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## org.apache.fop.layoutmgr
Class AbstractBreaker

    java.lang.Object
      org.apache.fop.layoutmgr.AbstractBreaker

Direct Known Subclasses:
  PageBreaker

    public abstract class AbstractBreaker

extends java.lang.Object

Abstract base class for breakers (page breakers, static region handlers etc.).

Nested Class Summary
`class` | `AbstractBreaker.BlockSequence` Helper class, extending the functionality of the basic `BlockKnuthSequence`.
`static class` | `AbstractBreaker.PageBreakPosition` A page break position.

Field Summary
`protected int` | `alignment` desired text alignment
`protected MinOptMax` | `footnoteSeparatorLength` footnote separator length
`protected static org.apache.commons.logging.Log` | `log` logging instance

Constructor Summary
`AbstractBreaker()`

Method Summary
`protected void` | `addAreas(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg, int partCount, AbstractBreaker.BlockSequence originalList, AbstractBreaker.BlockSequence effectiveList)` Phase 3 of Knuth algorithm: Adds the areas
`protected void` | `addAreas(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg, int startPart, int partCount, AbstractBreaker.BlockSequence originalList, AbstractBreaker.BlockSequence effectiveList)` Phase 3 of Knuth algorithm: Adds the areas
`protected abstract void` | `addAreas(PositionIterator posIter, LayoutContext context)` Tell the layout manager to add all the child areas implied by Position objects which will be returned by the Iterator.
`protected LayoutContext` | `createLayoutContext()` Creates the top-level LayoutContext for the breaker operation.
`protected PageBreakingAlgorithm.PageBreakingLayoutListener` | `createLayoutListener()` Creates and returns a PageBreakingLayoutListener for the PageBreakingAlgorithm to notify about layout problems.
`void` | `doLayout(int flowBPD, boolean autoHeight)` Starts the page breaking process.
`protected abstract void` | `doPhase3(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg, int partCount, AbstractBreaker.BlockSequence originalList, AbstractBreaker.BlockSequence effectiveList)` Phase 3 of Knuth algorithm: Adds the areas
`protected abstract void` | `finishPart(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg, AbstractBreaker.PageBreakPosition pbp)` Finish part.
`protected abstract LayoutManager` | `getCurrentChildLM()`
`protected abstract int` | `getCurrentDisplayAlign()`
`protected int` | `getNextBlockList(LayoutContext childLC, int nextSequenceStartsOn)` Gets the next block list (sequence) and adds it to a list of block lists if it's not empty.
`protected int` | `getNextBlockList(LayoutContext childLC, int nextSequenceStartsOn, Position positionAtIPDChange, LayoutManager restartAtLM, java.util.List<KnuthElement> firstElements)` Gets the next block list (sequence) and adds it to a list of block lists if it's not empty.
`protected abstract java.util.List<KnuthElement>` | `getNextKnuthElements(LayoutContext context, int alignment)` Get a sequence of KnuthElements representing the content of the node assigned to the LM
`protected java.util.List<KnuthElement>` | `getNextKnuthElements(LayoutContext context, int alignment, Position positionAtIPDChange, LayoutManager restartAtLM)` Get a sequence of KnuthElements representing the content of the node assigned to the LM
`protected PageProvider` | `getPageProvider()` Returns the PageProvider if any.
`protected abstract LayoutManager` | `getTopLevelLM()`
`protected void` | `handleEmptyContent()` This method is called when no content is available for a part.
`protected int` | `handleSpanChange(LayoutContext childLC, int nextSequenceStartsOn)` Handles span changes reported through the `LayoutContext`.
`protected abstract boolean` | `hasMoreContent()`
`boolean` | `isEmpty()`
`protected boolean` | `isPartOverflowRecoveryActivated()` Controls the behaviour of the algorithm in cases where the first element of a part overflows a line/page.
`protected boolean` | `isSinglePartFavored()`
`protected void` | `observeElementList(java.util.List elementList)` Used for debugging purposes.
`protected void` | `startPart(AbstractBreaker.BlockSequence list, int breakClass)` Start part.
`protected void` | `updateLayoutContext(LayoutContext context)` Used to update the LayoutContext in subclasses prior to starting a new element list.

