gfx/src/nsColor.cpp
author Stuart Parmenter <pavlov@pavlov.net>
Sun, 20 Apr 2008 04:25:15 -0700
changeset 16895 9294bb61588612bfa15985f425a90d4c9bf475b7
parent 13079 3e389aa50b72f4e8c268411e3bef9fc0fafd19f0
child 20804 003a5a6570af1a3fc6e9c0973839240dbfe62942
permissions -rw-r--r--
ignore objdir* rather than objdir-*

/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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 * 1.1 (the "License"); you may not use this file except in compliance with
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 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is mozilla.org code.
 *
 * The Initial Developer of the Original Code is
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 * Portions created by the Initial Developer are Copyright (C) 1998
 * the Initial Developer. All Rights Reserved.
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 *
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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#include "plstr.h"
#include "nsColor.h"
#include "nsColorNames.h"
#include "nsString.h"
#include "nscore.h"
#include "nsCoord.h"
#include "nsCOMPtr.h"
#include "nsIServiceManager.h"
#include <math.h>
#include "prprf.h"

static int ComponentValue(const PRUnichar* aColorSpec, int aLen, int color, int dpc)
{
  int component = 0;
  int index = (color * dpc);
  if (2 < dpc) {
    dpc = 2;
  }
  while (--dpc >= 0) {
    PRUnichar ch = ((index < aLen) ? aColorSpec[index++] : '0');
    if (('0' <= ch) && (ch <= '9')) {
      component = (component * 16) + (ch - '0');
    } else if ((('a' <= ch) && (ch <= 'f')) || 
               (('A' <= ch) && (ch <= 'F'))) {
      // "ch&7" handles lower and uppercase hex alphabetics
      component = (component * 16) + (ch & 7) + 9;
    }
    else {  // not a hex digit, treat it like 0
      component = (component * 16);
    }
  }
  return component;
}

NS_GFX_(PRBool) NS_HexToRGB(const nsString& aColorSpec,
                                       nscolor* aResult)
{
  const PRUnichar* buffer = aColorSpec.get();

  int nameLen = aColorSpec.Length();
  if ((nameLen == 3) || (nameLen == 6)) {
    // Make sure the digits are legal
    for (int i = 0; i < nameLen; i++) {
      PRUnichar ch = buffer[i];
      if (((ch >= '0') && (ch <= '9')) ||
          ((ch >= 'a') && (ch <= 'f')) ||
          ((ch >= 'A') && (ch <= 'F'))) {
        // Legal character
        continue;
      }
      // Whoops. Illegal character.
      return PR_FALSE;
    }

    // Convert the ascii to binary
    int dpc = ((3 == nameLen) ? 1 : 2);
    // Translate components from hex to binary
    int r = ComponentValue(buffer, nameLen, 0, dpc);
    int g = ComponentValue(buffer, nameLen, 1, dpc);
    int b = ComponentValue(buffer, nameLen, 2, dpc);
    if (dpc == 1) {
      // Scale single digit component to an 8 bit value. Replicate the
      // single digit to compute the new value.
      r = (r << 4) | r;
      g = (g << 4) | g;
      b = (b << 4) | b;
    }
    NS_ASSERTION((r >= 0) && (r <= 255), "bad r");
    NS_ASSERTION((g >= 0) && (g <= 255), "bad g");
    NS_ASSERTION((b >= 0) && (b <= 255), "bad b");
    if (nsnull != aResult) {
      *aResult = NS_RGB(r, g, b);
    }
    return PR_TRUE;
  }

  // Improperly formatted color value
  return PR_FALSE;
}

// compatible with legacy Nav behavior
NS_GFX_(PRBool) NS_LooseHexToRGB(const nsString& aColorSpec, nscolor* aResult)
{
  int nameLen = aColorSpec.Length();
  const PRUnichar* colorSpec = aColorSpec.get();
  if ('#' == colorSpec[0]) {
    ++colorSpec;
    --nameLen;
  }

  if (3 < nameLen) {
    // Convert the ascii to binary
    int dpc = (nameLen / 3) + (((nameLen % 3) != 0) ? 1 : 0);
    if (4 < dpc) {
      dpc = 4;
    }

