ncurses: init_color() has no effect

徘徊边缘 提交于 2020-01-05 11:47:59

问题


Trying to define color pairs, I was getting strange results. All 256 colors are already defined, and attempt to change any color with init_color() has no affect.

I'm using Putty with 256-colors enabled and TERM=xterm-256color (also putty-256color), ncurses 6.0 compiled with --enable-widec and --enable-ext-colors. This shows all colors are defined and the init_color() doesn't change anything even though it succeeds:

init_scr();
start_color();
if (has_colors() && COLORS == 256 && can_change_color()) {
  NCURSES_COLOR_T f;
  for (f = 1; f < 256; f++) {
    if (init_pair(f, f, COLOR_BLACK) == ERR) break;
    attron(COLOR_PAIR(f));
    printw("(%d)", f);
    attroff(COLOR_PAIR(f));
    refresh();
  }
  getch();
  clear();
  for (f = 1; f < 256; f++) {
    if (init_color(f, 0, 0, f*3) == ERR) break;
    if (init_pair(f, f, COLOR_BLACK) == ERR) break;
    attron(COLOR_PAIR(f));
    printw("(%d)", f);
    attroff(COLOR_PAIR(f));
    refresh();
  }
  getch();
  clear();
}

I've read that the default colors can't be changed, but only refers to COLOR_BLACK, etc (0-7).

Where are these 256 default colors defined and why can't I change them? If they can't be changed, I could make use of the colors defined, but only if I can rely on them being the same on any 256-color capable terminal.


回答1:


short: PuTTY doesn't do that, ncurses can't tell if PuTTY can...

long:

In ncurses, the init_color function checks its parameters (in the example given, those appear okay if your $TERM is "xterm-256color"), as well as checking if the terminal description has the initc (initialize_color) capability. If that is missing or cancelled, ncurses returns an error.

However, that's only the terminal description. ncurses cannot tell if you have chosen an incorrect or inappropriate terminal description.

In a quick check, PuTTY doesn't respond to the control sequence which is used in initc. This is a known limitation, as indicated in the (more appropriate) terminal description putty-256color provided by ncurses:

putty-256color|PuTTY 0.58 with xterm 256-colors,
        use=xterm+256setaf, use=putty,

That xterm+256setaf is used for terminals whose palette is hard-coded. PuTTY is not the only terminal which both sets TERM=xterm` and lacks the ability to change its palette. If you happen to be using an old version of the terminal database, you may be misled, since that error was fixed in 2014:

# 2014-03-30
#       * cancel ccc in putty-256color and konsole-256color for consistency
#         with the cancelled initc capability (patch by Sven Zuhlsdorf).
#       * add xterm+256setaf building block for various terminals which only
#         get the 256-color feature half-implemented -TD
#       * updated "st" entry (leaving the 0.1.1 version as "simpleterm") to
#         0.4.1 -TD
#

Like the other terminals whose developers set TERM=xterm (or TERM=xterm-256color), there are differences between those and xterm.

Further reading:

  • Why not just use TERM set to "xterm"?



回答2:


Couple of things I discovered. First, yes I was apparently referencing an old putty-256color terminfo that had "ccc", allowing can_change_color() to succeed, but then init_color() would fail. But the same Putty window using "xterm-256color" would init_color() OK and color_content() even shows the new values, but nothing changed on the screen. What was really confusing is sometimes the colors I set would appear and other times seemingly random colors appeared instead.

Here's what I found:

         putty-256color    xterm-256color  gnome-256color    xterm-256color
           (putty)         (putty)         (gnome-terminal)   (MobaXterm)
         --------------    --------------  ----------------   --------------
change_color  OK/ERR            OK              OK                 OK
init_color      ERR             ERR             OK                 OK
color_content   ERR           OK/NOCH           OK                 OK
color changed?  NO              NO              YES                YES

So there's basically no way to determine whether colors can be changed or not. But I did find that every terminal had already defined the standard 256 xterm colors, whether they could be changed or not. So, now, I just define the colors I want to use using the same color numbers as in the xterm palette. That way, the colors I expect will appear whether I needed to define them or not. So, to use "PaleGreen3", I just use:

init_color(77, 372, 843, 372)

If it works, it works, and if not, its probably already defined. For reference, I converting all the Xwindow/xterm colors from GUI hex notation to the ncurses (0-1000) values:

