color input for text/grids (color1), background (color0)

and graphs (color2-22) on Windows via
set color2=red
set color2=rgb:ff/0/0
set color2=rgbd:255,0,0
several examples given in the example files

examples/utf-8/стекло/ext-utf8-2.cir

@@ -1,10 +1,10 @@
 * test de titré
 .control
 set hcopydevtype = postscript
-set hcopypscolor=25
+set hcopypscolor=18
 set hcopypstxcolor=21
 set hcopyscale=1
-set color2=rgb:F/0/0
+set color2=rgb:FF/0/0
 setcs hcopyfont=Arial
 set hcopyfontsize=18
 
@@ -18,8 +18,6 @@ setcs xfont='Noto Sans Chinese'
 set gridwidth=4
 set xbrushwidth=1
 
-hardcopy
-
 plot y vs x xlabel 'Labellisé X' ylabel 'Labellisé Y: ÜüÖöÄäÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ' title 'Titré'
 plot y vs x xlabel '我能吞下玻璃而不伤身体' ylabel 'Я могу есть стекло, оно мне не вредит' title ' أنا قادر على أكل الزجاج و هذا لا يؤلمني.'
 * With Linux the next one requires: export LC_CTYPE ="de_DE.UTF-8"

examples/utf-8/стекло/ext-utf8-c.cir

@@ -1,4 +1,4 @@
-* test de titré
+titré 'test of various color inputs for background, text/grid and graphs 1'
 .control
 set hcopydevtype = postscript
 set hcopypscolor=25

examples/utf-8/стекло/ext-utf8-c2.cir

@@ -0,0 +1,59 @@
+* titré 'test of various color inputs for background, text/grid and graphs 2'
+.control
+set hcopydevtype = postscript
+set hcopypscolor=25
+set hcopypstxcolor=21
+set hcopyscale=1
+*set color2=rgb:F/0/0
+
+setcs hcopyfont=Arial
+set hcopyfontsize=18
+
+
+let x = vector(5)
+let y = exp(x)
+setcs wfont=Arial
+set wfont_size=18
+setcs xfont='Noto Sans'
+*set xfont_size=18
+
+set gridwidth=4
+set xbrushwidth=1
+set color0=white
+*set color2=brown
+set color2=rgbd:255/0/0
+plot y vs x xlabel 'Labellisé X' ylabel 'Labellisé Y: ÜüÖöÄäÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜÜ' title 'Titré'
+set color0=black
+plot y vs x xlabel '我能吞下玻璃而不伤身体' ylabel 'Я могу есть стекло, оно мне не вредит' title ' أنا قادر على أكل الزجاج و هذا لا يؤلمني.'
+* With Linux the next one requires: export LC_CTYPE ="de_DE.UTF-8"
+*gnuplot test.gn y vs x xlabel 'Labellisé X' ylabel 'tüTÄtö Äü @µ€~' title 'ฉันกินกระจกได้ แต่มันไม่ทำให้ฉันเจ็บ '
+set color0=Blue
+set color1=Yellow
+set color2=rgb:00/FF/00
+set gridwidth=1
+set xbrushwidth=4
+plot y vs x+0.001 xlabel 'Labellisé X' ylabel 'Labellisé Y' title 'Titré 私はガラスを食べられます。それは私を傷つけません' loglog
+unset color1
+set color0=MediumBlue
+set color2=Magenta
+plot y vs x+0.001 xlabel 'Labellisé X' title 'Titré' loglog
+set color0=GreenYellow
+set color2=rgbd:128/128/75
+plot y vs x+0.001 xlabel 'Labellisé X' title 'Titré' loglog
+set color0=black
+set color2=pink
+plot y vs x xlabel '래도 아프지 않아요' ylabel '私はガラスを食べられます' title ' أنا قادر على أكل الزجاج و هذا لا يؤلمني.'
+
+* With Linux the next one requires: export LC_CTYPE ="de_DE.UTF-8"
+*gnuplot test2.gn y vs x xlabel 'Labellisé X' ylabel 'tüTÄtö Äü @µ€~' title 'ฉันกินกระจกได้ แต่มันไม่ทำให้ฉันเจ็บ '
+
+*hardcopy plot_5.ps y vs x xlabel 'Labellisé X' ylabel 'Labellisé Y' title 'Titré Äü @µ€~'
+*shell Start /B plot_5.ps
+*shell gv plot_5.ps &
+
+echo 나는 유리를 먹을 수 있어요. 그래도 아프지 않아요
+echo 私はガラスを食べられます。それは私を傷つけません
+echo 我能吞下玻璃而不伤身体
+
+*quit
+.endc

