Rename PremeasuredText to MeasuredText

There is already MeasuredText, so renamed existing MeasuredText to
MeasuredParagraph, then renamed PremeasuredText to MeasuredText.

Bug: 67504091
Test: bit CtsWidgetTestCases:android.widget.cts.TextViewTest
Test: bit CtsTextTestCases:*
Change-Id: Ie20bea9501b18fabb36f64d388a7851c4643d4c3
diff --git a/core/java/android/text/MeasuredParagraph.java b/core/java/android/text/MeasuredParagraph.java
new file mode 100644
index 0000000..c93e036
--- /dev/null
+++ b/core/java/android/text/MeasuredParagraph.java
@@ -0,0 +1,677 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package android.text;
+
+import android.annotation.FloatRange;
+import android.annotation.IntRange;
+import android.annotation.NonNull;
+import android.annotation.Nullable;
+import android.graphics.Paint;
+import android.text.AutoGrowArray.ByteArray;
+import android.text.AutoGrowArray.FloatArray;
+import android.text.AutoGrowArray.IntArray;
+import android.text.Layout.Directions;
+import android.text.style.MetricAffectingSpan;
+import android.text.style.ReplacementSpan;
+import android.util.Pools.SynchronizedPool;
+
+import dalvik.annotation.optimization.CriticalNative;
+
+import libcore.util.NativeAllocationRegistry;
+
+import java.util.Arrays;
+
+/**
+ * MeasuredParagraph provides text information for rendering purpose.
+ *
+ * The first motivation of this class is identify the text directions and retrieving individual
+ * character widths. However retrieving character widths is slower than identifying text directions.
+ * Thus, this class provides several builder methods for specific purposes.
+ *
+ * - buildForBidi:
+ *   Compute only text directions.
+ * - buildForMeasurement:
+ *   Compute text direction and all character widths.
+ * - buildForStaticLayout:
+ *   This is bit special. StaticLayout also needs to know text direction and character widths for
+ *   line breaking, but all things are done in native code. Similarly, text measurement is done
+ *   in native code. So instead of storing result to Java array, this keeps the result in native
+ *   code since there is no good reason to move the results to Java layer.
+ *
+ * In addition to the character widths, some additional information is computed for each purposes,
+ * e.g. whole text length for measurement or font metrics for static layout.
+ *
+ * MeasuredParagraph is NOT a thread safe object.
+ * @hide
+ */
+public class MeasuredParagraph {
+    private static final char OBJECT_REPLACEMENT_CHARACTER = '\uFFFC';
+
+    private static final NativeAllocationRegistry sRegistry = new NativeAllocationRegistry(
+            MeasuredParagraph.class.getClassLoader(), nGetReleaseFunc(), 1024);
+
+    private MeasuredParagraph() {}  // Use build static functions instead.
+
+    private static final SynchronizedPool<MeasuredParagraph> sPool = new SynchronizedPool<>(1);
+
+    private static @NonNull MeasuredParagraph obtain() { // Use build static functions instead.
+        final MeasuredParagraph mt = sPool.acquire();
+        return mt != null ? mt : new MeasuredParagraph();
+    }
+
+    /**
+     * Recycle the MeasuredParagraph.
+     *
+     * Do not call any methods after you call this method.
+     */
+    public void recycle() {
+        release();
+        sPool.release(this);
+    }
+
+    // The casted original text.
+    //
+    // This may be null if the passed text is not a Spanned.
+    private @Nullable Spanned mSpanned;
+
+    // The start offset of the target range in the original text (mSpanned);
+    private @IntRange(from = 0) int mTextStart;
+
+    // The length of the target range in the original text.
+    private @IntRange(from = 0) int mTextLength;
+
+    // The copied character buffer for measuring text.
+    //
+    // The length of this array is mTextLength.
+    private @Nullable char[] mCopiedBuffer;
+
+    // The whole paragraph direction.
+    private @Layout.Direction int mParaDir;
+
+    // True if the text is LTR direction and doesn't contain any bidi characters.
