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Add experimental raw vt100 UI backend
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The intention of this is not to slowly reimplement curses but to provide
a minimal working terminal UI backend which can also be used for debugging,
fuzzing and in environments where curses is not available.

Currently no attempt is made to optimize terminal output. The amount of
flickering will depend on the smartness of your terminal emulator.
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martanne committed Mar 14, 2017
1 parent 9bcf266 commit b739323
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Showing 8 changed files with 273 additions and 31 deletions.
2 changes: 2 additions & 0 deletions Makefile
Original file line number Diff line number Diff line change
Expand Up @@ -21,6 +21,7 @@ MANPREFIX ?= ${PREFIX}/man
VERSION = $(shell git describe --always --dirty 2>/dev/null || echo "0.2-git")

CONFIG_HELP ?= 1
CONFIG_CURSES ?= 1
CONFIG_LUA ?= 1
CONFIG_LPEG ?= 0
CONFIG_TRE ?= 0
Expand All @@ -36,6 +37,7 @@ CFLAGS_VIS = $(CFLAGS_AUTO) $(CFLAGS_TERMKEY) $(CFLAGS_CURSES) $(CFLAGS_ACL) \

CFLAGS_VIS += -DVIS_PATH=\"${SHAREPREFIX}/vis\"
CFLAGS_VIS += -DCONFIG_HELP=${CONFIG_HELP}
CFLAGS_VIS += -DCONFIG_CURSES=${CONFIG_CURSES}
CFLAGS_VIS += -DCONFIG_LUA=${CONFIG_LUA}
CFLAGS_VIS += -DCONFIG_LPEG=${CONFIG_LPEG}
CFLAGS_VIS += -DCONFIG_TRE=${CONFIG_TRE}
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3 changes: 1 addition & 2 deletions README.md
Original file line number Diff line number Diff line change
Expand Up @@ -49,9 +49,8 @@ In order to build vis you will need a
compiler, a [POSIX.1-2008](http://pubs.opengroup.org/onlinepubs/9699919799/)
compatible environment as well as:

* [libcurses](http://www.gnu.org/software/ncurses/), preferably in the
wide-character version
* [libtermkey](http://www.leonerd.org.uk/code/libtermkey/)
* [curses](https://en.wikipedia.org/wiki/Curses_(programming_library)) (recommended)
* [Lua](http://www.lua.org/) >= 5.2 (optional)
* [LPeg](http://www.inf.puc-rio.br/~roberto/lpeg/) >= 0.12
(optional runtime dependency required for syntax highlighting)
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65 changes: 37 additions & 28 deletions configure
Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ Fine tuning of the installation directories:
--mandir=DIR man pages [PREFIX/share/man]
Optional features:
--enable-curses build with Curses terminal output [yes]
--enable-lua build with Lua support [auto]
--enable-lpeg build with support for statically linking to LPeg [auto]
--enable-tre build with TRE regex support [auto]
Expand Down Expand Up @@ -116,6 +117,7 @@ SHAREDIR='$(PREFIX)/share'
MANDIR='$(PREFIX)/share/man'

help=yes
curses=yes
lua=auto
lpeg=auto
tre=auto
Expand All @@ -135,6 +137,8 @@ case "$arg" in
--static) static=yes ;;
--enable-help|--enable-help=yes) help=yes ;;
--disable-help|--enable-help=no) help=no ;;
--enable-curses|--enable-curses=yes) curses=yes ;;
--disable-curses|--enable-curses=no) curses=no ;;
--enable-lua|--enable-lua=yes) lua=yes ;;
--disable-lua|--enable-lua=no) lua=no ;;
--enable-lpeg|--enable-lpeg=yes) lpeg=yes ;;
Expand Down Expand Up @@ -293,9 +297,12 @@ else
CONFIG_HELP=0
fi

# libcurses is a mandatory dependency
CONFIG_CURSES=0

if test "$curses" != "no" ; then

printf "checking for libcurses...\n"

printf "checking for libcurses...\n"
cat > "$tmpc" <<EOF
#include <curses.h>
Expand All @@ -306,36 +313,37 @@ int main(int argc, char *argv[]) {
}
EOF

