https://source.android.com/ 
/*
 * 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.graphics.Rect;
import android.text.style.ReplacementSpan;
import android.text.style.UpdateLayout;
import android.text.style.WrapTogetherSpan;
import android.util.ArraySet;
import android.util.Pools.SynchronizedPool;

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

import java.lang.ref.WeakReference;


DynamicLayout is a text layout that updates itself as the text is edited.

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 need to call 
 Canvas.drawText() directly.


/**
 * DynamicLayout is a text layout that updates itself as the text is edited.
 * <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 need to call
 * {@link android.graphics.Canvas#drawText(java.lang.CharSequence, int, int, float, float, android.graphics.Paint)
 *  Canvas.drawText()} directly.</p>
 */
public class DynamicLayout extends Layout {
    private static final int PRIORITY = 128;
    private static final int BLOCK_MINIMUM_CHARACTER_LENGTH = 400;

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

        
Obtain a builder for constructing DynamicLayout objects.

/**
         * Obtain a builder for constructing DynamicLayout objects.
         */
        @NonNull
        public static Builder obtain(@NonNull CharSequence base, @NonNull TextPaint paint,
                @IntRange(from = 0) int width) {
            Builder b = sPool.acquire();
            if (b == null) {
                b = new Builder();
            }

            // set default initial values
            b.mBase = base;
            b.mDisplay = base;
            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.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.

/**
         * 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.mBase = null;
            b.mDisplay = null;
            b.mPaint = null;
            sPool.release(b);
        }

        
Set the transformed text (password transformation being the primary example of a
transformation) that will be updated as the base text is changed. The default is the
'base' text passed to the builder's constructor.

Params:
  • display – the transformed text
Returns:this builder, useful for chaining
/**
         * Set the transformed text (password transformation being the primary example of a
         * transformation) that will be updated as the base text is changed. The default is the
         * 'base' text passed to the builder's constructor.
         *
         * @param display the transformed text
         * @return this builder, useful for chaining
         */
        @NonNull
        public Builder setDisplayText(@NonNull CharSequence display) {
            mDisplay = display;
            return this;
        }

        
Set the alignment. The default is Alignment.ALIGN_NORMAL. 
Params:
Returns:this builder, useful for chaining
/**
         * Set the alignment. The default is {@link Layout.Alignment#ALIGN_NORMAL}.
         *
         * @param alignment Alignment for the resulting {@link DynamicLayout}
         * @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 TextDirectionHeuristics.FIRSTSTRONG_LTR. 
Params:
  • textDir – text direction heuristic for resolving bidi behavior.
Returns:this builder, useful for chaining
/**
         * 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 spacingMult and then increased by spacingAdd. The default is 0.0 for spacingAdd and 1.0 for spacingMult. 
Params:
  • spacingAdd – the amount of line spacing addition
  • spacingMult – the line spacing multiplier
See Also:
Returns:this builder, useful for chaining
/**
         * 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 true. 
Params:
  • includePad – whether to include padding
See Also:
Returns:this builder, useful for chaining
/**
         * 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.

For backward compatibility reasons, the default is 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. 
Params:
  • useLineSpacingFromFallbacks – whether to expand linespacing based on fallback fonts
Returns:this builder, useful for chaining
/**
         * 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 width passed to obtain. 
Params:
  • ellipsizedWidth – width used for ellipsizing, in pixels
See Also:
Returns:this builder, useful for chaining
/**
         * 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 TruncateAt.END or TruncateAt.MARQUEE, to be ellipsized instead of broken. The default is null, indicating no ellipsis is to be applied. 
Params:
  • ellipsize – type of ellipsis behavior
See Also:
Returns:this builder, useful for chaining
/**
         * 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
         */
        public Builder setEllipsize(@Nullable TextUtils.TruncateAt ellipsize) {
            mEllipsize = ellipsize;
            return this;
        }

        
Set break strategy, useful for selecting high quality or balanced paragraph layout options. The default is Layout.BREAK_STRATEGY_SIMPLE. 
Params:
  • breakStrategy – break strategy for paragraph layout
See Also:
Returns:this builder, useful for chaining
/**
         * Set break strategy, useful for selecting high quality or balanced paragraph layout
         * options. The default is {@link Layout#BREAK_STRATEGY_SIMPLE}.
         *
         * @param breakStrategy break strategy for paragraph layout
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setBreakStrategy
         */
        @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 Layout, by constants named with the pattern HYPHENATION_FREQUENCY_*. The default is Layout.HYPHENATION_FREQUENCY_NONE. 
Params:
  • hyphenationFrequency – hyphenation frequency for the paragraph
See Also:
Returns:this builder, useful for chaining
/**
         * 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}.
         *
         * @param hyphenationFrequency hyphenation frequency for the paragraph
         * @return this builder, useful for chaining
         * @see android.widget.TextView#setHyphenationFrequency
         */
        @NonNull
        public Builder setHyphenationFrequency(@HyphenationFrequency int hyphenationFrequency) {
            mHyphenationFrequency = hyphenationFrequency;
            return this;
        }

        
Set paragraph justification mode. The default value is Layout.JUSTIFICATION_MODE_NONE. If the last line is too short for justification, the last line will be displayed with the alignment set by setAlignment. 
Params:
  • justificationMode – justification mode for the paragraph.
Returns:this builder, useful for chaining.
/**
         * 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;
        }

        
Build the DynamicLayout after options have been set. 
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.

