box::add_item(std::unique_ptr<line_box_item> item)
{
    item->get_el()->skip(false);
    bool add	= true;
	switch (item->get_type())
	{
		case line_box_item::type_text_part:
			if(item->get_el()->src_el()->is_white_space())
			{
				add = !is_empty() && !have_last_space();
			}
			break;
		case line_box_item::type_inline_start:
		case line_box_item::type_inline_end:
		case line_box_item::type_inline_continue:
			add = true;
			break;
	}
	if(add)
	{
		item->place_to(m_left + m_width, m_top);
		m_width += item->width();
		m_height = std::max(m_height, item->get_el()->height());
		m_items.emplace_back(std::move(item));
	} else
	{
		item->get_el()->skip(true);
	}
}

int litehtml::line_box::calc_va_baseline(const va_context& current, vertical_align va, const font_metrics& new_font, int top, int bottom)
{
	switch(va)
	{
		case va_super:
			return current.baseline - current.fm.super_shift;
		case va_sub:
			return current.baseline + current.fm.sub_shift;
		case va_middle:
			return current.baseline - current.fm.x_height / 2;
		case va_text_top:
			return current.baseline - (current.fm.height - current.fm.base_line()) +
										new_font.height - new_font.base_line();
		case va_text_bottom:
			return current.baseline + current.fm.base_line() - new_font.base_line();
		case va_bottom:
			return bottom - new_font.base_line();
		case va_top:
			return top + new_font.height - new_font.base_line();
		default:
			return current.baseline;
	}
}

std::list< std::unique_ptr<litehtml::line_box_item> > litehtml::line_box::finish(bool last_box, const containing_block_context &containing_block_size)
{
	std::list< std::unique_ptr<line_box_item> > ret_items;

	if(!last_box)
	{
		while(!m_items.empty())
		{
			if (m_items.back()->get_type() == line_box_item::type_text_part)
			{
				// remove trailing spaces
				if (m_items.back()->get_el()->src_el()->is_break() ||
					m_items.back()->get_el()->src_el()->is_white_space())
				{
					m_width -= m_items.back()->width();
					m_items.back()->get_el()->skip(true);
					m_items.pop_back();
				} else
				{
					break;
				}
			} else if (m_items.back()->get_type() == line_box_item::type_inline_start)
			{
				// remove trailing empty inline_start markers
				// these markers will be added at the beginning of the next line box
				m_width -= m_items.back()->width();
				ret_items.emplace_back(std::move(m_items.back()));
				m_items.pop_back();
			} else
			{
				break;
			}
		}
	} else
	{
		// remove trailing spaces
		auto iter = m_items.rbegin();
		while(iter != m_items.rend())
		{
			if ((*iter)->get_type() == line_box_item::type_text_part)
			{
				if((*iter)->get_el()->src_el()->is_white_space())
				{
					(*iter)->get_el()->skip(true);
					m_width -= (*iter)->width();
					// Space can be between text and inline_end marker
					// We have to shift all items on the right side
					if(iter != m_items.rbegin())
					{
						auto r_iter = iter;
						r_iter--;
						while (true)
						{
							(*r_iter)->pos().x -= (*iter)->width();
							if (r_iter == m_items.rbegin())
							{
								break;
							}
							r_iter--;
						}
					}
					// erase white space element
					iter = decltype(iter) (m_items.erase( std::next(iter).base() ));
				} else
				{
					break;
				}
			} else
			{
				iter++;
			}
		}
	}

    if( is_empty() || (!is_empty() && last_box && is_break_only()) )
    {
        m_height = m_default_line_height.computed_value;
		m_baseline = m_font_metrics.base_line();
        return ret_items;
    }

    int spacing_x = 0;	// Number of pixels to distribute between elements
    int shift_x = 0;	// Shift elements by X to apply the text-align

    switch(m_text_align)
    {
        case text_align_right:
            if(m_width < (m_right - m_left))
            {
				shift_x = (m_right - m_left) - m_width;
            }
            break;
        case text_align_center:
            if(m_width < (m_right - m_left))
            {
				shift_x = ((m_right - m_left) - m_width) / 2;
            }
            break;
        case text_align_justify:
            if (m_width < (m_right - m_left))
            {
				shift_x = 0;
				spacing_x = (m_right - m_left) - m_width;
				// don't justify for small lines
                if (spacing_x > m_width / 4)
					spacing_x = 0;
            }
            break;
        default:
			shift_x = 0;
    }

