use LCh color space (Rec.2020 for luma)

src/CMakeLists.txt

@@ -299,10 +299,10 @@ if(BUILD_INTEL_BACKLIGHT)
   set(optional_sources ${optional_sources} ${intel_backlight})
 endif(BUILD_INTEL_BACKLIGHT)
 
-if(BUILD_HSV_GRADIENT)
+if(BUILD_HCL_GRADIENT)
-  set(hsv_gradient hsv_gradient.cc hsv_gradient.h)
+  set(hcl_gradient hcl_gradient.cc hcl_gradient.h)
-  set(optional_sources ${optional_sources} ${hsv_gradient})
+  set(optional_sources ${optional_sources} ${hcl_gradient})
-endif(BUILD_HSV_GRADIENT)
+endif(BUILD_HCL_GRADIENT)
 
 if(BUILD_TESTS)
   # Create a library strictly for testing

src/conky.cc

@@ -130,9 +130,9 @@
 #include "openbsd.h"
 #endif /* __OpenBSD__ */
 
-#ifdef BUILD_HSV_GRADIENT
+#ifdef BUILD_HCL_GRADIENT
-#include "hsv_gradient.h"
+#include "hcl_gradient.h"
-#endif /* BUILD_HSV_GRADIENT */
+#endif /* BUILD_HCL_GRADIENT */
 
 #ifdef BUILD_OLD_CONFIG
 #include "convertconf.h"
@@ -1291,13 +1291,13 @@ int draw_each_line_inner(char *s, int special_index, int last_special_applied) {
               std::unique_ptr<unsigned long[]> tmpcolour;
 
               if (current->last_colour != 0 || current->first_colour != 0) {
-#ifdef BUILD_HSV_GRADIENT
+#ifdef BUILD_HCL_GRADIENT
-                tmpcolour = do_hsv_gradient(w - 1, current->last_colour,
+                tmpcolour = do_hcl_gradient(w - 1, current->last_colour,
                                             current->first_colour);
-#else  /* BUILD_HSV_GRADIENT */
+#else  /* BUILD_HCL_GRADIENT */
                 tmpcolour = do_gradient(w - 1, current->last_colour,
                                         current->first_colour);
-#endif /* BUILD_HSV_GRADIENT */
+#endif /* BUILD_HCL_GRADIENT */
               }
               colour_idx = 0;
               for (i = w - 2; i > -1; i--) {

