core/java/android/text/StaticLayout.java

/*
 * Copyright (C) 2006 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.FloatArray;
import android.text.style.LeadingMarginSpan;
import android.text.style.LeadingMarginSpan.LeadingMarginSpan2;
import android.text.style.LineHeightSpan;
import android.text.style.TabStopSpan;
import android.util.Log;
import android.util.Pools.SynchronizedPool;

import com.android.internal.util.ArrayUtils;
import com.android.internal.util.GrowingArrayUtils;

import dalvik.annotation.optimization.CriticalNative;
import dalvik.annotation.optimization.FastNative;

import java.util.Arrays;

/**
 * StaticLayout is a Layout for text that will not be edited after it
 * is laid out.  Use {@link DynamicLayout} for text that may change.
 * <p>This is used by widgets to control text layout. You should not need
 * to use this class directly unless you are implementing your own widget
 * or custom display object, or would be tempted to call
 * {@link android.graphics.Canvas#drawText(java.lang.CharSequence, int, int,
 * float, float, android.graphics.Paint)
 * Canvas.drawText()} directly.</p>
 */
public class StaticLayout extends Layout {
    /*
     * The break iteration is done in native code. The protocol for using the native code is as
     * follows.
     *
     * First, call nInit to setup native line breaker object. Then, for each paragraph, do the
     * following:
     *
     *   - Create MeasuredParagraph by MeasuredParagraph.buildForStaticLayout which measures in
     *     native.
     *   - Run nComputeLineBreaks() to obtain line breaks for the paragraph.
     *
     * After all paragraphs, call finish() to release expensive buffers.
     */

    static final String TAG = "StaticLayout";

    /**
     * Builder for static layouts. The builder is the preferred pattern for constructing
     * StaticLayout objects and should be preferred over the constructors, particularly to access
     * newer features. To build a static layout, first call {@link #obtain} with the required
     * arguments (text, paint, and width), then call setters for optional parameters, and finally
     * {@link #build} to build the StaticLayout object. Parameters not explicitly set will get
     * default values.
     */
    public final static class Builder {
        private Builder() {}

        /**
         * Obtain a builder for constructing StaticLayout objects.
         *
         * @param source The text to be laid out, optionally with spans
         * @param start The index of the start of the text
         * @param end The index + 1 of the end of the text
         * @param paint The base paint used for layout
         * @param width The width in pixels
         * @return a builder object used for constructing the StaticLayout
         */
        @NonNull
        public static Builder obtain(@NonNull CharSequence source, @IntRange(from = 0) int start,
                @IntRange(from = 0) int end, @NonNull TextPaint paint,
                @IntRange(from = 0) int width) {
            Builder b = sPool.acquire();
            if (b == null) {
                b = new Builder();
            }

            // set default initial values
            b.mText = source;
            b.mStart = start;
            b.mEnd = end;
            b.mPaint = paint;
            b.mWidth = width;
            b.mAlignment = Alignment.ALIGN_NORMAL;
            b.mTextDir = TextDirectionHeuristics.FIRSTSTRONG_LTR;
            b.mSpacingMult = DEFAULT_LINESPACING_MULTIPLIER;
            b.mSpacingAdd = DEFAULT_LINESPACING_ADDITION;
            b.mIncludePad = true;
            b.mFallbackLineSpacing = false;
            b.mEllipsizedWidth = width;
            b.mEllipsize = null;
            b.mMaxLines = Integer.MAX_VALUE;
            b.mBreakStrategy = Layout.BREAK_STRATEGY_SIMPLE;
            b.mHyphenationFrequency = Layout.HYPHENATION_FREQUENCY_NONE;
            b.mJustificationMode = Layout.JUSTIFICATION_MODE_NONE;
            return b;
        }

        /**
         * This method should be called after the layout is finished getting constructed and the
         * builder needs to be cleaned up and returned to the pool.
         */
        private static void recycle(@NonNull Builder b) {
            b.mPaint = null;
            b.mText = null;
            b.mLeftIndents = null;
            b.mRightIndents = null;
            sPool.release(b);
        }

        // release any expensive state
        /* package */ void finish() {
            mText = null;
            mPaint = null;
            mLeftIndents = null;
            mRightIndents = null;
        }

        public Builder setText(CharSequence source) {
            return setText(source, 0, source.length());
        }

        /**
         * Set the text. Only useful when re-using the builder, which is done for
         * the internal implementation of {@link DynamicLayout} but not as part
         * of normal {@link StaticLayout} usage.
         *
         * @param source The text to be laid out, optionally with spans
         * @param start The index of the start of the text
         * @param end The index + 1 of the end of the text
         * @return this builder, useful for chaining
         *
         * @hide
         */
        @NonNull
        public Builder setText(@NonNull CharSequence source, int start, int end) {
            mText = source;
            mStart = start;
            mEnd = end;
            return this;
        }

        /**
         * Set the paint. Internal for reuse cases only.
         *
         * @param paint The base paint used for layout
         * @return this builder, useful for chaining
         *
         * @hide
         */
        @NonNull
        public Builder setPaint(@NonNull TextPaint paint) {
            mPaint = paint;
            return this;
        }

        /**
         * Set the width. Internal for reuse cases only.
         *
         * @param width The width in pixels
         * @return this builder, useful for chaining
         *
         * @hide
         */
        @NonNull
        public Builder setWidth(@IntRange(from = 0) int width) {
            mWidth = width;
            if (mEllipsize == null) {
                mEllipsizedWidth = width;
            }
            return this;
        }

        /**
         * Set the alignment. The default is {@link Layout.Alignment#ALIGN_NORMAL}.
         *
         * @param alignment Alignment for the resulting {@link StaticLayout}
         * @return this builder, useful for chaining
         */
        @NonNull
        public Builder setAlignment(@NonNull Alignment alignment) {
            mAlignment = alignment;
            return this;
        }

        /**
         * Set the text direction heuristic. The text direction heuristic is used to
         * resolve text direction per-paragraph based on the input text. The default is
         * {@link TextDirectionHeuristics#FIRSTSTRONG_LTR}.
         *
         * @param textDir text direction heuristic for resolving bidi behavior.
         * @return this builder, useful for chaining
         */
        @NonNull
        public Builder setTextDirection(@NonNull TextDirectionHeuristic textDir) {
            mTextDir = textDir;
            return this;
        }