    int counter = 0;
    float offj  = float(spacing_x) / std::max(1.f, float(m_items.size()) - 1.f);
    float cixx  = 0.0f;

	std::optional<int> line_height;

	if(!m_default_line_height.css_value.is_predefined())
	{
		line_height = m_default_line_height.computed_value;
	}

	va_context current_context;
	std::list<va_context> contexts;

	current_context.baseline = 0;
	current_context.fm = m_font_metrics;
	current_context.start_lbi = nullptr;
	current_context.line_height = m_default_line_height.computed_value;

	m_min_width = 0;

	struct items_dimensions
	{
		int top = 0;
		int bottom = 0;
		int count = 0;
		int max_height = 0;

		void add_item(const line_box_item* item)
		{
			top = std::min(top, item->top());
			bottom = std::max(bottom, item->bottom());
			max_height = std::max(max_height, item->height());
			count++;
		}
		int height() const { return bottom - top; }
	};

	items_dimensions line_max_height;
	items_dimensions top_aligned_max_height;
	items_dimensions bottom_aligned_max_height;
	items_dimensions inline_boxes_dims;

	// First pass
	// 1. Apply text-align-justify
	// 1. Align all items by baseline
	// 2. top/button aligned items are aligned by baseline
	// 3. Calculate top and button of the linebox separately for items in baseline
	//    and for top and bottom aligned items
    for (const auto& lbi : m_items)
	{
		// Apply text-align-justify
		m_min_width += lbi->get_rendered_min_width();
		if (spacing_x && counter)
		{
			cixx += offj;
			if ((counter + 1) == int(m_items.size()))
				cixx += 0.99f;
			lbi->pos().x += int(cixx);
		}
		counter++;
		if ((m_text_align == text_align_right || spacing_x) && counter == int(m_items.size()))
		{
			// Forcible justify the last element to the right side for text align right and justify;
			lbi->pos().x = m_right - lbi->pos().width;
		} else if (shift_x)
		{
			lbi->pos().x += shift_x;
		}

		// Calculate new baseline for inline start/continue
		// Inline start/continue elements are inline containers like <span>
		if (lbi->get_type() == line_box_item::type_inline_start || lbi->get_type() == line_box_item::type_inline_continue)
		{
			contexts.push_back(current_context);
			if(is_one_of(lbi->get_el()->css().get_vertical_align(), va_top, va_bottom))
			{
				// top/bottom aligned inline boxes are aligned by baseline == 0
				current_context.baseline = 0;
				current_context.start_lbi = lbi.get();
				current_context.start_lbi->reset_items_height();
			} else if(current_context.start_lbi)
			{
				current_context.baseline = calc_va_baseline(current_context,
					lbi->get_el()->css().get_vertical_align(),
					lbi->get_el()->css().get_font_metrics(),
					current_context.start_lbi->top(), current_context.start_lbi->bottom());
			} else
			{
				current_context.start_lbi = nullptr;
				current_context.baseline = calc_va_baseline(current_context,
															lbi->get_el()->css().get_vertical_align(),
															lbi->get_el()->css().get_font_metrics(),
															line_max_height.top, line_max_height.bottom);
			}
			current_context.fm = lbi->get_el()->css().get_font_metrics();
			current_context.line_height = lbi->get_el()->css().line_height().computed_value;
		}

		int bl = current_context.baseline;
		int content_offset = 0;
		bool is_top_bottom_box = false;
		bool ignore = false;

