pjs/layout/base/nsBidiPresUtils.h

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#ifdef IBMBIDI

#ifndef nsBidiPresUtils_h___
#define nsBidiPresUtils_h___

#include "nsVoidArray.h"
#include "nsIFrame.h"
#include "nsBidi.h"
#include "nsBidiUtils.h"
#include "nsCOMPtr.h"
#include "nsDataHashtable.h"
#include "nsBlockFrame.h"

/**
 * A structure representing a logical position which should be resolved
 * into its visual position during BiDi processing.
 */
struct nsBidiPositionResolve
{
  // [in] Logical index within string.
  PRInt32 logicalIndex;
  // [out] Visual index within string.
  // If the logical position was not found, set to kNotFound.
  PRInt32 visualIndex;
  // [out] Visual position of the character, from the left (on the X axis), in twips.
  // Eessentially, this is the X position (relative to the rendering context) where the text was drawn + the font metric of the visual string to the left of the given logical position.
  // If the logical position was not found, set to kNotFound.
  PRInt32 visualLeftTwips;
};

class nsBidiPresUtils {
public:
  nsBidiPresUtils();
  ~nsBidiPresUtils();
  PRBool IsSuccessful(void) const;
  
  /**
   * Make Bidi engine calculate the embedding levels of the frames that are
   * descendants of a given block frame.
   *
   * @param aPresContext         The presContext
   * @param aBlockFrame          The block frame
   * @param aFirstChild          The first child frame of aBlockFrame
   * @param aIsVisualFormControl [IN]  Set if we are in a form control on a
   *                                   visual page.
   *                                   @see nsHTMLReflowState::IsBidiFormControl
   *
   *  @lina 06/18/2000
   */
  nsresult Resolve(nsPresContext* aPresContext,
                   nsBlockFrame*   aBlockFrame,
                   nsIFrame*       aFirstChild,
                   PRBool          aIsVisualFormControl);

  /**
   * Reorder this line using Bidi engine.
   * Update frame array, following the new visual sequence.
   * 
   * @lina 05/02/2000
   */
  void ReorderFrames(nsPresContext*      aPresContext,
                     nsIRenderingContext* aRendContext,
                     nsIFrame*            aFirstFrameOnLine,
                     PRInt32              aNumFramesOnLine);

  /**
   * Format Unicode text, taking into account bidi capabilities
   * of the platform. The formatting includes: reordering, Arabic shaping,
   * symmetric and numeric swapping, removing control characters.
   *
   * @lina 06/18/2000 
   */
  nsresult FormatUnicodeText(nsPresContext* aPresContext,
                             PRUnichar*      aText,
                             PRInt32&        aTextLength,
                             nsCharType      aCharType,
                             PRBool          aIsOddLevel,
                             PRBool          aIsBidiSystem);

  /**
   * Reorder Unicode text, taking into account bidi capabilities of the
   * platform. The reordering includes symmetric swapping and removing
   * control characters.
   */
  nsresult ReorderUnicodeText(PRUnichar*      aText,
                              PRInt32&        aTextLength,
                              nsCharType      aCharType,
                              PRBool          aIsOddLevel,
                              PRBool          aIsBidiSystem);

  /**
   * Return our nsBidi object (bidi reordering engine)
   */
  nsresult GetBidiEngine(nsBidi** aBidiEngine);

  /**
   * Reorder plain text using the Unicode Bidi algorithm and send it to
   * a rendering context for rendering.
   *
   * @param[in] aText  the string to be rendered (in logical order)
   * @param aLength the number of characters in the string
   * @param aBaseDirection the base direction of the string
   *  NSBIDI_LTR - left-to-right string
   *  NSBIDI_RTL - right-to-left string
   * @param aPresContext the presentation context
   * @param aRenderingContext the rendering context
   * @param aX the x-coordinate to render the string
   * @param aY the y-coordinate to render the string
   * @param[in,out] aPosResolve array of logical positions to resolve into visual positions; can be nsnull if this functionality is not required
   * @param aPosResolveCount number of items in the aPosResolve array
   */
  nsresult RenderText(const PRUnichar*     aText,
                      PRInt32              aLength,
                      nsBidiDirection      aBaseDirection,
                      nsPresContext*      aPresContext,
                      nsIRenderingContext& aRenderingContext,
                      nscoord              aX,
                      nscoord              aY,
                      nsBidiPositionResolve* aPosResolve = nsnull,
                      PRInt32              aPosResolveCount = 0);

  /**
   * Check if a line is reordered, i.e., if the child frames are not
   * all laid out left-to-right.
   * @param aFirstFrameOnLine : first frame of the line to be tested
   * @param aNumFramesOnLine : number of frames on this line
   * @param[out] aLeftMost : leftmost frame on this line
   * @param[out] aRightMost : rightmost frame on this line
   */
  PRBool CheckLineOrder(nsIFrame*  aFirstFrameOnLine,
                        PRInt32    aNumFramesOnLine,
                        nsIFrame** aLeftmost,
                        nsIFrame** aRightmost);

  /**
   * Get the frame to the right of the given frame, on the same line.
   * @param aFrame : We're looking for the frame to the right of this frame.
   *                 If null, return the leftmost frame on the line.
   * @param aFirstFrameOnLine : first frame of the line to be tested
   * @param aNumFramesOnLine : number of frames on this line
   */
  nsIFrame* GetFrameToRightOf(const nsIFrame*  aFrame,
                              nsIFrame*        aFirstFrameOnLine,
                              PRInt32          aNumFramesOnLine);
    
