--- a/layout/generic/nsTextFrameUtils.cpp
+++ b/layout/generic/nsTextFrameUtils.cpp
@@ -10,50 +10,180 @@
#include "nsIContent.h"
#include "nsStyleStruct.h"
#include "nsTextFragment.h"
#include "nsUnicharUtils.h"
#include <algorithm>
using namespace mozilla;
-static bool IsDiscardable(char16_t ch, uint32_t* aFlags)
+static bool
+IsDiscardable(char16_t ch, uint32_t* aFlags)
{
// Unlike IS_DISCARDABLE, we don't discard \r. \r will be ignored by gfxTextRun
// and discarding it would force us to copy text in many cases of preformatted
// text containing \r\n.
if (ch == CH_SHY) {
*aFlags |= nsTextFrameUtils::TEXT_HAS_SHY;
return true;
}
return IsBidiControl(ch);
}
-static bool IsDiscardable(uint8_t ch, uint32_t* aFlags)
+static bool
+IsDiscardable(uint8_t ch, uint32_t* aFlags)
{
if (ch == CH_SHY) {
*aFlags |= nsTextFrameUtils::TEXT_HAS_SHY;
return true;
}
return false;
}
+static bool
+IsSegmentBreak(char16_t aCh)
+{
+ return aCh == '\n' || aCh == '\r';
+}
+
+static bool
+IsSpaceOrTab(char16_t aCh)
+{
+ return aCh == ' ' || aCh == '\t';
+}
+
+static bool
+IsSpaceOrTabOrSegmentBreak(char16_t aCh)
+{
+ return IsSpaceOrTab(aCh) || IsSegmentBreak(aCh);
+}
+
+static char16_t*
+TransformWhiteSpaces(const char16_t* aText, uint32_t aLength,
+ uint32_t aBegin, uint32_t aEnd,
+ bool aHasSegmentBreak,
+ bool& aInWhitespace,
+ char16_t* aOutput,
+ uint32_t& aFlags,
+ nsTextFrameUtils::CompressionMode aCompression,
+ gfxSkipChars* aSkipChars)
+{
+ MOZ_ASSERT(aCompression == nsTextFrameUtils::COMPRESS_WHITESPACE ||
+ aCompression == nsTextFrameUtils::COMPRESS_WHITESPACE_NEWLINE,
+ "whitespaces should be skippable!!");
+ // Get the context preceding/following this white space range.
+ bool isSegmentBreakSkippable =
+ (aBegin > 0 && IS_ZERO_WIDTH_SPACE(aText[aBegin - 1])) ||
+ (aEnd < aLength && IS_ZERO_WIDTH_SPACE(aText[aEnd]));
+ if (!isSegmentBreakSkippable && aBegin > 0 && aEnd < aLength) {
+ uint32_t ucs4before;
+ uint32_t ucs4after;
+ if (aBegin > 1 &&
+ NS_IS_LOW_SURROGATE(aText[aBegin - 1]) &&
+ NS_IS_HIGH_SURROGATE(aText[aBegin - 2])) {
+ ucs4before = SURROGATE_TO_UCS4(aText[aBegin - 2], aText[aBegin - 1]);
+ } else {
+ ucs4before = aText[aBegin - 1];
+ }
+ if (aEnd + 1 < aLength &&
+ NS_IS_HIGH_SURROGATE(aText[aEnd]) &&
+ NS_IS_LOW_SURROGATE(aText[aEnd + 1])) {
+ ucs4after = SURROGATE_TO_UCS4(aText[aEnd], aText[aEnd + 1]);
+ } else {
+ ucs4after = aText[aEnd];
+ }
+ // Discard newlines between characters that have F, W, or H
+ // EastAsianWidth property and neither side is Hangul.
+ isSegmentBreakSkippable = IsSegmentBreakSkipChar(ucs4before) &&
+ IsSegmentBreakSkipChar(ucs4after);
+ }
+
+ for (uint32_t i = aBegin; i < aEnd; ++i) {
+ char16_t ch = aText[i];
+ bool keepChar = false;
+ bool keepTransformedWhiteSpace = false;
+ if (IsDiscardable(ch, &aFlags)) {
+ aSkipChars->SkipChar();
+ continue;
+ }
+ if (IsSpaceOrTab(ch)) {
+ if (aHasSegmentBreak) {
+ // If white-space is set to normal, nowrap, or pre-line, white space
+ // characters are considered collapsible and all spaces and tabs
+ // immediately preceding or following a segment break are removed.
