gecko/accessible/src/base/nsAccUtils.h

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 * Contributor(s):
 *   Alexander Surkov <surkov.alexander@gmail.com> (original author)
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#ifndef nsAccUtils_h_
#define nsAccUtils_h_

#include "nsIAccessible.h"
#include "nsIAccessNode.h"
#include "nsIAccessibleDocument.h"
#include "nsIAccessibleRole.h"
#include "nsIAccessibleText.h"
#include "nsIAccessibleTable.h"

#include "nsARIAMap.h"
#include "nsAccessibilityService.h"
#include "nsCoreUtils.h"

#include "mozilla/dom/Element.h"
#include "nsIDocShell.h"
#include "nsIDOMNode.h"
#include "nsIPersistentProperties2.h"
#include "nsIPresShell.h"
#include "nsPoint.h"

class nsAccessNode;
class nsAccessible;
class nsHyperTextAccessible;
class nsHTMLTableAccessible;
class nsDocAccessible;
#ifdef MOZ_XUL
class nsXULTreeAccessible;
#endif

class nsAccUtils
{
public:
  /**
   * Returns value of attribute from the given attributes container.
   *
   * @param aAttributes - attributes container
   * @param aAttrName - the name of requested attribute
   * @param aAttrValue - value of attribute
   */
  static void GetAccAttr(nsIPersistentProperties *aAttributes,
                         nsIAtom *aAttrName,
                         nsAString& aAttrValue);

  /**
   * Set value of attribute for the given attributes container.
   *
   * @param aAttributes - attributes container
   * @param aAttrName - the name of requested attribute
   * @param aAttrValue - new value of attribute
   */
  static void SetAccAttr(nsIPersistentProperties *aAttributes,
                         nsIAtom *aAttrName,
                         const nsAString& aAttrValue);

  /**
   * Set group attributes ('level', 'setsize', 'posinset').
   */
  static void SetAccGroupAttrs(nsIPersistentProperties *aAttributes,
                               PRInt32 aLevel, PRInt32 aSetSize,
                               PRInt32 aPosInSet);

  /**
   * Get default value of the level for the given accessible.
   */
  static PRInt32 GetDefaultLevel(nsAccessible *aAcc);

  /**
   * Return ARIA level value or the default one if ARIA is missed for the
   * given accessible.
   */
  static PRInt32 GetARIAOrDefaultLevel(nsAccessible *aAccessible);

  /**
   * Compute position in group (posinset) and group size (setsize) for
   * nsIDOMXULSelectControlItemElement node.
   */
  static void GetPositionAndSizeForXULSelectControlItem(nsIContent *aContent,
                                                        PRInt32 *aPosInSet,
                                                        PRInt32 *aSetSize);

  /**
   * Compute group position and group size (posinset and setsize) for
   * nsIDOMXULContainerItemElement node.
   */
  static void GetPositionAndSizeForXULContainerItem(nsIContent *aContent,
                                                    PRInt32 *aPosInSet,
                                                    PRInt32 *aSetSize);

  /**
   * Compute group level for nsIDOMXULContainerItemElement node.
   */
  static PRInt32 GetLevelForXULContainerItem(nsIContent *aContent);

  /**
   * Set container-foo live region attributes for the given node.
   *
   * @param aAttributes    where to store the attributes
   * @param aStartContent  node to start from
   * @param aTopContent    node to end at
   */
  static void SetLiveContainerAttributes(nsIPersistentProperties *aAttributes,
                                         nsIContent *aStartContent,
                                         nsIContent *aTopContent);

  /**
   * Any ARIA property of type boolean or NMTOKEN is undefined if the ARIA
   * property is not present, or is "" or "undefined". Do not call 
   * this method for properties of type string, decimal, IDREF or IDREFS.
   * 
   * Return PR_TRUE if the ARIA property is defined, otherwise PR_FALSE
   */
  static bool HasDefinedARIAToken(nsIContent *aContent, nsIAtom *aAtom);

  /**
   * Return atomic value of ARIA attribute of boolean or NMTOKEN type.
   */
  static nsIAtom* GetARIAToken(mozilla::dom::Element* aElement, nsIAtom* aAttr);