#   Name               Tk       Ncurses
--- ----------------   -------  -------------
16  Grey0              #000000  0,0,0
17  NavyBlue           #00005f  0,0,372
18  DarkBlue           #000087  0,0,529
19  Blue3              #0000af  0,0,686
20  Blue3              #0000d7  0,0,843
21  Blue1              #0000ff  0,0,1000
22  DarkGreen          #005f00  0,372,0
23  DeepSkyBlue4       #005f5f  0,372,372
24  DeepSkyBlue4       #005f87  0,372,529
25  DeepSkyBlue4       #005faf  0,372,686
26  DodgerBlue3        #005fd7  0,372,843
27  DodgerBlue2        #005fff  0,372,1000
28  Green4             #008700  0,529,0
29  SpringGreen4       #00875f  0,529,372
30  Turquoise4         #008787  0,529,529
31  DeepSkyBlue3       #0087af  0,529,686
32  DeepSkyBlue3       #0087d7  0,529,843
33  DodgerBlue1        #0087ff  0,529,1000
34  Green3             #00af00  0,686,0
35  SpringGreen3       #00af5f  0,686,372
36  DarkCyan           #00af87  0,686,529
37  LightSeaGreen      #00afaf  0,686,686
38  DeepSkyBlue2       #00afd7  0,686,843
39  DeepSkyBlue1       #00afff  0,686,1000
40  Green3             #00d700  0,843,0
41  SpringGreen3       #00d75f  0,843,372
42  SpringGreen2       #00d787  0,843,529
43  Cyan3              #00d7af  0,843,686
44  DarkTurquoise      #00d7d7  0,843,843
45  Turquoise2         #00d7ff  0,843,1000
46  Green1             #00ff00  0,1000,0
47  SpringGreen2       #00ff5f  0,1000,372
48  SpringGreen1       #00ff87  0,1000,529
49  MediumSpringGreen  #00ffaf  0,1000,686
50  Cyan2              #00ffd7  0,1000,843
51  Cyan1              #00ffff  0,1000,1000
52  DarkRed            #5f0000  372,0,0
53  DeepPink4          #5f005f  372,0,372
54  Purple4            #5f0087  372,0,529
55  Purple4            #5f00af  372,0,686
56  Purple3            #5f00d7  372,0,843
57  BlueViolet         #5f00ff  372,0,1000
58  Orange4            #5f5f00  372,372,0
59  Grey37             #5f5f5f  372,372,372
60  MediumPurple4      #5f5f87  372,372,529
61  SlateBlue3         #5f5faf  372,372,686
62  SlateBlue3         #5f5fd7  372,372,843
63  RoyalBlue1         #5f5fff  372,372,1000
64  Chartreuse4        #5f8700  372,529,0
65  DarkSeaGreen4      #5f875f  372,529,372
66  PaleTurquoise4     #5f8787  372,529,529
67  SteelBlue          #5f87af  372,529,686
68  SteelBlue3         #5f87d7  372,529,843
69  CornflowerBlue     #5f87ff  372,529,1000
70  Chartreuse3        #5faf00  372,686,0
71  DarkSeaGreen4      #5faf5f  372,686,372
72  CadetBlue          #5faf87  372,686,529
73  CadetBlue          #5fafaf  372,686,686
74  SkyBlue3           #5fafd7  372,686,843
75  SteelBlue1         #5fafff  372,686,1000
76  Chartreuse3        #5fd700  372,843,0
77  PaleGreen3         #5fd75f  372,843,372
78  SeaGreen3          #5fd787  372,843,529
79  Aquamarine3        #5fd7af  372,843,686
80  MediumTurquoise    #5fd7d7  372,843,843
81  SteelBlue1         #5fd7ff  372,843,1000
82  Chartreuse2        #5fff00  372,1000,0
83  SeaGreen2          #5fff5f  372,1000,372
84  SeaGreen1          #5fff87  372,1000,529
85  SeaGreen1          #5fffaf  372,1000,686
86  Aquamarine1        #5fffd7  372,1000,843
87  DarkSlateGray2     #5fffff  372,1000,1000
88  DarkRed            #870000  529,0,0
89  DeepPink4          #87005f  529,0,372
90  DarkMagenta        #870087  529,0,529
91  DarkMagenta        #8700af  529,0,686
92  DarkViolet         #8700d7  529,0,843
93  Purple             #8700ff  529,0,1000
94  Orange4            #875f00  529,372,0
95  LightPink4         #875f5f  529,372,372
96  Plum4              #875f87  529,372,529
