khtml_caret.cpp

konqueror3 embedded版本, KDE环境下的当家浏览器的嵌入式版本源码包.

/* This file is part of the KDE project
 *
 * Copyright (C) 2003-2004 Leo Savernik <[e-mail]>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Library General Public
 * License as published by the Free Software Foundation; either
 * version 2 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
 * Library General Public License for more details.
 *
 * You should have received a copy of the GNU Library General Public License
 * along with this library; see the file COPYING.LIB.  If not, write to
 * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */


#include "khtml_caret_p.h"

#include "html/html_documentimpl.h"

namespace khtml {

/** Flags representing the type of advance that has been made.
 * @param LeftObject a render object was left and an ascent to its parent has
 *	taken place
 * @param AdvancedToSibling an actual advance to a sibling has taken place
 * @param EnteredObject a render object was entered by descending into it from
 *	its parent object.
 */
enum ObjectAdvanceState {
  LeftObject = 0x01, AdvancedToSibling = 0x02, EnteredObject = 0x04
};

/** All possible states that may occur during render object traversal.
 * @param OutsideDescending outside of the current object, ready to descend
 *	into children
 * @param InsideDescending inside the current object, descending into
 *	children
 * @param InsideAscending inside the current object, ascending to parents
 * @param OutsideAscending outsie the current object, ascending to parents
 */
enum ObjectTraversalState {
  OutsideDescending, InsideDescending, InsideAscending, OutsideAscending
};

/** Traverses the render object tree in a fine granularity.
 * @param obj render object
 * @param trav object traversal state
 * @param toBegin traverse towards beginning
 * @param base base render object which this method must not advance beyond
 *	(0 means document)
 * @param state object advance state (enum ObjectAdvanceState)
 * @return the render object according to the state. May be the same as \c obj
 */
static RenderObject* traverseRenderObjects(RenderObject *obj,
		ObjectTraversalState &trav, bool toBegin, RenderObject *base,
                int &state)
{
  RenderObject *r;
  switch (trav) {
    case OutsideDescending:
      trav = InsideDescending;
      break;
    case InsideDescending:
      r = toBegin ? obj->lastChild() : obj->firstChild();
      if (r) {
        trav = OutsideDescending;
        obj = r;
        state |= EnteredObject;
      } else {
        trav = InsideAscending;
      }
      break;
    case InsideAscending:
      trav = OutsideAscending;
      break;
    case OutsideAscending:
      r = toBegin ? obj->previousSibling() : obj->nextSibling();
      if (r) {
        trav = OutsideDescending;
        state |= AdvancedToSibling;
      } else {
        r = obj->parent();
        if (r == base) r = 0;
        trav = InsideAscending;
        state |= LeftObject;
      }
      obj = r;
      break;
  }/*end switch*/

  return obj;
}

/** Like RenderObject::objectBelow, but confined to stay within \c base.
 * @param obj render object to begin with
 * @param trav object traversal state, will be reset within this function
 * @param base base render object (0: no base)
 */
static inline RenderObject *renderObjectBelow(RenderObject *obj, ObjectTraversalState &trav, RenderObject *base)
{
  trav = InsideDescending;
  int state;		// we don't need the state, so we don't initialize it
  RenderObject *r = obj;
  while (r && trav != OutsideDescending) {
    r = traverseRenderObjects(r, trav, false, base, state);
#if DEBUG_CARETMODE > 3
    kdDebug(6200) << "renderObjectBelow: r " << r << " trav " << trav << endl;
#endif
  }
  trav = InsideDescending;
  return r;
}

/** Like RenderObject::objectAbove, but confined to stay within \c base.
 * @param obj render object to begin with
 * @param trav object traversal state, will be reset within this function
 * @param base base render object (0: no base)
 */
static inline RenderObject *renderObjectAbove(RenderObject *obj, ObjectTraversalState &trav, RenderObject *base)
{
  trav = OutsideAscending;
  int state;		// we don't need the state, so we don't initialize it
  RenderObject *r = obj;
  while (r && trav != InsideAscending) {
    r = traverseRenderObjects(r, trav, true, base, state);
#if DEBUG_CARETMODE > 3
    kdDebug(6200) << "renderObjectAbove: r " << r << " trav " << trav << endl;
#endif
  }
  trav = InsideAscending;
  return r;
}