		// Align element by baseline
		if(!is_one_of(lbi->get_el()->src_el()->css().get_display(), display_inline_text, display_inline))
		{
			// Apply margins, paddings and border for inline boxes
			content_offset = lbi->get_el()->content_offset_top();
			switch (lbi->get_el()->css().get_vertical_align())
			{
			case va_bottom:
			case va_top:
				// Align by base line 0 all inline boxes with top and bottom vertical aling
				bl = 0;
				is_top_bottom_box = true;
				break;

			case va_text_bottom:
				lbi->pos().y = bl + current_context.fm.base_line() - lbi->get_el()->height() + content_offset;
				ignore = true;
				break;

			case va_text_top:
				lbi->pos().y = bl - current_context.fm.ascent + content_offset;
				ignore = true;
				break;

			case va_middle:
				lbi->pos().y = bl - current_context.fm.x_height / 2 - lbi->get_el()->height() / 2 + content_offset;
				ignore = true;
				break;

			default:
				bl = calc_va_baseline(current_context,
									  lbi->get_el()->css().get_vertical_align(),
									  lbi->get_el()->css().get_font_metrics(),
									  line_max_height.top, line_max_height.bottom);
				break;
			}
		}
		if(!ignore)
		{
			lbi->pos().y = bl - lbi->get_el()->get_last_baseline() + content_offset;
		}

		if(is_top_bottom_box)
		{
			switch (lbi->get_el()->css().get_vertical_align())
			{
				case va_top:
					top_aligned_max_height.add_item(lbi.get());
					break;
				case va_bottom:
					bottom_aligned_max_height.add_item(lbi.get());
					break;
				default:
					break;
			}
		} else if(current_context.start_lbi)
		{
			current_context.start_lbi->add_item_height(lbi->top(), lbi->bottom());
			switch (current_context.start_lbi->get_el()->css().get_vertical_align())
			{
				case va_top:
					top_aligned_max_height.add_item(lbi.get());
					break;
				case va_bottom:
					bottom_aligned_max_height.add_item(lbi.get());
					break;
				default:
					break;
			}
		} else
		{
			if(!lbi->get_el()->src_el()->is_inline_box())
			{
				line_max_height.add_item(lbi.get());
			} else
			{
				inline_boxes_dims.add_item(lbi.get());
			}
		}

		if(!lbi->get_el()->src_el()->is_inline_box() && !lbi->get_el()->css().line_height().css_value.is_predefined())
		{
			if(line_height.has_value())
			{
				line_height = std::max(line_height.value(), lbi->get_el()->css().line_height().computed_value);
			} else
			{
				line_height = lbi->get_el()->css().line_height().computed_value;
			}
		}

		if (lbi->get_type() == line_box_item::type_inline_end)
		{
			if(!contexts.empty())
			{
				current_context = contexts.back();
				contexts.pop_back();
			}
		}
	}

	int top_shift = 0;
	if(line_height.has_value())
	{
		m_height = line_height.value();
		if(line_max_height.count != 0)
		{
			// We have inline items
			top_shift = std::abs(line_max_height.top);
			const int top_shift_correction = (line_height.value() - line_max_height.height()) / 2;
			m_baseline = line_max_height.bottom + top_shift_correction;
			top_shift += top_shift_correction;
			if(inline_boxes_dims.count)
			{
				const int diff2 = std::abs(inline_boxes_dims.top) - std::abs(top_shift);
				if(diff2 > 0)
				{
					m_height += diff2;
					top_shift += diff2;
					m_baseline += diff2;
				}
				const int diff1 = inline_boxes_dims.bottom - (line_max_height.bottom + top_shift_correction);
				if(diff1 > 0)
				{
					m_height += diff1;
				}
			}
		} else if(inline_boxes_dims.count != 0)
		{
			// We have inline boxes only
			m_height = inline_boxes_dims.height();
			top_shift = std::abs(inline_boxes_dims.top);
			m_baseline = inline_boxes_dims.bottom;
		} else
		{
			// We don't have inline items and inline boxes
			top_shift = 0;
		}


		const int top_down_height = std::max(top_aligned_max_height.max_height, bottom_aligned_max_height.max_height);
		if(top_down_height > m_height)
		{
			if(bottom_aligned_max_height.count)
			{
				top_shift += bottom_aligned_max_height.height() - m_height;
			}
			m_height = top_down_height;
		}
	} else
	{
		// Add inline boxes dimentions
		line_max_height.top = std::min(line_max_height.top, inline_boxes_dims.top);
		line_max_height.bottom = std::max(line_max_height.bottom, inline_boxes_dims.bottom);