        /**
         * Set line spacing parameters. Each line will have its line spacing multiplied by
         * {@code spacingMult} and then increased by {@code spacingAdd}. The default is 0.0 for
         * {@code spacingAdd} and 1.0 for {@code spacingMult}.
         *
         * @param spacingAdd the amount of line spacing addition
         * @param spacingMult the line spacing multiplier
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setLineSpacing
         */
        @NonNull
        public Builder setLineSpacing(float spacingAdd, @FloatRange(from = 0.0) float spacingMult) {
            mSpacingAdd = spacingAdd;
            mSpacingMult = spacingMult;
            return this;
        }

        /**
         * Set whether to include extra space beyond font ascent and descent (which is
         * needed to avoid clipping in some languages, such as Arabic and Kannada). The
         * default is {@code true}.
         *
         * @param includePad whether to include padding
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setIncludeFontPadding
         */
        @NonNull
        public Builder setIncludePad(boolean includePad) {
            mIncludePad = includePad;
            return this;
        }

        /**
         * Set whether to respect the ascent and descent of the fallback fonts that are used in
         * displaying the text (which is needed to avoid text from consecutive lines running into
         * each other). If set, fallback fonts that end up getting used can increase the ascent
         * and descent of the lines that they are used on.
         *
         * <p>For backward compatibility reasons, the default is {@code false}, but setting this to
         * true is strongly recommended. It is required to be true if text could be in languages
         * like Burmese or Tibetan where text is typically much taller or deeper than Latin text.
         *
         * @param useLineSpacingFromFallbacks whether to expand linespacing based on fallback fonts
         * @return this builder, useful for chaining
         */
        @NonNull
        public Builder setUseLineSpacingFromFallbacks(boolean useLineSpacingFromFallbacks) {
            mFallbackLineSpacing = useLineSpacingFromFallbacks;
            return this;
        }

        /**
         * Set the width as used for ellipsizing purposes, if it differs from the
         * normal layout width. The default is the {@code width}
         * passed to {@link #obtain}.
         *
         * @param ellipsizedWidth width used for ellipsizing, in pixels
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setEllipsize
         */
        @NonNull
        public Builder setEllipsizedWidth(@IntRange(from = 0) int ellipsizedWidth) {
            mEllipsizedWidth = ellipsizedWidth;
            return this;
        }

        /**
         * Set ellipsizing on the layout. Causes words that are longer than the view
         * is wide, or exceeding the number of lines (see #setMaxLines) in the case
         * of {@link android.text.TextUtils.TruncateAt#END} or
         * {@link android.text.TextUtils.TruncateAt#MARQUEE}, to be ellipsized instead
         * of broken. The default is {@code null}, indicating no ellipsis is to be applied.
         *
         * @param ellipsize type of ellipsis behavior
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setEllipsize
         */
        @NonNull
        public Builder setEllipsize(@Nullable TextUtils.TruncateAt ellipsize) {
            mEllipsize = ellipsize;
            return this;
        }

        /**
         * Set maximum number of lines. This is particularly useful in the case of
         * ellipsizing, where it changes the layout of the last line. The default is
         * unlimited.
         *
         * @param maxLines maximum number of lines in the layout
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setMaxLines
         */
        @NonNull
        public Builder setMaxLines(@IntRange(from = 0) int maxLines) {
            mMaxLines = maxLines;
            return this;
        }

        /**
         * Set break strategy, useful for selecting high quality or balanced paragraph
         * layout options. The default is {@link Layout#BREAK_STRATEGY_SIMPLE}.
         * <p/>
         * Enabling hyphenation with either using {@link Layout#HYPHENATION_FREQUENCY_NORMAL} or
         * {@link Layout#HYPHENATION_FREQUENCY_FULL} while line breaking is set to one of
         * {@link Layout#BREAK_STRATEGY_BALANCED}, {@link Layout#BREAK_STRATEGY_HIGH_QUALITY}
         * improves the structure of text layout however has performance impact and requires more
         * time to do the text layout.
         *
         * @param breakStrategy break strategy for paragraph layout
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setBreakStrategy
         * @see #setHyphenationFrequency(int)
         */
        @NonNull
        public Builder setBreakStrategy(@BreakStrategy int breakStrategy) {
            mBreakStrategy = breakStrategy;
            return this;
        }

        /**
         * Set hyphenation frequency, to control the amount of automatic hyphenation used. The
         * possible values are defined in {@link Layout}, by constants named with the pattern
         * {@code HYPHENATION_FREQUENCY_*}. The default is
         * {@link Layout#HYPHENATION_FREQUENCY_NONE}.
         * <p/>
         * Enabling hyphenation with either using {@link Layout#HYPHENATION_FREQUENCY_NORMAL} or
         * {@link Layout#HYPHENATION_FREQUENCY_FULL} while line breaking is set to one of
         * {@link Layout#BREAK_STRATEGY_BALANCED}, {@link Layout#BREAK_STRATEGY_HIGH_QUALITY}
         * improves the structure of text layout however has performance impact and requires more
         * time to do the text layout.
         *
         * @param hyphenationFrequency hyphenation frequency for the paragraph
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setHyphenationFrequency
         * @see #setBreakStrategy(int)
         */
        @NonNull
        public Builder setHyphenationFrequency(@HyphenationFrequency int hyphenationFrequency) {
            mHyphenationFrequency = hyphenationFrequency;
            return this;
        }

        /**
         * Set indents. Arguments are arrays holding an indent amount, one per line, measured in
         * pixels. For lines past the last element in the array, the last element repeats.
         *
         * @param leftIndents array of indent values for left margin, in pixels
         * @param rightIndents array of indent values for right margin, in pixels
         * @return this builder, useful for chaining
         */
        @NonNull
        public Builder setIndents(@Nullable int[] leftIndents, @Nullable int[] rightIndents) {
            mLeftIndents = leftIndents;
            mRightIndents = rightIndents;
            return this;
        }