  /**
   * Return document accessible for the given presshell.
   */
  static nsDocAccessible *GetDocAccessibleFor(nsIWeakReference *aWeakShell)
  {
    nsCOMPtr<nsIPresShell> presShell(do_QueryReferent(aWeakShell));
    return presShell ?
      GetAccService()->GetDocAccessible(presShell->GetDocument()) : nsnull;
  }

  /**
   * Return document accessible for the given DOM node.
   */
  static nsDocAccessible *GetDocAccessibleFor(nsINode *aNode)
  {
    nsIPresShell *presShell = nsCoreUtils::GetPresShellFor(aNode);
    return presShell ?
      GetAccService()->GetDocAccessible(presShell->GetDocument()) : nsnull;
  }

  /**
   * Return document accessible for the given docshell.
   */
  static nsDocAccessible *GetDocAccessibleFor(nsIDocShellTreeItem *aContainer)
  {
    nsCOMPtr<nsIDocShell> docShell(do_QueryInterface(aContainer));
    nsCOMPtr<nsIPresShell> presShell;
    docShell->GetPresShell(getter_AddRefs(presShell));
    return presShell ?
      GetAccService()->GetDocAccessible(presShell->GetDocument()) : nsnull;
  }

  /**
    * Return ancestor in this document with the given role if it exists.
    *
    * @param  aDescendant  [in] descendant to start search with
    * @param  aRole        [in] role to find matching ancestor for
    * @return               the ancestor accessible with the given role, or
    *                       nsnull if no match is found
    */
   static nsAccessible * GetAncestorWithRole(nsAccessible *aDescendant,
                                             PRUint32 aRole);

  /**
   * Return single or multi selectable container for the given item.
   *
   * @param  aAccessible  [in] the item accessible
   * @param  aState       [in] the state of the item accessible
   */
  static nsAccessible* GetSelectableContainer(nsAccessible* aAccessible,
                                              PRUint64 aState);

  /**
   * Return multi selectable container for the given item.
   */
  static nsAccessible *GetMultiSelectableContainer(nsINode *aNode);

  /**
   * Return true if the DOM node of given accessible has aria-selected="true"
   * attribute.
   */
  static bool IsARIASelected(nsAccessible *aAccessible);

  /**
   * Return text accessible containing focus point of the given selection.
   * Used for normal and misspelling selection changes processing.
   *
   * @param aSelection  [in] the given selection
   * @return            text accessible
   */
  static nsHyperTextAccessible*
    GetTextAccessibleFromSelection(nsISelection* aSelection);

  /**
   * Converts the given coordinates to coordinates relative screen.
   *
   * @param aX               [in] the given x coord
   * @param aY               [in] the given y coord
   * @param aCoordinateType  [in] specifies coordinates origin (refer to
   *                         nsIAccessibleCoordinateType)
   * @param aAccessNode      [in] the accessible if coordinates are given
   *                         relative it.
   * @param aCoords          [out] converted coordinates
   */
  static nsresult ConvertToScreenCoords(PRInt32 aX, PRInt32 aY,
                                        PRUint32 aCoordinateType,
                                        nsAccessNode *aAccessNode,
                                        nsIntPoint *aCoords);

  /**
   * Converts the given coordinates relative screen to another coordinate
   * system.
   *
   * @param aX               [in, out] the given x coord
   * @param aY               [in, out] the given y coord
   * @param aCoordinateType  [in] specifies coordinates origin (refer to
   *                         nsIAccessibleCoordinateType)
   * @param aAccessNode      [in] the accessible if coordinates are given
   *                         relative it
   */
  static nsresult ConvertScreenCoordsTo(PRInt32 *aX, PRInt32 *aY,
                                        PRUint32 aCoordinateType,
                                        nsAccessNode *aAccessNode);

  /**
   * Returns coordinates relative screen for the top level window.
   *
   * @param aAccessNode  the accessible hosted in the window
   */
  static nsIntPoint GetScreenCoordsForWindow(nsAccessNode *aAccessNode);

  /**
   * Returns coordinates relative screen for the parent of the given accessible.
   *
   * @param aAccessNode  the accessible
   */
  static nsIntPoint GetScreenCoordsForParent(nsAccessNode *aAccessNode);

