Store hyphenated pieces in MeasuredText

Do hyphenation calculation at the same time of measuring character
widths. We can do the 93% of line break work beforehand.

Here is a raw performance score:
(walleye-userdebug, w/o patch -> w/ patch, N=30)

Measured Balanced Hyphenation  : 11,428,287 ->    703,417 (-93.8%)
Measured Balanced NoHyphenation:    535,660 ->    536,210 (+0.1%)
Random Balanced Hyphenation    : 18,903,251 -> 19,046,535 (+0.8%)
Random Balanced NoHyphenation  :  7,973,160 ->  7,956,803 (-0.2%)

Measured Greedy Hyphenation    :    486,633 ->    486,381 (-0.1%)
Measured Greedy NoHyphenation  :    484,716 ->    490,018 (+1.1%)
Random Greedy Hyphenation      :  7,966,823 ->  7,921,520 (-0.6%)
Random Greedy NoHyphenation    :  7,918,480 ->  7,925,110 (+0.1%)

This CL also removes overhang member variable from MeasuredText since
this is no longer used in line breaker.

Bug: 67504091
Test: bit CtsTextTestCases:*
Test: bit CtsWidgetTestCases:android.widget.cts.TextViewTest
Test: minikin_tests
Change-Id: I94c65980bf1190c9351d50dc0c811a377fb93ee6

1 files changed, 33 insertions, 11 deletions

diff --git a/include/minikin/MeasuredText.h b/include/minikin/MeasuredText.h
index 6937202..13f5fbb 100644
--- a/include/minikin/MeasuredText.h
+++ b/include/minikin/MeasuredText.h
@@ -125,12 +125,35 @@ private:
     const uint32_t mLocaleListId;
 };
 
+// Represents a hyphenation break point.
+struct HyphenBreak {
+    // The break offset.
+    uint32_t offset;
+
+    // The hyphenation type.
+    HyphenationType type;
+
+    // The width of preceding piece after break at hyphenation point.
+    float first;
+
+    // The width of following piece after break at hyphenation point.
+    float second;
+
+    HyphenBreak(uint32_t offset, HyphenationType type, float first, float second)
+            : offset(offset), type(type), first(first), second(second) {}
+};
+
 class MeasuredText {
 public:
-    // Following three vectors have the same length.
+    // Character widths.
     std::vector<float> widths;
+
+    // Font vertical extents for characters.
+    // TODO: Introduce compression for extents. Usually, this has the same values for all chars.
     std::vector<MinikinExtent> extents;
-    std::vector<LayoutOverhang> overhangs;
+
+    // Hyphenation points.
+    std::vector<HyphenBreak> hyphenBreaks;
 
     // The style information.
     std::vector<std::unique_ptr<Run>> runs;
@@ -143,15 +166,13 @@ public:
 private:
     friend class MeasuredTextBuilder;
 
-    void measure(const U16StringPiece& textBuf);
+    void measure(const U16StringPiece& textBuf, bool computeHyphenation);
 
     // Use MeasuredTextBuilder instead.
-    MeasuredText(const U16StringPiece& textBuf, std::vector<std::unique_ptr<Run>>&& runs)
-            : widths(textBuf.size()),
-              extents(textBuf.size()),
-              overhangs(textBuf.size()),
-              runs(std::move(runs)) {
-        measure(textBuf);
+    MeasuredText(const U16StringPiece& textBuf, std::vector<std::unique_ptr<Run>>&& runs,
+                 bool computeHyphenation)
+            : widths(textBuf.size()), extents(textBuf.size()), runs(std::move(runs)) {
+        measure(textBuf, computeHyphenation);
     }
 };
 
@@ -175,9 +196,10 @@ public:
         mRuns.emplace_back(std::make_unique<T>(std::forward<Args>(args)...));
     }
 
-    std::unique_ptr<MeasuredText> build(const U16StringPiece& textBuf) {
+    std::unique_ptr<MeasuredText> build(const U16StringPiece& textBuf, bool computeHyphenation) {
         // Unable to use make_unique here since make_unique is not a friend of MeasuredText.
-        return std::unique_ptr<MeasuredText>(new MeasuredText(textBuf, std::move(mRuns)));
+        return std::unique_ptr<MeasuredText>(
+                new MeasuredText(textBuf, std::move(mRuns), computeHyphenation));
     }
 
     PREVENT_COPY_ASSIGN_AND_MOVE(MeasuredTextBuilder);