Add a demo for drawing in curses

CMakeLists.txt

@@ -74,10 +74,13 @@ set_target_properties (termo-static PROPERTIES
 add_executable (demo-async EXCLUDE_FROM_ALL demo-async.c)
 target_link_libraries (demo-async termo-static ${lib_libraries})
 
+add_executable (demo-draw EXCLUDE_FROM_ALL demo-draw.c)
+target_link_libraries (demo-draw termo-static ${lib_libraries})
+
 add_executable (demo EXCLUDE_FROM_ALL demo.c)
 target_link_libraries (demo termo-static ${lib_libraries})
 
-set (demos demo demo-async)
+set (demos demo demo-async demo-draw)
 if (glib_FOUND)
 	include_directories (${glib_INCLUDE_DIRS})
 	add_executable (demo-glib EXCLUDE_FROM_ALL demo-glib.c)

demo-draw.c

@@ -0,0 +1,230 @@
+// <poll.h> might need this for sigset_t
+#define _XOPEN_SOURCE 600
+
+#include <stdio.h>
+#include <unistd.h>
+#include <locale.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include <poll.h>
+#include <signal.h>
+
+#include <curses.h>
+#include "termo.h"
+
+typedef struct app_data app_data_t;
+struct app_data
+{
+	termo_t *tk;
+
+	// Current attributes for the left mouse button
+	int current_attrs_left;
+	// Current attributes for the right mouse button
+	int current_attrs_right;
+};
+
+static int g_winch_pipe[2];
+
+static void
+display (const char *format, ...)
+{
+	va_list ap;
+
+	mvwhline (stdscr, 0, 0, A_REVERSE, COLS);
+	attron (A_REVERSE);
+
+	va_start (ap, format);
+	vw_printw (stdscr, format, ap);
+	va_end (ap);
+
+	attroff (A_REVERSE);
+	refresh ();
+}
+
+static void
+init_palette (app_data_t *app)
+{
+	start_color ();
+
+	// Also does init_pair (0, -1, -1);
+	use_default_colors ();
+	// Duplicate it for convenience.
+	init_pair (9, -1, -1);
+
+	// Add the basic 8 colors to the default pair.  Once normally, once
+	// inverted to workaround VTE's inability to set a bright background.
+	for (int i = 0; i < 8; i++)
+	{
+		init_pair (1  + i, COLOR_WHITE, COLOR_BLACK + i);
+		init_pair (10 + i, COLOR_BLACK + i, COLOR_WHITE);
+	}
+
+	// This usually creates a solid black or white.
+	app->current_attrs_left =
+	app->current_attrs_right = COLOR_PAIR (9) | A_REVERSE | A_BOLD;
+}
+
+static void
+redraw (void)
+{
+	int i;
+
+	mvwhline (stdscr, 1, 0, A_REVERSE, COLS);
+	mvwhline (stdscr, 2, 0, A_REVERSE, COLS);
+
+	for (i = 0; i < COLS; i++)
+	{
+		int pair = (float) i / COLS  * 9;
+		mvaddch (1, i, ' ' | COLOR_PAIR (pair));
+		mvaddch (2, i, ' ' | COLOR_PAIR (pair + 9) | A_REVERSE | A_BOLD);
+	}
+
+	display ("Choose a color from the palette and draw.  "
+		"Press Escape or ^C to quit.");
+	refresh ();
+}
+
+static bool
+on_key (app_data_t *app, termo_key_t *key)
+{
+	if (key->type == TERMO_TYPE_KEYSYM
+	 && key->code.sym == TERMO_SYM_ESCAPE)
+		return false;
+
+	if (key->type == TERMO_TYPE_KEY
+	 && (key->modifiers & TERMO_KEYMOD_CTRL)
+	 && (key->code.codepoint == 'C' || key->code.codepoint == 'c'))
+		return false;
+