/** Checks whether the given inline box matches the IndicatedFlows policy
 * @param box inline box to test
 * @return true on match
 */
static inline bool isIndicatedInlineBox(InlineBox *box)
{
  // text boxes are never indicated.
  if (box->isInlineTextBox()) return false;
  RenderStyle *s = box->object()->style();
  return s->borderLeftWidth() || s->borderRightWidth()
  	|| s->borderTopWidth() || s->borderBottomWidth()
	|| s->paddingLeft().value() || s->paddingRight().value()
	|| s->paddingTop().value() || s->paddingBottom().value()
	// ### Can inline elements have top/bottom margins? Couldn't find
	// it in the CSS 2 spec, but Mozilla ignores them, so we do, too.
	|| s->marginLeft().value() || s->marginRight().value();
}

/** Checks whether the given render object matches the IndicatedFlows policy
 * @param r render object to test
 * @return true on match
 */
static inline bool isIndicatedFlow(RenderObject *r)
{
  RenderStyle *s = r->style();
  return s->borderLeftStyle() != BNONE || s->borderRightStyle() != BNONE
  	|| s->borderTopStyle() != BNONE || s->borderBottomStyle() != BNONE
//	|| s->paddingLeft().value() || s->paddingRight().value()
//	|| s->paddingTop().value() || s->paddingBottom().value()
//	|| s->marginLeft().value() || s->marginRight().value()
	|| s->hasClip() || s->overflow() != OVISIBLE
	|| s->backgroundColor().isValid() || s->backgroundImage();
}

/** Advances to the next render object, taking into account the current
 * traversal state.
 *
 * @param r render object
 * @param trav object traversal state
 * @param toBegin @p true, advance towards beginning, @p false, advance toward end
 * @param base base render object which this method must not advance beyond
 *	(0 means document)
 * @param state object advance state (enum ObjectAdvanceState) (unchanged
 *	on LeafsOnly)
 * @return a pointer to the render object which we advanced to,
 *	or 0 if the last possible object has been reached.
 */
static RenderObject *advanceObject(RenderObject *r,
		ObjectTraversalState &trav, bool toBegin,
                RenderObject *base, int &state)
{

  ObjectTraversalState origtrav = trav;
  RenderObject *a = traverseRenderObjects(r, trav, toBegin, base, state);

  bool ignoreOutsideDesc = toBegin && origtrav == OutsideAscending;

  // render object and traversal state at which look ahead has been started
  RenderObject *la = 0;
  ObjectTraversalState latrav = trav;
  ObjectTraversalState lasttrav = origtrav;

  while (a) {
#if DEBUG_CARETMODE > 5
kdDebug(6200) << "a " << a << " trav " << trav << endl;
#endif
    if (a->element()) {
#if DEBUG_CARETMODE > 4
kdDebug(6200) << "a " << a << " trav " << trav << " origtrav " << origtrav << " ignoreOD " << ignoreOutsideDesc << endl;
#endif
      if (toBegin) {

        switch (origtrav) {
	  case OutsideDescending:
            if (trav == InsideAscending) return a;
	    if (trav == OutsideDescending) return a;
	    break;
          case InsideDescending:
	    if (trav == OutsideDescending) return a;
	    // fall through
          case InsideAscending:
            if (trav == OutsideAscending) return a;
	    break;
	  case OutsideAscending:
	    if (trav == OutsideAscending) return a;
            if (trav == InsideAscending && lasttrav == InsideDescending) return a;
	    if (trav == OutsideDescending && !ignoreOutsideDesc) return a;
	    // ignore this outside descending position, as it effectively
	    // demarkates the same position, but remember it in case we fall off
	    // the document.
	    la = a; latrav = trav;
	    ignoreOutsideDesc = false;
	    break;
        }/*end switch*/

