add --invert-colors option to image output

CHANGES

@@ -3,6 +3,9 @@
  - New
    - Show spinning animation at the beginning of -l / --live output line,
      visibility configurable using LiveSpinner configuration option
+   - Add --invert-colors option to image output for facilitating for example
+     dark mode switching without needing to have multiple separate color
+     configurations
 
 
 2.11 / 19-Aug-2023

man/vnstati.1

@@ -1,4 +1,4 @@
-.TH VNSTATI 1 "AUGUST 2023" "version 2.11" "User Manuals"
+.TH VNSTATI 1 "SEPTEMBER 2023" "version 2.12" "User Manuals"
 .SH NAME
 vnstati \- image output support for vnStat
 
@@ -45,6 +45,8 @@ vnstati \- image output support for vnStat
 .IR interface ]
 .RB [ \-\-iface
 .IR interface ]
+.RB [ \-\-invert\-colors
+.RI [ mode ]]
 .RB [ \-\-large ]
 .RB [ \-\-limit
 .IR limit ]
@@ -251,6 +253,16 @@ option is optional and
 can be used as parameter on the command line for selecting the used interface
 even without the option being explicitly used.
 
+.TP
+.BI "--invert-colors " [mode]
+Invert image colors. Results in black becoming white, dark colors becoming light,
+light colors becoming dark and white becoming black. The optional
+.I mode
+parameter can be used to change the color inversion behaviour. Available modes:
+0 = no color inversion, 1 = invert all colors except those used for rx and tx,
+2 = invert all colors. When
+.I mode
+isn't specific, mode 1 will be used.
 
 .TP
 .B "-L, --large"

src/image.c

@@ -11,6 +11,7 @@ void initimagecontent(IMAGECONTENT *ic)
 	ic->font = gdFontGetSmall();
 	ic->lineheight = 12;
 	ic->large = 0;
+	ic->invert = 0;
 	ic->showheader = 1;
 	ic->showedge = 1;
 	ic->showlegend = 1;

src/image.h

@@ -24,7 +24,7 @@ typedef struct {
 	interfaceinfo interface;
 	int cbackground, cedge, cheader, cheadertitle, cheaderdate, ctext, cline, clinel, cvnstat;
 	int crx, crxd, ctx, ctxd, cbgoffset, cbgoffsetmore, showheader, showedge, showlegend, altdate;
-	int lineheight, large;
+	int lineheight, large, invert;
 	char headertext[65], databegin[18], dataend[18];
 	time_t current;
 } IMAGECONTENT;

src/image_support.c

@@ -7,75 +7,93 @@
 
 void imageinit(IMAGECONTENT *ic, const int width, const int height)
 {
-	int rgb[3];
+	int rgb[3], invert = 1;
 
 	ic->im = gdImageCreate(width, height);
 
+	if (ic->invert > 0) {
+		invert = -1;
+	}
+
 	/* text, edge and header colors */
 	hextorgb(cfg.ctext, rgb);
+	if (ic->invert > 0) { invertcolor(rgb); }
 	ic->ctext = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("ctext", ic->ctext, cfg.ctext, rgb);
 	hextorgb(cfg.cedge, rgb);
+	if (ic->invert > 0) { invertcolor(rgb); }
 	ic->cedge = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cedge", ic->cedge, cfg.cedge, rgb);
 	hextorgb(cfg.cheader, rgb);
+	if (ic->invert > 0) { invertcolor(rgb); }
 	ic->cheader = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cheader", ic->cheader, cfg.cheader, rgb);
 	hextorgb(cfg.cheadertitle, rgb);
+	if (ic->invert > 0) { invertcolor(rgb); }
 	ic->cheadertitle = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cheadertitle", ic->cheadertitle, cfg.cheadertitle, rgb);
 	hextorgb(cfg.cheaderdate, rgb);
+	if (ic->invert > 0) { invertcolor(rgb); }
 	ic->cheaderdate = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cheaderdate", ic->cheaderdate, cfg.cheaderdate, rgb);
 