Returns:the newly constructed DynamicLayout object
/**
         * Build the {@link DynamicLayout} 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 DynamicLayout} object
         */
        @NonNull
        public DynamicLayout build() {
            final DynamicLayout result = new DynamicLayout(this);
            Builder.recycle(this);
            return result;
        }

        private CharSequence mBase;
        private CharSequence mDisplay;
        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 mBreakStrategy;
        private int mHyphenationFrequency;
        private int mJustificationMode;
        private TextUtils.TruncateAt mEllipsize;
        private int mEllipsizedWidth;

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

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

    
Deprecated:Use Builder instead.
/**
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public DynamicLayout(@NonNull CharSequence base,
                         @NonNull TextPaint paint,
                         @IntRange(from = 0) int width, @NonNull Alignment align,
                         @FloatRange(from = 0.0) float spacingmult, float spacingadd,
                         boolean includepad) {
        this(base, base, paint, width, align, spacingmult, spacingadd,
             includepad);
    }

    
Deprecated:Use Builder instead.
/**
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public DynamicLayout(@NonNull CharSequence base, @NonNull CharSequence display,
                         @NonNull TextPaint paint,
                         @IntRange(from = 0) int width, @NonNull Alignment align,
                         @FloatRange(from = 0.0) float spacingmult, float spacingadd,
                         boolean includepad) {
        this(base, display, paint, width, align, spacingmult, spacingadd,
             includepad, null, 0);
    }

    
Deprecated:Use Builder instead.
/**
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public DynamicLayout(@NonNull CharSequence base, @NonNull CharSequence display,
                         @NonNull TextPaint paint,
                         @IntRange(from = 0) int width, @NonNull Alignment align,
                         @FloatRange(from = 0.0) float spacingmult, float spacingadd,
                         boolean includepad,
                         @Nullable TextUtils.TruncateAt ellipsize,
                         @IntRange(from = 0) int ellipsizedWidth) {
        this(base, display, paint, width, align, TextDirectionHeuristics.FIRSTSTRONG_LTR,
                spacingmult, spacingadd, includepad,
                Layout.BREAK_STRATEGY_SIMPLE, Layout.HYPHENATION_FREQUENCY_NONE,
                Layout.JUSTIFICATION_MODE_NONE, ellipsize, ellipsizedWidth);
    }

    
Make a layout for the transformed text (password transformation being the primary example of
a transformation) that will be updated as the base text is changed. If ellipsize is non-null,
the Layout will ellipsize the text down to ellipsizedWidth.

@hide
Deprecated:Use Builder instead.
/**
     * Make a layout for the transformed text (password transformation being the primary example of
     * a transformation) that will be updated as the base text is changed. If ellipsize is non-null,
     * the Layout will ellipsize the text down to ellipsizedWidth.
     *
     * @hide
     * @deprecated Use {@link Builder} instead.
     */
    @Deprecated
    public DynamicLayout(@NonNull CharSequence base, @NonNull CharSequence display,
                         @NonNull TextPaint paint,
                         @IntRange(from = 0) int width,
                         @NonNull Alignment align, @NonNull TextDirectionHeuristic textDir,
                         @FloatRange(from = 0.0) float spacingmult, float spacingadd,
                         boolean includepad, @BreakStrategy int breakStrategy,
                         @HyphenationFrequency int hyphenationFrequency,
                         @JustificationMode int justificationMode,
                         @Nullable TextUtils.TruncateAt ellipsize,
                         @IntRange(from = 0) int ellipsizedWidth) {
        super(createEllipsizer(ellipsize, display),
              paint, width, align, textDir, spacingmult, spacingadd);

        final Builder b = Builder.obtain(base, paint, width)
                .setAlignment(align)
                .setTextDirection(textDir)
                .setLineSpacing(spacingadd, spacingmult)
                .setEllipsizedWidth(ellipsizedWidth)
                .setEllipsize(ellipsize);
        mDisplay = display;
        mIncludePad = includepad;
        mBreakStrategy = breakStrategy;
        mJustificationMode = justificationMode;
        mHyphenationFrequency = hyphenationFrequency;

        generate(b);