        /**
         * Set paragraph justification mode. The default value is
         * {@link Layout#JUSTIFICATION_MODE_NONE}. If the last line is too short for justification,
         * the last line will be displayed with the alignment set by {@link #setAlignment}.
         *
         * @param justificationMode justification mode for the paragraph.
         * @return this builder, useful for chaining.
         */
        @NonNull
        public Builder setJustificationMode(@JustificationMode int justificationMode) {
            mJustificationMode = justificationMode;
            return this;
        }

        /**
         * Sets whether the line spacing should be applied for the last line. Default value is
         * {@code false}.
         *
         * @hide
         */
        @NonNull
        /* package */ Builder setAddLastLineLineSpacing(boolean value) {
            mAddLastLineLineSpacing = value;
            return this;
        }

        /**
         * Build the {@link StaticLayout} after options have been set.
         *
         * <p>Note: the builder object must not be reused in any way after calling this
         * method. Setting parameters after calling this method, or calling it a second
         * time on the same builder object, will likely lead to unexpected results.
         *
         * @return the newly constructed {@link StaticLayout} object
         */
        @NonNull
        public StaticLayout build() {
            StaticLayout result = new StaticLayout(this);
            Builder.recycle(this);
            return result;
        }

        private CharSequence mText;
        private int mStart;
        private int mEnd;
        private TextPaint mPaint;
        private int mWidth;
        private Alignment mAlignment;
        private TextDirectionHeuristic mTextDir;
        private float mSpacingMult;
        private float mSpacingAdd;
        private boolean mIncludePad;
        private boolean mFallbackLineSpacing;
        private int mEllipsizedWidth;
        private TextUtils.TruncateAt mEllipsize;
        private int mMaxLines;
        private int mBreakStrategy;
        private int mHyphenationFrequency;
        @Nullable private int[] mLeftIndents;
        @Nullable private int[] mRightIndents;
        private int mJustificationMode;
        private boolean mAddLastLineLineSpacing;

        private final Paint.FontMetricsInt mFontMetricsInt = new Paint.FontMetricsInt();

        private static final SynchronizedPool<Builder> sPool = new SynchronizedPool<>(3);
    }

    /**
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public StaticLayout(CharSequence source, TextPaint paint,
                        int width,
                        Alignment align, float spacingmult, float spacingadd,
                        boolean includepad) {
        this(source, 0, source.length(), paint, width, align,
             spacingmult, spacingadd, includepad);
    }

    /**
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public StaticLayout(CharSequence source, int bufstart, int bufend,
                        TextPaint paint, int outerwidth,
                        Alignment align,
                        float spacingmult, float spacingadd,
                        boolean includepad) {
        this(source, bufstart, bufend, paint, outerwidth, align,
             spacingmult, spacingadd, includepad, null, 0);
    }

    /**
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public StaticLayout(CharSequence source, int bufstart, int bufend,
            TextPaint paint, int outerwidth,
            Alignment align,
            float spacingmult, float spacingadd,
            boolean includepad,
            TextUtils.TruncateAt ellipsize, int ellipsizedWidth) {
        this(source, bufstart, bufend, paint, outerwidth, align,
                TextDirectionHeuristics.FIRSTSTRONG_LTR,
                spacingmult, spacingadd, includepad, ellipsize, ellipsizedWidth, Integer.MAX_VALUE);
    }

    /**
     * @hide
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public StaticLayout(CharSequence source, int bufstart, int bufend,
                        TextPaint paint, int outerwidth,
                        Alignment align, TextDirectionHeuristic textDir,
                        float spacingmult, float spacingadd,
                        boolean includepad,
                        TextUtils.TruncateAt ellipsize, int ellipsizedWidth, int maxLines) {
        super((ellipsize == null)
                ? source
                : (source instanceof Spanned)
                    ? new SpannedEllipsizer(source)
                    : new Ellipsizer(source),
              paint, outerwidth, align, textDir, spacingmult, spacingadd);

        Builder b = Builder.obtain(source, bufstart, bufend, paint, outerwidth)
            .setAlignment(align)
            .setTextDirection(textDir)
            .setLineSpacing(spacingadd, spacingmult)
            .setIncludePad(includepad)
            .setEllipsizedWidth(ellipsizedWidth)
            .setEllipsize(ellipsize)
            .setMaxLines(maxLines);
        /*
         * This is annoying, but we can't refer to the layout until superclass construction is
         * finished, and the superclass constructor wants the reference to the display text.
         *
         * In other words, the two Ellipsizer classes in Layout.java need a (Dynamic|Static)Layout
         * as a parameter to do their calculations, but the Ellipsizers also need to be the input
         * to the superclass's constructor (Layout). In order to go around the circular
         * dependency, we construct the Ellipsizer with only one of the parameters, the text. And
         * we fill in the rest of the needed information (layout, width, and method) later, here.
         *
         * This will break if the superclass constructor ever actually cares about the content
         * instead of just holding the reference.
         */
        if (ellipsize != null) {
            Ellipsizer e = (Ellipsizer) getText();

            e.mLayout = this;
            e.mWidth = ellipsizedWidth;
            e.mMethod = ellipsize;
            mEllipsizedWidth = ellipsizedWidth;

            mColumns = COLUMNS_ELLIPSIZE;
        } else {
            mColumns = COLUMNS_NORMAL;
            mEllipsizedWidth = outerwidth;
        }

        mLineDirections = ArrayUtils.newUnpaddedArray(Directions.class, 2);
        mLines  = ArrayUtils.newUnpaddedIntArray(2 * mColumns);
        mMaximumVisibleLineCount = maxLines;

        generate(b, b.mIncludePad, b.mIncludePad);

