[css-text] New value 'break-spaces' for the white-space property

Finally the CSS WG decided [1] to move back the 'break-spaces' value to
the 'white-space' property. This makes the parsing logic easier than
the previous approach of using the 'overflow-wrap' property.

This new value prevents the white-space sequence to collapse and gives
breaking opportunities after every preserved white-space.

https://drafts.csswg.org/css-text-3/#valdef-white-space-break-spaces

Additionally, unlike 'pre-wrap', non-collapsible spaces or tabs at the
end of a line cannot be hung or visually collapsed, since we want them
to be preserved and broken.

[1] w3c/csswg-drafts#2841

Bug: 767634
Change-Id: I55e888d4472de11c64c4b14e2710c6e3d1832e67
Reviewed-on: https://chromium-review.googlesource.com/c/1136543
Reviewed-by: Koji Ishii <kojii@chromium.org>
Commit-Queue: Javier Fernandez <jfernandez@igalia.com>
Cr-Commit-Position: refs/heads/master@{#623324}

third_party/blink/renderer/build/scripts/core/style/templates/computed_style_base_constants.h.tmpl

@@ -14,7 +14,7 @@ namespace blink {
 {% for enum in enums %}
 enum class {{enum.type_name}} : unsigned {
   {% for value in enum.values %}
-  {{value}}{{print_if(enum.is_set, " = " ~ (0 if loop.first else 2**loop.index0))}},
+  {{value}}{{print_if(enum.is_set, " = " ~ (0 if loop.first else 2**(loop.index0 - 1)))}},
   {% endfor %}
 };
 

third_party/blink/renderer/core/css/css_properties.json5

@@ -3961,9 +3961,9 @@
       property_methods: ["CSSValueFromComputedStyleInternal"],
       independent: true,
       inherited: true,
-      field_template: "keyword",
+      field_template: "multi_keyword", // We use a bitflag field due peformance issues
       keywords: [
-        "normal", "pre", "pre-wrap", "pre-line", "nowrap", "-webkit-nowrap"
+        "none", "normal", "pre", "pre-wrap", "pre-line", "nowrap", "-webkit-nowrap", "break-spaces"
       ],
       typedom_types: ["Keyword"],
       default_value: "normal",

third_party/blink/renderer/core/css/css_value_keywords.json5

@@ -455,6 +455,7 @@
     "bidi-override",
     "blink",
     "both",
+    "break-spaces",
     "close-quote",
     "embed",
     "fixed",

third_party/blink/renderer/core/css/parser/css_parser_fast_paths.cc

@@ -877,7 +877,9 @@ bool CSSParserFastPaths::IsValidKeywordPropertyAndValue(
     case CSSPropertyWhiteSpace:
       return value_id == CSSValueNormal || value_id == CSSValuePre ||
              value_id == CSSValuePreWrap || value_id == CSSValuePreLine ||
-             value_id == CSSValueNowrap;
+             value_id == CSSValueNowrap ||
+             (RuntimeEnabledFeatures::CSS3TextBreakSpacesEnabled() &&
+              value_id == CSSValueBreakSpaces);
     case CSSPropertyWordBreak:
       return value_id == CSSValueNormal || value_id == CSSValueBreakAll ||
              value_id == CSSValueKeepAll || value_id == CSSValueBreakWord;

third_party/blink/renderer/core/layout/line/breaking_context_inline_headers.h

@@ -125,6 +125,7 @@ class BreakingContext {
                             const Font&,
                             bool apply_word_spacing,
                             float word_spacing);
+  void TrailingSpacesHang(bool can_break_mid_word);
   bool TrailingSpaceExceedsAvailableWidth(bool can_break_mid_word,
                                           const LineLayoutText&,
                                           WordMeasurement&,
@@ -205,6 +206,7 @@ class BreakingContext {
   bool at_start_;
   bool ignoring_spaces_;
   bool current_character_is_space_;
+  bool previous_character_is_space_;
   bool single_leading_space_;
   unsigned current_start_offset_;  // initial offset for the current text
   bool applied_start_width_;
@@ -1044,7 +1046,7 @@ inline bool BreakingContext::HandleText(WordMeasurements& word_measurements,
       layout_text_info_.line_break_iterator_.SecondToLastCharacter();
   for (; current_.Offset() < layout_text.TextLength();
        current_.FastIncrementInTextNode()) {
-    bool previous_character_is_space = current_character_is_space_;
+    previous_character_is_space_ = current_character_is_space_;
     UChar c = current_.Current();
     SetCurrentCharacterIsSpace(c);
 