+ aSkipChars->SkipChar();
+ continue;
+ }
+
+ if (aInWhitespace) {
+ aSkipChars->SkipChar();
+ continue;
+ } else {
+ keepTransformedWhiteSpace = true;
+ }
+ } else {
+ // Apply Segment Break Transformation Rules (CSS Text 3 - 4.1.2) for
+ // segment break characters.
+ if (aCompression == nsTextFrameUtils::COMPRESS_WHITESPACE ||
+ // XXX: According to CSS Text 3, a lone CR should not always be
+ // kept, but still go through the Segment Break Transformation
+ // Rules. However, this is what current modern browser engines
+ // (webkit/blink/edge) do. So, once we can get some clarity
+ // from the specification issue, we should either remove the
+ // lone CR condition here, or leave it here with this comment
+ // being rephrased.
+ // Please see https://github.com/w3c/csswg-drafts/issues/855.
+ ch == '\r') {
+ keepChar = true;
+ } else {
+ // aCompression == COMPRESS_WHITESPACE_NEWLINE
+
+ // Any collapsible segment break immediately following another
+ // collapsible segment break is removed. Then the remaining segment
+ // break is either transformed into a space (U+0020) or removed
+ // depending on the context before and after the break.
+ if (isSegmentBreakSkippable || aInWhitespace) {
+ aSkipChars->SkipChar();
+ continue;
+ }
+ isSegmentBreakSkippable = true;
+ keepTransformedWhiteSpace = true;
+ }
+ }
+
+ if (keepChar) {
+ *aOutput++ = ch;
+ aSkipChars->KeepChar();
+ aInWhitespace = IsSpaceOrTab(ch);
+ } else if (keepTransformedWhiteSpace) {
+ if (ch != ' ') {
+ aFlags |= nsTextFrameUtils::TEXT_WAS_TRANSFORMED;
+ }
+ *aOutput++ = ' ';
+ aSkipChars->KeepChar();
+ aInWhitespace = true;
+ } else {
+ MOZ_ASSERT_UNREACHABLE("Should've skipped the character!!");
+ }
+ }
+ return aOutput;
+}
+
char16_t*
nsTextFrameUtils::TransformText(const char16_t* aText, uint32_t aLength,
char16_t* aOutput,
CompressionMode aCompression,
uint8_t* aIncomingFlags,
gfxSkipChars* aSkipChars,
uint32_t* aAnalysisFlags)
{
uint32_t flags = 0;
char16_t* outputStart = aOutput;
bool lastCharArabic = false;
-
if (aCompression == COMPRESS_NONE ||
aCompression == COMPRESS_NONE_TRANSFORM_TO_SPACE) {
// Skip discardables.
uint32_t i;
for (i = 0; i < aLength; ++i) {
char16_t ch = aText[i];
if (IsDiscardable(ch, &flags)) {
aSkipChars->SkipChar();
@@ -81,77 +211,81 @@ nsTextFrameUtils::TransformText(const ch
*aIncomingFlags &= ~INCOMING_ARABICCHAR;
}
*aIncomingFlags &= ~INCOMING_WHITESPACE;
} else {
bool inWhitespace = (*aIncomingFlags & INCOMING_WHITESPACE) != 0;
uint32_t i;
for (i = 0; i < aLength; ++i) {
char16_t ch = aText[i];
- bool nowInWhitespace;
- if (ch == ' ' &&
- (i + 1 >= aLength ||
- !IsSpaceCombiningSequenceTail(&aText[i + 1], aLength - (i + 1)))) {
- nowInWhitespace = true;
- } else if (ch == '\n' && aCompression == COMPRESS_WHITESPACE_NEWLINE) {
- if ((i > 0 && IS_ZERO_WIDTH_SPACE(aText[i - 1])) ||
- (i + 1 < aLength && IS_ZERO_WIDTH_SPACE(aText[i + 1]))) {
- aSkipChars->SkipChar();
- continue;
- }
- uint32_t ucs4before;
- uint32_t ucs4after;
- if (i > 1 &&
- NS_IS_LOW_SURROGATE(aText[i - 1]) &&
- NS_IS_HIGH_SURROGATE(aText[i - 2])) {
- ucs4before = SURROGATE_TO_UCS4(aText[i - 2], aText[i - 1]);
- } else if (i > 0) {
- ucs4before = aText[i - 1];
- }
- if (i + 2 < aLength &&
- NS_IS_HIGH_SURROGATE(aText[i + 1]) &&
- NS_IS_LOW_SURROGATE(aText[i + 2])) {
- ucs4after = SURROGATE_TO_UCS4(aText[i + 1], aText[i + 2]);
- } else if (i + 1 < aLength) {
- ucs4after = aText[i + 1];
+ // CSS Text 3 - 4.1. The White Space Processing Rules
+ // White space processing in CSS affects only the document white space
+ // characters: spaces (U+0020), tabs (U+0009), and segment breaks.