src/hcl_gradient.cc

@@ -0,0 +1,240 @@
+/*
+ *
+ * Conky, a system monitor, based on torsmo
+ *
+ * Any original torsmo code is licensed under the BSD license
+ *
+ * All code written since the fork of torsmo is licensed under the GPL
+ *
+ * Please see COPYING for details
+ *
+ * Copyright (c) 2004, Hannu Saransaari and Lauri Hakkarainen
+ * Copyright (c) 2005-2021 Brenden Matthews, Philip Kovacs, et. al.
+ *	(see AUTHORS)
+ * All rights reserved.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#include "hcl_gradient.h"
+#include "colours.h"
+#include "conky.h"
+#include "logging.h"
+
+#ifdef BUILD_X11
+#include "x11.h"
+#endif /* BUILD_X11 */
+
+#define CONST_SCALE 512L
+#define CONST_SCALE_HALF (CONST_SCALE / 2)
+#define CONST_SCALE2 (CONST_SCALE * 2L)
+#define CONST_SCALE4 (CONST_SCALE * 4L)
+#define CONST_SCALE6 (CONST_SCALE * 6L)
+#define CONST_SCALE60 (CONST_SCALE * 60L)
+#define CONST_SCALE120 (CONST_SCALE * 120L)
+#define CONST_SCALE180 (CONST_SCALE * 180L)
+#define CONST_SCALE240 (CONST_SCALE * 240L)
+#define CONST_SCALE300 (CONST_SCALE * 300L)
+#define CONST_SCALE360 (CONST_SCALE * 360L)
+
+long to_decimal_scale(long value, long max_value) {
+  if (value == 0) {
+    return 0;
+  } else if (value > 0) {
+    return (value * CONST_SCALE + max_value - 1) / max_value;
+  }
+  return -((std::abs(value) * CONST_SCALE + max_value - 1) / max_value);
+}
+
+long from_decimal_scale(long value, long max_value) {
+  if (value == 0) {
+    return 0;
+  } else if (value > 0) {
+    return (value * max_value + CONST_SCALE_HALF) / CONST_SCALE;
+  }
+  return -((std::abs(value) * max_value + CONST_SCALE_HALF) / CONST_SCALE);
+}
+
+long cap_scaled_color(long colour) {
+  if (colour < 0) {
+    return 0;
+  } else if (colour > CONST_SCALE) {
+    return CONST_SCALE;
+  }
+  return colour;
+}
+
+void scaled_rgb_to_scaled_hcl(long *const rgb, long *hcl) {
+  long value = rgb[0] > rgb[1] ? std::max(rgb[0], rgb[2]) : std::max(rgb[1], rgb[2]);
+  long minimum = rgb[0] < rgb[1] ? std::min(rgb[0], rgb[2]) : std::min(rgb[1], rgb[2]);
+  long chroma = value - minimum;
+  long luma = (2627 * rgb[0] + 6780 * rgb[1] + 593 * rgb[2]) / 10000; //Use Rec.2020 color space
+  long hue;
+
+  if (chroma == 0) {
+    hue = 0;
+  } else {
+    long diff;
+    long offset;
+
+    if (rgb[0] == value) {
+      diff = rgb[1] - rgb[2];
+      offset = 0;
+    } else if (rgb[1] == value) {
+      diff = rgb[2] - rgb[0];
+      offset = CONST_SCALE2;
+    } else {
+      diff = rgb[0] - rgb[1];
+      offset = CONST_SCALE4;
+    }
+    long h = (CONST_SCALE * diff) / chroma + offset;
+    hue = 60L * ((CONST_SCALE6 + h) % CONST_SCALE6);
+  }
+
+  hcl[0] = hue;
+  hcl[1] = chroma * 360;
+  hcl[2] = luma * 360;
+}
+
+void scaled_hcl_to_scaled_rgb(long *const hcl, long *rgb) {
+  long hue = hcl[0] % CONST_SCALE360;
+  long chroma = hcl[1] / 360;
+  long luma = hcl[2] / 360;
+
+  long h = hue / 60L;
+  long x = (chroma * (CONST_SCALE - std::abs(h % CONST_SCALE2 - CONST_SCALE))) / CONST_SCALE;
+  long m;
+
+  // use Rec.2020 color space
+  if (hue < CONST_SCALE60) {
+    m = luma - (2627 * chroma + 6780 * x) / 10000;
+    rgb[0] = rgb[1] = rgb[2] = m;
+    rgb[0] += chroma;
+    rgb[1] += x;
+  } else if (hue < CONST_SCALE120) {
+    m = luma - (2627 * x + 6780 * chroma) / 10000;
+    rgb[0] = rgb[1] = rgb[2] = m;
+    rgb[0] += x;
+    rgb[1] += chroma;
+  } else if (hue < CONST_SCALE180) {
+    m = luma - (6780 * chroma + 593 * x) / 10000;
+    rgb[0] = rgb[1] = rgb[2] = m;
