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Diffstat (limited to 'accessible/base/nsTextEquivUtils.h')
| -rw-r--r-- | accessible/base/nsTextEquivUtils.h | 182 |
1 files changed, 182 insertions, 0 deletions
diff --git a/accessible/base/nsTextEquivUtils.h b/accessible/base/nsTextEquivUtils.h new file mode 100644 index 0000000000..525727b102 --- /dev/null +++ b/accessible/base/nsTextEquivUtils.h @@ -0,0 +1,182 @@ +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */ +/* vim:expandtab:shiftwidth=2:tabstop=2: + */ +/* This Source Code Form is subject to the terms of the Mozilla Public + * License, v. 2.0. If a copy of the MPL was not distributed with this + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ + +#ifndef _nsTextEquivUtils_H_ +#define _nsTextEquivUtils_H_ + +#include "mozilla/a11y/Accessible.h" +#include "mozilla/a11y/Role.h" + +class nsIContent; + +namespace mozilla { +namespace a11y { +class LocalAccessible; +} +} // namespace mozilla + +/** + * Text equivalent computation rules (see nsTextEquivUtils::gRoleToNameRulesMap) + */ +enum ETextEquivRule { + // No rule. + eNoNameRule = 0x00, + + // Walk into subtree only if the currently navigated accessible is not root + // accessible (i.e. if the accessible is part of text equivalent computation). + eNameFromSubtreeIfReqRule = 0x01, + + // Text equivalent computation from subtree is allowed. + eNameFromSubtreeRule = 0x03, + + // The accessible allows to append its value to text equivalent. + // XXX: This is temporary solution. Once we move accessible value of links + // and linkable accessibles to MSAA part we can remove this. + eNameFromValueRule = 0x04 +}; + +/** + * The class provides utils methods to compute the accessible name and + * description. + */ +class nsTextEquivUtils { + public: + typedef mozilla::a11y::LocalAccessible LocalAccessible; + typedef mozilla::a11y::Accessible Accessible; + + /** + * Determines if the accessible has a given name rule. + * + * @param aAccessible [in] the given accessible + * @param aRule [in] a given name rule + * @return true if the accessible has the rule + */ + static inline bool HasNameRule(Accessible* aAccessible, + ETextEquivRule aRule) { + return (GetRoleRule(aAccessible->Role()) & aRule) == aRule; + } + + /** + * Calculates the name from accessible subtree if allowed. + * + * @param aAccessible [in] the given accessible + * @param aName [out] accessible name + */ + static nsresult GetNameFromSubtree(const LocalAccessible* aAccessible, + nsAString& aName); + + /** + * Calculates text equivalent from the subtree. Similar to GetNameFromSubtree. + * However it returns not empty result for things like HTML p. + */ + static void GetTextEquivFromSubtree(const Accessible* aAccessible, + nsString& aTextEquiv) { + aTextEquiv.Truncate(); + + AppendFromAccessibleChildren(aAccessible, &aTextEquiv); + aTextEquiv.CompressWhitespace(); + } + + /** + * Calculates text equivalent for the given accessible from its IDRefs + * attribute (like aria-labelledby or aria-describedby). + * + * @param aAccessible [in] the accessible text equivalent is computed for + * @param aIDRefsAttr [in] IDRefs attribute on DOM node of the accessible + * @param aTextEquiv [out] result text equivalent + */ + static nsresult GetTextEquivFromIDRefs(const LocalAccessible* aAccessible, + nsAtom* aIDRefsAttr, + nsAString& aTextEquiv); + + /** + * Calculates the text equivalent from the given content and its subtree if + * allowed and appends it to the given string. + * + * @param aInitiatorAcc [in] the accessible text equivalent is computed for + * in the end (root accessible of text equivalent + * calculation recursion) + * @param aContent [in] the given content the text equivalent is + * computed from + * @param aString [in, out] the string + */ + static nsresult AppendTextEquivFromContent( + const LocalAccessible* aInitiatorAcc, nsIContent* aContent, + nsAString* aString); + + /** + * Calculates the text equivalent from the given text content (may be text + * node or html:br) and appends it to the given string. + * + * @param aContent [in] the text content + * @param aString [in, out] the string + */ + static nsresult AppendTextEquivFromTextContent(nsIContent* aContent, + nsAString* aString); + + /** + * Iterates DOM children and calculates text equivalent from each child node. + * Then, appends found text to the given string. + * + * @param aContent [in] the node to fetch DOM children from + * @param aString [in, out] the string + */ + static nsresult AppendFromDOMChildren(nsIContent* aContent, + nsAString* aString); + + private: + /** + * Iterates accessible children and calculates text equivalent from each + * child. + */ + static nsresult AppendFromAccessibleChildren(const Accessible* aAccessible, + nsAString* aString); + + /** + * Calculates text equivalent from the given accessible and its subtree if + * allowed. + */ + static nsresult AppendFromAccessible(Accessible* aAccessible, + nsAString* aString); + + /** + * Calculates text equivalent from the value of given accessible. + */ + static nsresult AppendFromValue(Accessible* aAccessible, nsAString* aString); + + /** + * Calculates text equivalent from the given DOM node and its subtree if + * allowed. + */ + static nsresult AppendFromDOMNode(nsIContent* aContent, nsAString* aString); + + /** + * Concatenates strings and appends space between them. Returns true if + * text equivalent string was appended. + */ + static bool AppendString(nsAString* aString, + const nsAString& aTextEquivalent); + + /** + * Returns the rule (constant of ETextEquivRule) for a given role. + */ + static uint32_t GetRoleRule(mozilla::a11y::roles::Role aRole); + + /** + * Returns true if a given accessible should be included when calculating + * the text equivalent for the initiator's subtree. + */ + static bool ShouldIncludeInSubtreeCalculation(Accessible* aAccessible); + + /** + * Returns true if a given accessible is a text leaf containing only + * whitespace. + */ + static bool IsWhitespaceLeaf(Accessible* aAccessible); +}; + +#endif |