+    private boolean mLtrWithoutBidi;
+
+    // The bidi level for individual characters.
+    //
+    // This is empty if mLtrWithoutBidi is true.
+    private @NonNull ByteArray mLevels = new ByteArray();
+
+    // The whole width of the text.
+    // See getWholeWidth comments.
+    private @FloatRange(from = 0.0f) float mWholeWidth;
+
+    // Individual characters' widths.
+    // See getWidths comments.
+    private @Nullable FloatArray mWidths = new FloatArray();
+
+    // The span end positions.
+    // See getSpanEndCache comments.
+    private @Nullable IntArray mSpanEndCache = new IntArray(4);
+
+    // The font metrics.
+    // See getFontMetrics comments.
+    private @Nullable IntArray mFontMetrics = new IntArray(4 * 4);
+
+    // The native MeasuredParagraph.
+    // See getNativePtr comments.
+    // Do not modify these members directly. Use bindNativeObject/unbindNativeObject instead.
+    private /* Maybe Zero */ long mNativePtr = 0;
+    private @Nullable Runnable mNativeObjectCleaner;
+
+    // Associate the native object to this Java object.
+    private void bindNativeObject(/* Non Zero*/ long nativePtr) {
+        mNativePtr = nativePtr;
+        mNativeObjectCleaner = sRegistry.registerNativeAllocation(this, nativePtr);
+    }
+
+    // Decouple the native object from this Java object and release the native object.
+    private void unbindNativeObject() {
+        if (mNativePtr != 0) {
+            mNativeObjectCleaner.run();
+            mNativePtr = 0;
+        }
+    }
+
+    // Following two objects are for avoiding object allocation.
+    private @NonNull TextPaint mCachedPaint = new TextPaint();
+    private @Nullable Paint.FontMetricsInt mCachedFm;
+
+    /**
+     * Releases internal buffers.
+     */
+    public void release() {
+        reset();
+        mLevels.clearWithReleasingLargeArray();
+        mWidths.clearWithReleasingLargeArray();
+        mFontMetrics.clearWithReleasingLargeArray();
+        mSpanEndCache.clearWithReleasingLargeArray();
+    }
+
+    /**
+     * Resets the internal state for starting new text.
+     */
+    private void reset() {
+        mSpanned = null;
+        mCopiedBuffer = null;
+        mWholeWidth = 0;
+        mLevels.clear();
+        mWidths.clear();
+        mFontMetrics.clear();
+        mSpanEndCache.clear();
+        unbindNativeObject();
+    }
+
+    /**
+     * Returns the characters to be measured.
+     *
+     * This is always available.
+     */
+    public @NonNull char[] getChars() {
+        return mCopiedBuffer;
+    }
+
+    /**
+     * Returns the paragraph direction.
+     *
+     * This is always available.
+     */
+    public @Layout.Direction int getParagraphDir() {
+        return mParaDir;
+    }
+
+    /**
+     * Returns the directions.
+     *
+     * This is always available.
+     */
+    public Directions getDirections(@IntRange(from = 0) int start,  // inclusive
+                                    @IntRange(from = 0) int end) {  // exclusive
+        if (mLtrWithoutBidi) {
+            return Layout.DIRS_ALL_LEFT_TO_RIGHT;
+        }
+
+        final int length = end - start;
+        return AndroidBidi.directions(mParaDir, mLevels.getRawArray(), start, mCopiedBuffer, start,
+                length);
+    }
+
+    /**
+     * Returns the whole text width.
+     *
+     * This is available only if the MeasureText is computed with computeForMeasurement.
+     * Returns 0 in other cases.
+     */
+    public @FloatRange(from = 0.0f) float getWholeWidth() {
+        return mWholeWidth;
+    }
+
+    /**
+     * Returns the individual character's width.
+     *
+     * This is available only if the MeasureText is computed with computeForMeasurement.
+     * Returns empty array in other cases.