		// Height is maximum from inline elements height and top/bottom aligned elements height
		m_height = std::max({line_max_height.height(), top_aligned_max_height.height(), bottom_aligned_max_height.height()});

		top_shift = -std::min(line_max_height.top, line_max_height.bottom - bottom_aligned_max_height.height());
		m_baseline = line_max_height.bottom;
	}

	struct inline_item_box
	{
		std::shared_ptr<render_item> element;
		position box;

		inline_item_box() = default;
		explicit inline_item_box(const std::shared_ptr<render_item>& el) : element(el) {}
	};

	std::list<inline_item_box> inlines;

	contexts.clear();

	current_context.baseline = 0;
	current_context.fm = m_font_metrics;
	current_context.start_lbi = nullptr;
	//int va_top_bottom = 0;

	// Second pass:
	// 1. Vertical align top/bottom
	// 2. Apply relative shift
	// 3. Calculate inline boxes
    for (const auto& lbi : m_items)
    {
		if(is_one_of(lbi->get_type(), line_box_item::type_inline_start, line_box_item::type_inline_continue))
		{
			contexts.push_back(current_context);
			current_context.fm = lbi->get_el()->css().get_font_metrics();

			if(lbi->get_el()->css().get_vertical_align() == va_top)
			{
				current_context.baseline = m_top - lbi->get_items_top();
				current_context.start_lbi = lbi.get();
			} else if(lbi->get_el()->css().get_vertical_align() == va_bottom)
			{
				current_context.baseline = m_top + m_height - lbi->get_items_bottom();
				current_context.start_lbi = lbi.get();
			}
		} else if(lbi->get_type() == line_box_item::type_inline_end)
		{
			if(!contexts.empty())
			{
				current_context = contexts.back();
				contexts.pop_back();
			}
		}

		if(current_context.start_lbi)
		{
			lbi->pos().y = current_context.baseline - lbi->get_el()->get_last_baseline() +
						   lbi->get_el()->content_offset_top();
		} else if(is_one_of(lbi->get_el()->css().get_vertical_align(), va_top, va_bottom) && lbi->get_type() == line_box_item::type_text_part)
		{
			if(lbi->get_el()->css().get_vertical_align() == va_top)
			{
				lbi->pos().y = m_top + lbi->get_el()->content_offset_top();
			} else
			{
				lbi->pos().y = m_top + m_height - (lbi->bottom() - lbi->top()) + lbi->get_el()->content_offset_bottom();
			}
		} else
		{
			// move element to the correct position
			lbi->pos().y += m_top + top_shift;
		}

        lbi->get_el()->apply_relative_shift(containing_block_size);

		// Calculate and push inline box into the render item element
		if(lbi->get_type() == line_box_item::type_inline_start || lbi->get_type() == line_box_item::type_inline_continue)
		{
			if(lbi->get_type() == line_box_item::type_inline_start)
			{
				lbi->get_el()->clear_inline_boxes();
			}
			inlines.emplace_back(lbi->get_el());
			inlines.back().box.x = lbi->left();
			inlines.back().box.y = lbi->top() - lbi->get_el()->content_offset_top();
			inlines.back().box.height = lbi->bottom() - lbi->top() + lbi->get_el()->content_offset_height();
		} else if(lbi->get_type() == line_box_item::type_inline_end)
		{
			if(!inlines.empty())
			{
				inlines.back().box.width = lbi->right() - inlines.back().box.x;
				inlines.back().element->add_inline_box(inlines.back().box);
				inlines.pop_back();
			}
		}
    }

	for(auto iter = inlines.rbegin(); iter != inlines.rend(); ++iter)
	{
		iter->box.width =  m_items.back()->right() - iter->box.x;
		iter->element->add_inline_box(iter->box);

		ret_items.emplace_front(std::unique_ptr<line_box_item>(new lbi_continue(iter->element)));
	}

	return ret_items;
}

std::shared_ptr<litehtml::render_item> litehtml::line_box::get_first_text_part() const
{
	for(const auto & item : m_items)
	{
		if(item->get_type() == line_box_item::type_text_part)
		{
			return item->get_el();
		}
	}
	return nullptr;
}