@@ -1106,7 +1108,7 @@ inline bool BreakingContext::HandleText(WordMeasurements& word_measurements,
       }
 
       PrepareForNextCharacter(layout_text, prohibit_break_inside,
-                              previous_character_is_space);
+                              previous_character_is_space_);
       at_start_ = false;
       NextCharacter(c, last_character, second_to_last_character);
       continue;
@@ -1146,7 +1148,7 @@ inline bool BreakingContext::HandleText(WordMeasurements& word_measurements,
     // We keep track of the total width contributed by trailing space as we
     // often want to exclude it when determining
     // if a run fits on a line.
-    if (collapse_white_space_ && previous_character_is_space &&
+    if (collapse_white_space_ && previous_character_is_space_ &&
         current_character_is_space_ && last_width_measurement)
       width_.SetTrailingWhitespaceWidth(last_width_measurement);
 
@@ -1210,7 +1212,7 @@ inline bool BreakingContext::HandleText(WordMeasurements& word_measurements,
     if (CanBreakAtWhitespace(
             break_words, word_measurement, stopped_ignoring_spaces, char_width,
             hyphenated, disable_soft_hyphen, hyphen_width, between_words,
-            mid_word_break, can_break_mid_word, previous_character_is_space,
+            mid_word_break, can_break_mid_word, previous_character_is_space_,
             last_width_measurement, layout_text, font, apply_word_spacing,
             word_spacing))
       return false;
@@ -1250,7 +1252,7 @@ inline bool BreakingContext::HandleText(WordMeasurements& word_measurements,
     // go ahead and break up this run and enter a mode where we start collapsing
     // spaces.
     if (!ignoring_spaces_ && current_style_->CollapseWhiteSpace()) {
-      if (current_character_is_space_ && previous_character_is_space) {
+      if (current_character_is_space_ && previous_character_is_space_) {
         ignoring_spaces_ = true;
 
         // We just entered a mode where we are ignoring spaces. Create a
@@ -1263,7 +1265,7 @@ inline bool BreakingContext::HandleText(WordMeasurements& word_measurements,
     }
 
     PrepareForNextCharacter(layout_text, prohibit_break_inside,
-                            previous_character_is_space);
+                            previous_character_is_space_);
     at_start_ = false;
     is_line_empty = line_info_.IsEmpty();
     NextCharacter(c, last_character, second_to_last_character);
@@ -1417,6 +1419,22 @@ inline WordMeasurement& BreakingContext::CalculateWordWidth(
   return word_measurement;
 }
 
+inline void BreakingContext::TrailingSpacesHang(bool can_break_mid_word) {
+  DCHECK(curr_ws_ == EWhiteSpace::kBreakSpaces);
+  // Avoid breaking before the first white-space after a word if there is a
+  // breaking opportunity before.
+  if (single_leading_space_ && !previous_character_is_space_)
+    return;
+
+  line_break_.MoveTo(current_.GetLineLayoutItem(), current_.Offset(),
+                     current_.NextBreakablePosition());
+
+  // Avoid breaking before the first white-space after a word, unless
+  // overflow-wrap or word-break allow to.
+  if (!previous_character_is_space_ && !can_break_mid_word)
+    line_break_.Increment();
+}
+
 inline bool BreakingContext::TrailingSpaceExceedsAvailableWidth(
     bool can_break_mid_word,
     const LineLayoutText& layout_text,
@@ -1439,8 +1457,13 @@ inline bool BreakingContext::TrailingSpaceExceedsAvailableWidth(
     // then move the line break to the space and skip all
     // additional whitespace.
     if (!width_.FitsOnLine(char_width)) {
+      if (curr_ws_ == EWhiteSpace::kBreakSpaces) {
+        TrailingSpacesHang(can_break_mid_word);
+        return true;
+      }
       line_break_.MoveTo(current_.GetLineLayoutItem(), current_.Offset(),
                          current_.NextBreakablePosition());
+
       SkipTrailingWhitespace(line_break_, line_info_);
       return true;
     }

