Allow both "light" and "dark" text colors

Introduce a distinction between light and dark text colors. Use different default colors in both cases. The text color scheme can be set via a command line option (--color=[light | dark]), or Julia can try to detect the terminal's background color. In this case, it roughly follows vim's approach: 1. Look for COLORFGBG environment variable 2. Use an ANSI escape sequence to query the terminal for the background color 3. Make an educated guess from the terminal name Tested with iTerm2, Terminal, xterm on MacOS, Linux.
JuliaLang · Nov 28, 2018 · afbbff4 · afbbff4
1 parent 7acacfc
commit afbbff4
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Showing 6 changed files with 156 additions and 26 deletions.
diff --git a/base/client.jl b/base/client.jl
@@ -4,12 +4,30 @@
 ##             and REPL
 
 have_color = false
-default_color_warn = :yellow
-default_color_error = :light_red
-default_color_info = :cyan
-default_color_debug = :blue
-default_color_input = :normal
-default_color_answer = :normal
+text_color_dark = false
+
+# Default light and dark colors
+default_color_light_warn = :yellow
+default_color_light_error = :light_red
+default_color_light_info = :cyan
+default_color_light_debug = :blue
+default_color_light_input = :normal
+default_color_light_answer = :normal
+
+default_color_dark_warn = :magenta
+default_color_dark_error = :red
+default_color_dark_info = :blue
+default_color_dark_debug = :cyan
+default_color_dark_input = :normal
+default_color_dark_answer = :normal
+
+default_color_warn() = text_color_dark ? default_color_dark_warn : default_color_light_warn
+default_color_error() = text_color_dark ? default_color_dark_error : default_color_light_error
+default_color_info() = text_color_dark ? default_color_dark_info : default_color_light_info
+default_color_debug() = text_color_dark ? default_color_dark_debug : default_color_light_debug
+default_color_input() = text_color_dark ? default_color_dark_input : default_color_light_input
+default_color_answer() = text_color_dark ? default_color_dark_answer : default_color_light_answer
+
 color_normal = text_colors[:normal]
 
 function repl_color(key, default)
@@ -19,13 +37,13 @@ function repl_color(key, default)
     haskey(text_colors, c_conv) ? c_conv : default
 end
 
-error_color() = repl_color("JULIA_ERROR_COLOR", default_color_error)
-warn_color()  = repl_color("JULIA_WARN_COLOR" , default_color_warn)
-info_color()  = repl_color("JULIA_INFO_COLOR" , default_color_info)
-debug_color()  = repl_color("JULIA_DEBUG_COLOR" , default_color_debug)
+error_color() = repl_color("JULIA_ERROR_COLOR", default_color_error())
+warn_color()  = repl_color("JULIA_WARN_COLOR" , default_color_warn())
+info_color()  = repl_color("JULIA_INFO_COLOR" , default_color_info())
+debug_color()  = repl_color("JULIA_DEBUG_COLOR" , default_color_debug())
 
-input_color()  = text_colors[repl_color("JULIA_INPUT_COLOR", default_color_input)]
-answer_color() = text_colors[repl_color("JULIA_ANSWER_COLOR", default_color_answer)]
+input_color()  = text_colors[repl_color("JULIA_INPUT_COLOR", default_color_input())]
+answer_color() = text_colors[repl_color("JULIA_ANSWER_COLOR", default_color_answer())]
 
 stackframe_lineinfo_color() = repl_color("JULIA_STACKFRAME_LINEINFO_COLOR", :bold)
 stackframe_function_color() = repl_color("JULIA_STACKFRAME_FUNCTION_COLOR", :bold)
@@ -195,12 +213,14 @@ function exec_options(opts)
         idxs = findall(x -> x == "--", ARGS)
         length(idxs) > 0 && deleteat!(ARGS, idxs[1])
     end
-    quiet                 = (opts.quiet != 0)
-    startup               = (opts.startupfile != 2)
-    history_file          = (opts.historyfile != 0)
-    color_set             = (opts.color != 0) # --color!=auto
-    global have_color     = (opts.color == 1) # --color=on
-    global is_interactive = (opts.isinteractive != 0)
+    quiet                  = (opts.quiet != 0)
+    startup                = (opts.startupfile != 2)
+    history_file           = (opts.historyfile != 0)
+    color_set              = (opts.color != 0)    # --color!=auto
+    global have_color      = (opts.color >= 2)    # --color=[on|light|dark]
+    text_color_set         = (opts.color >= 3)    # --color=[light|dark]
+    global text_color_dark = (opts.color == 4)    # --color=dark
+    global is_interactive  = (opts.isinteractive != 0)
 
     # pre-process command line argument list
     arg_is_program = !isempty(ARGS)
@@ -274,7 +294,7 @@ function exec_options(opts)
         else
             banner = (opts.banner == 1) # --banner=yes
         end
-        run_main_repl(interactiveinput, quiet, banner, history_file, color_set)
+        run_main_repl(interactiveinput, quiet, banner, history_file, color_set, text_color_set)
     end
     nothing
 end
@@ -321,7 +341,7 @@ _atreplinit(repl) = invokelatest(__atreplinit, repl)
 const REPL_MODULE_REF = Ref{Module}()
 
