Recompute PcT with existing PcT for different direction

The text direction can not be fully determined in detached state.
To improve even in that case, compute PrecomputedText from existing
PrecomputedText with new direction.

Here is the performance difference. According to the perf test result,
up to 80% of computation can be recycled from existing PrecomputedText.

android.text.StaticLayoutPerfTest (u sec):
    PrecomputedText Greedy NoHyphenation             :    371 ->    371: (   +0,  +0.0%)
    PrecomputedText Greedy NoHyphenation DirDifferent:  6,923 ->  1,437: (-5486, -79.2%)
    RandomText Greedy NoHyphenation                  :  6,633 ->  6,627: (   -6,  -0.1%)

On the other hand, this CL increase the memory usage of the
PrecomputedText up to 10%. Here is an reference memory usage.

android.text.PrecomputedTextMemoryUsageTest (bytes):
  MemoryUsage
    Arabic Hyphenation                               : 17,135 -> 18,116: ( +981, +5.7%)
    Arabic NoHyphenation                             : 17,135 -> 18,116: ( +981, +5.7%)
    CJK Hyphenation                                  : 29,000 -> 31,584: (+2584, +8.9%)
    CJK NoHyphenation                                : 29,000 -> 31,584: (+2584, +8.9%)
    Latin Hyphenation                                : 16,526 -> 17,185: ( +659, +4.0%)
    Latin NoHyphenation                              : 14,200 -> 14,784: ( +584, +4.1%)

Bug: 119312268
Test: atest CtsWidgetTestCases
Test: atest CtsTextTestCases
Test: atest CtsGraphicsTestCases
Test: minikin_tests

Change-Id: Ia02c201afac5d7d1c086a45f15696f39a6b2a76c

1 files changed, 105 insertions, 16 deletions

diff --git a/core/java/android/text/PrecomputedText.java b/core/java/android/text/PrecomputedText.java
index b7ea0122cb06..08741d6a7d88 100644
--- a/core/java/android/text/PrecomputedText.java
+++ b/core/java/android/text/PrecomputedText.java
@@ -17,6 +17,7 @@
 package android.text;
 
 import android.annotation.FloatRange;
+import android.annotation.IntDef;
 import android.annotation.IntRange;
 import android.annotation.NonNull;
 import android.annotation.Nullable;
@@ -25,6 +26,8 @@ import android.text.style.MetricAffectingSpan;
 
 import com.android.internal.util.Preconditions;
 
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
 import java.util.ArrayList;
 import java.util.Objects;
 
@@ -119,6 +122,16 @@ public class PrecomputedText implements Spannable {
             }
 
             /**
+             * Builder constructor from existing params.
+             */
+            public Builder(@NonNull Params params) {
+                mPaint = params.mPaint;
+                mTextDir = params.mTextDir;
+                mBreakStrategy = params.mBreakStrategy;
+                mHyphenationFrequency = params.mHyphenationFrequency;
+            }
+
+            /**
              * Set the line break strategy.
              *
              * The default value is {@link Layout#BREAK_STRATEGY_HIGH_QUALITY}.
@@ -220,13 +233,41 @@ public class PrecomputedText implements Spannable {
         }
 
         /** @hide */
-        public boolean isSameTextMetricsInternal(@NonNull TextPaint paint,
+        @IntDef(value = { UNUSABLE, NEED_RECOMPUTE, USABLE })
+        @Retention(RetentionPolicy.SOURCE)
+        public @interface CheckResultUsableResult {}
+
+        /**
+         * Constant for returning value of checkResultUsable indicating that given parameter is not
+         * compatible.
+         * @hide
+         */
+        public static final int UNUSABLE = 0;
+
+        /**
+         * Constant for returning value of checkResultUsable indicating that given parameter is not
+         * compatible but partially usable for creating new PrecomputedText.
+         * @hide
+         */
+        public static final int NEED_RECOMPUTE = 1;
+
+        /**
+         * Constant for returning value of checkResultUsable indicating that given parameter is
+         * compatible.
+         * @hide
+         */
+        public static final int USABLE = 2;
+
+        /** @hide */
+        public @CheckResultUsableResult int checkResultUsable(@NonNull TextPaint paint,
                 @NonNull TextDirectionHeuristic textDir, @Layout.BreakStrategy int strategy,
                 @Layout.HyphenationFrequency int frequency) {
-            return mTextDir == textDir
-                && mBreakStrategy == strategy
-                && mHyphenationFrequency == frequency
-                && mPaint.equalsForTextMeasurement(paint);
+            if (mBreakStrategy == strategy && mHyphenationFrequency == frequency
+                    && mPaint.equalsForTextMeasurement(paint)) {
+                return mTextDir == textDir ? USABLE : NEED_RECOMPUTE;
+            } else {
+                return UNUSABLE;
+            }
         }
 
