gfx/src/nsColor.cpp
author L. David Baron <dbaron@dbaron.org>
Wed, 27 Jan 2010 15:46:49 -0800
changeset 37583 2c2f2c6e7b5fc547f08b1d40eff411c2f3b08d82
parent 29533 ddee37e8a38e50fdfb4f9b6560611bd8da204a70
child 39314 8fc409b1e7b37821d13191467b6531589c9fccf7
permissions -rw-r--r--
Add CSS 2.1 test suite metadata for z-index reftests.

/* -*- 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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 *
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 * 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.
 *
 * Contributor(s):
 *
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 * either of the GNU General Public License Version 2 or later (the "GPL"),
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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"
#include "nsStaticNameTable.h"

// define an array of all color names
#define GFX_COLOR(_name, _value) #_name,
static const char* const kColorNames[] = {
#include "nsColorNameList.h"
};
#undef GFX_COLOR

// define an array of all color name values
#define GFX_COLOR(_name, _value) _value,
static const nscolor kColors[] = {
#include "nsColorNameList.h"
};
#undef GFX_COLOR

#define eColorName_COUNT (NS_ARRAY_LENGTH(kColorNames))
#define eColorName_UNKNOWN (-1)

static nsStaticCaseInsensitiveNameTable* gColorTable = nsnull;

void nsColorNames::AddRefTable(void) 
{
  NS_ASSERTION(!gColorTable, "pre existing array!");
  if (!gColorTable) {
    gColorTable = new nsStaticCaseInsensitiveNameTable();
    if (gColorTable) {
#ifdef DEBUG
    {
      // let's verify the table...
      for (PRUint32 index = 0; index < eColorName_COUNT; ++index) {
        nsCAutoString temp1(kColorNames[index]);
        nsCAutoString temp2(kColorNames[index]);
        ToLowerCase(temp1);
        NS_ASSERTION(temp1.Equals(temp2), "upper case char in table");
      }
    }
#endif      
      gColorTable->Init(kColorNames, eColorName_COUNT); 
    }
  }
}

void nsColorNames::ReleaseTable(void)
{
  if (gColorTable) {
    delete gColorTable;
    gColorTable = nsnull;
  }
}

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_(PRBool) NS_ColorNameToRGB(const nsAString& aColorName, nscolor* aResult)
{
  if (!gColorTable) return PR_FALSE;

  PRInt32 id = gColorTable->Lookup(aColorName);
  if (eColorName_UNKNOWN < id) {
    NS_ASSERTION(id < eColorName_COUNT, "LookupName mess up");
    if (aResult) {
      *aResult = kColors[id];
    }
    return PR_TRUE;
  }
  return PR_FALSE;
}

// Macro to blend two colors
//
// equivalent to target = (bg*(255-fgalpha) + fg*fgalpha)/255
#define MOZ_BLEND(target, bg, fg, fgalpha)       \
  FAST_DIVIDE_BY_255(target, (bg)*(255-fgalpha) + (fg)*(fgalpha))

NS_GFX_(nscolor)
NS_ComposeColors(nscolor aBG, nscolor aFG)
{
  // This function uses colors that are non premultiplied alpha.
  PRIntn r, g, b, a;

  PRIntn bgAlpha = NS_GET_A(aBG);
  PRIntn fgAlpha = NS_GET_A(aFG);

  // Compute the final alpha of the blended color
  // a = fgAlpha + bgAlpha*(255 - fgAlpha)/255;
  FAST_DIVIDE_BY_255(a, bgAlpha*(255-fgAlpha));
  a = fgAlpha + a;
  PRIntn blendAlpha;
  if (a == 0) {
    // In this case the blended color is totally trasparent,
    // we preserve the color information of the foreground color.
    blendAlpha = 255;
  } else {
    blendAlpha = (fgAlpha*255)/a;
  }
  MOZ_BLEND(r, NS_GET_R(aBG), NS_GET_R(aFG), blendAlpha);
  MOZ_BLEND(g, NS_GET_G(aBG), NS_GET_G(aFG), blendAlpha);
  MOZ_BLEND(b, NS_GET_B(aBG), NS_GET_B(aFG), blendAlpha);

  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);  
}