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Using non-breaking spaces as a hint to break too long words

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Change-Id: Ic88e961ea3fb08e61340895115f514c6f5dec163
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/379798
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Julia Lavrova <jlavrova@google.com>
This commit is contained in:
Julia Lavrova 2021-03-04 16:29:06 -05:00 committed by Skia Commit-Bot
parent 07ee548d5b
commit c70f8c331d
9 changed files with 57 additions and 23 deletions
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25
modules/skparagraph/samples/SampleParagraph.cpp
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@ -3416,20 +3416,6 @@ private:
using INHERITED = Sample;
};
void print_line_metrics(std::vector<LineMetrics> metrics) {
for (size_t i = 0; i < metrics.size(); ++i) {
auto& line = metrics[i];
printf("Line[%zd] startIndex=%zd, endIndex=%zd, endExcludingWhitespaces=%zd, _endIncludingNewline=%zd, hardBreak=%d, baseline=%.2f, ascent=%.2f, descent=%.2f, unscaledAscent=%.2f, height=%.2f, width=%.2f, left=%.2f, lineNumber=%zd\n",
i,
line.fStartIndex, line.fEndIndex,
line.fEndExcludingWhitespaces, line.fEndIncludingNewline,
line.fHardBreak,
line.fBaseline, line.fAscent, line.fDescent, line.fUnscaledAscent,
line.fHeight, line.fWidth, line.fLeft,
line.fLineNumber);
}
}
class ParagraphView58 : public ParagraphView_Base {
protected:
SkString name() override { return SkString("Paragraph58"); }
@ -3446,21 +3432,14 @@ protected:
ParagraphBuilderImpl builder(paragraph_style, fontCollection);
TextStyle text_style;
text_style.setFontFamilies({SkString("Roboto")});
text_style.setFontSize(32);
text_style.setHeight(5.0);
text_style.setHeightOverride(true);
text_style.setFontSize(40);
text_style.setColor(SK_ColorBLACK);
builder.pushStyle(text_style);
builder.addText("Line1\nLine2\nLine3\nLine4\n");
builder.addText(u"Text1 Google\u00A0Pay Text2");
auto paragraph = builder.Build();
paragraph->layout(width());
paragraph->paint(canvas, 0, 0);
std::vector<LineMetrics> metrics;
paragraph->getLineMetrics(metrics);
print_line_metrics(metrics);
}
private:

17
modules/skparagraph/src/ParagraphImpl.cpp
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@ -28,6 +28,11 @@ namespace textlayout {
namespace {
static inline SkUnichar nextUtf8Unit(const char** ptr, const char* end) {
SkUnichar val = SkUTF::NextUTF8(ptr, end);
return val < 0 ? 0xFFFD : val;
}
SkScalar littleRound(SkScalar a) {
// This rounding is done to match Flutter tests. Must be removed..
auto val = std::fabs(a);
@ -736,6 +741,18 @@ size_t ParagraphImpl::getWhitespacesLength(TextRange textRange) {
return len;
}
bool ParagraphImpl::isSpace(TextRange textRange) {
auto text = ParagraphImpl::text(textRange);
const char* ch = text.begin();
while (ch != text.end()) {
SkUnichar unicode = nextUtf8Unit(&ch, text.end());
if (!fUnicode->isSpace(unicode)) {
return false;
}
}
return true;
}
void ParagraphImpl::getLineMetrics(std::vector<LineMetrics>& metrics) {
metrics.clear();
for (auto& line : fLines) {

1
modules/skparagraph/src/ParagraphImpl.h
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@ -220,6 +220,7 @@ public:
using CodeUnitRangeVisitor = std::function<bool(TextRange textRange)>;
void forEachCodeUnitPropertyRange(CodeUnitFlags property, CodeUnitRangeVisitor visitor);
size_t getWhitespacesLength(TextRange textRange);
bool isSpace(TextRange textRange);
bool codeUnitHasProperty(size_t index, CodeUnitFlags property) const { return (fCodeUnitProperties[index] & property) == property; }

1
modules/skparagraph/src/Run.cpp
View File

@ -383,6 +383,7 @@ Cluster::Cluster(ParagraphImpl* owner,
, fHalfLetterSpacing(0.0) {
size_t len = fOwner->getWhitespacesLength(fTextRange);
fIsWhiteSpaces = (len == this->fTextRange.width());
fIsSpaces = fOwner->isSpace(fTextRange);
}
} // namespace textlayout