 # run the requested sort of evaluation loop on stdio
-function run_main_repl(interactive::Bool, quiet::Bool, banner::Bool, history_file::Bool, color_set::Bool)
+function run_main_repl(interactive::Bool, quiet::Bool, banner::Bool, history_file::Bool, color_set::Bool, text_color_set::Bool)
     global active_repl
     # load interactive-only libraries
     if !isdefined(Main, :InteractiveUtils)
@@ -340,6 +360,7 @@ function run_main_repl(interactive::Bool, quiet::Bool, banner::Bool, history_fil
             term_env = get(ENV, "TERM", @static Sys.iswindows() ? "" : "dumb")
             term = REPL.Terminals.TTYTerminal(term_env, stdin, stdout, stderr)
             color_set || (global have_color = REPL.Terminals.hascolor(term))
+            text_color_set || (global text_color_dark = REPL.Terminals.has_light_background(term))
             banner && Base.banner(term)
             if term.term_type == "dumb"
                 active_repl = REPL.BasicREPL(term)

diff --git a/base/loading.jl b/base/loading.jl
@@ -1102,10 +1102,11 @@ function create_expr_cache(input::String, output::String, concrete_deps::typeof(
             eval(Meta.parse(code))
         end
         """
+    color = have_color ? (text_color_dark ? "dark" : "light") : "no"
     io = open(pipeline(detach(`$(julia_cmd()) -O0
                               --output-ji $output --output-incremental=yes
                               --startup-file=no --history-file=no --warn-overwrite=yes
-                              --color=$(have_color ? "yes" : "no")
+                              --color=$color
                               --eval $code_object`), stderr=stderr),
               "w", stdout)
     in = io.in

diff --git a/src/jloptions.c b/src/jloptions.c
@@ -102,7 +102,8 @@ static const char opts[]  =
     " -i                        Interactive mode; REPL runs and isinteractive() is true\n"
     " -q, --quiet               Quiet startup: no banner, suppress REPL warnings\n"
     " --banner={yes|no|auto}    Enable or disable startup banner\n"
-    " --color={yes|no|auto}     Enable or disable color text\n"
+    " --color={yes|no|light|dark|auto}\n"
+    "                           Enable or disable color text, and/or choose a text color scheme\n"
     " --history-file={yes|no}   Load or save history\n\n"
 
     // error and warning options
@@ -402,10 +403,14 @@ JL_DLLEXPORT void jl_parse_opts(int *argcp, char ***argvp)
                 jl_options.color = JL_OPTIONS_COLOR_ON;
             else if (!strcmp(optarg, "no"))
                 jl_options.color = JL_OPTIONS_COLOR_OFF;
+            else if (!strcmp(optarg, "light"))
+                jl_options.color = JL_OPTIONS_COLOR_LIGHT;
+            else if (!strcmp(optarg, "dark"))
+                jl_options.color = JL_OPTIONS_COLOR_DARK;
             else if (!strcmp(optarg, "auto"))
                 jl_options.color = JL_OPTIONS_COLOR_AUTO;
             else
-                jl_errorf("julia: invalid argument to --color={yes|no|auto} (%s)", optarg);
+                jl_errorf("julia: invalid argument to --color={yes|no|light|dark|auto} (%s)", optarg);
             break;
         case opt_history_file:
             if (!strcmp(optarg,"yes"))

diff --git a/src/julia.h b/src/julia.h
@@ -1844,8 +1844,10 @@ JL_DLLEXPORT int jl_generating_output(void) JL_NOTSAFEPOINT;
 #define JL_OPTIONS_COMPILE_MIN 3
 
 #define JL_OPTIONS_COLOR_AUTO 0
-#define JL_OPTIONS_COLOR_ON 1
-#define JL_OPTIONS_COLOR_OFF 2
+#define JL_OPTIONS_COLOR_OFF 1
+#define JL_OPTIONS_COLOR_ON 2
+#define JL_OPTIONS_COLOR_LIGHT 3
+#define JL_OPTIONS_COLOR_DARK 4
 
 #define JL_OPTIONS_HISTORYFILE_ON 1
 #define JL_OPTIONS_HISTORYFILE_OFF 0

diff --git a/stdlib/REPL/src/Terminals.jl b/stdlib/REPL/src/Terminals.jl
@@ -22,6 +22,7 @@ export
     getX,
     getY,
     hascolor,
+    has_light_background,
     pos,
     raw!
 
