Added color.h

src/color.h

@@ -0,0 +1,389 @@
+
+//
+// color.h
+//
+// Copyright (c) 2010 LearnBoost <tj@learnboost.com>
+//
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+/*
+ * Consume whitespace.
+ */
+
+#define WHITESPACE \
+  while (' ' == *str) ++str;
+
+/*
+ * Parse color channel value
+ */
+
+#define CHANNEL(NAME) \
+   if (*str >= '0' && *str <= '9') { \
+     do { \
+       NAME *= 10; \
+       NAME += *str++ - '0'; \
+     } while (*str >= '0' && *str <= '9'); \
+   } else { \
+     return -1; \
+   } \
+   while (' ' == *str || ',' == *str) str++;
+
+/*
+ * Named colors.
+ */
+
+static struct named_color {
+  char *name;
+  uint32_t val;
+} named_colors[] = {
+    "transparent", 0xffffff00
+  , "aliceblue", 0xf0f8ffff
+  , "antiquewhite", 0xfaebd7ff
+  , "aqua", 0x00ffffff
+  , "aquamarine", 0x7fffd4ff
+  , "azure", 0xf0ffffff
+  , "beige", 0xf5f5dcff
+  , "bisque", 0xffe4c4ff
+  , "black", 0x000000ff
+  , "blanchedalmond", 0xffebcdff
+  , "blue", 0x0000ffff
+  , "blueviolet", 0x8a2be2ff
+  , "brown", 0xa52a2aff
+  , "burlywood", 0xdeb887ff
+  , "cadetblue", 0x5f9ea0ff
+  , "chartreuse", 0x7fff00ff
+  , "chocolate", 0xd2691eff
+  , "coral", 0xff7f50ff
+  , "cornflowerblue", 0x6495edff
+  , "cornsilk", 0xfff8dcff
+  , "crimson", 0xdc143cff
+  , "cyan", 0x00ffffff
+  , "darkblue", 0x00008bff
+  , "darkcyan", 0x008b8bff
+  , "darkgoldenrod", 0xb8860bff
+  , "darkgray", 0xa9a9a9ff
+  , "darkgreen", 0x006400ff
+  , "darkkhaki", 0xbdb76bff
+  , "darkmagenta", 0x8b008bff
+  , "darkolivegreen", 0x556b2fff
+  , "darkorange", 0xff8c00ff
+  , "darkorchid", 0x9932ccff
+  , "darkred", 0x8b0000ff
+  , "darksalmon", 0xe9967aff
+  , "darkseagreen", 0x8fbc8fff
+  , "darkslateblue", 0x483d8bff
+  , "darkslategray", 0x2f4f4fff
+  , "darkturquoise", 0x00ced1ff
+  , "darkviolet", 0x9400d3ff
+  , "deeppink", 0xff1493ff
+  , "deepskyblue", 0x00bfffff
+  , "dimgray", 0x696969ff
+  , "dodgerblue", 0x1e90ffff
+  , "feldspar", 0xd19275ff
+  , "firebrick", 0xb22222ff
+  , "floralwhite", 0xfffaf0ff
+  , "forestgreen", 0x228b22ff
+  , "fuchsia", 0xff00ffff
+  , "gainsboro", 0xdcdcdcff
+  , "ghostwhite", 0xf8f8ffff
+  , "gold", 0xffd700ff
+  , "goldenrod", 0xdaa520ff
+  , "gray", 0x808080ff
+  , "green", 0x008000ff
+  , "greenyellow", 0xadff2fff
+  , "honeydew", 0xf0fff0ff
+  , "hotpink", 0xff69b4ff
+  , "indianred ", 0xcd5c5cff
+  , "indigo ", 0x4b0082ff
+  , "ivory", 0xfffff0ff
+  , "khaki", 0xf0e68cff
+  , "lavender", 0xe6e6faff
+  , "lavenderblush", 0xfff0f5ff
+  , "lawngreen", 0x7cfc00ff
+  , "lemonchiffon", 0xfffacdff
+  , "lightblue", 0xadd8e6ff
+  , "lightcoral", 0xf08080ff
+  , "lightcyan", 0xe0ffffff
+  , "lightgoldenrodyellow", 0xfafad2ff
+  , "lightgrey", 0xd3d3d3ff