        Builder.recycle(b);
    }

    private DynamicLayout(@NonNull Builder b) {
        super(createEllipsizer(b.mEllipsize, b.mDisplay),
                b.mPaint, b.mWidth, b.mAlignment, b.mTextDir, b.mSpacingMult, b.mSpacingAdd);

        mDisplay = b.mDisplay;
        mIncludePad = b.mIncludePad;
        mBreakStrategy = b.mBreakStrategy;
        mJustificationMode = b.mJustificationMode;
        mHyphenationFrequency = b.mHyphenationFrequency;

        generate(b);
    }

    @NonNull
    private static CharSequence createEllipsizer(@Nullable TextUtils.TruncateAt ellipsize,
            @NonNull CharSequence display) {
        if (ellipsize == null) {
            return display;
        } else if (display instanceof Spanned) {
            return new SpannedEllipsizer(display);
        } else {
            return new Ellipsizer(display);
        }
    }

    private void generate(@NonNull Builder b) {
        mBase = b.mBase;
        mFallbackLineSpacing = b.mFallbackLineSpacing;
        if (b.mEllipsize != null) {
            mInts = new PackedIntVector(COLUMNS_ELLIPSIZE);
            mEllipsizedWidth = b.mEllipsizedWidth;
            mEllipsizeAt = b.mEllipsize;

            /*
             * 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 (in createEllipsizer). 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.
             */
            final Ellipsizer e = (Ellipsizer) getText();
            e.mLayout = this;
            e.mWidth = b.mEllipsizedWidth;
            e.mMethod = b.mEllipsize;
            mEllipsize = true;
        } else {
            mInts = new PackedIntVector(COLUMNS_NORMAL);
            mEllipsizedWidth = b.mWidth;
            mEllipsizeAt = null;
        }

        mObjects = new PackedObjectVector<>(1);

        // Initial state is a single line with 0 characters (0 to 0), with top at 0 and bottom at
        // whatever is natural, and undefined ellipsis.

        int[] start;

        if (b.mEllipsize != null) {
            start = new int[COLUMNS_ELLIPSIZE];
            start[ELLIPSIS_START] = ELLIPSIS_UNDEFINED;
        } else {
            start = new int[COLUMNS_NORMAL];
        }

        final Directions[] dirs = new Directions[] { DIRS_ALL_LEFT_TO_RIGHT };

        final Paint.FontMetricsInt fm = b.mFontMetricsInt;
        b.mPaint.getFontMetricsInt(fm);
        final int asc = fm.ascent;
        final int desc = fm.descent;

        start[DIR] = DIR_LEFT_TO_RIGHT << DIR_SHIFT;
        start[TOP] = 0;
        start[DESCENT] = desc;
        mInts.insertAt(0, start);

        start[TOP] = desc - asc;
        mInts.insertAt(1, start);

        mObjects.insertAt(0, dirs);

        final int baseLength = mBase.length();
        // Update from 0 characters to whatever the real text is
        reflow(mBase, 0, 0, baseLength);

        if (mBase instanceof Spannable) {
            if (mWatcher == null)
                mWatcher = new ChangeWatcher(this);

            // Strip out any watchers for other DynamicLayouts.
            final Spannable sp = (Spannable) mBase;
            final ChangeWatcher[] spans = sp.getSpans(0, baseLength, ChangeWatcher.class);
            for (int i = 0; i < spans.length; i++) {
                sp.removeSpan(spans[i]);
            }

            sp.setSpan(mWatcher, 0, baseLength,
                       Spannable.SPAN_INCLUSIVE_INCLUSIVE |
                       (PRIORITY << Spannable.SPAN_PRIORITY_SHIFT));
        }
    }

    
@hide
/** @hide */
    @VisibleForTesting(visibility = VisibleForTesting.Visibility.PACKAGE)
    public void reflow(CharSequence s, int where, int before, int after) {
        if (s != mBase)
            return;

        CharSequence text = mDisplay;
        int len = text.length();

        // seek back to the start of the paragraph

        int find = TextUtils.lastIndexOf(text, '\n', where - 1);
        if (find < 0)
            find = 0;
        else
            find = find + 1;

        {
            int diff = where - find;
            before += diff;
            after += diff;
            where -= diff;
        }

        // seek forward to the end of the paragraph

        int look = TextUtils.indexOf(text, '\n', where + after);
        if (look < 0)
            look = len;
        else
            look++; // we want the index after the \n

        int change = look - (where + after);
        before += change;
        after += change;

        // seek further out to cover anything that is forced to wrap together

        if (text instanceof Spanned) {
            Spanned sp = (Spanned) text;
            boolean again;

            do {
                again = false;