+    rgb[1] += chroma;
+    rgb[2] += x;
+  } else if (hue < CONST_SCALE240) {
+    m = luma - (6780 * x + 593 * chroma) / 10000;
+    rgb[0] = rgb[1] = rgb[2] = m;
+    rgb[1] += x;
+    rgb[2] += chroma;
+  } else if (hue < CONST_SCALE300) {
+    m = luma - (2627 * x + 593 * chroma) / 10000;
+    rgb[0] = rgb[1] = rgb[2] = m;
+    rgb[2] += chroma;
+    rgb[0] += x;
+  } else {
+    m = luma - (2627 * chroma + 593 * x) / 10000;
+    rgb[0] = rgb[1] = rgb[2] = m;
+    rgb[2] += x;
+    rgb[0] += chroma;
+  }
+
+  rgb[0] = cap_scaled_color(rgb[0]);
+  rgb[1] = cap_scaled_color(rgb[1]);
+  rgb[2] = cap_scaled_color(rgb[2]);
+}
+
+void rgb_to_scaled_rgb(unsigned long colour, long *scaled, int redshift, int greenshift) {
+  long red = (colour & redmask) >> redshift;
+  long green = (colour & greenmask) >> greenshift;
+  long blue = colour & bluemask;
+
+  long red_max = redmask >> redshift;
+  long green_max = greenmask >> greenshift;
+  long blue_max = bluemask;
+
+  scaled[0] = to_decimal_scale(red, red_max);
+  scaled[1] = to_decimal_scale(green, green_max);
+  scaled[2] = to_decimal_scale(blue, blue_max);
+}
+
+unsigned long scaled_rgb_to_rgb(long *const scaled, int redshift, int greenshift) {
+  long red_max = redmask >> redshift;
+  long green_max = greenmask >> greenshift;
+
+  long red = from_decimal_scale(scaled[0], red_max);
+  long green = from_decimal_scale(scaled[1], green_max);
+  long blue = from_decimal_scale(scaled[2], bluemask);
+
+  return (red << redshift) | (green << greenshift) | blue;
+}
+
+/* this function returns the next colour between two colours in hcl space for a
+ * gradient */
+std::unique_ptr<unsigned long[]> do_hcl_gradient(int width,
+                                                 unsigned long first_colour,
+                                                 unsigned long last_colour) {
+  long first_colour_rgb[3];
+  long last_colour_rgb[3];
+  long temp_colour_rgb[3];
+
+  long first_colour_hcl[3];
+  long final_colour_hcl[3];
+
+  long hueDiff, chromaDiff, lumaDiff;
+
+  int redshift = (2 * colour_depth / 3 + colour_depth % 3);
+  int greenshift = (colour_depth / 3);
+
+  // Make sure the width is always at least 2
+  width = std::max(2, width);
+
+  std::unique_ptr<unsigned long[]> colours(new unsigned long[width]);
+
+  if (colour_depth == 0) {
+    set_up_gradient();
+  }
+
+  rgb_to_scaled_rgb(first_colour, first_colour_rgb, redshift, greenshift);
+  rgb_to_scaled_rgb(last_colour, last_colour_rgb, redshift, greenshift);
+  scaled_rgb_to_scaled_hcl(first_colour_rgb, first_colour_hcl);
+  scaled_rgb_to_scaled_hcl(last_colour_rgb, final_colour_hcl);
+
+  hueDiff = final_colour_hcl[0] - first_colour_hcl[0];
+  chromaDiff = final_colour_hcl[1] - first_colour_hcl[1];
+  lumaDiff = final_colour_hcl[2] - first_colour_hcl[2];
+
+  colours[0] = first_colour;
+  colours[width - 1] = last_colour;
+
+  long divisor = width - 1;
+  long hueDelta = hueDiff/divisor;
+  long chromaDelta = chromaDiff/divisor;
+  long lumaDelta = lumaDiff/divisor;
+
+  for (int i = 1; i < (width - 1); i++) {
+    long h = first_colour_hcl[0] + hueDelta;
+
+    if (h < 0) {
+      first_colour_hcl[0] = CONST_SCALE360 + h;
+    } else {
+      first_colour_hcl[0] = h;
+    }
+    first_colour_hcl[1] += chromaDelta;
+    first_colour_hcl[2] += lumaDelta;
+
+    scaled_hcl_to_scaled_rgb(first_colour_hcl, temp_colour_rgb);
+    colours[i] = scaled_rgb_to_rgb(temp_colour_rgb, redshift, greenshift);
+  }
+
+  return colours;
+}

