dlls/riched20/wrap.c

/*
 * RichEdit - Paragraph wrapping. Don't try to understand it. You've been
 * warned !
 *
 * Copyright 2004 by Krzysztof Foltman
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */


#include "editor.h"

WINE_DEFAULT_DEBUG_CHANNEL(richedit);

/*
 * Unsolved problems:
 *  
 * - center and right align in WordPad omits all spaces at the start, we don't
 * - objects/images are not handled yet
 * - no tabs 
 */ 
 
ME_DisplayItem *ME_MakeRow(int height, int baseline, int width)
{
  ME_DisplayItem *item = ME_MakeDI(diStartRow);
  
  item->member.row.nHeight = height;
  item->member.row.nBaseline = baseline;
  item->member.row.nWidth = width;
  return item;
}

void ME_BeginRow(ME_WrapContext *wc)
{
  wc->pRowStart = NULL;
  wc->bOverflown = FALSE;
  wc->pLastSplittableRun = NULL;
  wc->nAvailWidth = wc->nTotalWidth - (wc->nRow ? wc->nLeftMargin : wc->nFirstMargin) - wc->nRightMargin;
  wc->pt.x = 0;
}  

void ME_InsertRowStart(ME_WrapContext *wc, ME_DisplayItem *pEnd)
{
  ME_DisplayItem *p, *row, *para;
  int ascent = 0, descent = 0, width=0, shift = 0, align = 0;
  /* wrap text */
  para = ME_GetParagraph(wc->pRowStart);
  for (p = wc->pRowStart; p!=pEnd; p = p->next)
  {
    /* ENDPARA run shouldn't affect row height, except if it's the only run in the paragraph */
    if (p->type==diRun && ((p==wc->pRowStart) || !(p->member.run.nFlags & MERF_ENDPARA))) { /* FIXME add more run types */
      if (p->member.run.nAscent>ascent)
        ascent = p->member.run.nAscent;
      if (p->member.run.nDescent>descent)
        descent = p->member.run.nDescent;
      if (!(p->member.run.nFlags & (MERF_ENDPARA|MERF_SKIPPED)))
        width += p->member.run.nWidth;
    }
  }
  row = ME_MakeRow(ascent+descent, ascent, width);
  row->member.row.nYPos = wc->pt.y;
  row->member.row.nLMargin = (!wc->nRow ? wc->nFirstMargin : wc->nLeftMargin);
  row->member.row.nRMargin = wc->nRightMargin;
  assert(para->member.para.pFmt->dwMask & PFM_ALIGNMENT);
  align = para->member.para.pFmt->wAlignment;
  if (align == PFA_CENTER)
    shift = (wc->nAvailWidth-width)/2;
  if (align == PFA_RIGHT)
    shift = wc->nAvailWidth-width;
  for (p = wc->pRowStart; p!=pEnd; p = p->next)
  {
    if (p->type==diRun) { /* FIXME add more run types */
      p->member.run.pt.x += row->member.row.nLMargin+shift;
    }
  }
  ME_InsertBefore(wc->pRowStart, row);
  wc->nRow++;
  wc->pt.y += ascent+descent;
  ME_BeginRow(wc);
}

void ME_WrapEndParagraph(ME_WrapContext *wc, ME_DisplayItem *p)
{
  if (wc->pRowStart)
    ME_InsertRowStart(wc, p->next);
    
  /*
  p = p->member.para.prev_para->next;
  while(p) {
    if (p->type == diParagraph || p->type == diTextEnd)
      return;
    if (p->type == diRun)
    {
      ME_Run *run = &p->member.run;
      TRACE("%s - (%d, %d)\n", debugstr_w(run->strText->szData), run->pt.x, run->pt.y);
    }
    p = p->next;
  }
  */
}  

void ME_WrapSizeRun(ME_WrapContext *wc, ME_DisplayItem *p)
{
  /* FIXME compose style (out of character and paragraph styles) here */
  
