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// Copyright 2014 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
/**
* @fileoverview An abstract class for walking at the sub-element level.
* For example, walking at the sentence, word, or character level.
* This class is an adapter around TraverseContent which exposes the interface
* required by walkers. Subclasses must override the this.grain attribute
* on initialization.
*/
goog.provide('cvox.AbstractSelectionWalker');
goog.require('cvox.AbstractWalker');
goog.require('cvox.BareObjectWalker');
goog.require('cvox.DescriptionUtil');
goog.require('cvox.DomUtil');
goog.require('cvox.Spannable');
goog.require('cvox.TraverseContent');
/**
* @constructor
* @extends {cvox.AbstractWalker}
*/
cvox.AbstractSelectionWalker = function() {
cvox.AbstractWalker.call(this);
this.objWalker_ = new cvox.BareObjectWalker();
this.tc_ = cvox.TraverseContent.getInstance();
this.grain /** @protected */ = ''; // child must override
};
goog.inherits(cvox.AbstractSelectionWalker, cvox.AbstractWalker);
/**
* @override
*/
cvox.AbstractSelectionWalker.prototype.next = function(sel) {
var r = sel.isReversed();
this.tc_.syncToCursorSelection(sel.clone().setReversed(false));
var ret = r ? this.tc_.prevElement(this.grain) :
this.tc_.nextElement(this.grain);
if (ret == null) {
// Unfortunately, we can't trust TraverseContent; fall back to ObjectWalker.
return this.objWalker_.next(sel);
}
var retSel = this.tc_.getCurrentCursorSelection().setReversed(r);
var objSel = this.objWalker_.next(sel);
objSel = objSel ? objSel.setReversed(r) : null;
// ObjectWalker wins when there's a discrepancy between it and
// TraverseContent. The only exception is with an end cursor on a text node.
// In all other cases, this makes sure we visit the same selections as
// object walker.
if (objSel &&
(retSel.end.node.constructor.name != 'Text' ||
objSel.end.node.constructor.name != 'Text') &&
!cvox.DomUtil.isDescendantOfNode(retSel.end.node, sel.end.node) &&
!cvox.DomUtil.isDescendantOfNode(retSel.end.node, objSel.end.node)) {
return objSel;
}
return retSel;
};
/**
* @override
*/
cvox.AbstractSelectionWalker.prototype.sync = function(sel) {
var r = sel.isReversed();
var newSel = null;
if (sel.start.equals(sel.end) && sel.start.node.constructor.name != 'Text') {
var node = sel.start.node;
// Find the deepest visible node; written specifically here because we want
// to move across siblings if necessary and take the deepest node which can
// be BODY.
while (node &&
cvox.DomUtil.directedFirstChild(node, r) &&
!cvox.TraverseUtil.treatAsLeafNode(node)) {
var child = cvox.DomUtil.directedFirstChild(node, r);
// Find the first visible child.
while (child) {
if (cvox.DomUtil.isVisible(child,
{checkAncestors: false, checkDescendants: false})) {
node = child;
break;
} else {
child = cvox.DomUtil.directedNextSibling(child, r);
}
}
// node has no visible children; it's therefore the deepest visible node.
if (!child) {
break;
}
}
newSel = cvox.CursorSelection.fromNode(node);
} else {
newSel = sel.clone();
if (r) {
newSel.start = newSel.end;
} else {
newSel.end = newSel.start;
}
}
// This.next places us at the correct initial position (except below).
newSel = this.next(newSel.setReversed(false));
// ObjectWalker wins when there's a discrepancy between it and
// TraverseContent. The only exception is with an end cursor on a text node.
// In all other cases, this makes sure we visit the same selections as
// object walker.
var objSel = this.objWalker_.sync(sel);
objSel = objSel ? objSel.setReversed(r) : null;
if (!newSel) {
return objSel;
}
newSel.setReversed(r);
if (objSel &&
(newSel.end.node.constructor.name != 'Text' ||
objSel.end.node.constructor.name != 'Text') &&
!cvox.DomUtil.isDescendantOfNode(newSel.end.node, sel.end.node) &&
!cvox.DomUtil.isDescendantOfNode(newSel.end.node, objSel.end.node)) {
return objSel;
}
return newSel;
};
/**
* @override
*/
cvox.AbstractSelectionWalker.prototype.getDescription = function(prevSel, sel) {
var description = cvox.DescriptionUtil.getDescriptionFromAncestors(
cvox.DomUtil.getUniqueAncestors(prevSel.end.node, sel.start.node),
true,
cvox.ChromeVox.verbosity);
description.text = sel.getText() || description.text;
return [description];
};
/**
* @override
*/
cvox.AbstractSelectionWalker.prototype.getBraille = function(prevSel, sel) {
var node = sel.absStart().node;
var text = cvox.TraverseUtil.getNodeText(node);
var spannable = new cvox.Spannable(text);
spannable.setSpan(node, 0, text.length);
return new cvox.NavBraille({
text: spannable,
startIndex: sel.absStart().index,
endIndex: sel.absEnd().index
});
};
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