+     */
+    public @NonNull FloatArray getWidths() {
+        return mWidths;
+    }
+
+    /**
+     * Returns the MetricsAffectingSpan end indices.
+     *
+     * If the input text is not a spanned string, this has one value that is the length of the text.
+     *
+     * This is available only if the MeasureText is computed with computeForStaticLayout.
+     * Returns empty array in other cases.
+     */
+    public @NonNull IntArray getSpanEndCache() {
+        return mSpanEndCache;
+    }
+
+    /**
+     * Returns the int array which holds FontMetrics.
+     *
+     * This array holds the repeat of top, bottom, ascent, descent of font metrics value.
+     *
+     * This is available only if the MeasureText is computed with computeForStaticLayout.
+     * Returns empty array in other cases.
+     */
+    public @NonNull IntArray getFontMetrics() {
+        return mFontMetrics;
+    }
+
+    /**
+     * Returns the native ptr of the MeasuredParagraph.
+     *
+     * This is available only if the MeasureText is computed with computeForStaticLayout.
+     * Returns 0 in other cases.
+     */
+    public /* Maybe Zero */ long getNativePtr() {
+        return mNativePtr;
+    }
+
+    /**
+     * Generates new MeasuredParagraph for Bidi computation.
+     *
+     * If recycle is null, this returns new instance. If recycle is not null, this fills computed
+     * result to recycle and returns recycle.
+     *
+     * @param text the character sequence to be measured
+     * @param start the inclusive start offset of the target region in the text
+     * @param end the exclusive end offset of the target region in the text
+     * @param textDir the text direction
+     * @param recycle pass existing MeasuredParagraph if you want to recycle it.
+     *
+     * @return measured text
+     */
+    public static @NonNull MeasuredParagraph buildForBidi(@NonNull CharSequence text,
+                                                     @IntRange(from = 0) int start,
+                                                     @IntRange(from = 0) int end,
+                                                     @NonNull TextDirectionHeuristic textDir,
+                                                     @Nullable MeasuredParagraph recycle) {
+        final MeasuredParagraph mt = recycle == null ? obtain() : recycle;
+        mt.resetAndAnalyzeBidi(text, start, end, textDir);
+        return mt;
+    }
+
+    /**
+     * Generates new MeasuredParagraph for measuring texts.
+     *
+     * If recycle is null, this returns new instance. If recycle is not null, this fills computed
+     * result to recycle and returns recycle.
+     *
+     * @param paint the paint to be used for rendering the text.
+     * @param text the character sequence to be measured
+     * @param start the inclusive start offset of the target region in the text
+     * @param end the exclusive end offset of the target region in the text
+     * @param textDir the text direction
+     * @param recycle pass existing MeasuredParagraph if you want to recycle it.
+     *
+     * @return measured text
+     */
+    public static @NonNull MeasuredParagraph buildForMeasurement(@NonNull TextPaint paint,
+                                                            @NonNull CharSequence text,
+                                                            @IntRange(from = 0) int start,
+                                                            @IntRange(from = 0) int end,
+                                                            @NonNull TextDirectionHeuristic textDir,
+                                                            @Nullable MeasuredParagraph recycle) {
+        final MeasuredParagraph mt = recycle == null ? obtain() : recycle;
+        mt.resetAndAnalyzeBidi(text, start, end, textDir);
+
+        mt.mWidths.resize(mt.mTextLength);
+        if (mt.mTextLength == 0) {
+            return mt;
+        }
+
+        if (mt.mSpanned == null) {
+            // No style change by MetricsAffectingSpan. Just measure all text.
+            mt.applyMetricsAffectingSpan(
+                    paint, null /* spans */, start, end, 0 /* native static layout ptr */);
+        } else {
+            // There may be a MetricsAffectingSpan. Split into span transitions and apply styles.