third_party/blink/renderer/core/style/computed_style.cc

@@ -85,6 +85,7 @@ ASSERT_SIZE(BorderValue, SameSizeAsBorderValue);
 // Since different compilers/architectures pack ComputedStyle differently,
 // re-create the same structure for an accurate size comparison.
 struct SameSizeAsComputedStyle : public RefCounted<SameSizeAsComputedStyle> {
+  unsigned extra_;
   struct ComputedStyleBase {
     void* data_refs[7];
     unsigned bitfields_[4];

third_party/blink/renderer/core/style/computed_style.h

@@ -2129,9 +2129,13 @@ class ComputedStyle : public ComputedStyleBase,
   }
 
   // Whitespace utility functions.
+  static bool Is(EWhiteSpace a, EWhiteSpace b) {
+    return static_cast<unsigned>(a) & static_cast<unsigned>(b);
+  }
+  static bool IsNot(EWhiteSpace a, EWhiteSpace b) { return !Is(a, b); }
   static bool AutoWrap(EWhiteSpace ws) {
     // Nowrap and pre don't automatically wrap.
-    return ws != EWhiteSpace::kNowrap && ws != EWhiteSpace::kPre;
+    return IsNot(ws, EWhiteSpace::kNowrap | EWhiteSpace::kPre);
   }
 
   bool AutoWrap() const { return AutoWrap(WhiteSpace()); }
@@ -2149,7 +2153,8 @@ class ComputedStyle : public ComputedStyleBase,
 
   static bool CollapseWhiteSpace(EWhiteSpace ws) {
     // Pre and prewrap do not collapse whitespace.
-    return ws != EWhiteSpace::kPre && ws != EWhiteSpace::kPreWrap;
+    return IsNot(ws, EWhiteSpace::kPre | EWhiteSpace::kPreWrap |
+                         EWhiteSpace::kBreakSpaces);
   }
 
   bool CollapseWhiteSpace() const { return CollapseWhiteSpace(WhiteSpace()); }
@@ -2165,15 +2170,15 @@ class ComputedStyle : public ComputedStyleBase,
     return false;
   }
   bool BreakOnlyAfterWhiteSpace() const {
-    return WhiteSpace() == EWhiteSpace::kPreWrap ||
+    return Is(WhiteSpace(),
+              EWhiteSpace::kPreWrap | EWhiteSpace::kBreakSpaces) ||
            GetLineBreak() == LineBreak::kAfterWhiteSpace;
   }
 
   bool BreakWords() const {
     return (WordBreak() == EWordBreak::kBreakWord ||
             OverflowWrap() == EOverflowWrap::kBreakWord) &&
-           WhiteSpace() != EWhiteSpace::kPre &&
-           WhiteSpace() != EWhiteSpace::kNowrap;
+           IsNot(WhiteSpace(), EWhiteSpace::kPre | EWhiteSpace::kNowrap);
   }
 
   // Text direction utility functions.

third_party/blink/renderer/platform/runtime_enabled_features.json5

@@ -243,6 +243,10 @@
       name: "CSS3Text",
       status: "experimental",
     },
+    {
+      name: "CSS3TextBreakSpaces",
+      status: "experimental",
+    },
     {
       name: "CSSAdditiveAnimations",
       depends_on: ["StackedCSSPropertyAnimations"],

third_party/blink/web_tests/FlagExpectations/enable-blink-features=LayoutNG

@@ -62,6 +62,29 @@ crbug.com/591099 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftest
 crbug.com/591099 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/sizing/vert-block-size-small-or-larger-than-container-with-min-or-max-content-2a.html [ Pass ]
 crbug.com/613663 external/wpt/quirks/table-cell-width-calculation.html [ Failure ]
 
+# The new 'break-spaces' value is not implemented yet in LayoutNG
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-001.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-002.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-003.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-004.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-005.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-006.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-007.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/break-spaces-008.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/textarea-break-spaces-001.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/textarea-break-spaces-002.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/tab-stop-threshold-005.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/tab-stop-threshold-006.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/white-space-intrinsic-size-001.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/white-space/white-space-intrinsic-size-002.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/word-break/word-break-break-all-012.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/word-break/word-break-break-all-013.html  [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/overflow-wrap/overflow-wrap-anywhere-002.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/overflow-wrap/overflow-wrap-anywhere-003.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-002.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-003.html [ Skip ]
+crbug.com/922437 external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-006.html [ Skip ]
+
 # New failures are appended below by the script.
 crbug.com/591099 css3/filters/backdrop-filter-rendering.html [ Pass ]
 crbug.com/591099 css3/filters/composited-layer-child-bounds-after-composited-to-sw-shadow-change.html [ Failure ]