+ // Since we need the context of segment breaks and their surrounding
+ // white spaces to proceed the white space processing, a consecutive run
+ // of spaces/tabs/segment breaks is collected in a first pass loop, then
+ // we apply the collapsing and transformation rules to this run in a
+ // second pass loop.
+ if (IsSpaceOrTabOrSegmentBreak(ch)) {
+ bool keepLastSpace = false;
+ bool hasSegmentBreak = IsSegmentBreak(ch);
+ uint32_t countTrailingDiscardables = 0;
+ uint32_t j;
+ for (j = i + 1; j < aLength &&
+ (IsSpaceOrTabOrSegmentBreak(aText[j]) ||
+ IsDiscardable(aText[j], &flags));
+ j++) {
+ if (IsSegmentBreak(aText[j])) {
+ hasSegmentBreak = true;
+ }
}
- if (i > 0 && IsSegmentBreakSkipChar(ucs4before) &&
- i + 1 < aLength && IsSegmentBreakSkipChar(ucs4after)) {
- // Discard newlines between characters that have F, W, or H
- // EastAsianWidth property and neither side is Hangul.
- aSkipChars->SkipChar();
- continue;
+ // Exclude trailing discardables before checking space combining
+ // sequence tail.
+ for (; IsDiscardable(aText[j - 1], &flags); j--) {
+ countTrailingDiscardables++;
}
- nowInWhitespace = true;
- } else {
- nowInWhitespace = ch == '\t';
- }
-
- if (!nowInWhitespace) {
- if (IsDiscardable(ch, &flags)) {
- aSkipChars->SkipChar();
- nowInWhitespace = inWhitespace;
- } else {
- *aOutput++ = ch;
- aSkipChars->KeepChar();
- lastCharArabic = IS_ARABIC_CHAR(ch);
+ // If the last white space is followed by a combining sequence tail,
+ // exclude it from the range of TransformWhiteSpaces.
+ if (aText[j - 1] == ' ' && j < aLength &&
+ IsSpaceCombiningSequenceTail(&aText[j], aLength - j)) {
+ keepLastSpace = true;
+ j--;
}
- } else {
- if (inWhitespace) {
- aSkipChars->SkipChar();
- } else {
- if (ch != ' ') {
- flags |= TEXT_WAS_TRANSFORMED;
- }
+ if (j > i) {
+ aOutput = TransformWhiteSpaces(aText, aLength, i, j, hasSegmentBreak,
+ inWhitespace, aOutput, flags,
+ aCompression, aSkipChars);
+ }
+ // We need to keep KeepChar()/SkipChar() in order, so process the
+ // last white space first, then process the trailing discardables.
+ if (keepLastSpace) {
+ keepLastSpace = false;
*aOutput++ = ' ';
aSkipChars->KeepChar();
+ lastCharArabic = false;
+ j++;
}
+ for (; countTrailingDiscardables > 0; countTrailingDiscardables--) {
+ aSkipChars->SkipChar();
+ j++;
+ }
+ i = j - 1;
+ continue;
}
- inWhitespace = nowInWhitespace;
+ // Process characters other than the document white space characters.
+ if (IsDiscardable(ch, &flags)) {
+ aSkipChars->SkipChar();
+ } else {
+ *aOutput++ = ch;
+ aSkipChars->KeepChar();
+ }
+ lastCharArabic = IS_ARABIC_CHAR(ch);
+ inWhitespace = false;
}
+
if (lastCharArabic) {
*aIncomingFlags |= INCOMING_ARABICCHAR;
} else {
*aIncomingFlags &= ~INCOMING_ARABICCHAR;
}
if (inWhitespace) {
*aIncomingFlags |= INCOMING_WHITESPACE;
} else {