CONFIG_CURSES=0
for libcurses in ncursesw ncurses libcurses; do
printf " checking for %s... " "$libcurses"

for curses in ncursesw ncurses curses; do
printf " checking for %s... " "$curses"
if test "$have_pkgconfig" = "yes" ; then
CFLAGS_CURSES=$(pkg-config --cflags $libcurses 2>/dev/null)
LDFLAGS_CURSES=$(pkg-config --libs $libcurses 2>/dev/null)
if test $? -eq 0 && $CC $CFLAGS $CFLAGS_CURSES "$tmpc" \
$LDFLAGS $LDFLAGS_CURSES -o "$tmpo" >/dev/null 2>&1 ; then
CONFIG_CURSES=1
printf "yes\n"
break
fi
fi

if test "$have_pkgconfig" = "yes" ; then
CFLAGS_CURSES=$(pkg-config --cflags $curses 2>/dev/null)
LDFLAGS_CURSES=$(pkg-config --libs $curses 2>/dev/null)
if test $? -eq 0 && $CC $CFLAGS $CFLAGS_CURSES "$tmpc" \
CFLAGS_CURSES=""
LDFLAGS_CURSES="-l$libcurses"

if $CC $CFLAGS $CFLAGS_CURSES "$tmpc" \
$LDFLAGS $LDFLAGS_CURSES -o "$tmpo" >/dev/null 2>&1 ; then
CONFIG_CURSES=1
printf "yes\n"
break
else
CFLAGS_CURSES=""
LDFLAGS_CURSES=""
printf "no\n"
fi
fi

CFLAGS_CURSES=""
LDFLAGS_CURSES="-l$curses"

if $CC $CFLAGS $CFLAGS_CURSES "$tmpc" \
$LDFLAGS $LDFLAGS_CURSES -o "$tmpo" >/dev/null 2>&1 ; then
CONFIG_CURSES=1
printf "yes\n"
break
else
printf "no\n"
fi
done
done

test $CONFIG_CURSES -ne 1 && fail "$0: cannot find libcurses"
test "$curses" = "yes" -a $CONFIG_CURSES -ne 1 && fail "$0: cannot find libcurses"
fi

# libtermkey is a mandatory dependency

Expand All @@ -356,7 +364,7 @@ fi

if test -z "$LDFLAGS_TERMKEY"; then
CFLAGS_TERMKEY=""
LDFLAGS_TERMKEY="-ltermkey"
LDFLAGS_TERMKEY="-ltermkey -lncursesw"
fi

if $CC $CFLAGS $CFLAGS_TERMKEY "$tmpc" $LDFLAGS $LDFLAGS_TERMKEY $LDFLAGS_CURSES \
Expand Down Expand Up @@ -591,11 +599,12 @@ printf "completing config.mk... "
exec 3>&1 1>>config.mk