2
modules/skparagraph/src/Run.h
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@ -248,6 +248,7 @@ public:
}
bool isWhitespaces() const { return fIsWhiteSpaces; }
bool isSpaces() const { return fIsSpaces; }
bool isHardBreak() const;
bool isSoftBreak() const;
bool isGraphemeBreak() const;
@ -297,6 +298,7 @@ private:
SkScalar fHeight;
SkScalar fHalfLetterSpacing;
bool fIsWhiteSpaces;
bool fIsSpaces;
};
class InternalLineMetrics {

25
modules/skparagraph/src/TextWrapper.cpp
View File

@ -29,6 +29,7 @@ void TextWrapper::lookAhead(SkScalar maxWidth, Cluster* endOfClusters) {
fClusters.startFrom(fEndLine.startCluster(), fEndLine.startPos());
fClip.startFrom(fEndLine.startCluster(), fEndLine.startPos());
Cluster* nextNonBreakingSpace = nullptr;
for (auto cluster = fEndLine.endCluster(); cluster < endOfClusters; ++cluster) {
// TODO: Trying to deal with flutter rounding problem. Must be removed...
auto width = fWords.width() + fClusters.width() + cluster->width();
@ -61,6 +62,7 @@ void TextWrapper::lookAhead(SkScalar maxWidth, Cluster* endOfClusters) {
// Walk further to see if there is a too long word, cluster or glyph
SkScalar nextWordLength = fClusters.width();
SkScalar nextShortWordLength = nextWordLength;
for (auto further = cluster; further != endOfClusters; ++further) {
if (further->isSoftBreak() || further->isHardBreak() || further->isWhitespaces()) {
break;
@ -69,6 +71,13 @@ void TextWrapper::lookAhead(SkScalar maxWidth, Cluster* endOfClusters) {
// Placeholder ends the word
break;
}
if (further->isSpaces() && nextWordLength <= maxWidth) {
// The cluster is spaces but not the end of the word in a normal sense
nextNonBreakingSpace = further;
nextShortWordLength = nextWordLength;
}
if (maxWidth == 0) {
// This is a tricky flutter case: layout(width:0) places 1 cluster on each line
nextWordLength = std::max(nextWordLength, further->width());
@ -77,6 +86,22 @@ void TextWrapper::lookAhead(SkScalar maxWidth, Cluster* endOfClusters) {
}
}
if (nextWordLength > maxWidth) {
if (nextNonBreakingSpace != nullptr) {
// We only get here if the non-breaking space improves our situation
// (allows us to break the text to fit the word)
auto shortLength = littleRound(fWords.width() + nextShortWordLength);
if (shortLength <= maxWidth) {
// We can add the short word to the existing line
fClusters = TextStretch(fClusters.startCluster(), nextNonBreakingSpace, fClusters.metrics().getForceStrut());
fMinIntrinsicWidth = std::max(fMinIntrinsicWidth, nextShortWordLength);
fWords.extend(fClusters);
} else {
// We can place the short word on the next line
fClusters.clean();
}
// Either way we are not in "word is too long" situation anymore
break;
}
// If the word is too long we can break it right now and hope it's enough
fMinIntrinsicWidth = std::max(fMinIntrinsicWidth, nextWordLength);
if (fClusters.endPos() - fClusters.startPos() > 1 ||

4
modules/skparagraph/src/TextWrapper.h
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@ -41,7 +41,11 @@ class TextWrapper {
if (c->run() != nullptr) {
fMetrics.add(c->run());
}
if (c < e) {
fWidth += c->width();
}
}
fWidthWithGhostSpaces = fWidth;
}
inline SkScalar width() const { return fWidth; }

1
modules/skshaper/src/SkUnicode.h
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@ -113,6 +113,7 @@ class SKUNICODE_API SkUnicode {
virtual bool isControl(SkUnichar utf8) = 0;
virtual bool isWhitespace(SkUnichar utf8) = 0;
virtual bool isSpace(SkUnichar utf8) = 0;
virtual SkString convertUtf16ToUtf8(const std::u16string& utf16) = 0;
// Methods used in SkShaper

4
modules/skshaper/src/SkUnicode_icu.cpp
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@ -459,6 +459,10 @@ public:
return u_isWhitespace(utf8);
}
bool isSpace(SkUnichar utf8) override {
return u_isspace(utf8);
}
static bool isHardLineBreak(SkUnichar utf8) {
auto property = u_getIntPropertyValue(utf8, UCHAR_LINE_BREAK);
return property == U_LB_LINE_FEED || property == U_LB_MANDATORY_BREAK;