      } else {

        switch (origtrav) {
	  case OutsideDescending:
            if (trav == InsideAscending) return a;
	    if (trav == OutsideDescending) return a;
	    break;
          case InsideDescending:
//	    if (trav == OutsideDescending) return a;
	    // fall through
          case InsideAscending:
//            if (trav == OutsideAscending) return a;
//	    break;
	  case OutsideAscending:
	    // ### what if origtrav == OA, and immediately afterwards trav
	    // becomes OD? In this case the effective position hasn't changed ->
	    // the caret gets stuck. Otherwise, it apparently cannot happen in
	    // real usage patterns.
	    if (trav == OutsideDescending) return a;
	    if (trav == OutsideAscending) {
	      if (la) return la;
              // starting lookahead here. Remember old object in case we fall off
	      // the document.
	      la = a; latrav = trav;
	    }
	    break;
	}/*end switch*/

      }/*end if*/
    }/*end if*/

    lasttrav = trav;
    a = traverseRenderObjects(a, trav, toBegin, base, state);
  }/*wend*/

  if (la) trav = latrav, a = la;
  return a;

}

/** Check whether the current render object is unsuitable in caret mode handling.
 *
 * Some render objects cannot be handled correctly in caret mode. These objects
 * are therefore considered to be unsuitable. The null object is suitable, as
 * it denotes reaching the end.
 * @param r current render object
 * @param trav current traversal state
 */
static inline bool isUnsuitable(RenderObject *r, ObjectTraversalState trav)
{
  if (!r) return false;
  return r->isTableCol() || r->isTableSection() || r->isTableRow()
  	|| (r->isText() && static_cast<RenderText *>(r)->inlineTextBoxCount() == 0);
      ;
  Q_UNUSED(trav);
}

/** Advances to the next render object, taking into account the current
 * traversal state, but skipping render objects which are not suitable for
 * having placed the caret into them.
 * @param r render object
 * @param trav object traversal state (unchanged on LeafsOnly)
 * @param toBegin @p true, advance towards beginning, @p false, advance toward end
 * @param base base render object which this method must not advance beyond
 *	(0 means document)
 * @param state object advance state (enum ObjectAdvanceState) (unchanged
 *	on LeafsOnly)
 * @return a pointer to the advanced render object or 0 if the last possible
 *	object has been reached.
 */
static inline RenderObject *advanceSuitableObject(RenderObject *r,
		ObjectTraversalState &trav, bool toBegin,
		RenderObject *base, int &state)
{
  do {
    r = advanceObject(r, trav, toBegin, base, state);
#if DEBUG_CARETMODE > 2
    kdDebug(6200) << "after advanceSWP: r " << r << " trav " << trav << " toBegin " << toBegin << endl;
#endif
  } while (isUnsuitable(r, trav));
  return r;
}

/**
  * Returns the next leaf node.
  *
  * Using this function delivers leaf nodes as if the whole DOM tree
  * were a linear chain of its leaf nodes.
  * @param r dom node
  * @param baseElem base element not to search beyond
  * @return next leaf node or 0 if there are no more.
  */
static NodeImpl *nextLeafNode(NodeImpl *r, NodeImpl *baseElem)
{
  NodeImpl *n = r->firstChild();
  if (n) {
    while (n) { r = n; n = n->firstChild(); }
    return const_cast<NodeImpl *>(r);
  }/*end if*/
  n = r->nextSibling();
  if (n) {
    r = n;
    while (n) { r = n; n = n->firstChild(); }
    return const_cast<NodeImpl *>(r);
  }/*end if*/

  n = r->parentNode();
  if (n == baseElem) n = 0;
  while (n) {
    r = n;
    n = r->nextSibling();
    if (n) {
      r = n;
      n = r->firstChild();
      while (n) { r = n; n = n->firstChild(); }
      return const_cast<NodeImpl *>(r);
    }/*end if*/
    n = r->parentNode();
    if (n == baseElem) n = 0;
  }/*wend*/
  return 0;
}

#if 0		// currently not used
/** (Not part of the official DOM)
  * Returns the previous leaf node.
  *
  * Using this function delivers leaf nodes as if the whole DOM tree
  * were a linear chain of its leaf nodes.
  * @param r dom node
  * @param baseElem base element not to search beyond
  * @return previous leaf node or 0 if there are no more.
  */
static NodeImpl *prevLeafNode(NodeImpl *r, NodeImpl *baseElem)
{
  NodeImpl *n = r->firstChild();
  if (n) {