        Builder.recycle(b);
    }

    /**
     * Used by DynamicLayout.
     */
    /* package */ StaticLayout(@Nullable CharSequence text) {
        super(text, null, 0, null, 0, 0);

        mColumns = COLUMNS_ELLIPSIZE;
        mLineDirections = ArrayUtils.newUnpaddedArray(Directions.class, 2);
        mLines  = ArrayUtils.newUnpaddedIntArray(2 * mColumns);
    }

    private StaticLayout(Builder b) {
        super((b.mEllipsize == null)
                ? b.mText
                : (b.mText instanceof Spanned)
                    ? new SpannedEllipsizer(b.mText)
                    : new Ellipsizer(b.mText),
                b.mPaint, b.mWidth, b.mAlignment, b.mTextDir, b.mSpacingMult, b.mSpacingAdd);

        if (b.mEllipsize != null) {
            Ellipsizer e = (Ellipsizer) getText();

            e.mLayout = this;
            e.mWidth = b.mEllipsizedWidth;
            e.mMethod = b.mEllipsize;
            mEllipsizedWidth = b.mEllipsizedWidth;

            mColumns = COLUMNS_ELLIPSIZE;
        } else {
            mColumns = COLUMNS_NORMAL;
            mEllipsizedWidth = b.mWidth;
        }

        mLineDirections = ArrayUtils.newUnpaddedArray(Directions.class, 2);
        mLines  = ArrayUtils.newUnpaddedIntArray(2 * mColumns);
        mMaximumVisibleLineCount = b.mMaxLines;

        mLeftIndents = b.mLeftIndents;
        mRightIndents = b.mRightIndents;
        setJustificationMode(b.mJustificationMode);

        generate(b, b.mIncludePad, b.mIncludePad);
    }

    /* package */ void generate(Builder b, boolean includepad, boolean trackpad) {
        final CharSequence source = b.mText;
        final int bufStart = b.mStart;
        final int bufEnd = b.mEnd;
        TextPaint paint = b.mPaint;
        int outerWidth = b.mWidth;
        TextDirectionHeuristic textDir = b.mTextDir;
        final boolean fallbackLineSpacing = b.mFallbackLineSpacing;
        float spacingmult = b.mSpacingMult;
        float spacingadd = b.mSpacingAdd;
        float ellipsizedWidth = b.mEllipsizedWidth;
        TextUtils.TruncateAt ellipsize = b.mEllipsize;
        final boolean addLastLineSpacing = b.mAddLastLineLineSpacing;
        LineBreaks lineBreaks = new LineBreaks();  // TODO: move to builder to avoid allocation costs
        FloatArray widths = new FloatArray();

        mLineCount = 0;
        mEllipsized = false;
        mMaxLineHeight = mMaximumVisibleLineCount < 1 ? 0 : DEFAULT_MAX_LINE_HEIGHT;

        int v = 0;
        boolean needMultiply = (spacingmult != 1 || spacingadd != 0);

        Paint.FontMetricsInt fm = b.mFontMetricsInt;
        int[] chooseHtv = null;

        final int[] indents;
        if (mLeftIndents != null || mRightIndents != null) {
            final int leftLen = mLeftIndents == null ? 0 : mLeftIndents.length;
            final int rightLen = mRightIndents == null ? 0 : mRightIndents.length;
            final int indentsLen = Math.max(leftLen, rightLen);
            indents = new int[indentsLen];
            for (int i = 0; i < leftLen; i++) {
                indents[i] = mLeftIndents[i];
            }
            for (int i = 0; i < rightLen; i++) {
                indents[i] += mRightIndents[i];
            }
        } else {
            indents = null;
        }

        final long nativePtr = nInit(
                b.mBreakStrategy, b.mHyphenationFrequency,
                // TODO: Support more justification mode, e.g. letter spacing, stretching.
                b.mJustificationMode != Layout.JUSTIFICATION_MODE_NONE,
                indents);

        PrecomputedText.ParagraphInfo[] paragraphInfo = null;
        final Spanned spanned = (source instanceof Spanned) ? (Spanned) source : null;
        if (source instanceof PrecomputedText) {
            PrecomputedText precomputed = (PrecomputedText) source;
            if (precomputed.canUseMeasuredResult(bufStart, bufEnd, textDir, paint,
                      b.mBreakStrategy, b.mHyphenationFrequency)) {
                // Some parameters are different from the ones when measured text is created.
                paragraphInfo = precomputed.getParagraphInfo();
            }
        }

        if (paragraphInfo == null) {
            final PrecomputedText.Params param = new PrecomputedText.Params(paint, textDir,
                    b.mBreakStrategy, b.mHyphenationFrequency);
            paragraphInfo = PrecomputedText.createMeasuredParagraphs(source, param, bufStart,
                    bufEnd, false /* computeLayout */);
        }

        try {
            for (int paraIndex = 0; paraIndex < paragraphInfo.length; paraIndex++) {
                final int paraStart = paraIndex == 0
                        ? bufStart : paragraphInfo[paraIndex - 1].paragraphEnd;
                final int paraEnd = paragraphInfo[paraIndex].paragraphEnd;

                int firstWidthLineCount = 1;
                int firstWidth = outerWidth;
                int restWidth = outerWidth;

                LineHeightSpan[] chooseHt = null;

                if (spanned != null) {
                    LeadingMarginSpan[] sp = getParagraphSpans(spanned, paraStart, paraEnd,
                            LeadingMarginSpan.class);
                    for (int i = 0; i < sp.length; i++) {
                        LeadingMarginSpan lms = sp[i];
                        firstWidth -= sp[i].getLeadingMargin(true);
                        restWidth -= sp[i].getLeadingMargin(false);

                        // LeadingMarginSpan2 is odd.  The count affects all
                        // leading margin spans, not just this particular one
                        if (lms instanceof LeadingMarginSpan2) {
                            LeadingMarginSpan2 lms2 = (LeadingMarginSpan2) lms;
                            firstWidthLineCount = Math.max(firstWidthLineCount,
                                    lms2.getLeadingMarginLineCount());
                        }
                    }

                    chooseHt = getParagraphSpans(spanned, paraStart, paraEnd, LineHeightSpan.class);

                    if (chooseHt.length == 0) {
                        chooseHt = null; // So that out() would not assume it has any contents
                    } else {
                        if (chooseHtv == null || chooseHtv.length < chooseHt.length) {
                            chooseHtv = ArrayUtils.newUnpaddedIntArray(chooseHt.length);
                        }