Methods inherited from class java.lang.Object
`clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Field Detail

### log

    protected static final org.apache.commons.logging.Log log

  logging instance

### alignment

    protected int alignment

  desired text alignment

### footnoteSeparatorLength

    protected MinOptMax footnoteSeparatorLength

  footnote separator length

Constructor Detail

### AbstractBreaker

    public AbstractBreaker()

Method Detail

### getCurrentDisplayAlign

    protected abstract int getCurrentDisplayAlign()

  Returns:
    current display alignment

### hasMoreContent

    protected abstract boolean hasMoreContent()

  Returns:
    true if content not exhausted

### addAreas

    protected abstract void addAreas(PositionIterator posIter,
                                     LayoutContext context)

  Tell the layout manager to add all the child areas implied by Position objects which will be returned by the Iterator.

  Parameters:
    `posIter` - the position iterator
    `context` - the context

### getTopLevelLM

    protected abstract LayoutManager getTopLevelLM()

  Returns:
    top level layout manager

### getCurrentChildLM

    protected abstract LayoutManager getCurrentChildLM()

  Returns:
    current child layout manager

### isPartOverflowRecoveryActivated

    protected boolean isPartOverflowRecoveryActivated()

  Controls the behaviour of the algorithm in cases where the first element of a part overflows a line/page.

  Returns:
    true if the algorithm should try to send the element to the next line/page.

### isSinglePartFavored

    protected boolean isSinglePartFavored()

  Returns:
    true if one a single part should be produced if possible (ex. for block-containers)

### getPageProvider

    protected PageProvider getPageProvider()

  Returns the PageProvider if any. PageBreaker overrides this method because each page may have a different available BPD which needs to be accessible to the breaking algorithm.

  Returns:
    the applicable PageProvider, or null if not applicable

### createLayoutListener

    protected PageBreakingAlgorithm.PageBreakingLayoutListener createLayoutListener()

  Creates and returns a PageBreakingLayoutListener for the PageBreakingAlgorithm to notify about layout problems.

  Returns:
    the listener instance or null if no notifications are needed

### getNextKnuthElements

    protected abstract java.util.List<KnuthElement> getNextKnuthElements(LayoutContext context,
                                                                         int alignment)

  Get a sequence of KnuthElements representing the content of the node assigned to the LM

  Parameters:
    `context` - the LayoutContext used to store layout information
    `alignment` - the desired text alignment
  Returns:
    the list of KnuthElements

### getNextKnuthElements

    protected java.util.List<KnuthElement> getNextKnuthElements(LayoutContext context,
                                                                int alignment,
                                                                Position positionAtIPDChange,
                                                                LayoutManager restartAtLM)

  Get a sequence of KnuthElements representing the content of the node assigned to the LM

  Parameters:
    `context` - the LayoutContext used to store layout information
    `alignment` - the desired text alignment
    `positionAtIPDChange` - last element on the part before an IPD change
    `restartAtLM` - the layout manager from which to restart, if IPD change occurs between two LMs
  Returns:
    the list of KnuthElements

### isEmpty

    public boolean isEmpty()

  Returns:
    true if there's no content that could be handled.

### startPart

    protected void startPart(AbstractBreaker.BlockSequence list,
                             int breakClass)

  Start part.

  Parameters:
    `list` - a block sequence
    `breakClass` - a break class

### handleEmptyContent

    protected void handleEmptyContent()

  This method is called when no content is available for a part. Used to force empty pages.

### finishPart

    protected abstract void finishPart(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg,
                                       AbstractBreaker.PageBreakPosition pbp)

  Finish part.

  Parameters:
    `alg` - a page breaking algorithm
    `pbp` - a page break posittion

### createLayoutContext

    protected LayoutContext createLayoutContext()

  Creates the top-level LayoutContext for the breaker operation.

