diff --git a/7.4.757 b/7.4.757
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+To: vim_dev@googlegroups.com
+Subject: Patch 7.4.757
+Fcc: outbox
+From: Bram Moolenaar <Bram@moolenaar.net>
+Mime-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+------------
+
+Patch 7.4.757
+Problem: Cannot detect the background color of a terminal.
+Solution: Add T_RBG to request the background color if possible. (Lubomir
+ Rintel)
+Files: src/main.c, src/term.c, src/term.h, src/proto/term.pro
+
+
+*** ../vim-7.4.756/src/main.c 2015-04-17 22:08:10.998772925 +0200
+--- src/main.c 2015-06-25 17:01:47.917747345 +0200
+***************
+*** 837,844 ****
+
+ starttermcap(); /* start termcap if not done by wait_return() */
+ TIME_MSG("start termcap");
+! #if defined(FEAT_TERMRESPONSE) && defined(FEAT_MBYTE)
+ may_req_ambiguous_char_width();
+ #endif
+
+ #ifdef FEAT_MOUSE
+--- 837,847 ----
+
+ starttermcap(); /* start termcap if not done by wait_return() */
+ TIME_MSG("start termcap");
+! #if defined(FEAT_TERMRESPONSE)
+! # if defined(FEAT_MBYTE)
+ may_req_ambiguous_char_width();
++ # endif
++ may_req_bg_color();
+ #endif
+
+ #ifdef FEAT_MOUSE
+*** ../vim-7.4.756/src/term.c 2015-03-31 18:30:09.139370916 +0200
+--- src/term.c 2015-06-25 16:52:59.359131386 +0200
+***************
+*** 124,129 ****
+--- 124,134 ----
+ # define U7_SENT 2 /* did send T_U7, waiting for answer */
+ # define U7_GOT 3 /* received T_U7 response */
+ static int u7_status = U7_GET;
++ /* Request background color report: */
++ # define RBG_GET 1 /* send T_RBG when switched to RAW mode */
++ # define RBG_SENT 2 /* did send T_RBG, waiting for answer */
++ # define RBG_GOT 3 /* received T_RBG response */
++ static int rbg_status = RBG_GET;
+ # endif
+
+ /*
+***************
+*** 949,954 ****
+--- 954,960 ----
+ {(int)KS_CWP, IF_EB("\033[3;%d;%dt", ESC_STR "[3;%d;%dt")},
+ # endif
+ {(int)KS_CRV, IF_EB("\033[>c", ESC_STR "[>c")},
++ {(int)KS_RBG, IF_EB("\033]11;?\007", ESC_STR "]11;?\007")},
+ {(int)KS_U7, IF_EB("\033[6n", ESC_STR "[6n")},
+
+ {K_UP, IF_EB("\033O*A", ESC_STR "O*A")},
+***************
+*** 1240,1245 ****
+--- 1246,1252 ----
+ # endif
+ {(int)KS_CRV, "[CRV]"},
+ {(int)KS_U7, "[U7]"},
++ {(int)KS_RBG, "[RBG]"},
+ {K_UP, "[KU]"},
+ {K_DOWN, "[KD]"},
+ {K_LEFT, "[KL]"},
+***************
+*** 3224,3230 ****
+ * doesn't work in Cooked mode, an external program may get
+ * them. */
+ if (tmode != TMODE_RAW && (crv_status == CRV_SENT
+! || u7_status == U7_SENT))
+ (void)vpeekc_nomap();
+ check_for_codes_from_term();
+ }
+--- 3231,3238 ----
+ * doesn't work in Cooked mode, an external program may get
+ * them. */
+ if (tmode != TMODE_RAW && (crv_status == CRV_SENT
+! || u7_status == U7_SENT
+! || rbg_status == RBG_SENT))
+ (void)vpeekc_nomap();
+ check_for_codes_from_term();
+ }
+***************
+*** 3285,3292 ****
+ if (!gui.in_use && !gui.starting)
+ # endif
+ {
+! /* May need to discard T_CRV or T_U7 response. */
+! if (crv_status == CRV_SENT || u7_status == U7_SENT)
+ {
+ # ifdef UNIX
+ /* Give the terminal a chance to respond. */
+--- 3293,3301 ----
+ if (!gui.in_use && !gui.starting)
+ # endif
+ {
+! /* May need to discard T_CRV, T_U7 or T_RBG response. */
+! if (crv_status == CRV_SENT || u7_status == U7_SENT
+! || rbg_status == RBG_SENT)
+ {
+ # ifdef UNIX
+ /* Give the terminal a chance to respond. */
+***************
+*** 3398,3403 ****
+--- 3407,3447 ----
+ }
+ # endif
+
++ #if defined(FEAT_TERMRESPONSE) || defined(PROTO)
++ /*
++ * Check how the terminal treats ambiguous character width (UAX #11).
++ * First, we move the cursor to (1, 0) and print a test ambiguous character
++ * \u25bd (WHITE DOWN-POINTING TRIANGLE) and query current cursor position.
++ * If the terminal treats \u25bd as single width, the position is (1, 1),
++ * or if it is treated as double width, that will be (1, 2).
++ * This function has the side effect that changes cursor position, so
++ * it must be called immediately after entering termcap mode.