third_party/blink/web_tests/TestExpectations

@@ -2203,7 +2203,6 @@ crbug.com/626703 external/wpt/css/css-text/word-break/word-break-break-all-007.h
 crbug.com/626703 external/wpt/css/css-text/word-break/word-break-break-all-004.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/word-break/word-break-break-all-006.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/word-break/word-break-break-all-008.html [ Failure ]
-crbug.com/626703 external/wpt/css/css-text/word-break/word-break-keep-all-003.html [ Failure ]
 crbug.com/626703 [ Linux ] external/wpt/css/css-text/word-break/word-break-normal-bo-000.html [ Failure ]
 crbug.com/626703 [ Win ] external/wpt/css/css-text/word-break/word-break-normal-km-000.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/word-break/word-break-normal-my-000.html [ Failure ]
@@ -3104,7 +3103,6 @@ crbug.com/626703 [ Win ] external/wpt/css/CSS2/text/white-space-bidirectionality
 crbug.com/626703 external/wpt/css/css-text/text-transform/text-transform-shaping-002.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/white-space/pre-wrap-012.html [ Failure ]
 crbug.com/626703 external/wpt/css/CSS2/text/white-space-pre-element-001.xht [ Failure ]
-crbug.com/626703 external/wpt/css/css-text/overflow-wrap/overflow-wrap-anywhere-002.html [ Failure ]
 crbug.com/626703 external/wpt/css/CSS2/text/white-space-003.xht [ Failure ]
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/sizing/hori-block-size-small-or-larger-than-container-with-min-or-max-content-2b.html [ Failure ]
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/sizing/block-size-with-min-or-max-content-1a.html [ Failure ]
@@ -3115,7 +3113,6 @@ crbug.com/626703 [ Mac ] external/wpt/css/css-text/overflow-wrap/overflow-wrap-m
 crbug.com/626703 external/wpt/css/css-text/white-space/pre-wrap-013.html [ Failure ]
 crbug.com/626703 external/wpt/css/CSS2/text/white-space-processing-040.xht [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/text-transform/text-transform-shaping-003.html [ Failure ]
-crbug.com/626703 external/wpt/css/css-text/white-space/tab-stop-threshold-006.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/white-space/white-space-intrinsic-size-003.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/overflow-wrap/overflow-wrap-anywhere-001.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/overflow-wrap/overflow-wrap-anywhere-003.html [ Failure ]
@@ -3132,9 +3129,7 @@ crbug.com/626703 [ Win7 ] external/wpt/css/vendor-imports/mozilla/mozilla-centra
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/sizing/block-size-with-min-or-max-content-1b.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/text-transform/text-transform-shaping-001.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/boundary-shaping/boundary-shaping-001.html [ Failure ]
-crbug.com/626703 external/wpt/css/css-text/white-space/white-space-intrinsic-size-002.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/text-indent/text-indent-percentage-004.html [ Failure ]
-crbug.com/626703 external/wpt/css/css-text/white-space/tab-stop-threshold-005.html [ Failure ]
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/sizing/vert-block-size-small-or-larger-than-container-with-min-or-max-content-1.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-text/boundary-shaping/boundary-shaping-004.html [ Failure ]
 crbug.com/626703 external/wpt/css/css-sizing/range-percent-intrinsic-size-2.html [ Failure ]
@@ -3544,15 +3539,13 @@ crbug.com/626703 external/wpt/content-security-policy/securitypolicyviolation/in
 crbug.com/626703 external/wpt/content-security-policy/securitypolicyviolation/inside-dedicated-worker.html [ Timeout ]
 crbug.com/626703 external/wpt/css/css-text/overflow-wrap/overflow-wrap-min-content-size-002.html [ Failure ]
 crbug.com/626703 external/wpt/content-security-policy/securitypolicyviolation/targeting.html [ Timeout ]
-crbug.com/626703 external/wpt/css/css-text/white-space/textarea-break-spaces-001.html [ Failure ]
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-column-row-gap-003.html [ Failure ]
 crbug.com/863355 [ Mac ] external/wpt/svg/shapes/reftests/pathlength-002.svg [ Failure ]
 crbug.com/366559 external/wpt/svg/shapes/reftests/pathlength-003.svg [ Failure ]
 crbug.com/366559 external/wpt/svg/text/reftests/textpath-side-001.svg [ Failure ]
 crbug.com/366559 external/wpt/svg/text/reftests/textpath-shape-001.svg [ Failure ]
 crbug.com/626703 external/wpt/svg/rendering/order/z-index.svg [ Failure ]
 crbug.com/626703 external/wpt/web-animations/timing-model/timelines/update-and-send-events.html [ Timeout ]
-crbug.com/626703 external/wpt/css/css-text/white-space/break-spaces-001.html [ Failure ]
 crbug.com/626703 [ Mac10.12 ] external/wpt/compat/webkit-text-fill-color-property-002.html [ Failure ]
 crbug.com/626703 [ Mac10.13 ] external/wpt/compat/webkit-text-fill-color-property-002.html [ Failure ]
 crbug.com/626703 external/wpt/css/vendor-imports/mozilla/mozilla-central-reftests/flexbox/flexbox-column-row-gap-001.html [ Failure ]
@@ -3685,8 +3678,6 @@ crbug.com/626703 [ Linux ] external/wpt/fetch/api/redirect/redirect-count.any.ht
 crbug.com/626703 [ Win10 ] external/wpt/fetch/api/redirect/redirect-count.any.html [ Timeout ]
 
