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Commit 71afc39d authored by Gilles Debunne's avatar Gilles Debunne
Browse files

Cut long text into multiple DL at start 

Bug 5763685

To improve performance, preventively cut the the into display
list of 3-10 lines of text. Further updates to small parts of
the text (such as adding an underline on a word) will only
invalidate and redraw the affected sub display list.

DLs are aligned with paragraphs, just like they will be during
text edition.

Change-Id: I0d60debc7fdaea8b29080a6eacb2d60205e7d547
parent c2e393f8

core/java/android/text/DynamicLayout.java

+65 −8
Original line number Diff line number Diff line
@@ -35,6 +35,7 @@ import java.lang.ref.WeakReference; 
public class DynamicLayout extends Layout

{

    private static final int PRIORITY = 128;

    private static final int BLOCK_MINIMUM_CHARACTER_LENGTH = 400;



    /**

     * Make a layout for the specified text that will be updated as
@@ -117,10 +118,6 @@ public class DynamicLayout extends Layout 


        mObjects = new PackedObjectVector<Directions>(1);



        mBlockEndLines = new int[] { 0 };

        mBlockIndices = new int[] { INVALID_BLOCK_INDEX };

        mNumberOfBlocks = 1;



        mIncludePad = includepad;



        /*
@@ -170,7 +167,6 @@ public class DynamicLayout extends Layout 
        mObjects.insertAt(0, dirs);



        // Update from 0 characters to whatever the real text is



        reflow(base, 0, 0, base.length());



        if (base instanceof Spannable) {
@@ -295,14 +291,12 @@ public class DynamicLayout extends Layout 
        // 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)

        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);

        updateBlocks(startline, endline - 1, n);



        // adjust offsets in layout for new height and offsets
@@ -362,12 +356,70 @@ public class DynamicLayout extends Layout 
            mObjects.insertAt(startline + i, objects);

        }



        updateBlocks(startline, endline - 1, n);



        synchronized (sLock) {

            sStaticLayout = reflowed;

            reflowed.finish();

        }

    }



    /**

     * 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;

        }

    }



    /**

     * 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 = new int[ArrayUtils.idealIntArraySize(1)];

            mBlockEndLines[mNumberOfBlocks] = line;

            mNumberOfBlocks++;

            return;

        }



        final int previousBlockEndLine = mBlockEndLines[mNumberOfBlocks - 1];

        if (line > previousBlockEndLine) {

            if (mNumberOfBlocks == mBlockEndLines.length) {

                // Grow the array if needed

                int[] blockEndLines = new int[ArrayUtils.idealIntArraySize(mNumberOfBlocks + 1)];

                System.arraycopy(mBlockEndLines, 0, blockEndLines, 0, mNumberOfBlocks);

                mBlockEndLines = blockEndLines;

            }

            mBlockEndLines[mNumberOfBlocks] = line;

            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
@@ -388,6 +440,11 @@ public class DynamicLayout extends Layout 
     * @hide

     */

    void updateBlocks(int startLine, int endLine, int newLineCount) {

        if (mBlockEndLines == null) {

            createBlocks();

            return;

        }



        int firstBlock = -1;

        int lastBlock = -1;

        for (int i = 0; i < mNumberOfBlocks; i++) {