                        for (int i = 0; i < chooseHt.length; i++) {
                            int o = spanned.getSpanStart(chooseHt[i]);

                            if (o < paraStart) {
                                // starts in this layout, before the
                                // current paragraph

                                chooseHtv[i] = getLineTop(getLineForOffset(o));
                            } else {
                                // starts in this paragraph

                                chooseHtv[i] = v;
                            }
                        }
                    }
                }

                // tab stop locations
                int[] variableTabStops = null;
                if (spanned != null) {
                    TabStopSpan[] spans = getParagraphSpans(spanned, paraStart,
                            paraEnd, TabStopSpan.class);
                    if (spans.length > 0) {
                        int[] stops = new int[spans.length];
                        for (int i = 0; i < spans.length; i++) {
                            stops[i] = spans[i].getTabStop();
                        }
                        Arrays.sort(stops, 0, stops.length);
                        variableTabStops = stops;
                    }
                }

                final MeasuredParagraph measuredPara = paragraphInfo[paraIndex].measured;
                final char[] chs = measuredPara.getChars();
                final int[] spanEndCache = measuredPara.getSpanEndCache().getRawArray();
                final int[] fmCache = measuredPara.getFontMetrics().getRawArray();
                // TODO: Stop keeping duplicated width copy in native and Java.
                widths.resize(chs.length);

                // measurement has to be done before performing line breaking
                // but we don't want to recompute fontmetrics or span ranges the
                // second time, so we cache those and then use those stored values

                int breakCount = nComputeLineBreaks(
                        nativePtr,

                        // Inputs
                        chs,
                        measuredPara.getNativePtr(),
                        paraEnd - paraStart,
                        firstWidth,
                        firstWidthLineCount,
                        restWidth,
                        variableTabStops,
                        TAB_INCREMENT,
                        mLineCount,

                        // Outputs
                        lineBreaks,
                        lineBreaks.breaks.length,
                        lineBreaks.breaks,
                        lineBreaks.widths,
                        lineBreaks.ascents,
                        lineBreaks.descents,
                        lineBreaks.flags,
                        widths.getRawArray());

                final int[] breaks = lineBreaks.breaks;
                final float[] lineWidths = lineBreaks.widths;
                final float[] ascents = lineBreaks.ascents;
                final float[] descents = lineBreaks.descents;
                final int[] flags = lineBreaks.flags;

                final int remainingLineCount = mMaximumVisibleLineCount - mLineCount;
                final boolean ellipsisMayBeApplied = ellipsize != null
                        && (ellipsize == TextUtils.TruncateAt.END
                            || (mMaximumVisibleLineCount == 1
                                    && ellipsize != TextUtils.TruncateAt.MARQUEE));
                if (0 < remainingLineCount && remainingLineCount < breakCount
                        && ellipsisMayBeApplied) {
                    // Calculate width and flag.
                    float width = 0;
                    int flag = 0; // XXX May need to also have starting hyphen edit
                    for (int i = remainingLineCount - 1; i < breakCount; i++) {
                        if (i == breakCount - 1) {
                            width += lineWidths[i];
                        } else {
                            for (int j = (i == 0 ? 0 : breaks[i - 1]); j < breaks[i]; j++) {
                                width += widths.get(j);
                            }
                        }
                        flag |= flags[i] & TAB_MASK;
                    }
                    // Treat the last line and overflowed lines as a single line.
                    breaks[remainingLineCount - 1] = breaks[breakCount - 1];
                    lineWidths[remainingLineCount - 1] = width;
                    flags[remainingLineCount - 1] = flag;

                    breakCount = remainingLineCount;
                }

                // here is the offset of the starting character of the line we are currently
                // measuring
                int here = paraStart;

                int fmTop = 0, fmBottom = 0, fmAscent = 0, fmDescent = 0;
                int fmCacheIndex = 0;
                int spanEndCacheIndex = 0;
                int breakIndex = 0;
                for (int spanStart = paraStart, spanEnd; spanStart < paraEnd; spanStart = spanEnd) {
                    // retrieve end of span
                    spanEnd = spanEndCache[spanEndCacheIndex++];

                    // retrieve cached metrics, order matches above
                    fm.top = fmCache[fmCacheIndex * 4 + 0];
                    fm.bottom = fmCache[fmCacheIndex * 4 + 1];
                    fm.ascent = fmCache[fmCacheIndex * 4 + 2];
                    fm.descent = fmCache[fmCacheIndex * 4 + 3];
                    fmCacheIndex++;

                    if (fm.top < fmTop) {
                        fmTop = fm.top;
                    }
                    if (fm.ascent < fmAscent) {
                        fmAscent = fm.ascent;
                    }
                    if (fm.descent > fmDescent) {
                        fmDescent = fm.descent;
                    }
                    if (fm.bottom > fmBottom) {
                        fmBottom = fm.bottom;
                    }

                    // skip breaks ending before current span range
                    while (breakIndex < breakCount && paraStart + breaks[breakIndex] < spanStart) {
                        breakIndex++;
                    }

                    while (breakIndex < breakCount && paraStart + breaks[breakIndex] <= spanEnd) {
                        int endPos = paraStart + breaks[breakIndex];

                        boolean moreChars = (endPos < bufEnd);

                        final int ascent = fallbackLineSpacing
                                ? Math.min(fmAscent, Math.round(ascents[breakIndex]))
                                : fmAscent;
                        final int descent = fallbackLineSpacing
                                ? Math.max(fmDescent, Math.round(descents[breakIndex]))
                                : fmDescent;
                        v = out(source, here, endPos,
                                ascent, descent, fmTop, fmBottom,
                                v, spacingmult, spacingadd, chooseHt, chooseHtv, fm,
                                flags[breakIndex], needMultiply, measuredPara, bufEnd,
                                includepad, trackpad, addLastLineSpacing, chs, widths.getRawArray(),
                                paraStart, ellipsize, ellipsizedWidth, lineWidths[breakIndex],
                                paint, moreChars);

                        if (endPos < spanEnd) {
                            // preserve metrics for current span
                            fmTop = fm.top;
                            fmBottom = fm.bottom;
                            fmAscent = fm.ascent;
                            fmDescent = fm.descent;
                        } else {
                            fmTop = fmBottom = fmAscent = fmDescent = 0;
                        }

