Add a library with TUI helpers

3 files changed, 301 insertions, 0 deletions

diff --git a/cmake/FindNcursesw.cmake b/cmake/FindNcursesw.cmake
new file mode 100644
index 0000000..88c1d01
--- /dev/null
+++ b/cmake/FindNcursesw.cmake
@@ -0,0 +1,17 @@
+# Public Domain
+
+find_package (PkgConfig REQUIRED)
+pkg_check_modules (NCURSESW QUIET ncursesw)
+
+# OpenBSD doesn't provide a pkg-config file
+set (required_vars NCURSESW_LIBRARIES)
+if (NOT NCURSESW_FOUND)
+	find_library (NCURSESW_LIBRARIES NAMES ncursesw)
+	find_path (NCURSESW_INCLUDE_DIRS ncurses.h)
+	list (APPEND required_vars NCURSESW_INCLUDE_DIRS)
+endif (NOT NCURSESW_FOUND)
+
+include (FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS (NCURSESW DEFAULT_MSG ${required_vars})
+
+mark_as_advanced (NCURSESW_LIBRARIES NCURSESW_INCLUDE_DIRS)
diff --git a/cmake/FindUnistring.cmake b/cmake/FindUnistring.cmake
new file mode 100644
index 0000000..6b74efb
--- /dev/null
+++ b/cmake/FindUnistring.cmake
@@ -0,0 +1,10 @@
+# Public Domain
+
+find_path (UNISTRING_INCLUDE_DIRS unistr.h)
+find_library (UNISTRING_LIBRARIES NAMES unistring libunistring)
+
+include (FindPackageHandleStandardArgs)
+FIND_PACKAGE_HANDLE_STANDARD_ARGS (UNISTRING DEFAULT_MSG
+	UNISTRING_INCLUDE_DIRS UNISTRING_LIBRARIES)
+
+mark_as_advanced (UNISTRING_LIBRARIES UNISTRING_INCLUDE_DIRS)
diff --git a/liberty-tui.c b/liberty-tui.c
new file mode 100644
index 0000000..c6e70e9
--- /dev/null
+++ b/liberty-tui.c
@@ -0,0 +1,274 @@
+/*
+ * liberty-tui.c: the ultimate C unlibrary: TUI
+ *
+ * Copyright (c) 2016 - 2017, Přemysl Janouch <p.janouch@gmail.com>
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
+ * SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
+ * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
+ * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+// This file includes some common stuff to build TUI applications with
+
+#include <ncurses.h>
+
+// It is surprisingly hard to find a good library to handle Unicode shenanigans,
+// and there's enough of those for it to be impractical to reimplement them.
+//
+//                         GLib          ICU     libunistring    utf8proc
+// Decently sized            .            .            x            x
+// Grapheme breaks           .            x            .            x
+// Character width           x            .            x            x
+// Locale handling           .            .            x            .
+// Liberal license           .            x            .            x
+//
+// Also note that the ICU API is icky and uses UTF-16 for its primary encoding.
+//
+// Currently we're chugging along with libunistring but utf8proc seems viable.
+// Non-Unicode locales can mostly be handled with simple iconv like in sdtui.
+// Similarly grapheme breaks can be guessed at using character width (a basic
+// test here is Zalgo text).
+//
+// None of this is ever going to work too reliably anyway because terminals
+// and Unicode don't go awfully well together.  In particular, character cell
+// devices have some problems with double-wide characters.
+
+#include <unistr.h>
+#include <uniwidth.h>
+#include <uniconv.h>
+#include <unicase.h>
+
+// --- Configurable display attributes -----------------------------------------
+
+struct attrs
+{
+	short fg;                           ///< Foreground colour index
+	short bg;                           ///< Background colour index
+	chtype attrs;                       ///< Other attributes
+};
+
+/// Decode attributes in the value using a subset of the git config format,
+/// ignoring all errors since it doesn't affect functionality
+static struct attrs
+attrs_decode (const char *value)
+{
+	struct str_vector v;
+	str_vector_init (&v);
+	cstr_split (value, " ", true, &v);
+
+	int colors = 0;
+	struct attrs attrs = { -1, -1, 0 };
+	for (char **it = v.vector; *it; it++)
+	{
+		char *end = NULL;
+		long n = strtol (*it, &end, 10);
+		if (*it != end && !*end && n >= SHRT_MIN && n <= SHRT_MAX)
+		{
+			if (colors == 0) attrs.fg = n;
+			if (colors == 1) attrs.bg = n;
+			colors++;
+		}
+		else if (!strcmp (*it, "bold"))    attrs.attrs |= A_BOLD;
+		else if (!strcmp (*it, "dim"))     attrs.attrs |= A_DIM;
+		else if (!strcmp (*it, "ul"))      attrs.attrs |= A_UNDERLINE;
+		else if (!strcmp (*it, "blink"))   attrs.attrs |= A_BLINK;
+		else if (!strcmp (*it, "reverse")) attrs.attrs |= A_REVERSE;
+#ifdef A_ITALIC
+		else if (!strcmp (*it, "italic"))  attrs.attrs |= A_ITALIC;
+#endif  // A_ITALIC
+	}
+	str_vector_free (&v);
+	return attrs;
+}
+
+// --- Terminal output ---------------------------------------------------------
+
+// Necessary abstraction to simplify aligned, formatted character output
+
+// This callback you need to implement in the application
+static bool app_is_character_in_locale (ucs4_t ch);
+
+struct row_char
+{
+	ucs4_t c;                           ///< Unicode codepoint
+	chtype attrs;                       ///< Special attributes
+	int width;                          ///< How many cells this takes
+};
+
+struct row_buffer
+{
+	ARRAY (struct row_char, chars)      ///< Characters
+	int total_width;                    ///< Total width of all characters
+};
+
+static void
+row_buffer_init (struct row_buffer *self)
+{
+	memset (self, 0, sizeof *self);
+	ARRAY_INIT_SIZED (self->chars, 256);
+}
+
+static void
+row_buffer_free (struct row_buffer *self)
+{
+	free (self->chars);
+}
+
+/// Replace invalid chars and push all codepoints to the array w/ attributes.