+            int spanEnd;
+            for (int spanStart = start; spanStart < end; spanStart = spanEnd) {
+                spanEnd = mt.mSpanned.nextSpanTransition(spanStart, end, MetricAffectingSpan.class);
+                MetricAffectingSpan[] spans = mt.mSpanned.getSpans(spanStart, spanEnd,
+                        MetricAffectingSpan.class);
+                spans = TextUtils.removeEmptySpans(spans, mt.mSpanned, MetricAffectingSpan.class);
+                mt.applyMetricsAffectingSpan(
+                        paint, spans, spanStart, spanEnd, 0 /* native static layout ptr */);
+            }
+        }
+        return mt;
+    }
+
+    /**
+     * Generates new MeasuredParagraph for StaticLayout.
+     *
+     * If recycle is null, this returns new instance. If recycle is not null, this fills computed
+     * result to recycle and returns recycle.
+     *
+     * @param paint the paint to be used for rendering the text.
+     * @param text the character sequence to be measured
+     * @param start the inclusive start offset of the target region in the text
+     * @param end the exclusive end offset of the target region in the text
+     * @param textDir the text direction
+     * @param recycle pass existing MeasuredParagraph if you want to recycle it.
+     *
+     * @return measured text
+     */
+    public static @NonNull MeasuredParagraph buildForStaticLayout(
+            @NonNull TextPaint paint,
+            @NonNull CharSequence text,
+            @IntRange(from = 0) int start,
+            @IntRange(from = 0) int end,
+            @NonNull TextDirectionHeuristic textDir,
+            @Nullable MeasuredParagraph recycle) {
+        final MeasuredParagraph mt = recycle == null ? obtain() : recycle;
+        mt.resetAndAnalyzeBidi(text, start, end, textDir);
+        if (mt.mTextLength == 0) {
+            // Need to build empty native measured text for StaticLayout.
+            // TODO: Stop creating empty measured text for empty lines.
+            long nativeBuilderPtr = nInitBuilder();
+            try {
+                mt.bindNativeObject(
+                        nBuildNativeMeasuredParagraph(nativeBuilderPtr, mt.mCopiedBuffer));
+            } finally {
+                nFreeBuilder(nativeBuilderPtr);
+            }
+            return mt;
+        }
+
+        long nativeBuilderPtr = nInitBuilder();
+        try {
+            if (mt.mSpanned == null) {
+                // No style change by MetricsAffectingSpan. Just measure all text.
+                mt.applyMetricsAffectingSpan(paint, null /* spans */, start, end, nativeBuilderPtr);
+                mt.mSpanEndCache.append(end);
+            } else {
+                // There may be a MetricsAffectingSpan. Split into span transitions and apply
+                // styles.
+                int spanEnd;
+                for (int spanStart = start; spanStart < end; spanStart = spanEnd) {
+                    spanEnd = mt.mSpanned.nextSpanTransition(spanStart, end,
+                                                             MetricAffectingSpan.class);
+                    MetricAffectingSpan[] spans = mt.mSpanned.getSpans(spanStart, spanEnd,
+                            MetricAffectingSpan.class);
+                    spans = TextUtils.removeEmptySpans(spans, mt.mSpanned,
+                                                       MetricAffectingSpan.class);
+                    mt.applyMetricsAffectingSpan(paint, spans, spanStart, spanEnd,
+                                                 nativeBuilderPtr);
+                    mt.mSpanEndCache.append(spanEnd);
+                }
+            }
+            mt.bindNativeObject(nBuildNativeMeasuredParagraph(nativeBuilderPtr, mt.mCopiedBuffer));
+        } finally {
+            nFreeBuilder(nativeBuilderPtr);
+        }
+
+        return mt;
+    }
+
+    /**
+     * Reset internal state and analyzes text for bidirectional runs.