                        here = endPos;
                        breakIndex++;

                        if (mLineCount >= mMaximumVisibleLineCount && mEllipsized) {
                            return;
                        }
                    }
                }

                if (paraEnd == bufEnd) {
                    break;
                }
            }

            if ((bufEnd == bufStart || source.charAt(bufEnd - 1) == CHAR_NEW_LINE)
                    && mLineCount < mMaximumVisibleLineCount) {
                final MeasuredParagraph measuredPara =
                        MeasuredParagraph.buildForBidi(source, bufEnd, bufEnd, textDir, null);
                paint.getFontMetricsInt(fm);
                v = out(source,
                        bufEnd, bufEnd, fm.ascent, fm.descent,
                        fm.top, fm.bottom,
                        v,
                        spacingmult, spacingadd, null,
                        null, fm, 0,
                        needMultiply, measuredPara, bufEnd,
                        includepad, trackpad, addLastLineSpacing, null,
                        null, bufStart, ellipsize,
                        ellipsizedWidth, 0, paint, false);
            }
        } finally {
            nFinish(nativePtr);
        }
    }

    private int out(final CharSequence text, final int start, final int end, int above, int below,
            int top, int bottom, int v, final float spacingmult, final float spacingadd,
            final LineHeightSpan[] chooseHt, final int[] chooseHtv, final Paint.FontMetricsInt fm,
            final int flags, final boolean needMultiply, @NonNull final MeasuredParagraph measured,
            final int bufEnd, final boolean includePad, final boolean trackPad,
            final boolean addLastLineLineSpacing, final char[] chs, final float[] widths,
            final int widthStart, final TextUtils.TruncateAt ellipsize, final float ellipsisWidth,
            final float textWidth, final TextPaint paint, final boolean moreChars) {
        final int j = mLineCount;
        final int off = j * mColumns;
        final int want = off + mColumns + TOP;
        int[] lines = mLines;
        final int dir = measured.getParagraphDir();

        if (want >= lines.length) {
            final int[] grow = ArrayUtils.newUnpaddedIntArray(GrowingArrayUtils.growSize(want));
            System.arraycopy(lines, 0, grow, 0, lines.length);
            mLines = grow;
            lines = grow;
        }

        if (j >= mLineDirections.length) {
            final Directions[] grow = ArrayUtils.newUnpaddedArray(Directions.class,
                    GrowingArrayUtils.growSize(j));
            System.arraycopy(mLineDirections, 0, grow, 0, mLineDirections.length);
            mLineDirections = grow;
        }

        if (chooseHt != null) {
            fm.ascent = above;
            fm.descent = below;
            fm.top = top;
            fm.bottom = bottom;

            for (int i = 0; i < chooseHt.length; i++) {
                if (chooseHt[i] instanceof LineHeightSpan.WithDensity) {
                    ((LineHeightSpan.WithDensity) chooseHt[i])
                            .chooseHeight(text, start, end, chooseHtv[i], v, fm, paint);
                } else {
                    chooseHt[i].chooseHeight(text, start, end, chooseHtv[i], v, fm);
                }
            }

            above = fm.ascent;
            below = fm.descent;
            top = fm.top;
            bottom = fm.bottom;
        }

        boolean firstLine = (j == 0);
        boolean currentLineIsTheLastVisibleOne = (j + 1 == mMaximumVisibleLineCount);

        if (ellipsize != null) {
            // If there is only one line, then do any type of ellipsis except when it is MARQUEE
            // if there are multiple lines, just allow END ellipsis on the last line
            boolean forceEllipsis = moreChars && (mLineCount + 1 == mMaximumVisibleLineCount);

            boolean doEllipsis =
                    (((mMaximumVisibleLineCount == 1 && moreChars) || (firstLine && !moreChars)) &&
                            ellipsize != TextUtils.TruncateAt.MARQUEE) ||
                    (!firstLine && (currentLineIsTheLastVisibleOne || !moreChars) &&
                            ellipsize == TextUtils.TruncateAt.END);
            if (doEllipsis) {
                calculateEllipsis(start, end, widths, widthStart,
                        ellipsisWidth, ellipsize, j,
                        textWidth, paint, forceEllipsis);
            }
        }

        final boolean lastLine;
        if (mEllipsized) {
            lastLine = true;
        } else {
            final boolean lastCharIsNewLine = widthStart != bufEnd && bufEnd > 0
                    && text.charAt(bufEnd - 1) == CHAR_NEW_LINE;
            if (end == bufEnd && !lastCharIsNewLine) {
                lastLine = true;
            } else if (start == bufEnd && lastCharIsNewLine) {
                lastLine = true;
            } else {
                lastLine = false;
            }
        }

        if (firstLine) {
            if (trackPad) {
                mTopPadding = top - above;
            }

            if (includePad) {
                above = top;
            }
        }

        int extra;

        if (lastLine) {
            if (trackPad) {
                mBottomPadding = bottom - below;
            }

            if (includePad) {
                below = bottom;
            }
        }

        if (needMultiply && (addLastLineLineSpacing || !lastLine)) {
            double ex = (below - above) * (spacingmult - 1) + spacingadd;
            if (ex >= 0) {
                extra = (int)(ex + EXTRA_ROUNDING);
            } else {
                extra = -(int)(-ex + EXTRA_ROUNDING);
            }
        } else {
            extra = 0;
        }

        lines[off + START] = start;
        lines[off + TOP] = v;
        lines[off + DESCENT] = below + extra;
        lines[off + EXTRA] = extra;

        // special case for non-ellipsized last visible line when maxLines is set
        // store the height as if it was ellipsized
        if (!mEllipsized && currentLineIsTheLastVisibleOne) {
            // below calculation as if it was the last line
            int maxLineBelow = includePad ? bottom : below;
            // similar to the calculation of v below, without the extra.
            mMaxLineHeight = v + (maxLineBelow - above);
        }

        v += (below - above) + extra;
        lines[off + mColumns + START] = end;
        lines[off + mColumns + TOP] = v;