                Object[] force = sp.getSpans(where, where + after,
                                             WrapTogetherSpan.class);

                for (int i = 0; i < force.length; i++) {
                    int st = sp.getSpanStart(force[i]);
                    int en = sp.getSpanEnd(force[i]);

                    if (st < where) {
                        again = true;

                        int diff = where - st;
                        before += diff;
                        after += diff;
                        where -= diff;
                    }

                    if (en > where + after) {
                        again = true;

                        int diff = en - (where + after);
                        before += diff;
                        after += diff;
                    }
                }
            } while (again);
        }

        // find affected region of old layout

        int startline = getLineForOffset(where);
        int startv = getLineTop(startline);

        int endline = getLineForOffset(where + before);
        if (where + after == len)
            endline = getLineCount();
        int endv = getLineTop(endline);
        boolean islast = (endline == getLineCount());

        // generate new layout for affected text

        StaticLayout reflowed;
        StaticLayout.Builder b;

        synchronized (sLock) {
            reflowed = sStaticLayout;
            b = sBuilder;
            sStaticLayout = null;
            sBuilder = null;
        }

        if (reflowed == null) {
            reflowed = new StaticLayout(null);
            b = StaticLayout.Builder.obtain(text, where, where + after, getPaint(), getWidth());
        }

        b.setText(text, where, where + after)
                .setPaint(getPaint())
                .setWidth(getWidth())
                .setTextDirection(getTextDirectionHeuristic())
                .setLineSpacing(getSpacingAdd(), getSpacingMultiplier())
                .setUseLineSpacingFromFallbacks(mFallbackLineSpacing)
                .setEllipsizedWidth(mEllipsizedWidth)
                .setEllipsize(mEllipsizeAt)
                .setBreakStrategy(mBreakStrategy)
                .setHyphenationFrequency(mHyphenationFrequency)
                .setJustificationMode(mJustificationMode)
                .setAddLastLineLineSpacing(!islast);

        reflowed.generate(b, false /*includepad*/, true /*trackpad*/);
        int n = reflowed.getLineCount();
        // If the new layout has a blank line at the end, but it is not
        // the very end of the buffer, then we already have a line that
        // starts there, so disregard the blank line.

        if (where + after != len && reflowed.getLineStart(n - 1) == where + after)
            n--;

        // remove affected lines from old layout
        mInts.deleteAt(startline, endline - startline);
        mObjects.deleteAt(startline, endline - startline);

        // adjust offsets in layout for new height and offsets

        int ht = reflowed.getLineTop(n);
        int toppad = 0, botpad = 0;

        if (mIncludePad && startline == 0) {
            toppad = reflowed.getTopPadding();
            mTopPadding = toppad;
            ht -= toppad;
        }
        if (mIncludePad && islast) {
            botpad = reflowed.getBottomPadding();
            mBottomPadding = botpad;
            ht += botpad;
        }

        mInts.adjustValuesBelow(startline, START, after - before);
        mInts.adjustValuesBelow(startline, TOP, startv - endv + ht);

        // insert new layout

        int[] ints;

        if (mEllipsize) {
            ints = new int[COLUMNS_ELLIPSIZE];
            ints[ELLIPSIS_START] = ELLIPSIS_UNDEFINED;
        } else {
            ints = new int[COLUMNS_NORMAL];
        }

        Directions[] objects = new Directions[1];

        for (int i = 0; i < n; i++) {
            final int start = reflowed.getLineStart(i);
            ints[START] = start;
            ints[DIR] |= reflowed.getParagraphDirection(i) << DIR_SHIFT;
            ints[TAB] |= reflowed.getLineContainsTab(i) ? TAB_MASK : 0;

            int top = reflowed.getLineTop(i) + startv;
            if (i > 0)
                top -= toppad;
            ints[TOP] = top;

            int desc = reflowed.getLineDescent(i);
            if (i == n - 1)
                desc += botpad;

            ints[DESCENT] = desc;
            ints[EXTRA] = reflowed.getLineExtra(i);
            objects[0] = reflowed.getLineDirections(i);

            final int end = (i == n - 1) ? where + after : reflowed.getLineStart(i + 1);
            ints[HYPHEN] = reflowed.getHyphen(i) & HYPHEN_MASK;
            ints[MAY_PROTRUDE_FROM_TOP_OR_BOTTOM] |=
                    contentMayProtrudeFromLineTopOrBottom(text, start, end) ?
                            MAY_PROTRUDE_FROM_TOP_OR_BOTTOM_MASK : 0;

            if (mEllipsize) {
                ints[ELLIPSIS_START] = reflowed.getEllipsisStart(i);
                ints[ELLIPSIS_COUNT] = reflowed.getEllipsisCount(i);
            }

