gfx/src/nsColor.cpp

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  37
  38 #include "plstr.h"
  39 #include "nsColor.h"
  40 #include "nsColorNames.h"
  41 #include "nsString.h"
  42 #include "nscore.h"
  43 #include "nsCoord.h"
  44 #include "nsCOMPtr.h"
  45 #include "nsIServiceManager.h"
  46 #include <math.h>
  47 #include "prprf.h"
  48
  49 static int ComponentValue(const PRUnichar* aColorSpec, int aLen, int color, int dpc)
  50 {
  51   int component = 0;
  52   int index = (color * dpc);
  53   if (2 < dpc) {
  54     dpc = 2;
  55   }
  56   while (--dpc >= 0) {
  57     PRUnichar ch = ((index < aLen) ? aColorSpec[index++] : '0');
  58     if (('0' <= ch) && (ch <= '9')) {
  59       component = (component * 16) + (ch - '0');
  60     } else if ((('a' <= ch) && (ch <= 'f')) ||
  61                (('A' <= ch) && (ch <= 'F'))) {
  62       // "ch&7" handles lower and uppercase hex alphabetics
  63       component = (component * 16) + (ch & 7) + 9;
  64     }
  65     else {  // not a hex digit, treat it like 0
  66       component = (component * 16);
  67     }
  68   }
  69   return component;
  70 }
  71
  72 NS_GFX_(PRBool) NS_HexToRGB(const nsString& aColorSpec,
  73                                        nscolor* aResult)
  74 {
  75   const PRUnichar* buffer = aColorSpec.get();
  76
  77   int nameLen = aColorSpec.Length();
  78   if ((nameLen == 3) || (nameLen == 6)) {
  79     // Make sure the digits are legal
  80     for (int i = 0; i < nameLen; i++) {
  81       PRUnichar ch = buffer[i];
  82       if (((ch >= '0') && (ch <= '9')) ||
  83           ((ch >= 'a') && (ch <= 'f')) ||
  84           ((ch >= 'A') && (ch <= 'F'))) {
  85         // Legal character
  86         continue;
  87       }
  88       // Whoops. Illegal character.
  89       return PR_FALSE;
  90     }
  91
  92     // Convert the ascii to binary
  93     int dpc = ((3 == nameLen) ? 1 : 2);
  94     // Translate components from hex to binary
  95     int r = ComponentValue(buffer, nameLen, 0, dpc);
  96     int g = ComponentValue(buffer, nameLen, 1, dpc);
  97     int b = ComponentValue(buffer, nameLen, 2, dpc);
  98     if (dpc == 1) {
  99       // Scale single digit component to an 8 bit value. Replicate the
 100       // single digit to compute the new value.
 101       r = (r << 4) | r;
 102       g = (g << 4) | g;
 103       b = (b << 4) | b;
 104     }
 105     NS_ASSERTION((r >= 0) && (r <= 255), "bad r");
 106     NS_ASSERTION((g >= 0) && (g <= 255), "bad g");
 107     NS_ASSERTION((b >= 0) && (b <= 255), "bad b");
 108     if (nsnull != aResult) {
 109       *aResult = NS_RGB(r, g, b);
 110     }
 111     return PR_TRUE;
 112   }
 113
 114   // Improperly formatted color value
 115   return PR_FALSE;
 116 }
 117
 118 // compatible with legacy Nav behavior
 119 NS_GFX_(PRBool) NS_LooseHexToRGB(const nsString& aColorSpec, nscolor* aResult)
 120 {
 121   int nameLen = aColorSpec.Length();
 122   const PRUnichar* colorSpec = aColorSpec.get();
 123   if ('#' == colorSpec[0]) {
 124     ++colorSpec;
 125     --nameLen;
 126   }
 127
 128   if (3 < nameLen) {
 129     // Convert the ascii to binary
 130     int dpc = (nameLen / 3) + (((nameLen % 3) != 0) ? 1 : 0);