 	/* lines */
 	hextorgb(cfg.cline, rgb);
+	if (ic->invert > 0) { invertcolor(rgb); }
 	ic->cline = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cline", ic->cline, cfg.cline, rgb);
 	if (cfg.clinel[0] == '-') {
-		modcolor(rgb, 50, 1);
+		modcolor(rgb, 50 * invert, 1);
 	} else {
 		hextorgb(cfg.clinel, rgb);
+		if (ic->invert > 0) { invertcolor(rgb); }
 	}
 	ic->clinel = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("clinel", ic->clinel, cfg.clinel, rgb);
 
 	/* background */
 	hextorgb(cfg.cbg, rgb);
+	if (ic->invert > 0) { invertcolor(rgb); }
 	ic->cbackground = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cbackground", ic->cbackground, cfg.cbg, rgb);
-	modcolor(rgb, -35, 0);
+	modcolor(rgb, -35 * invert, 0);
 	ic->cvnstat = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cvnstat", ic->cvnstat, cfg.cbg, rgb);
 	hextorgb(cfg.cbg, rgb);
-	modcolor(rgb, -15, 0);
+	if (ic->invert > 0) { invertcolor(rgb); }
+	modcolor(rgb, -15 * invert, 0);
 	ic->cbgoffset = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cbgoffset", ic->cbgoffset, cfg.cbg, rgb);
 	hextorgb(cfg.cbg, rgb);
-	modcolor(rgb, -40, 0);
+	if (ic->invert > 0) { invertcolor(rgb); }
+	modcolor(rgb, -40 * invert, 0);
 	ic->cbgoffsetmore = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("cbgoffsetmore", ic->cbgoffsetmore, cfg.cbg, rgb);
 
 	/* rx */
 	hextorgb(cfg.crx, rgb);
+	if (ic->invert > 1) { invertcolor(rgb); }
 	ic->crx = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("crx", ic->crx, cfg.crx, rgb);
 	if (cfg.crxd[0] == '-') {
-		modcolor(rgb, -50, 1);
+		modcolor(rgb, -50 * invert, 1);
 	} else {
 		hextorgb(cfg.crxd, rgb);
+		if (ic->invert > 1) { invertcolor(rgb); }
 	}
 	ic->crxd = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("crxd", ic->crxd, cfg.crxd, rgb);
 
 	/* tx */
 	hextorgb(cfg.ctx, rgb);
+	if (ic->invert > 1) { invertcolor(rgb); }
 	ic->ctx = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("ctx", ic->ctx, cfg.ctx, rgb);
 	if (cfg.ctxd[0] == '-') {
-		modcolor(rgb, -50, 1);
+		modcolor(rgb, -50 * invert, 1);
 	} else {
 		hextorgb(cfg.ctxd, rgb);
+		if (ic->invert > 1) { invertcolor(rgb); }
 	}
 	ic->ctxd = gdImageColorAllocate(ic->im, rgb[0], rgb[1], rgb[2]);
 	colorinitcheck("ctxd", ic->ctxd, cfg.ctxd, rgb);
@@ -429,6 +447,23 @@ void modcolor(int *rgb, const int offset, const int force)
 	}
 }
 
+void invertcolor(int *rgb)
+{
+	int i;
+
+	if (debug) {
+		printf("invert: %d, %d, %d -> ", rgb[0], rgb[1], rgb[2]);
+	}
+
+	for (i = 0; i < 3; i++) {
+		rgb[i] = 255 - rgb[i];
+	}
+
+	if (debug) {
+		printf("%d, %d, %d\n", rgb[0], rgb[1], rgb[2]);
+	}
+}
+
 char *getimagevalue(const uint64_t b, const int len, const int rate)
 {
 	static char buffer[64];

src/image_support.h

@@ -17,6 +17,7 @@ void drawarrowup(IMAGECONTENT *ic, const int x, const int y);
 void drawarrowright(IMAGECONTENT *ic, const int x, const int y);
 void hextorgb(const char *input, int *rgb);
 void modcolor(int *rgb, const int offset, const int force);
+void invertcolor(int *rgb);
 char *getimagevalue(const uint64_t b, const int len, const int rate);
 char *getimagescale(const uint64_t b, const int rate);
 uint64_t getscale(const uint64_t input, const int rate);