            mInts.insertAt(startline + i, ints);
            mObjects.insertAt(startline + i, objects);
        }

        updateBlocks(startline, endline - 1, n);

        b.finish();
        synchronized (sLock) {
            sStaticLayout = reflowed;
            sBuilder = b;
        }
    }

    private boolean contentMayProtrudeFromLineTopOrBottom(CharSequence text, int start, int end) {
        if (text instanceof Spanned) {
            final Spanned spanned = (Spanned) text;
            if (spanned.getSpans(start, end, ReplacementSpan.class).length > 0) {
                return true;
            }
        }
        // Spans other than ReplacementSpan can be ignored because line top and bottom are
        // disjunction of all tops and bottoms, although it's not optimal.
        final Paint paint = getPaint();
        if (text instanceof PrecomputedText) {
            PrecomputedText precomputed = (PrecomputedText) text;
            precomputed.getBounds(start, end, mTempRect);
        } else {
            paint.getTextBounds(text, start, end, mTempRect);
        }
        final Paint.FontMetricsInt fm = paint.getFontMetricsInt();
        return mTempRect.top < fm.top || mTempRect.bottom > fm.bottom;
    }

    
Create the initial block structure, cutting the text into blocks of at least
BLOCK_MINIMUM_CHARACTER_SIZE characters, aligned on the ends of paragraphs.

/**
     * Create the initial block structure, cutting the text into blocks of at least
     * BLOCK_MINIMUM_CHARACTER_SIZE characters, aligned on the ends of paragraphs.
     */
    private void createBlocks() {
        int offset = BLOCK_MINIMUM_CHARACTER_LENGTH;
        mNumberOfBlocks = 0;
        final CharSequence text = mDisplay;

        while (true) {
            offset = TextUtils.indexOf(text, '\n', offset);
            if (offset < 0) {
                addBlockAtOffset(text.length());
                break;
            } else {
                addBlockAtOffset(offset);
                offset += BLOCK_MINIMUM_CHARACTER_LENGTH;
            }
        }

        // mBlockIndices and mBlockEndLines should have the same length
        mBlockIndices = new int[mBlockEndLines.length];
        for (int i = 0; i < mBlockEndLines.length; i++) {
            mBlockIndices[i] = INVALID_BLOCK_INDEX;
        }
    }

    
@hide
/**
     * @hide
     */
    public ArraySet<Integer> getBlocksAlwaysNeedToBeRedrawn() {
        return mBlocksAlwaysNeedToBeRedrawn;
    }

    private void updateAlwaysNeedsToBeRedrawn(int blockIndex) {
        int startLine = blockIndex == 0 ? 0 : (mBlockEndLines[blockIndex - 1] + 1);
        int endLine = mBlockEndLines[blockIndex];
        for (int i = startLine; i <= endLine; i++) {
            if (getContentMayProtrudeFromTopOrBottom(i)) {
                if (mBlocksAlwaysNeedToBeRedrawn == null) {
                    mBlocksAlwaysNeedToBeRedrawn = new ArraySet<>();
                }
                mBlocksAlwaysNeedToBeRedrawn.add(blockIndex);
                return;
            }
        }
        if (mBlocksAlwaysNeedToBeRedrawn != null) {
            mBlocksAlwaysNeedToBeRedrawn.remove(blockIndex);
        }
    }

    
Create a new block, ending at the specified character offset.
A block will actually be created only if has at least one line, i.e. this offset is
not on the end line of the previous block.

/**
     * Create a new block, ending at the specified character offset.
     * A block will actually be created only if has at least one line, i.e. this offset is
     * not on the end line of the previous block.
     */
    private void addBlockAtOffset(int offset) {
        final int line = getLineForOffset(offset);
        if (mBlockEndLines == null) {
            // Initial creation of the array, no test on previous block ending line
            mBlockEndLines = ArrayUtils.newUnpaddedIntArray(1);
            mBlockEndLines[mNumberOfBlocks] = line;
            updateAlwaysNeedsToBeRedrawn(mNumberOfBlocks);
            mNumberOfBlocks++;
            return;
        }

        final int previousBlockEndLine = mBlockEndLines[mNumberOfBlocks - 1];
        if (line > previousBlockEndLine) {
            mBlockEndLines = GrowingArrayUtils.append(mBlockEndLines, mNumberOfBlocks, line);
            updateAlwaysNeedsToBeRedrawn(mNumberOfBlocks);
            mNumberOfBlocks++;
        }
    }

    
This method is called every time the layout is reflowed after an edition.
It updates the internal block data structure. The text is split in blocks
of contiguous lines, with at least one block for the entire text.
When a range of lines is edited, new blocks (from 0 to 3 depending on the
overlap structure) will replace the set of overlapping blocks.
Blocks are listed in order and are represented by their ending line number.
An index is associated to each block (which will be used by display lists),
this class simply invalidates the index of blocks overlapping a modification.