  ME_UpdateRunFlags(wc->context->editor, &p->member.run);
  
  ME_CalcRunExtent(wc->context, &p->member.run);
}

ME_DisplayItem *ME_MaximizeSplit(ME_WrapContext *wc, ME_DisplayItem *p, int i)
{
  ME_DisplayItem *pp, *piter = p;
  int j;
  if (!i)
    return NULL;
  j = ME_ReverseFindNonWhitespaceV(p->member.run.strText, i);
  if (j>0) {
    pp = ME_SplitRun(wc->context, piter, j);
    wc->pt.x += piter->member.run.nWidth;
    return pp;
  }
  else
  {
    pp = piter;
    /* omit all spaces before split point */
    while(piter != wc->pRowStart)
    {
      piter = ME_FindItemBack(piter, diRun);
      if (piter->member.run.nFlags & MERF_WHITESPACE) 
      {
        pp = piter;
        continue;
      }
      if (piter->member.run.nFlags & MERF_ENDWHITE)
      {
        j = ME_ReverseFindNonWhitespaceV(piter->member.run.strText, i);
        pp = ME_SplitRun(wc->context, piter, i);
        wc->pt = pp->member.run.pt;
        return pp;
      }
      /* this run is the end of spaces, so the run edge is a good point to split */
      wc->pt = pp->member.run.pt;
      wc->bOverflown = TRUE;
      TRACE("Split point is: %s|%s\n", debugstr_w(piter->member.run.strText->szData), debugstr_w(pp->member.run.strText->szData));
      return pp;
    }
    wc->pt = piter->member.run.pt;
    return piter;
  }
}

ME_DisplayItem *ME_SplitByBacktracking(ME_WrapContext *wc, ME_DisplayItem *p, int loc)
{
  ME_DisplayItem *piter = p, *pp;
  int i, idesp, len;
  ME_Run *run = &p->member.run;
  
  idesp = i = ME_CharFromPoint(wc->context->editor, loc, run);
  len = ME_StrVLen(run->strText);
  assert(len>0);
  assert(i<len);
  if (i) {
    /* don't split words */
    i = ME_ReverseFindWhitespaceV(run->strText, i);
    pp = ME_MaximizeSplit(wc, p, i);
    if (pp)
      return pp;
  }
  TRACE("Must backtrack to split at: %s\n", debugstr_w(p->member.run.strText->szData));
  if (wc->pLastSplittableRun)
  {
    if (wc->pLastSplittableRun->member.run.nFlags & MERF_GRAPHICS)
    {
      wc->pt = wc->ptLastSplittableRun;
      return wc->pLastSplittableRun;
    }
    else if (wc->pLastSplittableRun->member.run.nFlags & MERF_SPLITTABLE)
    {
      /* the following two lines are just to check if we forgot to call UpdateRunFlags earlier,
         they serve no other purpose */
      ME_UpdateRunFlags(wc->context->editor, run);
      assert((wc->pLastSplittableRun->member.run.nFlags & MERF_SPLITTABLE));
      
      piter = wc->pLastSplittableRun;
      run = &piter->member.run;
      len = ME_StrVLen(run->strText);
      /* don't split words */
      i = ME_ReverseFindWhitespaceV(run->strText, len);
      if (i == len)
        i = ME_ReverseFindNonWhitespaceV(run->strText, len);
      if (i) {        
        ME_DisplayItem *piter2 = ME_SplitRun(wc->context, piter, i);
        wc->pt = piter2->member.run.pt;
        return piter2;
      }
      /* splittable = must have whitespaces */
      assert(0 == "Splittable, but no whitespaces");
    }
    else
    {
      /* restart from the first run beginning with spaces */
      wc->pt = wc->ptLastSplittableRun;
      return wc->pLastSplittableRun;
    }
  }
  TRACE("Backtracking failed, trying desperate: %s\n", debugstr_w(p->member.run.strText->szData));
  /* OK, no better idea, so assume we MAY split words if we can split at all*/
  if (idesp)
    return ME_SplitRun(wc->context, piter, idesp);
  else
  if (wc->pRowStart && piter != wc->pRowStart)
  {
    /* don't need to break current run, because it's possible to split
       before this run */
    wc->bOverflown = TRUE;
    return piter;
  }
  else
  {
    /* split point inside first character - no choice but split after that char */
    int chars = 1;
    int pos2 = ME_StrRelPos(run->strText, 0, &chars);
    if (pos2 != len) {
      /* the run is more than 1 char, so we may split */
      return ME_SplitRun(wc->context, piter, pos2);
    }
    /* the run is one char, can't split it */
    return piter;
  }  
}

