From 22bb52e95b92d15919450ab3a360355be287463e Mon Sep 17 00:00:00 2001
From: Jason Simmons <jsimmons@google.com>
Date: Thu, 5 Dec 2019 17:56:59 -0800
Subject: [PATCH] Get baselines from cached default metrics if the text is
 empty

Change-Id: Ic04251d60d6d36f80c3e569312495190ba375d85
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/258488
Reviewed-by: Julia Lavrova <jlavrova@google.com>
Commit-Queue: Jason Simmons <jsimmons@google.com>
---
 modules/skparagraph/src/ParagraphImpl.cpp | 22 +++++++++-------------
 modules/skparagraph/src/ParagraphImpl.h   |  5 ++++-
 modules/skparagraph/src/TextWrapper.cpp   |  3 +--
 3 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/modules/skparagraph/src/ParagraphImpl.cpp b/modules/skparagraph/src/ParagraphImpl.cpp
index 26d128ea40..7d4f08b15f 100644
--- a/modules/skparagraph/src/ParagraphImpl.cpp
+++ b/modules/skparagraph/src/ParagraphImpl.cpp
@@ -132,6 +132,7 @@ void ParagraphImpl::layout(SkScalar rawWidth) {
         fClusters.reset();
         fGraphemes.reset();
         this->markGraphemes();
+        this->computeEmptyMetrics();
 
         if (!this->shapeTextIntoEndlessLine()) {
 
@@ -140,15 +141,14 @@ void ParagraphImpl::layout(SkScalar rawWidth) {
             this->fLines.reset();
 
             // Set the important values that are not zero
-            auto emptyMetrics = computeEmptyMetrics();
             fWidth = floorWidth;
-            fHeight = emptyMetrics.height();
+            fHeight = fEmptyMetrics.height();
             if (fParagraphStyle.getStrutStyle().getStrutEnabled() &&
                 fParagraphStyle.getStrutStyle().getForceStrutHeight()) {
                 fHeight = fStrutMetrics.height();
             }
-            fAlphabeticBaseline = emptyMetrics.alphabeticBaseline();
-            fIdeographicBaseline = emptyMetrics.ideographicBaseline();
+            fAlphabeticBaseline = fEmptyMetrics.alphabeticBaseline();
+            fIdeographicBaseline = fEmptyMetrics.ideographicBaseline();
             fMinIntrinsicWidth = 0;
             fMaxIntrinsicWidth = 0;
             this->fOldWidth = floorWidth;
@@ -384,7 +384,6 @@ bool ParagraphImpl::shapeTextIntoEndlessLine() {
 }
 
 void ParagraphImpl::breakShapedTextIntoLines(SkScalar maxWidth) {
-
     TextWrapper textWrapper;
     textWrapper.breakTextIntoLines(
             this,
@@ -413,8 +412,8 @@ void ParagraphImpl::breakShapedTextIntoLines(SkScalar maxWidth) {
     fWidth = maxWidth;
     fMaxIntrinsicWidth = textWrapper.maxIntrinsicWidth();
     fMinIntrinsicWidth = textWrapper.minIntrinsicWidth();
-    fAlphabeticBaseline = fLines.empty() ? 0 : fLines.front().alphabeticBaseline();
-    fIdeographicBaseline = fLines.empty() ? 0 : fLines.front().ideographicBaseline();
+    fAlphabeticBaseline = fLines.empty() ? fEmptyMetrics.alphabeticBaseline() : fLines.front().alphabeticBaseline();
+    fIdeographicBaseline = fLines.empty() ? fEmptyMetrics.ideographicBaseline() : fLines.front().ideographicBaseline();
     fExceededMaxLines = textWrapper.exceededMaxLines();
 }
 
@@ -1092,8 +1091,7 @@ void ParagraphImpl::setState(InternalState state) {
 
 }
 
-InternalLineMetrics ParagraphImpl::computeEmptyMetrics() {
-
+void ParagraphImpl::computeEmptyMetrics() {
   auto defaultTextStyle = paragraphStyle().getTextStyle();
 
   auto typefaces = fontCollection()->findTypefaces(
@@ -1101,10 +1099,8 @@ InternalLineMetrics ParagraphImpl::computeEmptyMetrics() {
   auto typeface = typefaces.size() ? typefaces.front() : nullptr;
 
   SkFont font(typeface, defaultTextStyle.getFontSize());
-  InternalLineMetrics metrics(font, paragraphStyle().getStrutStyle().getForceStrutHeight());
-  fStrutMetrics.updateLineMetrics(metrics);
-
-  return metrics;
+  fEmptyMetrics = InternalLineMetrics(font, paragraphStyle().getStrutStyle().getForceStrutHeight());
+  fStrutMetrics.updateLineMetrics(fEmptyMetrics);
 }
 
 void ParagraphImpl::updateText(size_t from, SkString text) {
diff --git a/modules/skparagraph/src/ParagraphImpl.h b/modules/skparagraph/src/ParagraphImpl.h
index eb79275e91..25f6f134fc 100644
--- a/modules/skparagraph/src/ParagraphImpl.h
+++ b/modules/skparagraph/src/ParagraphImpl.h
@@ -196,7 +196,7 @@ public:
     void updateForegroundPaint(size_t from, size_t to, SkPaint paint) override;
     void updateBackgroundPaint(size_t from, size_t to, SkPaint paint) override;
 
-    InternalLineMetrics computeEmptyMetrics();
+    InternalLineMetrics getEmptyMetrics() const { return fEmptyMetrics; }
     InternalLineMetrics getStrutMetrics() const { return fStrutMetrics; }
 
 private:
@@ -215,6 +215,8 @@ private:
     void markGraphemes16();
     void markGraphemes();
 
+    void computeEmptyMetrics();
+
     // Input
     SkTArray<StyleBlock<SkScalar>> fLetterSpaceStyles;
     SkTArray<StyleBlock<SkScalar>> fWordSpaceStyles;
@@ -241,6 +243,7 @@ private:
 
     SkTArray<ResolvedFontDescriptor> fFontSwitches;
 
+    InternalLineMetrics fEmptyMetrics;
     InternalLineMetrics fStrutMetrics;
 
     SkScalar fOldWidth;
diff --git a/modules/skparagraph/src/TextWrapper.cpp b/modules/skparagraph/src/TextWrapper.cpp
index a0fb5813bf..98fc5a42a4 100644
--- a/modules/skparagraph/src/TextWrapper.cpp
+++ b/modules/skparagraph/src/TextWrapper.cpp
@@ -205,8 +205,7 @@ void TextWrapper::breakTextIntoLines(ParagraphImpl* parent,
 
         // If the line is empty with the hard line break, let's take the paragraph font (flutter???)
         if (fHardLineBreak && fEndLine.width() == 0) {
-            auto emptyMetrics = parent->computeEmptyMetrics();
-            fEndLine.setMetrics(emptyMetrics);
+            fEndLine.setMetrics(parent->getEmptyMetrics());
         }
 
         // Deal with placeholder clusters == runs[@size==1]