+     *
+     * @param text the character sequence to be measured
+     * @param start the inclusive start offset of the target region in the text
+     * @param end the exclusive end offset of the target region in the text
+     * @param textDir the text direction
+     */
+    private void resetAndAnalyzeBidi(@NonNull CharSequence text,
+                                     @IntRange(from = 0) int start,  // inclusive
+                                     @IntRange(from = 0) int end,  // exclusive
+                                     @NonNull TextDirectionHeuristic textDir) {
+        reset();
+        mSpanned = text instanceof Spanned ? (Spanned) text : null;
+        mTextStart = start;
+        mTextLength = end - start;
+
+        if (mCopiedBuffer == null || mCopiedBuffer.length != mTextLength) {
+            mCopiedBuffer = new char[mTextLength];
+        }
+        TextUtils.getChars(text, start, end, mCopiedBuffer, 0);
+
+        // Replace characters associated with ReplacementSpan to U+FFFC.
+        if (mSpanned != null) {
+            ReplacementSpan[] spans = mSpanned.getSpans(start, end, ReplacementSpan.class);
+
+            for (int i = 0; i < spans.length; i++) {
+                int startInPara = mSpanned.getSpanStart(spans[i]) - start;
+                int endInPara = mSpanned.getSpanEnd(spans[i]) - start;
+                // The span interval may be larger and must be restricted to [start, end)
+                if (startInPara < 0) startInPara = 0;
+                if (endInPara > mTextLength) endInPara = mTextLength;
+                Arrays.fill(mCopiedBuffer, startInPara, endInPara, OBJECT_REPLACEMENT_CHARACTER);
+            }
+        }
+
+        if ((textDir == TextDirectionHeuristics.LTR
+                || textDir == TextDirectionHeuristics.FIRSTSTRONG_LTR
+                || textDir == TextDirectionHeuristics.ANYRTL_LTR)
+                && TextUtils.doesNotNeedBidi(mCopiedBuffer, 0, mTextLength)) {
+            mLevels.clear();
+            mParaDir = Layout.DIR_LEFT_TO_RIGHT;
+            mLtrWithoutBidi = true;
+        } else {
+            final int bidiRequest;
+            if (textDir == TextDirectionHeuristics.LTR) {
+                bidiRequest = Layout.DIR_REQUEST_LTR;
+            } else if (textDir == TextDirectionHeuristics.RTL) {
+                bidiRequest = Layout.DIR_REQUEST_RTL;
+            } else if (textDir == TextDirectionHeuristics.FIRSTSTRONG_LTR) {
+                bidiRequest = Layout.DIR_REQUEST_DEFAULT_LTR;
+            } else if (textDir == TextDirectionHeuristics.FIRSTSTRONG_RTL) {
+                bidiRequest = Layout.DIR_REQUEST_DEFAULT_RTL;
+            } else {
+                final boolean isRtl = textDir.isRtl(mCopiedBuffer, 0, mTextLength);
+                bidiRequest = isRtl ? Layout.DIR_REQUEST_RTL : Layout.DIR_REQUEST_LTR;
+            }
+            mLevels.resize(mTextLength);
+            mParaDir = AndroidBidi.bidi(bidiRequest, mCopiedBuffer, mLevels.getRawArray());
+            mLtrWithoutBidi = false;
+        }
+    }
+
+    private void applyReplacementRun(@NonNull ReplacementSpan replacement,
+                                     @IntRange(from = 0) int start,  // inclusive, in copied buffer
+                                     @IntRange(from = 0) int end,  // exclusive, in copied buffer
+                                     /* Maybe Zero */ long nativeBuilderPtr) {
+        // Use original text. Shouldn't matter.
+        // TODO: passing uninitizlied FontMetrics to developers. Do we need to keep this for
+        //       backward compatibility? or Should we initialize them for getFontMetricsInt?
+        final float width = replacement.getSize(
+                mCachedPaint, mSpanned, start + mTextStart, end + mTextStart, mCachedFm);
+        if (nativeBuilderPtr == 0) {
+            // Assigns all width to the first character. This is the same behavior as minikin.