ME_DisplayItem *ME_WrapHandleRun(ME_WrapContext *wc, ME_DisplayItem *p)
{
  ME_DisplayItem *pp;
  ME_Run *run;
  int len;

  assert(p->type == diRun);  
  if (!wc->pRowStart)
    wc->pRowStart = p;
  ME_WrapSizeRun(wc, p);
  run = &p->member.run;
  run->pt.x = wc->pt.x;
  run->pt.y = wc->pt.y;
  len = ME_StrVLen(run->strText);  
  
  if (wc->bOverflown) /* just skipping final whitespaces */
  {    
    if (run->nFlags & MERF_WHITESPACE) {
      p->member.run.nFlags |= MERF_SKIPPED;
      /* wc->pt.x += run->nWidth; */
      /* skip runs consisting of only whitespaces */
      return p->next;
    }
    
    if (run->nFlags & MERF_STARTWHITE) {
      /* try to split the run at the first non-white char */
      int black;
      black = ME_FindNonWhitespaceV(run->strText, 0);
      if (black) {
        wc->bOverflown = FALSE;
        pp = ME_SplitRun(wc->context, p, black);
        p->member.run.nFlags |= MERF_SKIPPED;
        ME_InsertRowStart(wc, pp);
        return pp;
      }
    }
    /* black run: the row goes from pRowStart to the previous run */
    ME_InsertRowStart(wc, p);
    return p;
  }
  /* we're not at the end of the row */
  /* will current run fit? */
  if (wc->pt.x + run->nWidth > wc->nAvailWidth)
  {
    int loc = wc->nAvailWidth - wc->pt.x;    
    /* total white run ? */
    if (run->nFlags & MERF_WHITESPACE) {
      /* let the overflow logic handle it */
      wc->bOverflown = TRUE;
      return p;
    }
    /* graphics - we can split before */
    if (run->nFlags & MERF_GRAPHICS) {
      wc->bOverflown = TRUE;
      return p;
    }
    /* can we separate out the last spaces ? (to use overflow logic later) */
    if (run->nFlags & MERF_ENDWHITE)
    {
      /* we aren't sure if it's *really* necessary, it's a good start however */
      int black = ME_ReverseFindNonWhitespaceV(run->strText, len);
      ME_SplitRun(wc->context, p, black);
      /* handle both parts again */
      return p;
    }
    /* determine the split point by backtracking */
    pp = ME_SplitByBacktracking(wc, p, loc);
    if (pp == wc->pRowStart)
    {
      /* we had only spaces so far, entire content can be omitted */
      wc->pt.x = 0;
      return p->next;
    }
    if (p != pp) /* found a suitable split point */
    {
      wc->bOverflown = TRUE;
      return pp;
    }
    /* we detected that it's best to split on start of this run */
    if (wc->bOverflown)
      return pp;
    ERR("failure!\n");
    /* not found anything - writing over margins is the only option left */
  }
  if ((run->nFlags & (MERF_SPLITTABLE | MERF_STARTWHITE)) 
    || ((run->nFlags & MERF_GRAPHICS) && (p != wc->pRowStart)))
  {
    wc->pLastSplittableRun = p;
    wc->ptLastSplittableRun = wc->pt;
  }
  wc->pt.x += run->nWidth;
  return p->next;
}
  
