terminal_status_line/StatusBarManager.cpp

#include "StatusBarManager.h"

#include <iostream>
#include <string>

#include <sys/ioctl.h>
#include <unistd.h>

using std::cout;
using std::flush;
using std::string;

StatusBarManager::StatusBarManager()
: m_is_started(false)
{}

StatusBarManager::~StatusBarManager()
{
	if(m_is_started)
	{
		stop();
	}
}

StatusBarManager::TermSize StatusBarManager::get_terminal_size()
{
	struct winsize win;
	StatusBarManager::TermSize result = { 0, 0 };

	if(ioctl(STDOUT_FILENO, TIOCGWINSZ, (char *)&win) != 0)
	{
		return result;
	}

	result.rows = win.ws_row;
	result.columns = win.ws_col;

	return result;
}

void StatusBarManager::setup_terminal_scroll_area(int nr_rows)
{
	int status_rows = m_progress_messages.size();
	if (nr_rows <= 1)
	{
		return;
	}

	// scroll down a bit to avoid visual glitch when the screen
	// area shrinks by needed ammount of rows
	for (int i = 0; i < status_rows; ++i)
	{
		cout << std::endl;
	}

	// save cursor
	cout << "\e7";

	// set scroll region (this will place the cursor in the top left)
	cout << "\e[0;" << std::to_string(nr_rows - status_rows) << "r";

	// restore cursor but ensure its inside the scrolling area
	cout << "\e8";
	cout << "\e[" << status_rows << "A";

	// ensure its flushed
	flush(cout);

// Leftovers from apt
#if 0
	// setup tty size to ensure xterm/linux console are working properly too
	// see bug #731738
	struct winsize win;
	if (ioctl(child_pty, TIOCGWINSZ, (char *)&win) != -1)
	{
		win.ws_row = nr_rows - 1;
		ioctl(child_pty, TIOCSWINSZ, (char *)&win);
	}
#endif
}

void StatusBarManager::start()
{
	if (!m_is_started)
	{
		int const nr_terminal_rows = get_terminal_size().rows;
		setup_terminal_scroll_area(nr_terminal_rows);
		m_is_started = true;
	}
}

void StatusBarManager::stop()
{
	if (m_is_started)
	{
		int const nr_terminal_rows = get_terminal_size().rows;
		if (nr_terminal_rows > 0)
		{
			setup_terminal_scroll_area(nr_terminal_rows + m_progress_messages.size());

			// override the progress line (sledgehammer)
			static const char* clear_screen_below_cursor = "\e[J";
			cout << clear_screen_below_cursor;
			flush(cout);
		}

		m_is_started = false;
	}
}

bool StatusBarManager::draw_status_line()
{
	if (!m_is_started)
	{
		return false;
	}

	StatusBarManager::TermSize const size = get_terminal_size();
	if (size.rows < 1 || size.columns < 1)
	{
		return false;
	}

	static string save_cursor = "\e7";
	static string restore_cursor = "\e8";

	// green
	static string set_bg_color = "\e[42m";
	// black
	static string set_fg_color = "\e[30m";

	static string restore_bg =  "\e[49m";
	static string restore_fg = "\e[39m";

	cout << save_cursor;

	int status_rows = m_progress_messages.size();
	for (int i = 0; i < status_rows; ++i)
	{
		// move cursor position to current row
		cout << "\e[" << std::to_string(size.rows + 1 - status_rows + i) << ";0f"
			<< set_bg_color
			<< set_fg_color;
		if (nullptr != m_progress_messages[i])
		{
			cout << *(m_progress_messages[i]);
		}
		flush(cout);
	}

	cout << restore_bg
		<< restore_fg;
	flush(cout);

	// leftover progress-bar from apt
#if 0
	// draw text progress bar
	int padding = 4;
	auto const progressbar_size = size.columns - padding - String::DisplayLength(progress_str);
	auto const current_percent = percentage / 100.0f;
	cout << " "
					<< GetTextProgressStr(current_percent, progressbar_size)
					<< " ";
	flush(cout);
#endif

	// restore
	cout << restore_cursor;
	flush(cout);

	return true;
}

void StatusBarManager::add_progress_message(Progress* message)
{
	if (message == nullptr)
	{
		return;
	}

	m_progress_messages.push_back(message);
}

void StatusBarManager::clear()
{
	m_progress_messages.clear();
}