layout/style/nsStyleUtil.cpp

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "nsStyleUtil.h"
   7 #include "nsStyleConsts.h"
   8
   9 #include "nsIContent.h"
  10 #include "nsReadableUtils.h"
  11 #include "nsCSSProps.h"
  12 #include "nsRuleNode.h"
  13
  14 using namespace mozilla;
  15
  16 //------------------------------------------------------------------------------
  17 // Font Algorithm Code
  18 //------------------------------------------------------------------------------
  19
  20 // Compare two language strings
  21 bool nsStyleUtil::DashMatchCompare(const nsAString& aAttributeValue,
  22                                      const nsAString& aSelectorValue,
  23                                      const nsStringComparator& aComparator)
  24 {
  25   bool result;
  26   uint32_t selectorLen = aSelectorValue.Length();
  27   uint32_t attributeLen = aAttributeValue.Length();
  28   if (selectorLen > attributeLen) {
  29     result = false;
  30   }
  31   else {
  32     nsAString::const_iterator iter;
  33     if (selectorLen != attributeLen &&
  34         *aAttributeValue.BeginReading(iter).advance(selectorLen) !=
  35             PRUnichar('-')) {
  36       // to match, the aAttributeValue must have a dash after the end of
  37       // the aSelectorValue's text (unless the aSelectorValue and the
  38       // aAttributeValue have the same text)
  39       result = false;
  40     }
  41     else {
  42       result = StringBeginsWith(aAttributeValue, aSelectorValue, aComparator);
  43     }
  44   }
  45   return result;
  46 }
  47
  48 void nsStyleUtil::AppendEscapedCSSString(const nsAString& aString,
  49                                          nsAString& aReturn,
  50                                          PRUnichar quoteChar)
  51 {
  52   NS_PRECONDITION(quoteChar == '\'' || quoteChar == '"',
  53                   "CSS strings must be quoted with ' or \"");
  54   aReturn.Append(quoteChar);
  55
  56   const PRUnichar* in = aString.BeginReading();
  57   const PRUnichar* const end = aString.EndReading();
  58   for (; in != end; in++) {
  59     if (*in < 0x20 || (*in >= 0x7F && *in < 0xA0)) {
  60       // Escape U+0000 through U+001F and U+007F through U+009F numerically.
  61       aReturn.AppendPrintf("\\%hX ", *in);
  62     } else {
  63       if (*in == '"' || *in == '\'' || *in == '\\') {
  64         // Escape backslash and quote characters symbolically.
  65         // It's not technically necessary to escape the quote
  66         // character that isn't being used to delimit the string,
  67         // but we do it anyway because that makes testing simpler.
  68         aReturn.Append(PRUnichar('\\'));
  69       }
  70       aReturn.Append(*in);
  71     }
  72   }
  73
  74   aReturn.Append(quoteChar);
  75 }
  76
  77 /* static */ void
  78 nsStyleUtil::AppendEscapedCSSIdent(const nsAString& aIdent, nsAString& aReturn)
  79 {
  80   // The relevant parts of the CSS grammar are:
  81   //   ident    [-]?{nmstart}{nmchar}*
  82   //   nmstart  [_a-z]|{nonascii}|{escape}
  83   //   nmchar   [_a-z0-9-]|{nonascii}|{escape}
  84   //   nonascii [^\0-\177]
  85   //   escape   {unicode}|\\[^\n\r\f0-9a-f]
  86   //   unicode  \\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?
  87   // from http://www.w3.org/TR/CSS21/syndata.html#tokenization
  88
  89   const PRUnichar* in = aIdent.BeginReading();
  90   const PRUnichar* const end = aIdent.EndReading();
  91
  92   if (in == end)
  93     return;
  94
  95   // A leading dash does not need to be escaped as long as it is not the
  96   // *only* character in the identifier.
  97   if (in + 1 != end && *in == '-') {
  98     aReturn.Append(PRUnichar('-'));
  99     ++in;
 100   }
 101
 102   // Escape a digit at the start (including after a dash),
 103   // numerically.  If we didn't escape it numerically, it would get
 104   // interpreted as a numeric escape for the wrong character.
 105   // A second dash immediately after a leading dash must also be
 106   // escaped, but this may be done symbolically.