  /**
   * Get the frame to the left of the given frame, on the same line.
   * @param aFrame : We're looking for the frame to the left of this frame.
   *                 If null, return the rightmost frame on the line.
   * @param aFirstFrameOnLine : first frame of the line to be tested
   * @param aNumFramesOnLine : number of frames on this line
   */
  nsIFrame* GetFrameToLeftOf(const nsIFrame*  aFrame,
                             nsIFrame*        aFirstFrameOnLine,
                             PRInt32          aNumFramesOnLine);
    
  /**
   * Get the bidi embedding level of the given (inline) frame.
   */
  static nsBidiLevel GetFrameEmbeddingLevel(nsIFrame* aFrame);

  /**
   * Get the bidi base level of the given (inline) frame.
   */
  static nsBidiLevel GetFrameBaseLevel(nsIFrame* aFrame);

private:
  /**
   *  Create a string containing entire text content of this block.
   *
   *  @lina 05/02/2000
   */
  void CreateBlockBuffer(nsPresContext* aPresContext);

  /**
   * Set up an array of the frames after splitting frames so that each frame has
   * consistent directionality. At this point the frames are still in logical
   * order
   */
  nsresult InitLogicalArray(nsPresContext* aPresContext,
                            nsIFrame*       aCurrentFrame,
                            nsIFrame*       aNextInFlow,
                            PRBool          aAddMarkers = PR_FALSE);

  /**
   * Initialize the logically-ordered array of frames
   * using the top-level frames of a single line
   */
  void InitLogicalArrayFromLine(nsIFrame* aFirstFrameOnLine,
                                PRInt32   aNumFramesOnLine);

  /**
   * Reorder the frame array from logical to visual order
   * 
   * @param aReordered TRUE on return if the visual order is different from
   *                   the logical order
   * @param aHasRTLFrames TRUE on return if at least one of the frames is RTL
   *                      (and therefore might have reordered descendents)
   */
  nsresult Reorder(PRBool& aReordered, PRBool& aHasRTLFrames);
  
  /**
   *  Adjust frame positions following their visual order
   *
   *  @param  <code>nsPresContext*</code>, the first kid
   *
   *  @lina 04/11/2000
   */
  void RepositionInlineFrames(nsPresContext*      aPresContext,
                              nsIRenderingContext* aRendContext,
                              nsIFrame*            aFirstChild,
                              PRBool               aReordered) const;
  
  void RepositionContainerFrame(nsPresContext* aPresContext,
                                nsIFrame*       aContainer,
                                PRInt32&        aMinX,
                                PRInt32&        aMaxX) const;
  /**
   * Helper method for Resolve()
   * Truncate a text frame and possibly create a continuation frame with the
   * remainder of its content.
   *
   * @param aPresContext the pres context
   * @param aFrame       the original frame
   * @param aNewFrame    [OUT] the new frame that was created
   * @param aFrameIndex  [IN/OUT] index of aFrame in mLogicalFrames
   *
   * If there is already a bidi continuation for this frame in mLogicalFrames,
   * no new frame will be created. On exit aNewFrame will point to the existing
   * bidi continuation and aFrameIndex will contain its index.
   * @see Resolve()
   * @see RemoveBidiContinuation()
   */
  PRBool EnsureBidiContinuation(nsPresContext* aPresContext,
                                nsIFrame*       aFrame,
                                nsIFrame**      aNewFrame,
                                PRInt32&        aFrameIndex);

  /**
   * Helper method for Resolve()
   * Convert one or more bidi continuation frames created in a previous reflow by
   * EnsureBidiContinuation() into fluid continuations.
   * @param aPresContext the pres context
   * @param aFrame       the frame whose continuations are to be removed
   * @param aFirstIndex  index of aFrame in mLogicalFrames
   * @param aLastIndex   index of the last frame to be removed
   * @param aOffset      [OUT] count of directional frames removed. Since
   *                     directional frames have control characters
   *                     corresponding to them in mBuffer, the pointers to
   *                     mBuffer in Resolve() will need to be updated after
   *                     deleting the frames.
   *
   * @see Resolve()
   * @see EnsureBidiContinuation()
   */
  void RemoveBidiContinuation(nsPresContext* aPresContext,
                              nsIFrame*       aFrame,
                              PRInt32         aFirstIndex,
                              PRInt32         aLastIndex,
                              PRInt32&        aOffset) const;
  void CalculateCharType(PRInt32& aOffset,
                         PRInt32  aCharTypeLimit,
                         PRInt32& aRunLimit,
                         PRInt32& aRunLength,
                         PRInt32& aRunCount,
                         PRUint8& aCharType,
                         PRUint8& aPrevCharType) const;
  
  void StripBidiControlCharacters(PRUnichar* aText,
                                  PRInt32&   aTextLength) const;
  nsAutoString    mBuffer;
  nsVoidArray     mLogicalFrames;
  nsVoidArray     mVisualFrames;
  nsDataHashtable<nsISupportsHashKey, PRInt32> mContentToFrameIndex;
  PRInt32         mArraySize;
  PRInt32*        mIndexMap;
  PRUint8*        mLevels;
  nsresult        mSuccess;

  nsBidi*         mBidiEngine;
};

#endif /* nsBidiPresUtils_h___ */

#endif // IBMBIDI