    // Translate components from hex to binary
    int r = ComponentValue(colorSpec, nameLen, 0, dpc);
    int g = ComponentValue(colorSpec, nameLen, 1, dpc);
    int b = ComponentValue(colorSpec, nameLen, 2, dpc);
    NS_ASSERTION((r >= 0) && (r <= 255), "bad r");
    NS_ASSERTION((g >= 0) && (g <= 255), "bad g");
    NS_ASSERTION((b >= 0) && (b <= 255), "bad b");
    if (nsnull != aResult) {
      *aResult = NS_RGB(r, g, b);
    }
  }
  else {
    if (nsnull != aResult) {
      *aResult = NS_RGB(0, 0, 0);
    }
  }
  return PR_TRUE;
}

NS_GFX_(void) NS_RGBToHex(nscolor aColor, nsAString& aResult)
{
  char buf[10];
  PR_snprintf(buf, sizeof(buf), "#%02x%02x%02x",
              NS_GET_R(aColor), NS_GET_G(aColor), NS_GET_B(aColor));
  CopyASCIItoUTF16(buf, aResult);
}

NS_GFX_(PRBool) NS_ColorNameToRGB(const nsAString& aColorName, nscolor* aResult)
{
  nsColorName id = nsColorNames::LookupName(aColorName);
  if (eColorName_UNKNOWN < id) {
    NS_ASSERTION(id < eColorName_COUNT, "LookupName mess up");
    if (nsnull != aResult) {
      *aResult = nsColorNames::kColors[id];
    }
    return PR_TRUE;
  }
  return PR_FALSE;
}

NS_GFX_(nscolor)
NS_ComposeColors(nscolor aBG, nscolor aFG)
{
  PRIntn bgAlpha = NS_GET_A(aBG);
  PRIntn r, g, b, a;

  // First compute what we get drawing aBG onto RGBA(0,0,0,0)
  MOZ_BLEND(r, 0, NS_GET_R(aBG), bgAlpha);
  MOZ_BLEND(g, 0, NS_GET_G(aBG), bgAlpha);
  MOZ_BLEND(b, 0, NS_GET_B(aBG), bgAlpha);
  a = bgAlpha;

  // Now draw aFG on top of that
  PRIntn fgAlpha = NS_GET_A(aFG);
  MOZ_BLEND(r, r, NS_GET_R(aFG), fgAlpha);
  MOZ_BLEND(g, g, NS_GET_G(aFG), fgAlpha);
  MOZ_BLEND(b, b, NS_GET_B(aFG), fgAlpha);
  MOZ_BLEND(a, a, 255, fgAlpha);
  
  return NS_RGBA(r, g, b, a);
}

// Functions to convert from HSL color space to RGB color space.
// This is the algorithm described in the CSS3 specification

// helper
static float
HSL_HueToRGB(float m1, float m2, float h)
{
  if (h < 0.0f)
    h += 1.0f;
  if (h > 1.0f)
    h -= 1.0f;
  if (h < (float)(1.0/6.0))
    return m1 + (m2 - m1)*h*6.0f;
  if (h < (float)(1.0/2.0))
    return m2;
  if (h < (float)(2.0/3.0))
    return m1 + (m2 - m1)*((float)(2.0/3.0) - h)*6.0f;
  return m1;      
}

// The float parameters are all expected to be in the range 0-1
NS_GFX_(nscolor)
NS_HSL2RGB(float h, float s, float l)
{
  PRUint8 r, g, b;
  float m1, m2;
  if (l <= 0.5f) {
    m2 = l*(s+1);
  } else {
    m2 = l + s - l*s;
  }
  m1 = l*2 - m2;
  r = PRUint8(255 * HSL_HueToRGB(m1, m2, h + 1.0f/3.0f));
  g = PRUint8(255 * HSL_HueToRGB(m1, m2, h));
  b = PRUint8(255 * HSL_HueToRGB(m1, m2, h - 1.0f/3.0f));
  return NS_RGB(r, g, b);  
}