 107   if (in != end && (*in == '-' ||
 108                     ('0' <= *in && *in <= '9'))) {
 109     if (*in == '-') {
 110       aReturn.Append(PRUnichar('\\'));
 111       aReturn.Append(PRUnichar('-'));
 112     } else {
 113       aReturn.AppendPrintf("\\%hX ", *in);
 114     }
 115     ++in;
 116   }
 117
 118   for (; in != end; ++in) {
 119     PRUnichar ch = *in;
 120     if (ch < 0x20 || (0x7F <= ch && ch < 0xA0)) {
 121       // Escape U+0000 through U+001F and U+007F through U+009F numerically.
 122       aReturn.AppendPrintf("\\%hX ", *in);
 123     } else {
 124       // Escape ASCII non-identifier printables as a backslash plus
 125       // the character.
 126       if (ch < 0x7F &&
 127           ch != '_' && ch != '-' &&
 128           (ch < '0' || '9' < ch) &&
 129           (ch < 'A' || 'Z' < ch) &&
 130           (ch < 'a' || 'z' < ch)) {
 131         aReturn.Append(PRUnichar('\\'));
 132       }
 133       aReturn.Append(ch);
 134     }
 135   }
 136 }
 137
 138 /* static */ void
 139 nsStyleUtil::AppendBitmaskCSSValue(nsCSSProperty aProperty,
 140                                    int32_t aMaskedValue,
 141                                    int32_t aFirstMask,
 142                                    int32_t aLastMask,
 143                                    nsAString& aResult)
 144 {
 145   for (int32_t mask = aFirstMask; mask <= aLastMask; mask <<= 1) {
 146     if (mask & aMaskedValue) {
 147       AppendASCIItoUTF16(nsCSSProps::LookupPropertyValue(aProperty, mask),
 148                          aResult);
 149       aMaskedValue &= ~mask;
 150       if (aMaskedValue) { // more left
 151         aResult.Append(PRUnichar(' '));
 152       }
 153     }
 154   }
 155   NS_ABORT_IF_FALSE(aMaskedValue == 0, "unexpected bit remaining in bitfield");
 156 }
 157
 158 /* static */ void
 159 nsStyleUtil::AppendPaintOrderValue(uint8_t aValue,
 160                                    nsAString& aResult)
 161 {
 162   MOZ_STATIC_ASSERT
 163     (NS_STYLE_PAINT_ORDER_BITWIDTH * NS_STYLE_PAINT_ORDER_LAST_VALUE <= 8,
 164      "SVGStyleStruct::mPaintOrder and local variables not big enough");
 165
 166   if (aValue == NS_STYLE_PAINT_ORDER_NORMAL) {
 167     aResult.AppendLiteral("normal");
 168     return;
 169   }
 170
 171   // Append the minimal value necessary for the given paint order.
 172   MOZ_STATIC_ASSERT(NS_STYLE_PAINT_ORDER_LAST_VALUE == 3,
 173                     "paint-order values added; check serialization");
 174
 175   // The following relies on the default order being the order of the
 176   // constant values.
