Package org.apache.fop.layoutmgr

Class AbstractBreaker

java.lang.Object
org.apache.fop.layoutmgr.AbstractBreaker
Direct Known Subclasses:
LocalBreaker, PageBreaker
public abstract class AbstractBreaker extends Object
Abstract base class for breakers (page breakers, static region handlers etc.).

  • Field Details

    • log

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

    • originalRestartAtLM

      protected LayoutManager originalRestartAtLM

    • positionAtBreak

      protected Position positionAtBreak

    • firstElementsForRestart

      protected List firstElementsForRestart

    • pslm

      protected PageSequenceLayoutManager pslm

    • blockLists

      protected List<AbstractBreaker.BlockSequence> blockLists

    • blockListIndex

      protected int blockListIndex
      blockListIndex of the current BlockSequence in blockLists

    • alignment

      protected int alignment
      desired text alignment

    • footnoteSeparatorLength

      protected MinOptMax footnoteSeparatorLength
      footnote separator length

  • Constructor Details

    • AbstractBreaker

      public AbstractBreaker()

  • Method Details

    • 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 org.apache.fop.layoutmgr.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 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 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, boolean emptyContent)
      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(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 boolean 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)

    • containsNonRestartableLM

      protected boolean containsNonRestartableLM(Position position)
      Returns true if the given position or one of its descendants corresponds to a non-restartable LM.
      Parameters:
      position - a position
      Returns:
      true if there is a non-restartable LM in the hierarchy

    • 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)

    • addAreas

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

    • shouldRedoLayout

      protected boolean shouldRedoLayout()

    • prepareToRedoLayout

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

    • wasLayoutRedone

      protected boolean wasLayoutRedone()

    • lastPageHasIPDChange

      protected boolean lastPageHasIPDChange(int optimalPageCount)

    • handleFloatLayout

      protected int handleFloatLayout(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg, int optimalPageCount, AbstractBreaker.BlockSequence blockList, LayoutContext childLC)

    • addAreasForFloats

      protected void addAreasForFloats(org.apache.fop.layoutmgr.PageBreakingAlgorithm alg, int startPart, int partCount, AbstractBreaker.BlockSequence originalList, AbstractBreaker.BlockSequence effectiveList, LayoutContext childLC, int lastBreak, int startElementIndex, int endElementIndex)