97  MediumPurple3      #875faf  529,372,686
98  MediumPurple3      #875fd7  529,372,843
99  SlateBlue1         #875fff  529,372,1000
100 Yellow4            #878700  529,529,0
101 Wheat4             #87875f  529,529,372
102 Grey53             #878787  529,529,529
103 LightSlateGrey     #8787af  529,529,686
104 MediumPurple       #8787d7  529,529,843
105 LightSlateBlue     #8787ff  529,529,1000
106 Yellow4            #87af00  529,686,0
107 DarkOliveGreen3    #87af5f  529,686,372
108 DarkSeaGreen       #87af87  529,686,529
109 LightSkyBlue3      #87afaf  529,686,686
110 LightSkyBlue3      #87afd7  529,686,843
111 SkyBlue2           #87afff  529,686,1000
112 Chartreuse2        #87d700  529,843,0
113 DarkOliveGreen3    #87d75f  529,843,372
114 PaleGreen3         #87d787  529,843,529
115 DarkSeaGreen3      #87d7af  529,843,686
116 DarkSlateGray3     #87d7d7  529,843,843
117 SkyBlue1           #87d7ff  529,843,1000
118 Chartreuse1        #87ff00  529,1000,0
119 LightGreen         #87ff5f  529,1000,372
120 LightGreen         #87ff87  529,1000,529
121 PaleGreen1         #87ffaf  529,1000,686
122 Aquamarine1        #87ffd7  529,1000,843
123 DarkSlateGray1     #87ffff  529,1000,1000
124 Red3               #af0000  686,0,0
125 DeepPink4          #af005f  686,0,372
126 MediumVioletRed    #af0087  686,0,529
127 Magenta3           #af00af  686,0,686
128 DarkViolet         #af00d7  686,0,843
129 Purple             #af00ff  686,0,1000
130 DarkOrange3        #af5f00  686,372,0
131 IndianRed          #af5f5f  686,372,372
132 HotPink3           #af5f87  686,372,529
133 MediumOrchid3      #af5faf  686,372,686
134 MediumOrchid       #af5fd7  686,372,843
135 MediumPurple2      #af5fff  686,372,1000
136 DarkGoldenrod      #af8700  686,529,0
137 LightSalmon3       #af875f  686,529,372
138 RosyBrown          #af8787  686,529,529
139 Grey63             #af87af  686,529,686
140 MediumPurple2      #af87d7  686,529,843
141 MediumPurple1      #af87ff  686,529,1000
142 Gold3              #afaf00  686,686,0
143 DarkKhaki          #afaf5f  686,686,372
144 NavajoWhite3       #afaf87  686,686,529
145 Grey69             #afafaf  686,686,686
146 LightSteelBlue3    #afafd7  686,686,843
147 LightSteelBlue     #afafff  686,686,1000
148 Yellow3            #afd700  686,843,0
149 DarkOliveGreen3    #afd75f  686,843,372
150 DarkSeaGreen3      #afd787  686,843,529
151 DarkSeaGreen2      #afd7af  686,843,686
152 LightCyan3         #afd7d7  686,843,843
153 LightSkyBlue1      #afd7ff  686,843,1000
154 GreenYellow        #afff00  686,1000,0
155 DarkOliveGreen2    #afff5f  686,1000,372
156 PaleGreen1         #afff87  686,1000,529
157 DarkSeaGreen2      #afffaf  686,1000,686
158 DarkSeaGreen1      #afffd7  686,1000,843
159 PaleTurquoise1     #afffff  686,1000,1000
160 Red3               #d70000  843,0,0
161 DeepPink3          #d7005f  843,0,372
162 DeepPink3          #d70087  843,0,529
163 Magenta3           #d700af  843,0,686
164 Magenta3           #d700d7  843,0,843
165 Magenta2           #d700ff  843,0,1000
166 DarkOrange3        #d75f00  843,372,0
167 IndianRed          #d75f5f  843,372,372
168 HotPink3           #d75f87  843,372,529
169 HotPink2           #d75faf  843,372,686
170 Orchid             #d75fd7  843,372,843
171 MediumOrchid1      #d75fff  843,372,1000
172 Orange3            #d78700  843,529,0
173 LightSalmon3       #d7875f  843,529,372
174 LightPink3         #d78787  843,529,529
175 Pink3              #d787af  843,529,686
176 Plum3              #d787d7  843,529,843
177 Violet             #d787ff  843,529,1000
178 Gold3              #d7af00  843,686,0