src/hcl_gradient.h

@@ -26,22 +26,24 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  */
-#ifndef _HSV_GRADIENT_H
+
-#define _HSV_GRADIENT_H
+// Use Hue-Chroma-Luma to create gradients
+#ifndef _HCL_GRADIENT_H
+#define _HCL_GRADIENT_H
 
 #include <memory>
 
-// needed by hsv_gradient
+// needed by hcl_gradient
 extern short colour_depth;
 extern long redmask, greenmask, bluemask;
 extern void set_up_gradient();
 
-std::unique_ptr<unsigned long[]> do_hsv_gradient(int, unsigned long,
+std::unique_ptr<unsigned long[]> do_hcl_gradient(int, unsigned long,
                                                  unsigned long);
 
 long to_decimal_scale(long value, long max_value);
 long from_decimal_scale(long value, long max_value);
-void scaled_rgb_to_scaled_hsv(long *const rgb, long *hsv);
+void scaled_rgb_to_scaled_hcl(long *const rgb, long *hcl);
-void scaled_hsv_to_scaled_rgb(long *const hsv, long *rgb);
+void scaled_hcl_to_scaled_rgb(long *const hcl, long *rgb);
 
-#endif /* _COLOURS_H */
+#endif /* _HCL_GRADIENT_H */

src/hsv_gradient.cc

@@ -1,221 +0,0 @@
-/*
- *
- * Conky, a system monitor, based on torsmo
- *
- * Any original torsmo code is licensed under the BSD license
- *
- * All code written since the fork of torsmo is licensed under the GPL
- *
- * Please see COPYING for details
- *
- * Copyright (c) 2004, Hannu Saransaari and Lauri Hakkarainen
- * Copyright (c) 2005-2021 Brenden Matthews, Philip Kovacs, et. al.
- *	(see AUTHORS)
- * All rights reserved.
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- *
- */
-#include "hsv_gradient.h"
-#include "colours.h"
-#include "conky.h"
-#include "logging.h"
-
-#ifdef BUILD_X11
-#include "x11.h"
-#endif /* BUILD_X11 */
-
-#define CONST_SCALE 512L
-#define CONST_SCALE_HALF (CONST_SCALE / 2)
-#define CONST_SCALE2 (CONST_SCALE * 2L)
-#define CONST_SCALE4 (CONST_SCALE * 4L)
-#define CONST_SCALE6 (CONST_SCALE * 6L)
-#define CONST_SCALE60 (CONST_SCALE * 60L)
-#define CONST_SCALE120 (CONST_SCALE * 120L)
-#define CONST_SCALE180 (CONST_SCALE * 180L)
-#define CONST_SCALE240 (CONST_SCALE * 240L)
-#define CONST_SCALE300 (CONST_SCALE * 300L)
-#define CONST_SCALE360 (CONST_SCALE * 360L)
-
-long to_decimal_scale(long value, long max_value) {
-  if (value == 0) {
-    return 0;
-  } else if (value > 0) {
-    return (value * CONST_SCALE + max_value - 1) / max_value;
-  }
-  return -((std::abs(value) * CONST_SCALE + max_value - 1) / max_value);
-}
-
-long from_decimal_scale(long value, long max_value) {
-  if (value == 0) {
-    return 0;
-  } else if (value > 0) {
-    return (value * max_value + CONST_SCALE_HALF) / CONST_SCALE;
-  }
-  return -((std::abs(value) * max_value + CONST_SCALE_HALF) / CONST_SCALE);
-}
-
-void scaled_rgb_to_scaled_hsv(long *const rgb, long *hsv) {
-  long val =
-      rgb[0] > rgb[1] ? std::max(rgb[0], rgb[2]) : std::max(rgb[1], rgb[2]);
-  long cmin =
-      rgb[0] < rgb[1] ? std::min(rgb[0], rgb[2]) : std::min(rgb[1], rgb[2]);
-  long delta = val - cmin;
-
-  long hue;
-
-  if (delta == 0) {
-    hue = 0;
-  } else {
-    long d;
-    long offset;
-
-    if (rgb[0] == val) {
-      d = rgb[1] - rgb[2];
-      offset = 0;
-    } else if (rgb[1] == val) {
-      d = rgb[2] - rgb[0];
-      offset = CONST_SCALE2;
-    } else {
-      d = rgb[0] - rgb[1];
-      offset = CONST_SCALE4;
-    }
-    long h = (CONST_SCALE * d + delta / 2) / delta + offset;
-    hue = 60L * ((CONST_SCALE6 + h) % CONST_SCALE6);
-  }
-
-  long sat;
-  if (val == 0) {
-    sat = 0;
-  } else {