Params:
  • startLine – the first line of the range of modified lines
  • endLine – the last line of the range, possibly equal to startLine, lower
than getLineCount()
  • newLineCount – the number of lines that will replace the range, possibly 0
@hide
/**
     * This method is called every time the layout is reflowed after an edition.
     * It updates the internal block data structure. The text is split in blocks
     * of contiguous lines, with at least one block for the entire text.
     * When a range of lines is edited, new blocks (from 0 to 3 depending on the
     * overlap structure) will replace the set of overlapping blocks.
     * Blocks are listed in order and are represented by their ending line number.
     * An index is associated to each block (which will be used by display lists),
     * this class simply invalidates the index of blocks overlapping a modification.
     *
     * @param startLine the first line of the range of modified lines
     * @param endLine the last line of the range, possibly equal to startLine, lower
     * than getLineCount()
     * @param newLineCount the number of lines that will replace the range, possibly 0
     *
     * @hide
     */
    @VisibleForTesting(visibility = VisibleForTesting.Visibility.PACKAGE)
    public void updateBlocks(int startLine, int endLine, int newLineCount) {
        if (mBlockEndLines == null) {
            createBlocks();
            return;
        }

        /*final*/ int firstBlock = -1;
        /*final*/ int lastBlock = -1;
        for (int i = 0; i < mNumberOfBlocks; i++) {
            if (mBlockEndLines[i] >= startLine) {
                firstBlock = i;
                break;
            }
        }
        for (int i = firstBlock; i < mNumberOfBlocks; i++) {
            if (mBlockEndLines[i] >= endLine) {
                lastBlock = i;
                break;
            }
        }
        final int lastBlockEndLine = mBlockEndLines[lastBlock];

        final boolean createBlockBefore = startLine > (firstBlock == 0 ? 0 :
                mBlockEndLines[firstBlock - 1] + 1);
        final boolean createBlock = newLineCount > 0;
        final boolean createBlockAfter = endLine < mBlockEndLines[lastBlock];

        int numAddedBlocks = 0;
        if (createBlockBefore) numAddedBlocks++;
        if (createBlock) numAddedBlocks++;
        if (createBlockAfter) numAddedBlocks++;

        final int numRemovedBlocks = lastBlock - firstBlock + 1;
        final int newNumberOfBlocks = mNumberOfBlocks + numAddedBlocks - numRemovedBlocks;

        if (newNumberOfBlocks == 0) {
            // Even when text is empty, there is actually one line and hence one block
            mBlockEndLines[0] = 0;
            mBlockIndices[0] = INVALID_BLOCK_INDEX;
            mNumberOfBlocks = 1;
            return;
        }

        if (newNumberOfBlocks > mBlockEndLines.length) {
            int[] blockEndLines = ArrayUtils.newUnpaddedIntArray(
                    Math.max(mBlockEndLines.length * 2, newNumberOfBlocks));
            int[] blockIndices = new int[blockEndLines.length];
            System.arraycopy(mBlockEndLines, 0, blockEndLines, 0, firstBlock);
            System.arraycopy(mBlockIndices, 0, blockIndices, 0, firstBlock);
            System.arraycopy(mBlockEndLines, lastBlock + 1,
                    blockEndLines, firstBlock + numAddedBlocks, mNumberOfBlocks - lastBlock - 1);
            System.arraycopy(mBlockIndices, lastBlock + 1,
                    blockIndices, firstBlock + numAddedBlocks, mNumberOfBlocks - lastBlock - 1);
            mBlockEndLines = blockEndLines;
            mBlockIndices = blockIndices;
        } else if (numAddedBlocks + numRemovedBlocks != 0) {
            System.arraycopy(mBlockEndLines, lastBlock + 1,
                    mBlockEndLines, firstBlock + numAddedBlocks, mNumberOfBlocks - lastBlock - 1);
            System.arraycopy(mBlockIndices, lastBlock + 1,
                    mBlockIndices, firstBlock + numAddedBlocks, mNumberOfBlocks - lastBlock - 1);
        }

        if (numAddedBlocks + numRemovedBlocks != 0 && mBlocksAlwaysNeedToBeRedrawn != null) {
            final ArraySet<Integer> set = new ArraySet<>();
            final int changedBlockCount = numAddedBlocks - numRemovedBlocks;
            for (int i = 0; i < mBlocksAlwaysNeedToBeRedrawn.size(); i++) {
                Integer block = mBlocksAlwaysNeedToBeRedrawn.valueAt(i);
                if (block < firstBlock) {
                    // block index is before firstBlock add it since it did not change
                    set.add(block);
                }
                if (block > lastBlock) {
                    // block index is after lastBlock, the index reduced to += changedBlockCount
                    block += changedBlockCount;
                    set.add(block);
                }
            }
            mBlocksAlwaysNeedToBeRedrawn = set;
        }