 177
 178   const uint8_t MASK = (1 << NS_STYLE_PAINT_ORDER_BITWIDTH) - 1;
 179
 180   uint32_t lastPositionToSerialize = 0;
 181   for (uint32_t position = NS_STYLE_PAINT_ORDER_LAST_VALUE - 1;
 182        position > 0;
 183        position--) {
 184     uint8_t component =
 185       (aValue >> (position * NS_STYLE_PAINT_ORDER_BITWIDTH)) & MASK;
 186     uint8_t earlierComponent =
 187       (aValue >> ((position - 1) * NS_STYLE_PAINT_ORDER_BITWIDTH)) & MASK;
 188     if (component < earlierComponent) {
 189       lastPositionToSerialize = position - 1;
 190       break;
 191     }
 192   }
 193
 194   for (uint32_t position = 0; position <= lastPositionToSerialize; position++) {
 195     if (position > 0) {
 196       aResult.AppendLiteral(" ");
 197     }
 198     uint8_t component = aValue & MASK;
 199     switch (component) {
 200       case NS_STYLE_PAINT_ORDER_FILL:
 201         aResult.AppendLiteral("fill");
 202         break;
 203
 204       case NS_STYLE_PAINT_ORDER_STROKE:
 205         aResult.AppendLiteral("stroke");
 206         break;
 207
 208       case NS_STYLE_PAINT_ORDER_MARKERS:
 209         aResult.AppendLiteral("markers");
 210         break;
 211
 212       default:
 213         NS_NOTREACHED("unexpected paint-order component value");
 214     }
 215     aValue >>= NS_STYLE_PAINT_ORDER_BITWIDTH;
 216   }
 217 }
 218
 219 /* static */ void
 220 nsStyleUtil::AppendFontFeatureSettings(const nsTArray<gfxFontFeature>& aFeatures,
 221                                        nsAString& aResult)
 222 {
 223   for (uint32_t i = 0, numFeat = aFeatures.Length(); i < numFeat; i++) {
 224     const gfxFontFeature& feat = aFeatures[i];
 225
 226     if (i != 0) {
 227         aResult.AppendLiteral(", ");
 228     }
 229
 230     // output tag
 231     char tag[7];
 232     tag[0] = '"';
 233     tag[1] = (feat.mTag >> 24) & 0xff;
 234     tag[2] = (feat.mTag >> 16) & 0xff;
 235     tag[3] = (feat.mTag >> 8) & 0xff;
 236     tag[4] = feat.mTag & 0xff;
 237     tag[5] = '"';
 238     tag[6] = 0;
 239     aResult.AppendASCII(tag);
 240
 241     // output value, if necessary
 242     if (feat.mValue == 0) {
 243       // 0 ==> off
 244       aResult.AppendLiteral(" off");
 245     } else if (feat.mValue > 1) {
 246       aResult.AppendLiteral(" ");
 247       aResult.AppendInt(feat.mValue);
 248     }
 249     // else, omit value if 1, implied by default
 250   }
 251 }
 252
 253 /* static */ void
 254 nsStyleUtil::AppendFontFeatureSettings(const nsCSSValue& aSrc,
 255                                        nsAString& aResult)
 256 {
 257   nsCSSUnit unit = aSrc.GetUnit();
 258
 259   if (unit == eCSSUnit_Normal) {
 260     aResult.AppendLiteral("normal");
 261     return;
 262   }
 263
 264   NS_PRECONDITION(unit == eCSSUnit_PairList || unit == eCSSUnit_PairListDep,
 265                   "improper value unit for font-feature-settings:");
 266
 267   nsTArray<gfxFontFeature> featureSettings;
 268   nsRuleNode::ComputeFontFeatures(aSrc.GetPairListValue(), featureSettings);
 269   AppendFontFeatureSettings(featureSettings, aResult);
 270 }
 271
 272 /* static */ float
 273 nsStyleUtil::ColorComponentToFloat(uint8_t aAlpha)
 274 {
 275   // Alpha values are expressed as decimals, so we should convert
 276   // back, using as few decimal places as possible for
 277   // round-tripping.
 278   // First try two decimal places:
 279   float rounded = NS_roundf(float(aAlpha) * 100.0f / 255.0f) / 100.0f;
 280   if (FloatToColorComponent(rounded) != aAlpha) {
 281     // Use three decimal places.
 282     rounded = NS_roundf(float(aAlpha) * 1000.0f / 255.0f) / 1000.0f;
 283   }
 284   return rounded;
 285 }
 286
 287 /* static */ bool
 288 nsStyleUtil::IsSignificantChild(nsIContent* aChild, bool aTextIsSignificant,
 289                                 bool aWhitespaceIsSignificant)
 290 {
 291   NS_ASSERTION(!aWhitespaceIsSignificant || aTextIsSignificant,
 292                "Nonsensical arguments");
 293
 294   bool isText = aChild->IsNodeOfType(nsINode::eTEXT);
 295
 296   if (!isText && !aChild->IsNodeOfType(nsINode::eCOMMENT) &&
 297       !aChild->IsNodeOfType(nsINode::ePROCESSING_INSTRUCTION)) {
 298     return true;
 299   }
 300
 301   return aTextIsSignificant && isText && aChild->TextLength() != 0 &&
 302          (aWhitespaceIsSignificant ||
 303           !aChild->TextIsOnlyWhitespace());
 304 }
 305