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DynamicLayout.javaAPI DocAndroid 5.1 API25220Thu Mar 12 22:22:10 GMT 2015android.text

DynamicLayout

public class DynamicLayout extends Layout
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 {@link android.graphics.Canvas#drawText(java.lang.CharSequence, int, int, float, float, android.graphics.Paint) Canvas.drawText()} directly.

Fields Summary
private static final int
PRIORITY
private static final int
BLOCK_MINIMUM_CHARACTER_LENGTH
private CharSequence
mBase
private CharSequence
mDisplay
private ChangeWatcher
mWatcher
private boolean
mIncludePad
private boolean
mEllipsize
private int
mEllipsizedWidth
private TextUtils.TruncateAt
mEllipsizeAt
private PackedIntVector
mInts
private PackedObjectVector
mObjects
public static final int
INVALID_BLOCK_INDEX
Value used in mBlockIndices when a block has been created or recycled and indicating that its display list needs to be re-created.
private int[]
mBlockEndLines
private int[]
mBlockIndices
private int
mNumberOfBlocks
private int
mIndexFirstChangedBlock
private int
mTopPadding
private int
mBottomPadding
private static StaticLayout
sStaticLayout
private static final Object[]
sLock
private static final int
START
private static final int
DIR
private static final int
TAB
private static final int
TOP
private static final int
DESCENT
private static final int
COLUMNS_NORMAL
private static final int
ELLIPSIS_START
private static final int
ELLIPSIS_COUNT
private static final int
COLUMNS_ELLIPSIZE
private static final int
START_MASK
private static final int
DIR_SHIFT
private static final int
TAB_MASK
private static final int
ELLIPSIS_UNDEFINED
Constructors Summary
public DynamicLayout(CharSequence base, TextPaint paint, int width, Alignment align, float spacingmult, float spacingadd, boolean includepad)
Make a layout for the specified text that will be updated as the text is changed.


                         
      
                          
                            
                            
                           
        this(base, base, paint, width, align, spacingmult, spacingadd,
             includepad);
public DynamicLayout(CharSequence base, CharSequence display, TextPaint paint, int width, Alignment align, float spacingmult, float spacingadd, boolean includepad)
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.

        this(base, display, paint, width, align, spacingmult, spacingadd,
             includepad, null, 0);
public DynamicLayout(CharSequence base, CharSequence display, TextPaint paint, int width, Alignment align, float spacingmult, float spacingadd, boolean includepad, TextUtils.TruncateAt ellipsize, int 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.

        this(base, display, paint, width, align, TextDirectionHeuristics.FIRSTSTRONG_LTR,
                spacingmult, spacingadd, includepad, ellipsize, ellipsizedWidth);
public DynamicLayout(CharSequence base, CharSequence display, TextPaint paint, int width, Alignment align, TextDirectionHeuristic textDir, float spacingmult, float spacingadd, boolean includepad, TextUtils.TruncateAt ellipsize, int 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

        super((ellipsize == null)
                ? display
                : (display instanceof Spanned)
                    ? new SpannedEllipsizer(display)
                    : new Ellipsizer(display),
              paint, width, align, textDir, spacingmult, spacingadd);

        mBase = base;
        mDisplay = display;

        if (ellipsize != null) {
            mInts = new PackedIntVector(COLUMNS_ELLIPSIZE);
            mEllipsizedWidth = ellipsizedWidth;
            mEllipsizeAt = ellipsize;
        } else {
            mInts = new PackedIntVector(COLUMNS_NORMAL);
            mEllipsizedWidth = width;
            mEllipsizeAt = null;
        }

        mObjects = new PackedObjectVector<Directions>(1);

        mIncludePad = includepad;

        /*
         * 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.
         *
         * 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;
            mEllipsize = true;
        }

        // 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 (ellipsize != null) {
            start = new int[COLUMNS_ELLIPSIZE];
            start[ELLIPSIS_START] = ELLIPSIS_UNDEFINED;
        } else {
            start = new int[COLUMNS_NORMAL];
        }

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

        Paint.FontMetricsInt fm = paint.getFontMetricsInt();
        int asc = fm.ascent;
        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);

        // Update from 0 characters to whatever the real text is
        reflow(base, 0, 0, base.length());

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

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

            sp.setSpan(mWatcher, 0, base.length(),
                       Spannable.SPAN_INCLUSIVE_INCLUSIVE |
                       (PRIORITY << Spannable.SPAN_PRIORITY_SHIFT));
        }
Methods Summary
private voidaddBlockAtOffset(int offset)
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.