@@ -74,6 +75,7 @@ cmove_col(t::TextTerminal, c) = cmove(c, getY(t))
 
 # Defaults
 hascolor(::TextTerminal) = false
+has_light_background(::TextTerminal) = false
 
 # Utility Functions
 width(t::TextTerminal) = displaysize(t)[2]
@@ -169,7 +171,101 @@ else
     end
 end
 
-# use cached value of have_color
+function has_light_background(term::TTYTerminal)
+    # Don't bother if there is no support for colors
+    !hascolor(term) && return false
+
+    # This function is called when the user did not explicitly choose
+    # either "light" or "dark" text color via a command line option.
+    # We try various ways to determine the terminal's background
+    # color, and use the first valid result. This is inspired by vim,
+    # which uses a very similar approach:
+    #
+    # 1. First check the environment variable COLORFGBG
+    # 2. Use the OSC 11 escape sequence to query the terminal
+    # 3. Make an educated guess from the terminal name
+
+    # See
+    # <https://unix.stackexchange.com/questions/245378/common-environment-variable-to-set-dark-or-light-terminal-background>
+    # for how to detect the terminal background color
+
+    # Check COLORFGBG environment variable, which is set by rxvt and
+    # derivatives. This variable contains either two or three values
+    # separated by semicolons; we want the last value in either case.
+    # If this value is 0-6 or 8, our background is dark.
+    colorfgbg = get(ENV, "COLORFGBG", "")
+    sep = findlast(";", colorfgbg)
+    if sep !== nothing
+        # See e.g. <https://en.wikipedia.org/wiki/ANSI_escape_code>
+        # for the 16 possible colors
+        colorbg = tryparse(Int, colorfgbg[last(sep)+1:end])
+        if colorbg !== nothing && colorbg >= 0 && colorbg <= 15
+            return colorbg == 7 || colorbg >= 9
+        end
+    end
+
+    # Use OSC 11 escape sequence
+    BEL = "\a"                  # "\007"
+    ESC = "\e"                  # "\033"
+    OSC = "$(ESC)]"
+    send = "$(OSC)11;?$(BEL)"
+    reply = mktemp() do path, io
+        # Shell script idea taken from
+        # <https://stackoverflow.com/questions/2507337/is-there-a-way-to-determine-a-terminals-background-color>
+        cmds = ["printf %s '$send'",
+                "sleep 0.00000001", # xterm needs the sleep
+                "read -r recv",
+                "printf %s \"\$recv\" >'$path'"]
+        cmd = join(cmds, "; ")
+
+        oldstty = chomp(read(open(`stty -g`, "r", term.in_stream).out, String))
+        try
+            read(open(`stty raw -echo min 0 time 0`, "r", term.in_stream).out,
+                 String)
+            run(pipeline(`/bin/sh -c $cmd`;
+                         stdin=term.in_stream, stdout=term.out_stream))
+        finally
+            read(open(pipeline(`stty $oldstty`; stderr=devnull),
+                      "r", term.in_stream).out, String)
+        end
+        String(read(io))
+    end
+    # We expect a reply such as "$(OSC)11;rgb:00/00/00$(BEL)" or
+    # "$(OSC)11;rgba:0000/0000/0000/0000$(BEL)" or similar
+    if startswith(reply, "$(OSC)11;rgb")
+        col = findfirst(":", reply)
+        bel = findfirst(BEL, reply)
+        if col !== nothing && bel !== nothing
+            colors = reply[col.stop+1 : bel.start-1]
+            rgb = Float64[]
+            for str in split(colors, "/")
+                val = tryparse(UInt, str, base=16)
+                if val !== nothing
+                    maxval = UInt(1) << (4 * length(str)) - UInt(1)
+                    val /= maxval # normalize
+                    push!(rgb, val)
+                end
+            end
+            if length(rgb) >= 3
+                R, G, B = rgb
+                Y = 0.299 * R + 0.587 * G + 0.114 * B
+                return Y >= 0.5
+            end
+        end
+    end
+
+    # Guess from terminal name.
+    # This list of terminal names is taken from vim.
+    if term.term_type == "linux" ||         # Linux console
+        term.term_type == "screen.linux" || # Linux console with screen
+        startswith(term.term_type, "cygwin") || # Cygwin shell
+        startswith(term.term_type, "putty")     # Putty progrem
+        return false
+    else
+        return true
+    end
+end
+
 Base.in(key_value::Pair, t::TTYTerminal) = in(key_value, pipe_writer(t))
 Base.haskey(t::TTYTerminal, key) = haskey(pipe_writer(t), key)
 Base.getindex(t::TTYTerminal, key) = getindex(pipe_writer(t), key)

diff --git a/test/cmdlineargs.jl b/test/cmdlineargs.jl
@@ -176,6 +176,11 @@ let exename = `$(Base.julia_cmd()) --sysimage-native-code=yes --startup-file=no`
     # --color
     @test readchomp(`$exename --color=yes -E "Base.have_color"`) == "true"
     @test readchomp(`$exename --color=no -E "Base.have_color"`) == "false"
+    @test readchomp(`$exename --color=light -E "Base.have_color"`) == "true"
+    @test readchomp(`$exename --color=dark -E "Base.have_color"`) == "true"
+    @test readchomp(`$exename --color=light -E "Base.text_color_dark"`) == "false"
+    @test readchomp(`$exename --color=dark -E "Base.text_color_dark"`) == "true"
+    @test !success(`$exename --color=true`)
     @test !success(`$exename --color=false`)
 
     # --history-file