+dnl CF_CHECK_WCWIDTH_GRAPHICS version: 1 updated: 2015/12/19 17:47:56
+dnl -------------------------
+dnl Most "modern" terminal emulators are based to some degree on VT100, and
+dnl should support line-drawing. Even with Unicode. There is a problem.
+dnl
+dnl While most of the VT100 graphics characters were incorporated into Unicode,
+dnl all of those were combined into a page of useful graphics characters.
+dnl
+dnl So far, so good.
+dnl
+dnl However, while they are useful, there are other considerations. CJK
+dnl is (because of poor device resolution) often rendered as double-width
+dnl characters. So... for these generally-useful characters, what should
+dnl be the width (to make them consistent with adjacent characters)?
+dnl
+dnl The obvious choice would have been to make this locale-dependent, and use
+dnl wcwidth() to tell applications what the actual width is. That was too
+dnl obvious. Instead, we have a slew of "ambiguous-width" characters.
+dnl See for example
+dnl http://www.unicode.org/reports/tr11/tr11-29.html
+dnl http://www.cl.cam.ac.uk/~mgk25/ucs/scw-proposal.html
+dnl
+dnl The EastAsianWidth-6.2.0.txt file from the Unicode organization lists
+dnl more than 22,000 characters, with 1281 of those as ambiguous-width. For
+dnl instance, it lists half (44/96) of the Latin-1 characters as
+dnl ambiguous-width. Also, all of the box-characters at 0x2500 are ambiguous.
+dnl
+dnl What this means for the implementor is that on some systems wcwidth() can
+dnl give bad advice. On Solaris, some of the ambiguous widths are returned as
+dnl 1 (the Latin-1 characters), while others are returned as 2 (line-drawing
+dnl characters). These do not necessarily match the behavior of the terminal
+dnl emulator. xterm, for instance, does an optional startup check to find if
+dnl this problem (or similar) exists with the system's locale tables, rejecting
+dnl them if they are too unreliable.
+AC_DEFUN([CF_CHECK_WCWIDTH_GRAPHICS],[
+AC_CACHE_CHECK(if wcwidth agrees graphics are single-width, cf_cv_wcwidth_graphics,[
+cat >conftest.in <<CF_EOF
+- VT100 symbols
+0x250c upper left corner
+0x2514 lower left corner
+0x2510 upper right corner
+0x2518 lower right corner
+0x251c tee pointing left
+0x2524 tee pointing right
+0x2534 tee pointing up
+0x252c tee pointing down
+0x2500 horizontal line
+0x2502 vertical line
+0x253c large plus or crossover
+0x23ba scan line 1
+0x23bd scan line 9
+0x25c6 diamond
+0x2592 checker board (stipple)
+0x00b0 degree symbol
+0x00b1 plus/minus
+0x00b7 bullet
+- Teletype 5410v1 symbols
+0x2190 arrow pointing left
+0x2192 arrow pointing right
+0x2193 arrow pointing down
+0x2191 arrow pointing up
+0x2592 board of squares
+0x2603 lantern symbol
+0x25ae solid square block
+- these defaults were invented for ncurses
+0x23bb scan line 3
+0x23bc scan line 7
+0x2264 less-than-or-equal-to
+0x2265 greater-than-or-equal-to
+0x03c0 greek pi
+0x2260 not-equal
+0x00a3 pound-sterling symbol
+- thick-line-drawing
+0x250f upper left corner
+0x2517 lower left corner
+0x2513 upper right corner
+0x251b lower right corner
+0x2523 tee pointing left
+0x252b tee pointing right
+0x253b tee pointing up
+0x2533 tee pointing down
+0x2501 horizontal line
+0x2503 vertical line
+0x254b large plus or crossover
+- double-line-drawing
+0x2554 upper left corner
+0x255a lower left corner
+0x2557 upper right corner
+0x255d lower right corner
+0x2563 tee pointing left
+0x2560 tee pointing right
+0x2569 tee pointing up
+0x2566 tee pointing down
+0x2550 horizontal line
+0x2551 vertical line
+0x256c large plus or crossover
+CF_EOF
+AC_TRY_RUN([
+#include <locale.h>
+#include <stdio.h>
+#include <wchar.h>
+
+#define MY_LEN 80
+
+int
+main(void)
+{
+ FILE *fp;
+ int value;
+ char buffer[MY_LEN + 1];
+ char notes[MY_LEN + 1];
+ int totals = 0;
+ int passed = 0;
+
+ if (setlocale(LC_ALL, "en_US.UTF8") ||
+ setlocale(LC_ALL, "en_US.UTF-8") ||
+ setlocale(LC_ALL, "en_US.utf8") ||
+ setlocale(LC_ALL, "en_US.utf-8")) {
+ if ((fp = fopen("conftest.in", "r")) != 0) {
+ while (fgets(buffer, MY_LEN, fp) != 0) {
+ if (*buffer == '-') {
+ fprintf(stderr, "\t%s", buffer);
+ } else if (sscanf(buffer, "%x %s", &value, notes) == 2) {
+ ++totals;
+ if (wcwidth(value) == 1)
+ ++passed;
+ fprintf(stderr, "%d\t%s", wcwidth(value), buffer);
+ } else {
+ fprintf(stderr, "?\t%s", buffer);
+ }
+ }
+ }
+ }
+ fprintf(stderr, "%d/%d passed wcwidth/graphics check\n", passed, totals);
+ return (totals == passed) ? 0 : 1;
+}
+],
+[cf_cv_wcwidth_graphics=yes],
+[cf_cv_wcwidth_graphics=no],
+[cf_cv_wcwidth_graphics=unknown])
+])
+])dnl
+dnl ---------------------------------------------------------------------------
projects / ncurses.git / blobdiff