+	if (key->type != TERMO_TYPE_MOUSE)
+		return true;
+
+	int line, col, button;
+	termo_mouse_event_t event;
+
+	termo_interpret_mouse (app->tk, key, &event, &button, &line, &col);
+	if (event != TERMO_MOUSE_PRESS && event != TERMO_MOUSE_DRAG)
+		return true;
+
+	int *attrs;
+	if (button == 1)
+		attrs = &app->current_attrs_left;
+	else if (button == 3)
+		attrs = &app->current_attrs_right;
+	else
+		return true;
+
+	chtype ch = mvwinch (stdscr, line, col);
+	if (line >= 3)
+	{
+		// Paste the attributes where the user clicked.
+		addch (' ' | *attrs);
+		refresh ();
+	}
+	else if (line > 0)
+		// Copy attributes from the pallete.
+		*attrs = ch & (A_COLOR | A_ATTRIBUTES);
+
+	return true;
+}
+
+static void
+winch_handler (int signum)
+{
+	(void) signum;
+	write (g_winch_pipe[1], "x", 1);
+}
+
+int
+main (int argc, char *argv[])
+{
+	(void) argc;
+	(void) argv;
+
+	TERMO_CHECK_VERSION;
+	setlocale (LC_CTYPE, "");
+
+	struct sigaction act;
+	act.sa_handler = winch_handler;
+	act.sa_flags = SA_RESTART;
+	sigemptyset (&act.sa_mask);
+
+	// Set up a self-pipe so that we can actually poll on SIGWINCH
+	if (sigaction (SIGWINCH, &act, NULL) || pipe (g_winch_pipe))
+	{
+		fprintf (stderr, "Cannot set up signal handler\n");
+		exit (EXIT_FAILURE);
+	}
+
+	termo_t *tk = termo_new (STDIN_FILENO, NULL, 0);
+	if (!tk)
+	{
+		fprintf (stderr, "Cannot allocate termo instance\n");
+		exit (EXIT_FAILURE);
+	}
+
+	termo_set_mouse_proto (tk, termo_guess_mouse_proto (tk));
+	termo_set_mouse_tracking_mode (tk, TERMO_MOUSE_TRACKING_DRAG);
+
+	// Set up curses for our drawing needs
+	if (!initscr () || nonl () == ERR || curs_set (0) == ERR)
+	{
+		fprintf (stderr, "Cannot initialize curses\n");
+		exit (EXIT_FAILURE);
+	}
+
+	app_data_t app;
+	memset (&app, 0, sizeof app);
+	app.tk = tk;
+
+	init_palette (&app);
+	redraw ();
+
+	termo_result_t ret;
+	termo_key_t key;
+
+	// We listen for mouse/key input and terminal resize events
+	struct pollfd fds[2] =
+	{
+		{ .fd = STDIN_FILENO,    .events = POLLIN },
+		{ .fd = g_winch_pipe[0], .events = POLLIN },
+	};
+
+	// Run a simple event loop with poll()
+	int nextwait = -1;
+	bool running = true;
+	while (running)
+	{
+		if (!poll (fds, 2, nextwait))
+			if (termo_getkey_force (tk, &key) == TERMO_RES_KEY)
+				running &= on_key (&app, &key);
+
+		if (fds[1].revents & (POLLIN | POLLHUP | POLLERR))
+		{
+			char x;
+			read (fds[1].fd, &x, 1);
+
+			// The "official" simple and flicker-prone method of resizing
+			// the internal buffers of curses
+			endwin ();
+			refresh ();
+
+			redraw ();
+		}
+		if (fds[0].revents & (POLLIN | POLLHUP | POLLERR))
+			termo_advisereadable (tk);
+
+		while ((ret = termo_getkey (tk, &key)) == TERMO_RES_KEY)
+			running &= on_key (&app, &key);
+
+		nextwait = -1;
+		if (ret == TERMO_RES_AGAIN)
+			nextwait = termo_get_waittime (tk);
+	}
+
+	endwin ();
+	termo_destroy (tk);
+}
+