cat << EOF
CFLAGS_CURSES = $CFLAGS_CURSES
LDFLAGS_CURSES = $LDFLAGS_CURSES
CONFIG_HELP = $CONFIG_HELP
CFLAGS_TERMKEY = $CFLAGS_TERMKEY
LDFLAGS_TERMKEY = $LDFLAGS_TERMKEY
CONFIG_HELP = $CONFIG_HELP
CONFIG_CURSES = $CONFIG_CURSES
CFLAGS_CURSES = $CFLAGS_CURSES
LDFLAGS_CURSES = $LDFLAGS_CURSES
REGEX_SRC = $REGEX_SRC
CONFIG_TRE = $CONFIG_TRE
CFLAGS_TRE = $CFLAGS_TRE
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3 changes: 2 additions & 1 deletion main.c
Original file line number Diff line number Diff line change
Expand Up @@ -2061,7 +2061,8 @@ int main(int argc, char *argv[]) {
} else if (strcmp(argv[i], "--") == 0) {
break;
} else if (strcmp(argv[i], "-v") == 0) {
printf("vis %s%s%s%s%s%s\n", VERSION,
printf("vis %s%s%s%s%s%s%s\n", VERSION,
CONFIG_CURSES ? " +curses" : "",
CONFIG_LUA ? " +lua" : "",
CONFIG_LPEG ? " +lpeg" : "",
CONFIG_TRE ? " +tre" : "",
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211 changes: 211 additions & 0 deletions ui-terminal-vt100.c
Original file line number Diff line number Diff line change
@@ -0,0 +1,211 @@
/* This file is included from ui-terminal.c
*
* The goal is *not* to reimplement curses. Instead we aim to provide the
* simplest possible drawing backend for VT-100 compatible terminals.
* This is useful for debugging and fuzzing purposes as well as for environments
* with no curses support.
*
* Currently no attempt is made to optimize terminal output. The amount of
* flickering will depend on the smartness of your terminal emulator.
*
* The following terminal escape sequences are used:
*
* - CSI ? 1049 h Save cursor and use Alternate Screen Buffer (DECSET)
* - CSI ? 1049 l Use Normal Screen Buffer and restore cursor (DECRST)
* - CSI ? 25 l Hide Cursor (DECTCEM)
* - CSI ? 25 h Show Cursor (DECTCEM)
* - CSI 2 J Erase in Display (ED)
* - CSI row ; column H Cursor Position (CUP)
* - CSI ... m Character Attributes (SGR)
* - CSI 0 m Normal
* - CSI 1 m Bold
* - CSI 3 m Italicized
* - CSI 4 m Underlined
* - CSI 5 m Blink
* - CSI 7 m Inverse
* - CSI 22 m Normal (not bold)
* - CSI 23 m Not italicized
* - CSI 24 m Not underlined
* - CSI 25 m Not blinking
* - CSI 27 m Not inverse
* - CSI 30-37,39 Set foreground color
* - CSI 38 ; 2 ; R ; G ; B m Set RGB foreground color
* - CSI 40-47,49 Set background color
* - CSI 48 ; 2 ; R ; G ; B m Set RGB background color
*
* See http://invisible-island.net/xterm/ctlseqs/ctlseqs.txt
* for further information.
*/
#include <stdio.h>
#include "buffer.h"

#define ui_term_backend_init ui_vt100_init
#define ui_term_backend_blit ui_vt100_blit
#define ui_term_backend_clear ui_vt100_clear
#define ui_term_backend_colors ui_vt100_colors
#define ui_term_backend_resize ui_vt100_resize
#define ui_term_backend_save ui_vt100_save
#define ui_term_backend_restore ui_vt100_restore
#define ui_term_backend_suspend ui_vt100_suspend
#define ui_term_backend_resume ui_vt100_resume
#define ui_term_backend_new ui_vt100_new
#define ui_term_backend_free ui_vt100_free

#define CELL_COLOR_BLACK (CellColor){ .index = 0 }
#define CELL_COLOR_RED (CellColor){ .index = 1 }
#define CELL_COLOR_GREEN (CellColor){ .index = 2 }
#define CELL_COLOR_YELLOW (CellColor){ .index = 3 }
#define CELL_COLOR_BLUE (CellColor){ .index = 4 }
#define CELL_COLOR_MAGENTA (CellColor){ .index = 5 }
#define CELL_COLOR_CYAN (CellColor){ .index = 6 }
#define CELL_COLOR_WHITE (CellColor){ .index = 7 }
#define CELL_COLOR_DEFAULT (CellColor){ .index = 9 }

#define CELL_ATTR_NORMAL 0
#define CELL_ATTR_UNDERLINE (1 << 0)
#define CELL_ATTR_REVERSE (1 << 1)
#define CELL_ATTR_BLINK (1 << 2)
#define CELL_ATTR_BOLD (1 << 3)
#define CELL_ATTR_ITALIC (1 << 4)

typedef struct {
UiTerm uiterm;
Buffer buf;
} UiVt100;

static CellColor color_rgb(UiTerm *ui, uint8_t r, uint8_t g, uint8_t b) {
return (CellColor){ .r = r, .g = g, .b = b, .index = (uint8_t)-1 };
}

static CellColor color_terminal(UiTerm *ui, uint8_t index) {
return (CellColor){ .r = 0, .g = 0, .b = 0, .index = index };
}


static void output(const char *data, size_t len) {
fwrite(data, len, 1, stderr);
fflush(stderr);
}

static void output_literal(const char *data) {
output(data, strlen(data));
}

static void screen_alternate(bool alternate) {
output_literal(alternate ? "\x1b[?1049h" : "\x1b[0m" "\x1b[?1049l");
}