 crbug.com/626703 external/wpt/css/cssom-view/scroll-behavior-smooth.html [ Timeout ]
-crbug.com/626703 external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-003.html [ Failure ]
-crbug.com/626703 external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-002.html [ Failure ]
 crbug.com/626703 external/wpt/websockets/Create-Secure-extensions-empty.any.html [ Timeout ]
 crbug.com/626703 external/wpt/websockets/Create-Secure-extensions-empty.any.worker.html [ Timeout ]
 crbug.com/626703 external/wpt/html/semantics/scripting-1/the-script-element/module/dynamic-import/string-compilation-integrity-classic.sub.html [ Skip ]

third_party/blink/web_tests/W3CImportExpectations

@@ -191,10 +191,6 @@ external/wpt/css/css-text/text-transform/text-transform-fullwidth-001.xht [ Skip
 external/wpt/css/css-text/text-transform/text-transform-fullwidth-002.xht [ Skip ]
 external/wpt/css/css-text/text-transform/text-transform-fullwidth-004.xht [ Skip ]
 external/wpt/css/css-text/text-transform/text-transform-fullwidth-005.xht [ Skip ]
-external/wpt/css/css-text/white-space/pre-wrap-008.html [ Skip ]
-external/wpt/css/css-text/white-space/pre-wrap-010.html [ Skip ]
-external/wpt/css/css-text/white-space/textarea-pre-wrap-010.html [ Skip ]
-external/wpt/css/css-text/white-space/textarea-pre-wrap-008.html [ Skip ]
 external/wpt/css/css-text/white-space/white-space-collapsing-discard-001.xht [ Skip ]
 external/wpt/css/css-text/white-space/white-space-collapsing-preserve-breaks-001.xht [ Skip ]
 

third_party/blink/web_tests/external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-002.html

@@ -22,7 +22,7 @@
 </style>
 
 <p>This test passes if there is nothing below this sentence.
-<div> FAIL <div>
+<div> FAIL </div>
 <!--
 white-space:break-spaces should cause the spaces at the end of the line to be preserved.
 Since there is an allowed break point between the first space and the F,

third_party/blink/web_tests/external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-003.html

@@ -22,4 +22,4 @@
 </style>
 
 <p>This test passes if the word FAIL does not appear below.
-<div>PASS FAIL<div>
+<div>PASS FAIL</div>

third_party/blink/web_tests/external/wpt/css/css-text/overflow-wrap/overflow-wrap-break-word-004.html

@@ -3,6 +3,7 @@
 <title>CSS Text Test: overflow-wrap: break-word</title>
 <link rel="author" title="Javier Fernandez Garcia-Boente" href="mailto:jfernandez@igalia.com">
 <link rel="help" href="https://drafts.csswg.org/css-text-3/#valdef-overflow-wrap-break-word">
+<link rel="help" href="https://drafts.csswg.org/css-text-3/#valdef-white-space-pre-wrap">
 <meta name="flags" content="ahem">
 <link rel="match" href="reference/overflow-wrap-break-word-001-ref.html">
 <meta name="assert" content="A Single leading white-space constitutes a soft breaking opportunity, honoring the 'white-space: pre-wrap' property, that must prevent the word to be broken.">