        // TODO: could move TAB to share same column as HYPHEN, simplifying this code and gaining
        // one bit for start field
        lines[off + TAB] |= flags & TAB_MASK;
        lines[off + HYPHEN] = flags;
        lines[off + DIR] |= dir << DIR_SHIFT;
        mLineDirections[j] = measured.getDirections(start - widthStart, end - widthStart);

        mLineCount++;
        return v;
    }

    private void calculateEllipsis(int lineStart, int lineEnd,
                                   float[] widths, int widthStart,
                                   float avail, TextUtils.TruncateAt where,
                                   int line, float textWidth, TextPaint paint,
                                   boolean forceEllipsis) {
        avail -= getTotalInsets(line);
        if (textWidth <= avail && !forceEllipsis) {
            // Everything fits!
            mLines[mColumns * line + ELLIPSIS_START] = 0;
            mLines[mColumns * line + ELLIPSIS_COUNT] = 0;
            return;
        }

        float ellipsisWidth = paint.measureText(TextUtils.getEllipsisString(where));
        int ellipsisStart = 0;
        int ellipsisCount = 0;
        int len = lineEnd - lineStart;

        // We only support start ellipsis on a single line
        if (where == TextUtils.TruncateAt.START) {
            if (mMaximumVisibleLineCount == 1) {
                float sum = 0;
                int i;

                for (i = len; i > 0; i--) {
                    float w = widths[i - 1 + lineStart - widthStart];
                    if (w + sum + ellipsisWidth > avail) {
                        while (i < len && widths[i + lineStart - widthStart] == 0.0f) {
                            i++;
                        }
                        break;
                    }

                    sum += w;
                }

                ellipsisStart = 0;
                ellipsisCount = i;
            } else {
                if (Log.isLoggable(TAG, Log.WARN)) {
                    Log.w(TAG, "Start Ellipsis only supported with one line");
                }
            }
        } else if (where == TextUtils.TruncateAt.END || where == TextUtils.TruncateAt.MARQUEE ||
                where == TextUtils.TruncateAt.END_SMALL) {
            float sum = 0;
            int i;

            for (i = 0; i < len; i++) {
                float w = widths[i + lineStart - widthStart];

                if (w + sum + ellipsisWidth > avail) {
                    break;
                }

                sum += w;
            }

            ellipsisStart = i;
            ellipsisCount = len - i;
            if (forceEllipsis && ellipsisCount == 0 && len > 0) {
                ellipsisStart = len - 1;
                ellipsisCount = 1;
            }
        } else {
            // where = TextUtils.TruncateAt.MIDDLE We only support middle ellipsis on a single line
            if (mMaximumVisibleLineCount == 1) {
                float lsum = 0, rsum = 0;
                int left = 0, right = len;

                float ravail = (avail - ellipsisWidth) / 2;
                for (right = len; right > 0; right--) {
                    float w = widths[right - 1 + lineStart - widthStart];

                    if (w + rsum > ravail) {
                        while (right < len && widths[right + lineStart - widthStart] == 0.0f) {
                            right++;
                        }
                        break;
                    }
                    rsum += w;
                }

                float lavail = avail - ellipsisWidth - rsum;
                for (left = 0; left < right; left++) {
                    float w = widths[left + lineStart - widthStart];

                    if (w + lsum > lavail) {
                        break;
                    }

                    lsum += w;
                }

                ellipsisStart = left;
                ellipsisCount = right - left;
            } else {
                if (Log.isLoggable(TAG, Log.WARN)) {
                    Log.w(TAG, "Middle Ellipsis only supported with one line");
                }
            }
        }
        mEllipsized = true;
        mLines[mColumns * line + ELLIPSIS_START] = ellipsisStart;
        mLines[mColumns * line + ELLIPSIS_COUNT] = ellipsisCount;
    }

    private float getTotalInsets(int line) {
        int totalIndent = 0;
        if (mLeftIndents != null) {
            totalIndent = mLeftIndents[Math.min(line, mLeftIndents.length - 1)];
        }
        if (mRightIndents != null) {
            totalIndent += mRightIndents[Math.min(line, mRightIndents.length - 1)];
        }
        return totalIndent;
    }

    // Override the base class so we can directly access our members,
    // rather than relying on member functions.
    // The logic mirrors that of Layout.getLineForVertical
    // FIXME: It may be faster to do a linear search for layouts without many lines.
    @Override
    public int getLineForVertical(int vertical) {
        int high = mLineCount;
        int low = -1;
        int guess;
        int[] lines = mLines;
        while (high - low > 1) {
            guess = (high + low) >> 1;
            if (lines[mColumns * guess + TOP] > vertical){
                high = guess;
            } else {
                low = guess;
            }
        }
        if (low < 0) {
            return 0;
        } else {
            return low;
        }
    }

    @Override
    public int getLineCount() {
        return mLineCount;
    }

    @Override
    public int getLineTop(int line) {
        return mLines[mColumns * line + TOP];
    }

    /**
     * @hide
     */
    @Override
    public int getLineExtra(int line) {
        return mLines[mColumns * line + EXTRA];
    }

    @Override
    public int getLineDescent(int line) {
        return mLines[mColumns * line + DESCENT];
    }

    @Override
    public int getLineStart(int line) {
        return mLines[mColumns * line + START] & START_MASK;
    }

    @Override
    public int getParagraphDirection(int line) {
        return mLines[mColumns * line + DIR] >> DIR_SHIFT;
    }

    @Override
    public boolean getLineContainsTab(int line) {
        return (mLines[mColumns * line + TAB] & TAB_MASK) != 0;
    }

    @Override
    public final Directions getLineDirections(int line) {
        if (line > getLineCount()) {
            throw new ArrayIndexOutOfBoundsException();
        }
        return mLineDirections[line];
    }

    @Override
    public int getTopPadding() {
        return mTopPadding;
    }

    @Override
    public int getBottomPadding() {
        return mBottomPadding;
    }

    /**
     * @hide
     */
    @Override
    public int getHyphen(int line) {
        return mLines[mColumns * line + HYPHEN] & HYPHEN_MASK;
    }