-    sat = (CONST_SCALE * delta + val / 2) / val;
-  }
-
-  hsv[0] = hue;
-  hsv[1] = sat;
-  hsv[2] = val;
-}
-
-void scaled_hsv_to_scaled_rgb(long *const hsv, long *rgb) {
-  long c = (hsv[2] * hsv[1] + CONST_SCALE_HALF) / CONST_SCALE;
-
-  long hue = hsv[0] % CONST_SCALE360;
-  long x = (c * (CONST_SCALE -
-                 std::abs(((hue + 30L) / 60L) % CONST_SCALE2 - CONST_SCALE)) +
-            CONST_SCALE_HALF) /
-           CONST_SCALE;
-  long m = hsv[2] - c;
-
-  rgb[0] = m;
-  rgb[1] = m;
-  rgb[2] = m;
-
-  if (hue < CONST_SCALE60) {
-    rgb[0] += c;
-    rgb[1] += x;
-  } else if (hue < CONST_SCALE120) {
-    rgb[0] += x;
-    rgb[1] += c;
-  } else if (hue < CONST_SCALE180) {
-    rgb[1] += c;
-    rgb[2] += x;
-  } else if (hue < CONST_SCALE240) {
-    rgb[1] += x;
-    rgb[2] += c;
-  } else if (hue < CONST_SCALE300) {
-    rgb[2] += c;
-    rgb[0] += x;
-  } else {
-    rgb[2] += x;
-    rgb[0] += c;
-  }
-}
-
-/* this function returns the next colour between two colours in hsv space for a
- * gradient */
-std::unique_ptr<unsigned long[]> do_hsv_gradient(int width,
-                                                 unsigned long first_colour,
-                                                 unsigned long last_colour) {
-  long rgb1[3], rgb2[3], rgb3[3];
-  long hsv1[3], hsv2[3];
-  long hueDiff, satDiff, valDiff;
-
-  int redshift = (2 * colour_depth / 3 + colour_depth % 3);
-  int greenshift = (colour_depth / 3);
-
-  // Make sure the width is always at least 2
-  width = std::max(2, width);
-
-  std::unique_ptr<unsigned long[]> colours(new unsigned long[width]);
-
-  if (colour_depth == 0) { set_up_gradient(); }
-
-  rgb1[0] = to_decimal_scale((first_colour & redmask) >> redshift,
-                             redmask >> redshift);
-  rgb1[1] = to_decimal_scale((first_colour & greenmask) >> greenshift,
-                             greenmask >> greenshift);
-  rgb1[2] = to_decimal_scale(first_colour & bluemask, bluemask);
-  rgb2[0] = to_decimal_scale((last_colour & redmask) >> redshift,
-                             redmask >> redshift);
-  rgb2[1] = to_decimal_scale((last_colour & greenmask) >> greenshift,
-                             greenmask >> greenshift);
-  rgb2[2] = to_decimal_scale(last_colour & bluemask, bluemask);
-
-  scaled_rgb_to_scaled_hsv(rgb1, hsv1);
-  scaled_rgb_to_scaled_hsv(rgb2, hsv2);
-
-  hueDiff = hsv2[0] - hsv1[0];
-  // use shortest hue path
-  if (hueDiff > CONST_SCALE180) {
-    hueDiff = hueDiff - CONST_SCALE360;
-  } else if (hueDiff < -CONST_SCALE180) {
-    hueDiff = hueDiff + CONST_SCALE360;
-  }
-  satDiff = hsv2[1] - hsv1[1];
-  valDiff = hsv2[2] - hsv1[2];
-
-  colours[0] = first_colour;
-  colours[width - 1] = last_colour;
-
-  for (int i = 1; i < (width - 1); i++) {
-    long k;
-
-    long divisor = width - i;
-    k = (hueDiff + divisor / 2) / divisor;
-    hueDiff -= k;
-    long h = hsv1[0] + k;
-    if (h < 0) {
-      hsv1[0] = CONST_SCALE360 + h;
-    } else {
-      hsv1[0] = h;
-    }
-
-    k = (satDiff + divisor / 2) / divisor;
-    satDiff -= k;
-    hsv1[1] += k;
-
-    k = (valDiff + divisor / 2) / divisor;
-    valDiff -= k;
-    hsv1[2] += k;
-
-    scaled_hsv_to_scaled_rgb(hsv1, rgb3);
-
-    long red3 = from_decimal_scale(rgb3[0], bluemask);
-    long green3 = from_decimal_scale(rgb3[1], bluemask);
-    long blue3 = from_decimal_scale(rgb3[2], bluemask);
-
-    colours[i] = (red3 << redshift) | (green3 << greenshift) | blue3;
-  }
-
-  return colours;
-}