        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;
            mNumberOfBlocks++;
            return;
        }

        final int previousBlockEndLine = mBlockEndLines[mNumberOfBlocks - 1];
        if (line > previousBlockEndLine) {
            mBlockEndLines = GrowingArrayUtils.append(mBlockEndLines, mNumberOfBlocks, line);
            mNumberOfBlocks++;
        }
private voidcreateBlocks()
Create the initial block structure, cutting the text into blocks of at least BLOCK_MINIMUM_CHARACTER_SIZE characters, aligned on the ends of paragraphs.

        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;
        }
public int[]getBlockEndLines()

hide

        return mBlockEndLines;
public int[]getBlockIndices()

hide

        return mBlockIndices;
public intgetBottomPadding()

        return mBottomPadding;
public intgetEllipsisCount(int line)

        if (mEllipsizeAt == null) {
            return 0;
        }

        return mInts.getValue(line, ELLIPSIS_COUNT);
public intgetEllipsisStart(int line)

        if (mEllipsizeAt == null) {
            return 0;
        }

        return mInts.getValue(line, ELLIPSIS_START);
public intgetEllipsizedWidth()

        return mEllipsizedWidth;
public intgetIndexFirstChangedBlock()

hide

        return mIndexFirstChangedBlock;
public booleangetLineContainsTab(int line)

        return (mInts.getValue(line, TAB) & TAB_MASK) != 0;
public intgetLineCount()

        return mInts.size() - 1;
public intgetLineDescent(int line)

        return mInts.getValue(line, DESCENT);
public final DirectionsgetLineDirections(int line)

        return mObjects.getValue(line, 0);
public intgetLineStart(int line)

        return mInts.getValue(line, START) & START_MASK;
public intgetLineTop(int line)

        return mInts.getValue(line, TOP);
public intgetNumberOfBlocks()

hide

        return mNumberOfBlocks;
public intgetParagraphDirection(int line)

        return mInts.getValue(line, DIR) >> DIR_SHIFT;
public intgetTopPadding()

        return mTopPadding;
private voidreflow(java.lang.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;

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

        if (reflowed == null) {
            reflowed = new StaticLayout(null);
        } else {
            reflowed.prepare();
        }

        reflowed.generate(text, where, where + after,
                getPaint(), getWidth(), getTextDirectionHeuristic(), getSpacingMultiplier(),
                getSpacingAdd(), false,
                true, mEllipsizedWidth, mEllipsizeAt);
        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++) {
            ints[START] = reflowed.getLineStart(i) |
                          (reflowed.getParagraphDirection(i) << DIR_SHIFT) |
                          (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;
            objects[0] = reflowed.getLineDirections(i);

            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);

        synchronized (sLock) {
            sStaticLayout = reflowed;
            reflowed.finish();
        }
voidsetBlocksDataForTest(int[] blockEndLines, int[] blockIndices, int numberOfBlocks)
This package private method is used for test purposes only

hide

        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;
public voidsetIndexFirstChangedBlock(int i)

hide

        mIndexFirstChangedBlock = i;
voidupdateBlocks(int startLine, int endLine, int newLineCount)
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. This method is package private and not private so that it can be tested.

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

        if (mBlockEndLines == null) {
            createBlocks();
            return;
        }

        int firstBlock = -1;
        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];

        boolean createBlockBefore = startLine > (firstBlock == 0 ? 0 :
                mBlockEndLines[firstBlock - 1] + 1);
        boolean createBlock = newLineCount > 0;
        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 {
            System.arraycopy(mBlockEndLines, lastBlock + 1,
                    mBlockEndLines, firstBlock + numAddedBlocks, mNumberOfBlocks - lastBlock - 1);
            System.arraycopy(mBlockIndices, lastBlock + 1,
                    mBlockIndices, firstBlock + numAddedBlocks, mNumberOfBlocks - lastBlock - 1);
        }

        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;
            mBlockIndices[blockIndex] = INVALID_BLOCK_INDEX;
            blockIndex++;
        }

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

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