+            mWidths.set(start, width);
+            if (end > start + 1) {
+                Arrays.fill(mWidths.getRawArray(), start + 1, end, 0.0f);
+            }
+            mWholeWidth += width;
+        } else {
+            nAddReplacementRun(nativeBuilderPtr, mCachedPaint.getNativeInstance(), start, end,
+                               width);
+        }
+    }
+
+    private void applyStyleRun(@IntRange(from = 0) int start,  // inclusive, in copied buffer
+                               @IntRange(from = 0) int end,  // exclusive, in copied buffer
+                               /* Maybe Zero */ long nativeBuilderPtr) {
+        if (nativeBuilderPtr != 0) {
+            mCachedPaint.getFontMetricsInt(mCachedFm);
+        }
+
+        if (mLtrWithoutBidi) {
+            // If the whole text is LTR direction, just apply whole region.
+            if (nativeBuilderPtr == 0) {
+                mWholeWidth += mCachedPaint.getTextRunAdvances(
+                        mCopiedBuffer, start, end - start, start, end - start, false /* isRtl */,
+                        mWidths.getRawArray(), start);
+            } else {
+                nAddStyleRun(nativeBuilderPtr, mCachedPaint.getNativeInstance(), start, end,
+                        false /* isRtl */);
+            }
+        } else {
+            // If there is multiple bidi levels, split into individual bidi level and apply style.
+            byte level = mLevels.get(start);
+            // Note that the empty text or empty range won't reach this method.
+            // Safe to search from start + 1.
+            for (int levelStart = start, levelEnd = start + 1;; ++levelEnd) {
+                if (levelEnd == end || mLevels.get(levelEnd) != level) {  // transition point
+                    final boolean isRtl = (level & 0x1) != 0;
+                    if (nativeBuilderPtr == 0) {
+                        final int levelLength = levelEnd - levelStart;
+                        mWholeWidth += mCachedPaint.getTextRunAdvances(
+                                mCopiedBuffer, levelStart, levelLength, levelStart, levelLength,
+                                isRtl, mWidths.getRawArray(), levelStart);
+                    } else {
+                        nAddStyleRun(nativeBuilderPtr, mCachedPaint.getNativeInstance(), levelStart,
+                                levelEnd, isRtl);
+                    }
+                    if (levelEnd == end) {
+                        break;
+                    }
+                    levelStart = levelEnd;
+                    level = mLevels.get(levelEnd);
+                }
+            }
+        }
+    }
+
+    private void applyMetricsAffectingSpan(
+            @NonNull TextPaint paint,
+            @Nullable MetricAffectingSpan[] spans,
+            @IntRange(from = 0) int start,  // inclusive, in original text buffer
+            @IntRange(from = 0) int end,  // exclusive, in original text buffer
+            /* Maybe Zero */ long nativeBuilderPtr) {
+        mCachedPaint.set(paint);
+        // XXX paint should not have a baseline shift, but...
+        mCachedPaint.baselineShift = 0;
+
+        final boolean needFontMetrics = nativeBuilderPtr != 0;
+
+        if (needFontMetrics && mCachedFm == null) {
+            mCachedFm = new Paint.FontMetricsInt();
+        }
+
+        ReplacementSpan replacement = null;
+        if (spans != null) {
+            for (int i = 0; i < spans.length; i++) {
+                MetricAffectingSpan span = spans[i];
+                if (span instanceof ReplacementSpan) {
+                    // The last ReplacementSpan is effective for backward compatibility reasons.
+                    replacement = (ReplacementSpan) span;
+                } else {
+                    // TODO: No need to call updateMeasureState for ReplacementSpan as well?