  Returns:
    the top-level LayoutContext

### updateLayoutContext

    protected void updateLayoutContext(LayoutContext context)

  Used to update the LayoutContext in subclasses prior to starting a new element list.

  Parameters:
    `context` - the LayoutContext to update

### observeElementList

    protected void observeElementList(java.util.List elementList)

  Used for debugging purposes. Notifies all registered observers about the element list. Override to set different parameters.

  Parameters:
    `elementList` - the Knuth element list

### doLayout

    public void doLayout(int flowBPD,
                         boolean autoHeight)

  Starts the page breaking process.

  Parameters:
    `flowBPD` - the constant available block-progression-dimension (used for every part)
    `autoHeight` - true if warnings about overflows should be disabled because the the BPD is really undefined (for footnote-separators, for example)

### doPhase3

    protected abstract void doPhase3(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg,
                                     int partCount,
                                     AbstractBreaker.BlockSequence originalList,
                                     AbstractBreaker.BlockSequence effectiveList)

  Phase 3 of Knuth algorithm: Adds the areas

  Parameters:
    `alg` - PageBreakingAlgorithm instance which determined the breaks
    `partCount` - number of parts (pages) to be rendered
    `originalList` - original Knuth element list
    `effectiveList` - effective Knuth element list (after adjustments)

### addAreas

    protected void addAreas(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg,
                            int partCount,
                            AbstractBreaker.BlockSequence originalList,
                            AbstractBreaker.BlockSequence effectiveList)

  Phase 3 of Knuth algorithm: Adds the areas

  Parameters:
    `alg` - PageBreakingAlgorithm instance which determined the breaks
    `partCount` - number of parts (pages) to be rendered
    `originalList` - original Knuth element list
    `effectiveList` - effective Knuth element list (after adjustments)

### addAreas

    protected void addAreas(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg,
                            int startPart,
                            int partCount,
                            AbstractBreaker.BlockSequence originalList,
                            AbstractBreaker.BlockSequence effectiveList)

  Phase 3 of Knuth algorithm: Adds the areas

  Parameters:
    `alg` - PageBreakingAlgorithm instance which determined the breaks
    `startPart` - index of the first part (page) to be rendered
    `partCount` - number of parts (pages) to be rendered
    `originalList` - original Knuth element list
    `effectiveList` - effective Knuth element list (after adjustments)

### handleSpanChange

    protected int handleSpanChange(LayoutContext childLC,
                                   int nextSequenceStartsOn)

  Handles span changes reported through the `LayoutContext`. Only used by the PSLM and called by `getNextBlockList()`.

  Parameters:
    `childLC` - the LayoutContext
    `nextSequenceStartsOn` - previous value for break handling
  Returns:
    effective value for break handling

### getNextBlockList

    protected int getNextBlockList(LayoutContext childLC,
                                   int nextSequenceStartsOn)

  Gets the next block list (sequence) and adds it to a list of block lists if it's not empty.

  Parameters:
    `childLC` - LayoutContext to use
    `nextSequenceStartsOn` - indicates on what page the next sequence should start
  Returns:
    the page on which the next content should appear after a hard break

### getNextBlockList

    protected int getNextBlockList(LayoutContext childLC,
                                   int nextSequenceStartsOn,
                                   Position positionAtIPDChange,
                                   LayoutManager restartAtLM,
                                   java.util.List<KnuthElement> firstElements)

  Gets the next block list (sequence) and adds it to a list of block lists if it's not empty.

  Parameters:
    `childLC` - LayoutContext to use
    `nextSequenceStartsOn` - indicates on what page the next sequence should start
    `positionAtIPDChange` - last element on the part before an IPD change
    `restartAtLM` - the layout manager from which to restart, if IPD change occurs between two LMs
    `firstElements` - elements from non-restartable LMs on the new page
  Returns:
    the page on which the next content should appear after a hard break

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