++ */
++ void
++ may_req_bg_color()
++ {
++ if (rbg_status == RBG_GET
++ && cur_tmode == TMODE_RAW
++ && termcap_active
++ && p_ek
++ # ifdef UNIX
++ && isatty(1)
++ && isatty(read_cmd_fd)
++ # endif
++ && *T_RBG != NUL
++ && !option_was_set((char_u *)"bg"))
++ {
++ LOG_TR("Sending BG request");
++ out_str(T_RBG);
++ rbg_status = RBG_SENT;
++ /* check for the characters now, otherwise they might be eaten by
++ * get_keystroke() */
++ out_flush();
++ (void)vpeekc_nomap();
++ }
++ }
++ # endif
++
+ # ifdef DEBUG_TERMRESPONSE
+ static void
+ log_tr(char *msg)
+***************
+*** 4222,4233 ****
+ * - Cursor position report: <Esc>[{row};{col}R
+ * The final byte must be 'R'. It is used for checking the
+ * ambiguous-width character state.
+ */
+! p = tp[0] == CSI ? tp + 1 : tp + 2;
+! if ((*T_CRV != NUL || *T_U7 != NUL)
+ && ((tp[0] == ESC && tp[1] == '[' && len >= 3)
+ || (tp[0] == CSI && len >= 2))
+! && (VIM_ISDIGIT(*p) || *p == '>' || *p == '?'))
+ {
+ #ifdef FEAT_MBYTE
+ int col;
+--- 4266,4283 ----
+ * - Cursor position report: <Esc>[{row};{col}R
+ * The final byte must be 'R'. It is used for checking the
+ * ambiguous-width character state.
++ *
++ * - Background color response:
++ * <Esc>]11;rgb:{rrrr}/{gggg}/{bbbb}\007
++ * The final byte must be '\007'.
+ */
+! char_u *argp = tp[0] == CSI ? tp + 1 : tp + 2;
+!
+! if ((*T_CRV != NUL || *T_U7 != NUL || *T_RBG != NUL)
+ && ((tp[0] == ESC && tp[1] == '[' && len >= 3)
++ || (tp[0] == ESC && tp[1] == ']' && len >= 24)
+ || (tp[0] == CSI && len >= 2))
+! && (VIM_ISDIGIT(*argp) || *argp == '>' || *argp == '?'))
+ {
+ #ifdef FEAT_MBYTE
+ int col;
+***************
+*** 4363,4368 ****
+--- 4413,4439 ----
+ key_name[1] = (int)KE_IGNORE;
+ slen = i + 1;
+ }
++ else if (*T_RBG != NUL && len >= 24 - (tp[0] == CSI)
++ && argp[0] == '1' && argp[1] == '1'
++ && argp[2] == ';' && argp[3] == 'r' && argp[4] == 'g'
++ && argp[5] == 'b' && argp[6] == ':'
++ && argp[11] == '/' && argp[16] == '/'
++ && argp[21] == '\007')
++ {
++ LOG_TR("Received RBG");
++ rbg_status = RBG_GOT;
++ if (!option_was_set((char_u *)"bg"))
++ {
++ set_option_value((char_u *)"bg", 0L, (char_u *)(
++ (3 * '6' < argp[7] + argp[12] + argp[17])
++ ? "light" : "dark"), 0);
++ reset_option_was_set((char_u *)"bg");
++ redraw_asap(CLEAR);
++ }
++ key_name[0] = (int)KS_EXTRA;
++ key_name[1] = (int)KE_IGNORE;
++ slen = 24;
++ }
+ }
+
+ /* Check for '<Esc>P1+r<hex bytes><Esc>\'. A "0" instead of the
+*** ../vim-7.4.756/src/term.h 2015-03-31 18:30:09.143370872 +0200
+--- src/term.h 2015-06-25 16:21:55.222506530 +0200
+***************
+*** 79,84 ****
+--- 79,85 ----
+ KS_CWP, /* set window position in pixels */
+ KS_CWS, /* set window size in characters */
+ KS_CRV, /* request version string */
++ KS_RBG, /* request background color */
+ KS_CSI, /* start insert mode (bar cursor) */
+ KS_CEI, /* end insert mode (block cursor) */
+ KS_CSR, /* start replace mode (underline cursor) */
+***************
+*** 162,167 ****
+--- 163,169 ----
+ #define T_CEI (term_str(KS_CEI)) /* end insert mode */
+ #define T_CSR (term_str(KS_CSR)) /* start replace mode */
+ #define T_CRV (term_str(KS_CRV)) /* request version string */
++ #define T_RBG (term_str(KS_RBG)) /* request background RGB */
+ #define T_OP (term_str(KS_OP)) /* original color pair */
+ #define T_U7 (term_str(KS_U7)) /* request cursor position */
+
+*** ../vim-7.4.756/src/proto/term.pro 2014-07-30 17:21:53.819518506 +0200
+--- src/proto/term.pro 2015-06-25 16:39:46.095228111 +0200
+***************
+*** 36,41 ****
+--- 36,42 ----
+ void stoptermcap __ARGS((void));
+ void may_req_termresponse __ARGS((void));
+ void may_req_ambiguous_char_width __ARGS((void));
++ void may_req_bg_color __ARGS((void));
+ int swapping_screen __ARGS((void));
+ void setmouse __ARGS((void));
+ int mouse_has __ARGS((int c));
+*** ../vim-7.4.756/src/version.c 2015-06-25 16:13:37.779750062 +0200
+--- src/version.c 2015-06-25 16:20:48.475209933 +0200
+***************
+*** 743,744 ****
+--- 743,746 ----
+ { /* Add new patch number below this line */
++ /**/
++ 757,
+ /**/
+
+--
+We are the Borg of GNU GPL. We will assimilate your source code.
+Resistance is futile.
+
+ /// Bram Moolenaar -- Bram@Moolenaar.net -- http://www.Moolenaar.net \\\
+/// sponsor Vim, vote for features -- http://www.Vim.org/sponsor/ \\\
+\\\ an exciting new programming language -- http://www.Zimbu.org ///
+ \\\ help me help AIDS victims -- http://ICCF-Holland.org ///