        mNumberOfBlocks = newNumberOfBlocks;
        int newFirstChangedBlock;
        final int deltaLines = newLineCount - (endLine - startLine + 1);
        if (deltaLines != 0) {
            // Display list whose index is >= mIndexFirstChangedBlock is valid
            // but it needs to update its drawing location.
            newFirstChangedBlock = firstBlock + numAddedBlocks;
            for (int i = newFirstChangedBlock; i < mNumberOfBlocks; i++) {
                mBlockEndLines[i] += deltaLines;
            }
        } else {
            newFirstChangedBlock = mNumberOfBlocks;
        }
        mIndexFirstChangedBlock = Math.min(mIndexFirstChangedBlock, newFirstChangedBlock);

        int blockIndex = firstBlock;
        if (createBlockBefore) {
            mBlockEndLines[blockIndex] = startLine - 1;
            updateAlwaysNeedsToBeRedrawn(blockIndex);
            mBlockIndices[blockIndex] = INVALID_BLOCK_INDEX;
            blockIndex++;
        }

        if (createBlock) {
            mBlockEndLines[blockIndex] = startLine + newLineCount - 1;
            updateAlwaysNeedsToBeRedrawn(blockIndex);
            mBlockIndices[blockIndex] = INVALID_BLOCK_INDEX;
            blockIndex++;
        }

        if (createBlockAfter) {
            mBlockEndLines[blockIndex] = lastBlockEndLine + deltaLines;
            updateAlwaysNeedsToBeRedrawn(blockIndex);
            mBlockIndices[blockIndex] = INVALID_BLOCK_INDEX;
        }
    }

    
This method is used for test purposes only.

@hide
/**
     * This method is used for test purposes only.
     * @hide
     */
    @VisibleForTesting(visibility = VisibleForTesting.Visibility.PACKAGE)
    public void setBlocksDataForTest(int[] blockEndLines, int[] blockIndices, int numberOfBlocks,
            int totalLines) {
        mBlockEndLines = new int[blockEndLines.length];
        mBlockIndices = new int[blockIndices.length];
        System.arraycopy(blockEndLines, 0, mBlockEndLines, 0, blockEndLines.length);
        System.arraycopy(blockIndices, 0, mBlockIndices, 0, blockIndices.length);
        mNumberOfBlocks = numberOfBlocks;
        while (mInts.size() < totalLines) {
            mInts.insertAt(mInts.size(), new int[COLUMNS_NORMAL]);
        }
    }

    
@hide
/**
     * @hide
     */
    public int[] getBlockEndLines() {
        return mBlockEndLines;
    }

    
@hide
/**
     * @hide
     */
    public int[] getBlockIndices() {
        return mBlockIndices;
    }

    
@hide
/**
     * @hide
     */
    public int getBlockIndex(int index) {
        return mBlockIndices[index];
    }

    
Params:
  • index – 
@hide
/**
     * @hide
     * @param index
     */
    public void setBlockIndex(int index, int blockIndex) {
        mBlockIndices[index] = blockIndex;
    }

    
@hide
/**
     * @hide
     */
    public int getNumberOfBlocks() {
        return mNumberOfBlocks;
    }

    
@hide
/**
     * @hide
     */
    public int getIndexFirstChangedBlock() {
        return mIndexFirstChangedBlock;
    }

    
@hide
/**
     * @hide
     */
    public void setIndexFirstChangedBlock(int i) {
        mIndexFirstChangedBlock = i;
    }

    @Override
    public int getLineCount() {
        return mInts.size() - 1;
    }

    @Override
    public int getLineTop(int line) {
        return mInts.getValue(line, TOP);
    }

    @Override
    public int getLineDescent(int line) {
        return mInts.getValue(line, DESCENT);
    }

    
@hide
/**
     * @hide
     */
    @Override
    public int getLineExtra(int line) {
        return mInts.getValue(line, EXTRA);
    }

    @Override
    public int getLineStart(int line) {
        return mInts.getValue(line, START) & START_MASK;
    }

    @Override
    public boolean getLineContainsTab(int line) {
        return (mInts.getValue(line, TAB) & TAB_MASK) != 0;
    }

    @Override
    public int getParagraphDirection(int line) {
        return mInts.getValue(line, DIR) >> DIR_SHIFT;
    }

    @Override
    public final Directions getLineDirections(int line) {
        return mObjects.getValue(line, 0);
    }