179 LightGoldenrod3    #d7af5f  843,686,372
180 Tan                #d7af87  843,686,529
181 MistyRose3         #d7afaf  843,686,686
182 Thistle3           #d7afd7  843,686,843
183 Plum2              #d7afff  843,686,1000
184 Yellow3            #d7d700  843,843,0
185 Khaki3             #d7d75f  843,843,372
186 LightGoldenrod2    #d7d787  843,843,529
187 LightYellow3       #d7d7af  843,843,686
188 Grey84             #d7d7d7  843,843,843
189 LightSteelBlue1    #d7d7ff  843,843,1000
190 Yellow2            #d7ff00  843,1000,0
191 DarkOliveGreen1    #d7ff5f  843,1000,372
192 DarkOliveGreen1    #d7ff87  843,1000,529
193 DarkSeaGreen1      #d7ffaf  843,1000,686
194 Honeydew2          #d7ffd7  843,1000,843
195 LightCyan1         #d7ffff  843,1000,1000
196 Red1               #ff0000  1000,0,0
197 DeepPink2          #ff005f  1000,0,372
198 DeepPink1          #ff0087  1000,0,529
199 DeepPink1          #ff00af  1000,0,686
200 Magenta2           #ff00d7  1000,0,843
201 Magenta1           #ff00ff  1000,0,1000
202 OrangeRed1         #ff5f00  1000,372,0
203 IndianRed1         #ff5f5f  1000,372,372
204 IndianRed1         #ff5f87  1000,372,529
205 HotPink            #ff5faf  1000,372,686
206 HotPink            #ff5fd7  1000,372,843
207 MediumOrchid1      #ff5fff  1000,372,1000
208 DarkOrange         #ff8700  1000,529,0
209 Salmon1            #ff875f  1000,529,372
210 LightCoral         #ff8787  1000,529,529
211 PaleVioletRed1     #ff87af  1000,529,686
212 Orchid2            #ff87d7  1000,529,843
213 Orchid1            #ff87ff  1000,529,1000
214 Orange1            #ffaf00  1000,686,0
215 SandyBrown         #ffaf5f  1000,686,372
216 LightSalmon1       #ffaf87  1000,686,529
217 LightPink1         #ffafaf  1000,686,686
218 Pink1              #ffafd7  1000,686,843
219 Plum1              #ffafff  1000,686,1000
220 Gold1              #ffd700  1000,843,0
221 LightGoldenrod2    #ffd75f  1000,843,372
222 LightGoldenrod2    #ffd787  1000,843,529
223 NavajoWhite1       #ffd7af  1000,843,686
224 MistyRose1         #ffd7d7  1000,843,843
225 Thistle1           #ffd7ff  1000,843,1000
226 Yellow1            #ffff00  1000,1000,0
227 LightGoldenrod1    #ffff5f  1000,1000,372
228 Khaki1             #ffff87  1000,1000,529
229 Wheat1             #ffffaf  1000,1000,686
230 Cornsilk1          #ffffd7  1000,1000,843
231 Grey100            #ffffff  1000,1000,1000
232 Grey3              #080808  31,31,31
233 Grey7              #121212  70,70,70
234 Grey11             #1c1c1c  109,109,109
235 Grey15             #262626  149,149,149
236 Grey19             #303030  188,188,188
237 Grey23             #3a3a3a  227,227,227
238 Grey27             #444444  266,266,266
239 Grey30             #4e4e4e  305,305,305
240 Grey35             #585858  345,345,345
241 Grey39             #626262  384,384,384
242 Grey42             #6c6c6c  423,423,423
243 Grey46             #767676  462,462,462
244 Grey50             #808080  501,501,501
245 Grey54             #8a8a8a  541,541,541
246 Grey58             #949494  580,580,580
247 Grey62             #9e9e9e  619,619,619
248 Grey66             #a8a8a8  658,658,658
249 Grey70             #b2b2b2  698,698,698
250 Grey74             #bcbcbc  737,737,737
251 Grey78             #c6c6c6  776,776,776
252 Grey82             #d0d0d0  815,815,815
253 Grey85             #dadada  854,854,854
254 Grey89             #e4e4e4  894,894,894
255 Grey93             #eeeeee  933,933,933


来源:https://stackoverflow.com/questions/47686906/ncurses-init-color-has-no-effect

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