         /**
@@ -243,8 +284,8 @@ public class PrecomputedText implements Spannable {
                 return false;
             }
             Params param = (Params) o;
-            return isSameTextMetricsInternal(param.mPaint, param.mTextDir, param.mBreakStrategy,
-                    param.mHyphenationFrequency);
+            return checkResultUsable(param.mPaint, param.mTextDir, param.mBreakStrategy,
+                    param.mHyphenationFrequency) == Params.USABLE;
         }
 
         @Override
@@ -321,11 +362,55 @@ public class PrecomputedText implements Spannable {
      * @return A {@link PrecomputedText}
      */
     public static PrecomputedText create(@NonNull CharSequence text, @NonNull Params params) {
-        ParagraphInfo[] paraInfo = createMeasuredParagraphs(
-                text, params, 0, text.length(), true /* computeLayout */);
+        ParagraphInfo[] paraInfo = null;
+        if (text instanceof PrecomputedText) {
+            final PrecomputedText hintPct = (PrecomputedText) text;
+            final PrecomputedText.Params hintParams = hintPct.getParams();
+            final @Params.CheckResultUsableResult int checkResult =
+                    hintParams.checkResultUsable(params.mPaint, params.mTextDir,
+                            params.mBreakStrategy, params.mHyphenationFrequency);
+            switch (checkResult) {
+                case Params.USABLE:
+                    return hintPct;
+                case Params.NEED_RECOMPUTE:
+                    // To be able to use PrecomputedText for new params, at least break strategy and
+                    // hyphenation frequency must be the same.
+                    if (params.getBreakStrategy() == hintParams.getBreakStrategy()
+                            && params.getHyphenationFrequency()
+                                == hintParams.getHyphenationFrequency()) {
+                        paraInfo = createMeasuredParagraphsFromPrecomputedText(
+                                hintPct, params, true /* compute layout */);
+                    }
+                    break;
+                case Params.UNUSABLE:
+                    // Unable to use anything in PrecomputedText. Create PrecomputedText as the
+                    // normal text input.
+            }
+
+        }
+        if (paraInfo == null) {
+            paraInfo = createMeasuredParagraphs(
+                    text, params, 0, text.length(), true /* computeLayout */);
+        }
         return new PrecomputedText(text, 0, text.length(), params, paraInfo);
     }
 
+    private static ParagraphInfo[] createMeasuredParagraphsFromPrecomputedText(
+            @NonNull PrecomputedText pct, @NonNull Params params, boolean computeLayout) {
+        final boolean needHyphenation = params.getBreakStrategy() != Layout.BREAK_STRATEGY_SIMPLE
+                && params.getHyphenationFrequency() != Layout.HYPHENATION_FREQUENCY_NONE;
+        ArrayList<ParagraphInfo> result = new ArrayList<>();
+        for (int i = 0; i < pct.getParagraphCount(); ++i) {
+            final int paraStart = pct.getParagraphStart(i);
+            final int paraEnd = pct.getParagraphEnd(i);
+            result.add(new ParagraphInfo(paraEnd, MeasuredParagraph.buildForStaticLayout(
+                    params.getTextPaint(), pct, paraStart, paraEnd, params.getTextDirection(),
+                    needHyphenation, computeLayout, pct.getMeasuredParagraph(i),
+                    null /* no recycle */)));
+        }
+        return result.toArray(new ParagraphInfo[result.size()]);
+    }
+
     /** @hide */
     public static ParagraphInfo[] createMeasuredParagraphs(
             @NonNull CharSequence text, @NonNull Params params,
@@ -350,7 +435,8 @@ public class PrecomputedText implements Spannable {
 
             result.add(new ParagraphInfo(paraEnd, MeasuredParagraph.buildForStaticLayout(
                     params.getTextPaint(), text, paraStart, paraEnd, params.getTextDirection(),
-                    needHyphenation, computeLayout, null /* no recycle */)));
+                    needHyphenation, computeLayout, null /* no hint */,
+                    null /* no recycle */)));
         }
         return result.toArray(new ParagraphInfo[result.size()]);
     }
@@ -434,12 +520,15 @@ public class PrecomputedText implements Spannable {
      * Returns true if the given TextPaint gives the same result of text layout for this text.
      * @hide
      */
-    public boolean canUseMeasuredResult(@IntRange(from = 0) int start, @IntRange(from = 0) int end,
-            @NonNull TextDirectionHeuristic textDir, @NonNull TextPaint paint,
-            @Layout.BreakStrategy int strategy, @Layout.HyphenationFrequency int frequency) {
-        return mStart == start
-            && mEnd == end
-            && mParams.isSameTextMetricsInternal(paint, textDir, strategy, frequency);
+    public @Params.CheckResultUsableResult int checkResultUsable(@IntRange(from = 0) int start,
+            @IntRange(from = 0) int end, @NonNull TextDirectionHeuristic textDir,
+            @NonNull TextPaint paint, @Layout.BreakStrategy int strategy,
+            @Layout.HyphenationFrequency int frequency) {
+        if (mStart != start || mEnd != end) {
+            return Params.UNUSABLE;
+        } else {
+            return mParams.checkResultUsable(paint, textDir, strategy, frequency);
+        }
     }
 
     /** @hide */