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

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

    
@hide
/**
     * @hide
     */
    @Override
    public int getHyphen(int line) {
        return mInts.getValue(line, HYPHEN) & HYPHEN_MASK;
    }

    private boolean getContentMayProtrudeFromTopOrBottom(int line) {
        return (mInts.getValue(line, MAY_PROTRUDE_FROM_TOP_OR_BOTTOM)
                & MAY_PROTRUDE_FROM_TOP_OR_BOTTOM_MASK) != 0;
    }

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

    private static class ChangeWatcher implements TextWatcher, SpanWatcher {
        public ChangeWatcher(DynamicLayout layout) {
            mLayout = new WeakReference<>(layout);
        }

        private void reflow(CharSequence s, int where, int before, int after) {
            DynamicLayout ml = mLayout.get();

            if (ml != null) {
                ml.reflow(s, where, before, after);
            } else if (s instanceof Spannable) {
                ((Spannable) s).removeSpan(this);
            }
        }

        public void beforeTextChanged(CharSequence s, int where, int before, int after) {
            // Intentionally empty
        }

        public void onTextChanged(CharSequence s, int where, int before, int after) {
            reflow(s, where, before, after);
        }

        public void afterTextChanged(Editable s) {
            // Intentionally empty
        }

        public void onSpanAdded(Spannable s, Object o, int start, int end) {
            if (o instanceof UpdateLayout)
                reflow(s, start, end - start, end - start);
        }

        public void onSpanRemoved(Spannable s, Object o, int start, int end) {
            if (o instanceof UpdateLayout)
                reflow(s, start, end - start, end - start);
        }

        public void onSpanChanged(Spannable s, Object o, int start, int end, int nstart, int nend) {
            if (o instanceof UpdateLayout) {
                if (start > end) {
                    // Bug: 67926915 start cannot be determined, fallback to reflow from start
                    // instead of causing an exception
                    start = 0;
                }
                reflow(s, start, end - start, end - start);
                reflow(s, nstart, nend - nstart, nend - nstart);
            }
        }

        private WeakReference<DynamicLayout> mLayout;
    }

    @Override
    public int getEllipsisStart(int line) {
        if (mEllipsizeAt == null) {
            return 0;
        }

        return mInts.getValue(line, ELLIPSIS_START);
    }

    @Override
    public int getEllipsisCount(int line) {
        if (mEllipsizeAt == null) {
            return 0;
        }

        return mInts.getValue(line, ELLIPSIS_COUNT);
    }

    private CharSequence mBase;
    private CharSequence mDisplay;
    private ChangeWatcher mWatcher;
    private boolean mIncludePad;
    private boolean mFallbackLineSpacing;
    private boolean mEllipsize;
    private int mEllipsizedWidth;
    private TextUtils.TruncateAt mEllipsizeAt;
    private int mBreakStrategy;
    private int mHyphenationFrequency;
    private int mJustificationMode;

    private PackedIntVector mInts;
    private PackedObjectVector<Directions> mObjects;

    
Value used in mBlockIndices when a block has been created or recycled and indicating that its
display list needs to be re-created.

@hide
/**
     * Value used in mBlockIndices when a block has been created or recycled and indicating that its
     * display list needs to be re-created.
     * @hide
     */
    public static final int INVALID_BLOCK_INDEX = -1;
    // Stores the line numbers of the last line of each block (inclusive)
    private int[] mBlockEndLines;
    // The indices of this block's display list in TextView's internal display list array or
    // INVALID_BLOCK_INDEX if this block has been invalidated during an edition
    private int[] mBlockIndices;
    // Set of blocks that always need to be redrawn.
    private ArraySet<Integer> mBlocksAlwaysNeedToBeRedrawn;
    // Number of items actually currently being used in the above 2 arrays
    private int mNumberOfBlocks;
    // The first index of the blocks whose locations are changed
    private int mIndexFirstChangedBlock;

    private int mTopPadding, mBottomPadding;

    private Rect mTempRect = new Rect();

    private static StaticLayout sStaticLayout = null;
    private static StaticLayout.Builder sBuilder = null;

    private static final Object[] sLock = new Object[0];

    // START, DIR, and TAB share the same entry.
    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;
    // HYPHEN and MAY_PROTRUDE_FROM_TOP_OR_BOTTOM share the same entry.
    private static final int HYPHEN = 4;
    private static final int MAY_PROTRUDE_FROM_TOP_OR_BOTTOM = HYPHEN;
    private static final int COLUMNS_NORMAL = 5;

    private static final int ELLIPSIS_START = 5;
    private static final int ELLIPSIS_COUNT = 6;
    private static final int COLUMNS_ELLIPSIZE = 7;

    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 MAY_PROTRUDE_FROM_TOP_OR_BOTTOM_MASK = 0x100;

    private static final int ELLIPSIS_UNDEFINED = 0x80000000;
}