+  , "lightgreen", 0x90ee90ff
+  , "lightpink", 0xffb6c1ff
+  , "lightsalmon", 0xffa07aff
+  , "lightseagreen", 0x20b2aaff
+  , "lightskyblue", 0x87cefaff
+  , "lightslateblue", 0x8470ffff
+  , "lightslategray", 0x778899ff
+  , "lightsteelblue", 0xb0c4deff
+  , "lightyellow", 0xffffe0ff
+  , "lime", 0x00ff00ff
+  , "limegreen", 0x32cd32ff
+  , "linen", 0xfaf0e6ff
+  , "magenta", 0xff00ffff
+  , "maroon", 0x800000ff
+  , "mediumaquamarine", 0x66cdaaff
+  , "mediumblue", 0x0000cdff
+  , "mediumorchid", 0xba55d3ff
+  , "mediumpurple", 0x9370d8ff
+  , "mediumseagreen", 0x3cb371ff
+  , "mediumslateblue", 0x7b68eeff
+  , "mediumspringgreen", 0x00fa9aff
+  , "mediumturquoise", 0x48d1ccff
+  , "mediumvioletred", 0xc71585ff
+  , "midnightblue", 0x191970ff
+  , "mintcream", 0xf5fffaff
+  , "mistyrose", 0xffe4e1ff
+  , "moccasin", 0xffe4b5ff
+  , "navajowhite", 0xffdeadff
+  , "navy", 0x000080ff
+  , "oldlace", 0xfdf5e6ff
+  , "olive", 0x808000ff
+  , "olivedrab", 0x6b8e23ff
+  , "orange", 0xffa500ff
+  , "orangered", 0xff4500ff
+  , "orchid", 0xda70d6ff
+  , "palegoldenrod", 0xeee8aaff
+  , "palegreen", 0x98fb98ff
+  , "paleturquoise", 0xafeeeeff
+  , "palevioletred", 0xd87093ff
+  , "papayawhip", 0xffefd5ff
+  , "peachpuff", 0xffdab9ff
+  , "peru", 0xcd853fff
+  , "pink", 0xffc0cbff
+  , "plum", 0xdda0ddff
+  , "powderblue", 0xb0e0e6ff
+  , "purple", 0x800080ff
+  , "red", 0xff0000ff
+  , "rosybrown", 0xbc8f8fff
+  , "royalblue", 0x4169e1ff
+  , "saddlebrown", 0x8b4513ff
+  , "salmon", 0xfa8072ff
+  , "sandybrown", 0xf4a460ff
+  , "seagreen", 0x2e8b57ff
+  , "seashell", 0xfff5eeff
+  , "sienna", 0xa0522dff
+  , "silver", 0xc0c0c0ff
+  , "skyblue", 0x87ceebff
+  , "slateblue", 0x6a5acdff
+  , "slategray", 0x708090ff
+  , "snow", 0xfffafaff
+  , "springgreen", 0x00ff7fff
+  , "steelblue", 0x4682b4ff
+  , "tan", 0xd2b48cff
+  , "teal", 0x008080ff
+  , "thistle", 0xd8bfd8ff
+  , "tomato", 0xff6347ff
+  , "turquoise", 0x40e0d0ff
+  , "violet", 0xee82eeff
+  , "violetred", 0xd02090ff
+  , "wheat", 0xf5deb3ff
+  , "white", 0xffffffff
+  , "whitesmoke", 0xf5f5f5ff
+  , "yellow", 0xffff00ff
+  , "yellowgreen", 0x9acd32ff
+  , NULL, NULL
+};
+
+/*
+ * Hex digit int val.
+ */
+
+static int
+h(char c) {
+  switch (c) {
+    case '0':
+    case '1':
+    case '2':
+    case '3':
+    case '4':
+    case '5':
+    case '6':
+    case '7':
+    case '8':
+    case '9':
+      return c - '0';
+    case 'a':
+    case 'b':
+    case 'c':
+    case 'd':
+    case 'e':
+    case 'f':
+      return (c - 'a') + 10;
+    case 'A':
+    case 'B':
+    case 'C':
+    case 'D':
+    case 'E':
+    case 'F':
+      return (c - 'A') + 10;
+  }
+  return 0;
+}
+
+/*
+ * Return rgba from (r,g,b,a).