    /**
     * @hide
     */
    @Override
    public int getIndentAdjust(int line, Alignment align) {
        if (align == Alignment.ALIGN_LEFT) {
            if (mLeftIndents == null) {
                return 0;
            } else {
                return mLeftIndents[Math.min(line, mLeftIndents.length - 1)];
            }
        } else if (align == Alignment.ALIGN_RIGHT) {
            if (mRightIndents == null) {
                return 0;
            } else {
                return -mRightIndents[Math.min(line, mRightIndents.length - 1)];
            }
        } else if (align == Alignment.ALIGN_CENTER) {
            int left = 0;
            if (mLeftIndents != null) {
                left = mLeftIndents[Math.min(line, mLeftIndents.length - 1)];
            }
            int right = 0;
            if (mRightIndents != null) {
                right = mRightIndents[Math.min(line, mRightIndents.length - 1)];
            }
            return (left - right) >> 1;
        } else {
            throw new AssertionError("unhandled alignment " + align);
        }
    }

    @Override
    public int getEllipsisCount(int line) {
        if (mColumns < COLUMNS_ELLIPSIZE) {
            return 0;
        }

        return mLines[mColumns * line + ELLIPSIS_COUNT];
    }

    @Override
    public int getEllipsisStart(int line) {
        if (mColumns < COLUMNS_ELLIPSIZE) {
            return 0;
        }

        return mLines[mColumns * line + ELLIPSIS_START];
    }

    @Override
    public int getEllipsizedWidth() {
        return mEllipsizedWidth;
    }

    /**
     * Return the total height of this layout.
     *
     * @param cap if true and max lines is set, returns the height of the layout at the max lines.
     *
     * @hide
     */
    public int getHeight(boolean cap) {
        if (cap && mLineCount > mMaximumVisibleLineCount && mMaxLineHeight == -1
                && Log.isLoggable(TAG, Log.WARN)) {
            Log.w(TAG, "maxLineHeight should not be -1. "
                    + " maxLines:" + mMaximumVisibleLineCount
                    + " lineCount:" + mLineCount);
        }

        return cap && mLineCount > mMaximumVisibleLineCount && mMaxLineHeight != -1
                ? mMaxLineHeight : super.getHeight();
    }

    @FastNative
    private static native long nInit(
            @BreakStrategy int breakStrategy,
            @HyphenationFrequency int hyphenationFrequency,
            boolean isJustified,
            @Nullable int[] indents);

    @CriticalNative
    private static native void nFinish(long nativePtr);

    // populates LineBreaks and returns the number of breaks found
    //
    // the arrays inside the LineBreaks objects are passed in as well
    // to reduce the number of JNI calls in the common case where the
    // arrays do not have to be resized
    // The individual character widths will be returned in charWidths. The length of charWidths must
    // be at least the length of the text.
    private static native int nComputeLineBreaks(
            /* non zero */ long nativePtr,

            // Inputs
            @NonNull char[] text,
            /* Non Zero */ long measuredTextPtr,
            @IntRange(from = 0) int length,
            @FloatRange(from = 0.0f) float firstWidth,
            @IntRange(from = 0) int firstWidthLineCount,
            @FloatRange(from = 0.0f) float restWidth,
            @Nullable int[] variableTabStops,
            int defaultTabStop,
            @IntRange(from = 0) int indentsOffset,

            // Outputs
            @NonNull LineBreaks recycle,
            @IntRange(from  = 0) int recycleLength,
            @NonNull int[] recycleBreaks,
            @NonNull float[] recycleWidths,
            @NonNull float[] recycleAscents,
            @NonNull float[] recycleDescents,
            @NonNull int[] recycleFlags,
            @NonNull float[] charWidths);

    private int mLineCount;
    private int mTopPadding, mBottomPadding;
    private int mColumns;
    private int mEllipsizedWidth;

    /**
     * Keeps track if ellipsize is applied to the text.
     */
    private boolean mEllipsized;

    /**
     * If maxLines is set, ellipsize is not set, and the actual line count of text is greater than
     * or equal to maxLine, this variable holds the ideal visual height of the maxLine'th line
     * starting from the top of the layout. If maxLines is not set its value will be -1.
     *
     * The value is the same as getLineTop(maxLines) for ellipsized version where structurally no
     * more than maxLines is contained.
     */
    private int mMaxLineHeight = DEFAULT_MAX_LINE_HEIGHT;

    private static final int COLUMNS_NORMAL = 5;
    private static final int COLUMNS_ELLIPSIZE = 7;
    private static final int START = 0;
    private static final int DIR = START;
    private static final int TAB = START;
    private static final int TOP = 1;
    private static final int DESCENT = 2;
    private static final int EXTRA = 3;
    private static final int HYPHEN = 4;
    private static final int ELLIPSIS_START = 5;
    private static final int ELLIPSIS_COUNT = 6;

    private int[] mLines;
    private Directions[] mLineDirections;
    private int mMaximumVisibleLineCount = Integer.MAX_VALUE;

    private static final int START_MASK = 0x1FFFFFFF;
    private static final int DIR_SHIFT  = 30;
    private static final int TAB_MASK   = 0x20000000;
    private static final int HYPHEN_MASK = 0xFF;

    private static final int TAB_INCREMENT = 20; // same as Layout, but that's private

    private static final char CHAR_NEW_LINE = '\n';

    private static final double EXTRA_ROUNDING = 0.5;

    private static final int DEFAULT_MAX_LINE_HEIGHT = -1;

    // This is used to return three arrays from a single JNI call when
    // performing line breaking
    /*package*/ static class LineBreaks {
        private static final int INITIAL_SIZE = 16;
        public int[] breaks = new int[INITIAL_SIZE];
        public float[] widths = new float[INITIAL_SIZE];
        public float[] ascents = new float[INITIAL_SIZE];
        public float[] descents = new float[INITIAL_SIZE];
        public int[] flags = new int[INITIAL_SIZE]; // hasTab
        // breaks, widths, and flags should all have the same length
    }

    @Nullable private int[] mLeftIndents;
    @Nullable private int[] mRightIndents;
}