static void cursor_visible(bool visible) {
output_literal(visible ? "\x1b[?25h" : "\x1b[?25l");
}

static void ui_vt100_blit(UiTerm *tui) {
Buffer *buf = &((UiVt100*)tui)->buf;
buffer_clear(buf);
CellAttr attr = CELL_ATTR_NORMAL;
CellColor fg = CELL_COLOR_DEFAULT, bg = CELL_COLOR_DEFAULT;
int w = tui->width, h = tui->height;
Cell *cell = tui->cells;
/* erase screen, reposition cursor, reset attributes */
buffer_append0(buf, "\x1b[2J" "\x1b[H" "\x1b[0m");
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
CellStyle *style = &cell->style;
if (style->attr != attr) {

static struct {
CellAttr attr;
char on[4], off[4];
} cell_attrs[] = {
{ CELL_ATTR_BOLD, "1", "22" },
{ CELL_ATTR_ITALIC, "3", "23" },
{ CELL_ATTR_UNDERLINE, "4", "24" },
{ CELL_ATTR_BLINK, "5", "25" },
{ CELL_ATTR_REVERSE, "7", "27" },
};

for (size_t i = 0; i < LENGTH(cell_attrs); i++) {
CellAttr a = cell_attrs[i].attr;
if ((style->attr & a) == (attr & a))
continue;
buffer_appendf(buf, "\x1b[%sm",
style->attr & a ?
cell_attrs[i].on :
cell_attrs[i].off);
}

attr = style->attr;
}

if (!cell_color_equal(fg, style->fg)) {
fg = style->fg;
if (fg.index != (uint8_t)-1) {
buffer_appendf(buf, "\x1b[%dm", 30 + fg.index);
} else {
buffer_appendf(buf, "\x1b[38;2;%d;%d;%dm",
fg.r, fg.g, fg.b);
}
}

if (!cell_color_equal(bg, style->bg)) {
bg = style->bg;
if (bg.index != (uint8_t)-1) {
buffer_appendf(buf, "\x1b[%dm", 40 + bg.index);
} else {
buffer_appendf(buf, "\x1b[48;2;%d;%d;%dm",
bg.r, bg.g, bg.b);
}
}

buffer_append0(buf, cell->data);
cell++;
}
}
output(buffer_content(buf), buffer_length0(buf));
}

static void ui_vt100_clear(UiTerm *tui) { }

static void ui_vt100_resize(UiTerm *tui, int width, int height) { }

static void ui_vt100_save(UiTerm *tui) {
cursor_visible(true);
}

static void ui_vt100_restore(UiTerm *tui) {
cursor_visible(false);
}

static int ui_vt100_colors(Ui *ui) {
char *term = getenv("TERM");
return (term && strstr(term, "-256color")) ? 256 : 16;
}

static void ui_vt100_suspend(UiTerm *term) {
cursor_visible(true);
screen_alternate(false);
}

static void ui_vt100_resume(UiTerm *term) {
screen_alternate(true);
cursor_visible(false);
}

static bool ui_vt100_init(UiTerm *tui, const char *term) {
ui_vt100_resume(tui);
return true;
}

static UiTerm *ui_vt100_new(void) {
UiVt100 *vtui = calloc(1, sizeof *vtui);
if (!vtui)
return NULL;
buffer_init(&vtui->buf);
return (UiTerm*)vtui;
}

static void ui_vt100_free(UiTerm *tui) {
UiVt100 *vtui = (UiVt100*)tui;
ui_vt100_suspend(tui);
buffer_release(&vtui->buf);
}
4 changes: 4 additions & 0 deletions ui-terminal.c
Original file line number Diff line number Diff line change
Expand Up @@ -62,7 +62,11 @@ struct UiTermWin {
enum UiOption options; /* display settings for this window */
};

#if CONFIG_CURSES
#include "ui-terminal-curses.c"
#else
#include "ui-terminal-vt100.c"
#endif

__attribute__((noreturn)) static void ui_die(Ui *ui, const char *msg, va_list ap) {
UiTerm *tui = (UiTerm*)ui;
Expand Down
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