+ */
+
+int32_t
+rgba_from_rgba(uint8_t r, uint8_t g, uint8_t b, uint8_t a) {
+  return
+      r << 24
+    | g << 16
+    | b << 8
+    | a;
+}
+
+/*
+ * Return rgba from (r,g,b).
+ */
+
+int32_t
+rgba_from_rgb(uint8_t r, uint8_t g, uint8_t b) {
+  return rgba_from_rgba(r, g, b, 0);
+}
+
+/*
+ * Return rgb from "#RRGGBB".
+ */
+
+int32_t
+rgba_from_hex6_string(const char *str) {
+  return rgba_from_rgb(
+      (h(str[0]) << 4) + h(str[1])
+    , (h(str[2]) << 4) + h(str[3])
+    , (h(str[4]) << 4) + h(str[5])
+    );
+}
+
+/*
+ * Return rgb from "#RGB"
+ */
+
+int32_t
+rgba_from_hex3_string(const char *str) {
+  return rgba_from_rgb(
+      (h(str[0]) << 4) + h(str[0])
+    , (h(str[1]) << 4) + h(str[1])
+    , (h(str[2]) << 4) + h(str[2])
+    );
+}
+
+/*
+ * Return rgb from "rgb()"
+ */
+
+int32_t
+rgba_from_rgb_string(const char *str) {
+  if (str == strnstr(str, "rgb(", 4)) {
+    str += 4;
+    WHITESPACE;
+    uint8_t r = 0, g = 0, b = 0;
+    CHANNEL(r);
+    CHANNEL(g);
+    CHANNEL(b);
+    return rgba_from_rgb(r, g, b);
+  }
+  return -1;
+}
+
+/*
+ * Return rgb from "rgba()"
+ */
+
+int32_t
+rgba_from_rgba_string(const char *str) {
+  if (str == strnstr(str, "rgba(", 5)) {
+    str += 5;
+    WHITESPACE;
+    uint8_t r = 0, g = 0, b = 0;
+    float a = 0;
+    CHANNEL(r);
+    CHANNEL(g);
+    CHANNEL(b);
+    // TODO: less strict
+    if ('1' == *str) {
+      a = 1;
+    } else {
+      if ('0' == *str) a = 0, ++str;
+      if ('.' == *str) {
+        ++str;
+        float n = .1;
+        while (*str >= '0' && *str <= '9') {
+          a += (*str++ - '0') * n;
+          n *= .1;
+        }
+      }
+    }
+    return rgba_from_rgba(r, g, b, a * 255);
+  }
+  return -1;
+}
+
+/*
+ * Return rgb from:
+ *  
+ *  - "#RGB"
+ *  - "#RRGGBB"
+ *
+ */
+
+int32_t
+rgba_from_hex_string(const char *str) {
+  size_t len = strlen(str);
+  if (6 == len) return rgba_from_hex6_string(str);
+  if (3 == len) return rgba_from_hex3_string(str);
+  return -1;
+}
+
+/*
+ * Return named color value.
+ */
+
+int32_t
+rgba_from_name_string(const char *str) {
+  int i = 0;
+  struct named_color color;
+  while ((color = named_colors[i++]).name) {
+    if (*str == *color.name && 0 == strcmp(str, color.name))
+      return color.val;
+  }
+  return -1;
+}
+
+/*
+ * Return rgb from:
+ *  
+ *  - #RGB
+ *  - #RRGGBB
+ *  - rgb(r,g,b)
+ *  - rgba(r,g,b,a)
+ *  - name
+ *
+ */
+
+int32_t
+rgba_from_string(const char *str) {
+  if ('#' == str[0]) 
+    return rgba_from_hex_string(++str);
+  if (str == strnstr(str, "rgba", 4))
+    return rgba_from_rgba_string(str);
+  if (str == strnstr(str, "rgb", 3))
+    return rgba_from_rgb_string(str);
+  return rgba_from_name_string(str);
+}
+
+/*
+ * Inspect the given rgba color.
+ */
+
+void
+rgba_inspect(int32_t rgba) {
+  printf("rgba(%d,%d,%d,%d)\n"
+    , rgba >> 24 & 0xFF
+    , rgba >> 16 & 0xFF
+    , rgba >> 8 & 0xFF
+    , rgba & 0xFF
+    );
+}