+                    span.updateMeasureState(mCachedPaint);
+                }
+            }
+        }
+
+        final int startInCopiedBuffer = start - mTextStart;
+        final int endInCopiedBuffer = end - mTextStart;
+
+        if (replacement != null) {
+            applyReplacementRun(replacement, startInCopiedBuffer, endInCopiedBuffer,
+                                nativeBuilderPtr);
+        } else {
+            applyStyleRun(startInCopiedBuffer, endInCopiedBuffer, nativeBuilderPtr);
+        }
+
+        if (needFontMetrics) {
+            if (mCachedPaint.baselineShift < 0) {
+                mCachedFm.ascent += mCachedPaint.baselineShift;
+                mCachedFm.top += mCachedPaint.baselineShift;
+            } else {
+                mCachedFm.descent += mCachedPaint.baselineShift;
+                mCachedFm.bottom += mCachedPaint.baselineShift;
+            }
+
+            mFontMetrics.append(mCachedFm.top);
+            mFontMetrics.append(mCachedFm.bottom);
+            mFontMetrics.append(mCachedFm.ascent);
+            mFontMetrics.append(mCachedFm.descent);
+        }
+    }
+
+    /**
+     * Returns the maximum index that the accumulated width not exceeds the width.
+     *
+     * If forward=false is passed, returns the minimum index from the end instead.
+     *
+     * This only works if the MeasuredParagraph is computed with computeForMeasurement.
+     * Undefined behavior in other case.
+     */
+    @IntRange(from = 0) int breakText(int limit, boolean forwards, float width) {
+        float[] w = mWidths.getRawArray();
+        if (forwards) {
+            int i = 0;
+            while (i < limit) {
+                width -= w[i];
+                if (width < 0.0f) break;
+                i++;
+            }
+            while (i > 0 && mCopiedBuffer[i - 1] == ' ') i--;
+            return i;
+        } else {
+            int i = limit - 1;
+            while (i >= 0) {
+                width -= w[i];
+                if (width < 0.0f) break;
+                i--;
+            }
+            while (i < limit - 1 && (mCopiedBuffer[i + 1] == ' ' || w[i + 1] == 0.0f)) {
+                i++;
+            }
+            return limit - i - 1;
+        }
+    }
+
+    /**
+     * Returns the length of the substring.
+     *
+     * This only works if the MeasuredParagraph is computed with computeForMeasurement.
+     * Undefined behavior in other case.
+     */
+    @FloatRange(from = 0.0f) float measure(int start, int limit) {
+        float width = 0;
+        float[] w = mWidths.getRawArray();
+        for (int i = start; i < limit; ++i) {
+            width += w[i];
+        }
+        return width;
+    }
+
+    private static native /* Non Zero */ long nInitBuilder();
+
+    /**
+     * Apply style to make native measured text.
+     *
+     * @param nativeBuilderPtr The native MeasuredParagraph builder pointer.
+     * @param paintPtr The native paint pointer to be applied.
+     * @param start The start offset in the copied buffer.
+     * @param end The end offset in the copied buffer.
+     * @param isRtl True if the text is RTL.
+     */
+    private static native void nAddStyleRun(/* Non Zero */ long nativeBuilderPtr,
+                                            /* Non Zero */ long paintPtr,
+                                            @IntRange(from = 0) int start,
+                                            @IntRange(from = 0) int end,
+                                            boolean isRtl);
+
+    /**
+     * Apply ReplacementRun to make native measured text.
+     *
+     * @param nativeBuilderPtr The native MeasuredParagraph builder pointer.
+     * @param paintPtr The native paint pointer to be applied.
+     * @param start The start offset in the copied buffer.
+     * @param end The end offset in the copied buffer.
+     * @param width The width of the replacement.
+     */
+    private static native void nAddReplacementRun(/* Non Zero */ long nativeBuilderPtr,
+                                                  /* Non Zero */ long paintPtr,
+                                                  @IntRange(from = 0) int start,
+                                                  @IntRange(from = 0) int end,
+                                                  @FloatRange(from = 0) float width);
+
+    private static native long nBuildNativeMeasuredParagraph(/* Non Zero */ long nativeBuilderPtr,
+                                                 @NonNull char[] text);
+
+    private static native void nFreeBuilder(/* Non Zero */ long nativeBuilderPtr);
+
+    @CriticalNative
+    private static native /* Non Zero */ long nGetReleaseFunc();
+}