src/frontend/wdisp/wincolor.c

@@ -43,7 +43,57 @@ void wincolor_init_hash(COLORREF *ColorTable, int noc)
             ColorTable[i] = 0; 
     }
 }
+/* evaluate rgb:0/FF/F0 rgb:0/F/0 rgbd:295/0/128 */
+static COLORREF get_wincolor_rgb(char *costr)
+{
+    char *tmpstr;
+    if (ciprefix("rgb:", costr)) {
+        char *t1, *t2, *t3;
+        tmpstr = costr + 4;
+        if (tmpstr) {
+            t1 = gettok_char(&tmpstr, '/', FALSE, FALSE);
+            tmpstr++;
+            t2 = gettok_char(&tmpstr, '/', FALSE, FALSE);
+            tmpstr++;
+            t3 = copy(tmpstr);
+            if (t1 && t2 && t3) {
+                int c1, c2, c3;
+                c1 = (int) strtol(t1, NULL, 16);
+                c2 = (int) strtol(t2, NULL, 16);
+                c3 = (int) strtol(t3, NULL, 16);
+                tfree(t1);
+                tfree(t2);
+                tfree(t3);
+                return RGB(c1, c2, c3);
+            }
+        }
+
+    }
+    else if (ciprefix("rgbd:", costr)) {
+        char *t1, *t2, *t3;
+        tmpstr = costr + 5;
+        if (tmpstr) {
+            t1 = gettok_char(&tmpstr, '/', FALSE, FALSE);
+            tmpstr++;
+            t2 = gettok_char(&tmpstr, '/', FALSE, FALSE);
+            tmpstr++;
+            t3 = copy(tmpstr);
+            if (t1 && t2 && t3) {
+                int c1, c2, c3;
+                c1 = (int) strtol(t1, NULL, 10);
+                c2 = (int) strtol(t2, NULL, 10);
+                c3 = (int) strtol(t3, NULL, 10);
+                tfree(t1);
+                tfree(t2);
+                tfree(t3);
+                return RGB(c1, c2, c3);
+            }
+        }
+    }
 
+    fprintf(stderr, "Error: Cannot detect color in string %s, setting Web Green\n", costr);
+    return RGB(0, 128, 0);
+}
 
 /* ColorTable[0]: background, ColorTable[1]: grid, text */
 void wincolor_init(COLORREF* ColorTable, int noc)
@@ -64,8 +114,9 @@ void wincolor_init(COLORREF* ColorTable, int noc)
         if (!cp_getvar(buf, CP_STRING, colorstring, sizeof(colorstring))) {
             if (i == 1) {
                 /* switch the grid and text color depending on background */
-                int tcolor = GetRValue(ColorTable[0]) + GetGValue(ColorTable[0]) + GetBValue(ColorTable[0]);
-                if (tcolor > 250) {
+                int tcolor = GetRValue(ColorTable[0]) +
+                    (int)(1.5 * GetGValue(ColorTable[0])) + GetBValue(ColorTable[0]);
+                if (tcolor > 360) {
                     ColorTable[1] = RGB(0, 0, 0);
                     i++;
                     bgisblack = FALSE;
@@ -84,6 +135,11 @@ void wincolor_init(COLORREF* ColorTable, int noc)
             else
                 (void)strcpy(colorstring, stdcolornames[i]);
         }
+        else if (ciprefix("rgb", colorstring)){
+            ColorTable[i] =  get_wincolor_rgb(colorstring);
+            i++;
+            continue;
+        }
         ColorTable[i] =  get_wincolor(colorstring, nocolor);
         i++;
     }
@@ -97,7 +153,10 @@ void wincolor_redo(COLORREF* ColorTable, int noc)
     int nocolor = NUMELEMS(ctable);
 
     while (i < noc) {
-        /* when color0 is set to white and color1 is not given, set ColorTable[2] to black */
+        /* when color0 is set to white and color1 is not given, set text and grid color 
+        as ColorTable[1] to black, when color0 is any other color, select black or 
+        white text and grid color according to a weighted value derived from color0. 
+        This selection is a compromise based on visibility.*/
         (void)sprintf(buf, "color%d", i);
         if (!cp_getvar(buf, CP_STRING, colorstring, sizeof(colorstring))) {
             if (i == 1) {
@@ -123,6 +182,11 @@ void wincolor_redo(COLORREF* ColorTable, int noc)
             else
                 (void)strcpy(colorstring, stdcolornames[i]);
         }
+        else if (ciprefix("rgb", colorstring)) {
+            ColorTable[i] = get_wincolor_rgb(colorstring);
+            i++;
+            continue;
+        }
         ColorTable[i] = get_wincolor(colorstring, nocolor);
         i++;
     }