void ME_WrapTextParagraph(ME_Context *c, ME_DisplayItem *tp) {
  ME_DisplayItem *p;
  ME_WrapContext wc;

  assert(tp->type == diParagraph);  
  if (!(tp->member.para.nFlags & MEPF_REWRAP)) {
    return;
  }
  ME_PrepareParagraphForWrapping(c, tp);
  
  wc.context = c;
/*   wc.para_style = tp->member.para.style; */
  wc.style = NULL;
  wc.nFirstMargin = tp->member.para.nFirstMargin;
  wc.nLeftMargin = tp->member.para.nLeftMargin;
  wc.nRightMargin = tp->member.para.nRightMargin;
  wc.nRow = 0;
  wc.pt.x = 0;
  wc.pt.y = 0;
  wc.nTotalWidth = c->rcView.right - c->rcView.left;
  wc.nAvailWidth = wc.nTotalWidth - wc.nFirstMargin - wc.nRightMargin;
  wc.pRowStart = NULL;
  
  ME_BeginRow(&wc);
  for (p = tp->next; p!=tp->member.para.next_para; ) {
    assert(p->type != diStartRow);
    if (p->type == diRun) {
      p = ME_WrapHandleRun(&wc, p);
      continue;
    }
    p = p->next;
  }
  ME_WrapEndParagraph(&wc, p);
  tp->member.para.nFlags &= ~MEPF_REWRAP;
  tp->member.para.nHeight = wc.pt.y;
}


void ME_PrepareParagraphForWrapping(ME_Context *c, ME_DisplayItem *tp) {
  ME_DisplayItem *p;
  /* remove all items that will be reinserted by paragraph wrapper anyway */
  for (p = tp->next; p!=tp->member.para.next_para; p = p->next) {
    switch(p->type) {
      case diStartRow:
        p = p->prev;
        ME_Remove(p->next);
        break;
      default:
        break;
    }
  }
  /* join runs that can be joined, set up flags */
  for (p = tp->next; p!=tp->member.para.next_para; p = p->next) {
    int changed = 0;
    switch(p->type) {
      case diStartRow: assert(0); break; /* should have deleted it */
      case diRun:
        while (p->next->type == diRun) { /* FIXME */
          if (ME_CanJoinRuns(&p->member.run, &p->next->member.run)) {
            ME_JoinRuns(c->editor, p);
            changed = 1;
          }
          else
            break;
        }
        p->member.run.nFlags &= ~MERF_CALCBYWRAP;
        break;
      default:
        break;
    }
  }
}

void ME_WrapMarkedParagraphs(ME_TextEditor *editor) {
  HWND hWnd = editor->hWnd;
  HDC hDC = GetDC(hWnd);
  ME_DisplayItem *item;
  ME_Context c;
  
  ME_InitContext(&c, editor, hDC);
  c.pt.x = 0;
  c.pt.y = 0;
  item = editor->pBuffer->pFirst->next;
  while(item != editor->pBuffer->pLast) {
    BOOL bRedraw = FALSE;
    
    assert(item->type == diParagraph);
    if ((item->member.para.nFlags & MEPF_REWRAP)
     || (item->member.para.nYPos != c.pt.y))
      bRedraw = TRUE;
    item->member.para.nYPos = c.pt.y;
    
    ME_WrapTextParagraph(&c, item);

    if (bRedraw)
      item->member.para.nFlags |= MEPF_REPAINT;

    c.pt.y += item->member.para.nHeight;
    item = item->member.para.next_para;
  }
  editor->sizeWindow.cx = c.rcView.right-c.rcView.left;
  editor->sizeWindow.cy = c.rcView.bottom-c.rcView.top;
  editor->nTotalLength = c.pt.y;
  
  ME_DestroyContext(&c);
  ReleaseDC(hWnd, hDC);
}