src/main.cc

@@ -179,9 +179,9 @@ static void print_version() {
             << _("  * Own window\n")
 #endif
 #endif /* BUILD_X11 */
-#ifdef BUILD_HSV_GRADIENT
+#ifdef BUILD_HCL_GRADIENT
-            << _("  * HSV Gradient\n")
+            << _("  * HCL Gradient\n")
-#endif /* BUILD_HSV_GRADIENT */
+#endif /* BUILD_HCL_GRADIENT */
 #if defined BUILD_AUDACIOUS || defined BUILD_CMUS || defined BUILD_MPD || \
     defined BUILD_MOC || defined BUILD_XMMS2
             << _("\n Music detection:\n")

tests/CMakeLists.txt

@@ -17,9 +17,9 @@ endif()
 set(test_srcs ${test_srcs} test-core.cc)
 set(test_srcs ${test_srcs} test-diskio.cc)
 set(test_srcs ${test_srcs} test-fs.cc)
-if(BUILD_HSV_GRADIENT)
+if(BUILD_HCL_GRADIENT)
-  set(test_srcs ${test_srcs} test-hsv.cc)
+  set(test_srcs ${test_srcs} test-hcl.cc)
-endif(BUILD_HSV_GRADIENT)
+endif(BUILD_HCL_GRADIENT)
 
 add_executable(test-conky test-common.cc ${test_srcs})
 target_link_libraries(test-conky conky_core)

tests/test-hcl.cc

@@ -29,11 +29,11 @@
 #include "catch2/catch.hpp"
 
 #include <conky.h>
-#include <hsv_gradient.h>
+#include <hcl_gradient.h>
 #include <lua-config.hh>
 
 int testColor(long *rgb, int scale) {
-  long hsv[3];
+  long hcl[3];
   long rgb1[3];
   long rgb2[3];
   long rgb3[3];
@@ -42,8 +42,8 @@ int testColor(long *rgb, int scale) {
   rgb1[1] = to_decimal_scale(rgb[1], scale);
   rgb1[2] = to_decimal_scale(rgb[2], scale);
 
-  scaled_rgb_to_scaled_hsv(rgb1, hsv);
+  scaled_rgb_to_scaled_hcl(rgb1, hcl);
-  scaled_hsv_to_scaled_rgb(hsv, rgb2);
+  scaled_hcl_to_scaled_rgb(hcl, rgb2);
 
   rgb3[0] = from_decimal_scale(rgb2[0], scale);
   rgb3[1] = from_decimal_scale(rgb2[1], scale);
@@ -52,8 +52,8 @@ int testColor(long *rgb, int scale) {
   return (rgb[0] != rgb3[0] || rgb[1] != rgb3[1] || rgb[2] != rgb3[2]);
 }
 
-TEST_CASE("hsv gradient tests") {
+TEST_CASE("hcl gradient tests") {
-  SECTION("rgb -> hsv -> rgb should returns original value") {
+  SECTION("rgb -> hcl -> rgb should returns original value") {
     int failedCount = 0;
     long rgb1[3];