 131     if (4 < dpc) {
 132       dpc = 4;
 133     }
 134
 135     // Translate components from hex to binary
 136     int r = ComponentValue(colorSpec, nameLen, 0, dpc);
 137     int g = ComponentValue(colorSpec, nameLen, 1, dpc);
 138     int b = ComponentValue(colorSpec, nameLen, 2, dpc);
 139     NS_ASSERTION((r >= 0) && (r <= 255), "bad r");
 140     NS_ASSERTION((g >= 0) && (g <= 255), "bad g");
 141     NS_ASSERTION((b >= 0) && (b <= 255), "bad b");
 142     if (nsnull != aResult) {
 143       *aResult = NS_RGB(r, g, b);
 144     }
 145   }
 146   else {
 147     if (nsnull != aResult) {
 148       *aResult = NS_RGB(0, 0, 0);
 149     }
 150   }
 151   return PR_TRUE;
 152 }
 153
 154 NS_GFX_(void) NS_RGBToHex(nscolor aColor, nsAString& aResult)
 155 {
 156   char buf[10];
 157   PR_snprintf(buf, sizeof(buf), "#%02x%02x%02x",
 158               NS_GET_R(aColor), NS_GET_G(aColor), NS_GET_B(aColor));
 159   CopyASCIItoUTF16(buf, aResult);
 160 }
 161
 162 NS_GFX_(PRBool) NS_ColorNameToRGB(const nsAString& aColorName, nscolor* aResult)
 163 {
 164   nsColorName id = nsColorNames::LookupName(aColorName);
 165   if (eColorName_UNKNOWN < id) {
 166     NS_ASSERTION(id < eColorName_COUNT, "LookupName mess up");
 167     if (nsnull != aResult) {
 168       *aResult = nsColorNames::kColors[id];
 169     }
 170     return PR_TRUE;
 171   }
 172   return PR_FALSE;
 173 }
 174
 175 NS_GFX_(nscolor)
 176 NS_ComposeColors(nscolor aBG, nscolor aFG)
 177 {
 178   PRIntn bgAlpha = NS_GET_A(aBG);
 179   PRIntn r, g, b, a;
 180
 181   // First compute what we get drawing aBG onto RGBA(0,0,0,0)
 182   MOZ_BLEND(r, 0, NS_GET_R(aBG), bgAlpha);
 183   MOZ_BLEND(g, 0, NS_GET_G(aBG), bgAlpha);
 184   MOZ_BLEND(b, 0, NS_GET_B(aBG), bgAlpha);
 185   a = bgAlpha;
 186
 187   // Now draw aFG on top of that
 188   PRIntn fgAlpha = NS_GET_A(aFG);
 189   MOZ_BLEND(r, r, NS_GET_R(aFG), fgAlpha);
 190   MOZ_BLEND(g, g, NS_GET_G(aFG), fgAlpha);
 191   MOZ_BLEND(b, b, NS_GET_B(aFG), fgAlpha);
 192   MOZ_BLEND(a, a, 255, fgAlpha);
 193
 194   return NS_RGBA(r, g, b, a);
 195 }
 196
 197 // Functions to convert from HSL color space to RGB color space.
 198 // This is the algorithm described in the CSS3 specification
 199
 200 // helper
 201 static float
 202 HSL_HueToRGB(float m1, float m2, float h)
 203 {
 204   if (h < 0.0f)
 205     h += 1.0f;
 206   if (h > 1.0f)
 207     h -= 1.0f;
 208   if (h < (float)(1.0/6.0))
 209     return m1 + (m2 - m1)*h*6.0f;
 210   if (h < (float)(1.0/2.0))
 211     return m2;
 212   if (h < (float)(2.0/3.0))
 213     return m1 + (m2 - m1)*((float)(2.0/3.0) - h)*6.0f;
 214   return m1;
 215 }
 216
 217 // The float parameters are all expected to be in the range 0-1
 218 NS_GFX_(nscolor)
 219 NS_HSL2RGB(float h, float s, float l)
 220 {
 221   PRUint8 r, g, b;
 222   float m1, m2;
 223   if (l <= 0.5f) {
 224     m2 = l*(s+1);
 225   } else {
 226     m2 = l + s - l*s;
 227   }
 228   m1 = l*2 - m2;
 229   r = PRUint8(255 * HSL_HueToRGB(m1, m2, h + 1.0f/3.0f));
 230   g = PRUint8(255 * HSL_HueToRGB(m1, m2, h));
 231   b = PRUint8(255 * HSL_HueToRGB(m1, m2, h - 1.0f/3.0f));
 232   return NS_RGB(r, g, b);
 233 }