std::shared_ptr<litehtml::render_item> litehtml::line_box::get_last_text_part() const
{
	for(auto iter = m_items.rbegin(); iter != m_items.rend(); iter++)
	{
		if((*iter)->get_type() == line_box_item::type_text_part)
		{
			return (*iter)->get_el();
		}
	}
	return nullptr;
}


bool litehtml::line_box::can_hold(const std::unique_ptr<line_box_item>& item, white_space ws) const
{
    if(!item->get_el()->src_el()->is_inline()) return false;

	if(item->get_type() == line_box_item::type_text_part)
	{
		// force new line on floats clearing
		if (item->get_el()->src_el()->is_break() && item->get_el()->css().get_clear() != clear_none)
		{
			return false;
		}

		auto last_el = get_last_text_part();

		// the first word is always can be hold
		if(!last_el)
		{
			return true;
		}

		// force new line if the last placed element was line break
		// Skip If the break item is float clearing
		if (last_el && last_el->src_el()->is_break() && last_el->css().get_clear() == clear_none)
		{
			return false;
		}

		// line break should stay in current line box
		if (item->get_el()->src_el()->is_break())
		{
			return true;
		}

		if (ws == white_space_nowrap || ws == white_space_pre ||
			(ws == white_space_pre_wrap && item->get_el()->src_el()->is_space()))
		{
			return true;
		}

		if (m_left + m_width + item->width() > m_right)
		{
			return false;
		}
	}

    return true;
}

bool litehtml::line_box::have_last_space()  const
{
	auto last_el = get_last_text_part();
	if(last_el)
	{
		return last_el->src_el()->is_white_space() || last_el->src_el()->is_break();
	}
	return false;
}

bool litehtml::line_box::is_empty() const
{
    if(m_items.empty()) return true;
	if(m_items.size() == 1 &&
		m_items.front()->get_el()->src_el()->is_break() &&
		m_items.front()->get_el()->src_el()->css().get_clear() != clear_none)
	{
		return true;
	}
    for (const auto& el : m_items)
    {
		if(el->get_type() == line_box_item::type_text_part)
		{
			if (!el->get_el()->skip() || el->get_el()->src_el()->is_break())
			{
				return false;
			}
		}
    }
    return true;
}

int litehtml::line_box::baseline() const
{
    return m_baseline;
}

int litehtml::line_box::top_margin() const
{
    return 0;
}

int litehtml::line_box::bottom_margin() const
{
    return 0;
}

void litehtml::line_box::y_shift( int shift )
{
	m_top += shift;
    for (auto& el : m_items)
    {
        el->pos().y += shift;
    }
}

bool litehtml::line_box::is_break_only() const
{
    if(m_items.empty()) return false;

	bool break_found = false;

	for (auto iter = m_items.rbegin(); iter != m_items.rend(); iter++)
	{
		if((*iter)->get_type() == line_box_item::type_text_part)
		{
			if((*iter)->get_el()->src_el()->is_break())
			{
				break_found = true;
			} else if(!(*iter)->get_el()->skip())
			{
				return false;
			}
		}
	}
	return break_found;
}

std::list< std::unique_ptr<litehtml::line_box_item> > litehtml::line_box::new_width( int left, int right)
{
	std::list< std::unique_ptr<line_box_item> > ret_items;
    int add = left - m_left;
    if(add)
    {
		m_left	= left;
		m_right	= right;
        m_width = 0;
        auto remove_begin = m_items.end();
		auto i = m_items.begin();
		i++;
		while (i != m_items.end())
        {
            if(!(*i)->get_el()->skip())
            {
                if(m_left + m_width + (*i)->width() > m_right)
                {
                    remove_begin = i;
                    break;
                }
				(*i)->pos().x += add;
				m_width += (*i)->get_el()->width();
            }
			i++;
        }
        if(remove_begin != m_items.end())
        {
			while(remove_begin != m_items.end())
			{
				ret_items.emplace_back(std::move(*remove_begin));
			}
            m_items.erase(remove_begin, m_items.end());
        }
    }
	return ret_items;
}