src/vnstati.c

@@ -165,7 +165,8 @@ void showihelp(const IPARAMS *p)
 #if HAVE_DECL_GD_NEAREST_NEIGHBOUR
 	printf("      --scale <percent>                  change image size by scaling it\n");
 #endif
-	printf("      --transparent [enabled]            toggle background transparency\n\n");
+	printf("      --transparent [enabled]            toggle background transparency\n");
+	printf("      --invert-colors <mode>             invert image colors (0-2)\n\n");
 
 	printf("See also \"man vnstati\".\n");
 }
@@ -502,6 +503,26 @@ void parseargs(IPARAMS *p, IMAGECONTENT *ic, int argc, char **argv)
 				fprintf(stderr, "Error: Invalid or missing parameter for %s.\n", argv[currentarg]);
 				exit(EXIT_FAILURE);
 			}
+		} else if (strcmp(argv[currentarg], "--invert-colors") == 0) {
+			if (currentarg + 1 < argc && (strlen(argv[currentarg + 1]) == 1 || ishelprequest(argv[currentarg + 1]))) {
+				if (!isdigit(argv[currentarg + 1][0]) || atoi(argv[currentarg + 1]) > 2 || atoi(argv[currentarg + 1]) < 0) {
+					if (!ishelprequest(argv[currentarg + 1]))
+						fprintf(stderr, "Error: Invalid parameter \"%s\".\n", argv[currentarg + 1]);
+					printf(" Valid parameters for %s:\n", argv[currentarg]);
+					printf("    0 - no color inversion\n");
+					printf("    1 - invert all colors except rx and tx\n");
+					printf("    2 - invert all colors\n");
+					exit(EXIT_FAILURE);
+				}
+				ic->invert = atoi(argv[currentarg + 1]);
+				if (debug)
+					printf("Invert colors changed: %d\n", ic->invert);
+				currentarg++;
+			} else {
+				ic->invert = !ic->invert;
+				if (debug)
+					printf("Invert colors changed: %d\n", ic->invert);
+			}
 		} else if ((strcmp(argv[currentarg], "-v") == 0) || (strcmp(argv[currentarg], "--version")) == 0) {
 			printf("vnStat image output %s by Teemu Toivola <tst at iki dot fi> (SQLite %s, LibGD %d.%d.%d)\n", getversion(), sqlite3_libversion(), GD_MAJOR_VERSION, GD_MINOR_VERSION, GD_RELEASE_VERSION);
 			exit(EXIT_SUCCESS);

tests/image_tests.c

@@ -871,6 +871,31 @@ START_TEST(modcolor_mods_colors)
 }
 END_TEST
 
+START_TEST(invertcolor_inverts_colors)
+{
+	int rgb[3];
+
+	debug = 1;
+	suppress_output();
+
+	rgb[0] = 0;
+	rgb[1] = 10;
+	rgb[2] = 255;
+	invertcolor(rgb);
+	ck_assert_int_eq(rgb[0], 255);
+	ck_assert_int_eq(rgb[1], 245);
+	ck_assert_int_eq(rgb[2], 0);
+
+	rgb[0] = 50;
+	rgb[1] = 150;
+	rgb[2] = 200;
+	invertcolor(rgb);
+	ck_assert_int_eq(rgb[0], 205);
+	ck_assert_int_eq(rgb[1], 105);
+	ck_assert_int_eq(rgb[2], 55);
+}
+END_TEST
+
 void add_image_tests(Suite *s)
 {
 	TCase *tc_image = tcase_create("Image");
@@ -897,5 +922,6 @@ void add_image_tests(Suite *s)
 	tcase_add_test(tc_image, element_output_check);
 	tcase_add_test(tc_image, hextorgb_can_convert);
 	tcase_add_test(tc_image, modcolor_mods_colors);
+	tcase_add_test(tc_image, invertcolor_inverts_colors);
 	suite_add_tcase(s, tc_image);
 }