+static void
+row_buffer_append (struct row_buffer *self, const char *str, chtype attrs)
+{
+	// The encoding is only really used internally for some corner cases
+	const char *encoding = locale_charset ();
+
+	// Note that this function is a hotspot, try to keep it decently fast
+	struct row_char current = { .attrs = attrs };
+	struct row_char invalid = { .attrs = attrs, .c = '?', .width = 1 };
+	const uint8_t *next = (const uint8_t *) str;
+	while ((next = u8_next (&current.c, next)))
+	{
+		current.width = uc_width (current.c, encoding);
+		if (current.width < 0 || !app_is_character_in_locale (current.c))
+			current = invalid;
+
+		ARRAY_RESERVE (self->chars, 1);
+		self->chars[self->chars_len++] = current;
+		self->total_width += current.width;
+	}
+}
+
+static void
+row_buffer_append_args (struct row_buffer *self, const char *s, ...)
+	ATTRIBUTE_SENTINEL;
+
+static void
+row_buffer_append_args (struct row_buffer *self, const char *s, ...)
+{
+	va_list ap;
+	va_start (ap, s);
+
+	while (s)
+	{
+		row_buffer_append (self, s, va_arg (ap, chtype));
+		s = va_arg (ap, const char *);
+	}
+	va_end (ap);
+}
+
+static void
+row_buffer_append_buffer (struct row_buffer *self, const struct row_buffer *rb)
+{
+	ARRAY_RESERVE (self->chars, rb->chars_len);
+	memcpy (self->chars + self->chars_len, rb->chars,
+		rb->chars_len * sizeof *rb->chars);
+
+	self->chars_len   += rb->chars_len;
+	self->total_width += rb->total_width;
+}
+
+/// Pop as many codepoints as needed to free up "space" character cells.
+/// Given the suffix nature of combining marks, this should work pretty fine.
+static int
+row_buffer_pop_cells (struct row_buffer *self, int space)
+{
+	int made = 0;
+	while (self->chars_len && made < space)
+		made += self->chars[--self->chars_len].width;
+	self->total_width -= made;
+	return made;
+}
+
+static void
+row_buffer_space (struct row_buffer *self, int width, chtype attrs)
+{
+	if (width < 0)
+		return;
+
+	while (self->chars_len + width >= self->chars_alloc)
+		self->chars = xreallocarray (self->chars,
+			sizeof *self->chars, (self->chars_alloc <<= 1));
+
+	struct row_char space = { .attrs = attrs, .c = ' ', .width = 1 };
+	self->total_width += width;
+	while (width-- > 0)
+		self->chars[self->chars_len++] = space;
+}
+
+static void
+row_buffer_ellipsis (struct row_buffer *self, int target)
+{
+	if (self->total_width <= target
+	 || !row_buffer_pop_cells (self, self->total_width - target))
+		return;
+
+	// We use attributes from the last character we've removed,
+	// assuming that we don't shrink the array (and there's no real need)
+	ucs4_t ellipsis = 0x2026; // …
+	if (app_is_character_in_locale (ellipsis))
+	{
+		if (self->total_width >= target)
+			row_buffer_pop_cells (self, 1);
+		if (self->total_width + 1 <= target)
+			row_buffer_append (self, "…",   self->chars[self->chars_len].attrs);
+	}
+	else if (target >= 3)
+	{
+		if (self->total_width >= target)
+			row_buffer_pop_cells (self, 3);
+		if (self->total_width + 3 <= target)
+			row_buffer_append (self, "...", self->chars[self->chars_len].attrs);
+	}
+}
+
+static void
+row_buffer_align (struct row_buffer *self, int target, chtype attrs)
+{
+	row_buffer_ellipsis (self, target);
+	row_buffer_space (self, target - self->total_width, attrs);
+}
+
+static void
+row_buffer_print (uint32_t *ucs4, chtype attrs)
+{
+	// This assumes that we can reset the attribute set without consequences
+	char *str = u32_strconv_to_locale (ucs4);
+	if (str)
+	{
+		attrset (attrs);
+		addstr (str);
+		attrset (0);
+		free (str);
+	}
+}
+
+static void
+row_buffer_flush (struct row_buffer *self)
+{
+	if (!self->chars_len)
+		return;
+
+	// We only NUL-terminate the chunks because of the libunistring API
+	uint32_t chunk[self->chars_len + 1], *insertion_point = chunk;
+	for (size_t i = 0; i < self->chars_len; i++)
+	{
+		struct row_char *iter = self->chars + i;
+		if (i && iter[0].attrs != iter[-1].attrs)
+		{
+			row_buffer_print (chunk, iter[-1].attrs);
+			insertion_point = chunk;
+		}
+		*insertion_point++ = iter->c;
+		*insertion_point = 0;
+	}
+	row_buffer_print (chunk, self->chars[self->chars_len - 1].attrs);
+}