  /**
   * Get the role map entry for a given DOM node. This will use the first
   * ARIA role if the role attribute provides a space delimited list of roles.
   *
   * @param aNode  [in] the DOM node to get the role map entry for
   * @return        a pointer to the role map entry for the ARIA role, or nsnull
   *                if none
   */
  static nsRoleMapEntry *GetRoleMapEntry(nsINode *aNode);

  /**
   * Return the role of the given accessible.
   */
  static PRUint32 Role(nsIAccessible *aAcc)
  {
    PRUint32 role = nsIAccessibleRole::ROLE_NOTHING;
    if (aAcc)
      aAcc->GetRole(&role);

    return role;
  }

  /**
   * Get the ARIA attribute characteristics for a given ARIA attribute.
   * 
   * @param aAtom  ARIA attribute
   * @return       A bitflag representing the attribute characteristics
   *               (see nsARIAMap.h for possible bit masks, prefixed "ARIA_")
   */
  static PRUint8 GetAttributeCharacteristics(nsIAtom* aAtom);

  /**
   * Get the 'live' or 'container-live' object attribute value from the given
   * ELiveAttrRule constant.
   *
   * @param  aRule   [in] rule constant (see ELiveAttrRule in nsAccMap.h)
   * @param  aValue  [out] object attribute value
   *
   * @return         true if object attribute should be exposed
   */
  static bool GetLiveAttrValue(PRUint32 aRule, nsAString& aValue);

#ifdef DEBUG_A11Y
  /**
   * Detect whether the given accessible object implements nsIAccessibleText,
   * when it is text or has text child node.
   */
  static bool IsTextInterfaceSupportCorrect(nsAccessible *aAccessible);
#endif

  /**
   * Return true if the given accessible has text role.
   */
  static bool IsText(nsIAccessible *aAcc)
  {
    PRUint32 role = Role(aAcc);
    return role == nsIAccessibleRole::ROLE_TEXT_LEAF ||
           role == nsIAccessibleRole::ROLE_STATICTEXT;
  }

  /**
   * Return text length of the given accessible, return 0 on failure.
   */
  static PRUint32 TextLength(nsAccessible *aAccessible);

  /**
   * Return true if the given accessible is embedded object.
   */
  static bool IsEmbeddedObject(nsIAccessible *aAcc)
  {
    PRUint32 role = Role(aAcc);
    return role != nsIAccessibleRole::ROLE_TEXT_LEAF &&
           role != nsIAccessibleRole::ROLE_WHITESPACE &&
           role != nsIAccessibleRole::ROLE_STATICTEXT;
  }

  /**
   * Transform nsIAccessibleStates constants to internal state constant.
   */
  static inline PRUint64 To64State(PRUint32 aState1, PRUint32 aState2)
  {
    return static_cast<PRUint64>(aState1) +
        (static_cast<PRUint64>(aState2) << 31);
  }

  /**
   * Transform internal state constant to nsIAccessibleStates constants.
   */
  static inline void To32States(PRUint64 aState64,
                                PRUint32* aState1, PRUint32* aState2)
  {
    *aState1 = aState64 & 0x7fffffff;
    if (aState2)
      *aState2 = static_cast<PRUint32>(aState64 >> 31);
  }

  /**
   * Return true if the given accessible can't have children. Used when exposing
   * to platform accessibility APIs, should the children be pruned off?
   */
  static bool MustPrune(nsIAccessible *aAccessible);

  /**
   * Search hint enum constants. Used by GetHeaderCellsFor() method.
   */
  enum {
    // search for row header cells, left direction
    eRowHeaderCells,
    // search for column header cells, top direction
    eColumnHeaderCells
  };

  /**
   * Return an array of row or column header cells for the given cell.
   *
   * @param aTable                [in] table accessible
   * @param aCell                 [in] cell accessible within the given table to
   *                               get header cells
   * @param aRowOrColHeaderCells  [in] specifies whether column or row header
   *                               cells are returned (see enum constants
   *                               above)
   * @param aCells                [out] array of header cell accessibles
   */
  static nsresult GetHeaderCellsFor(nsIAccessibleTable *aTable,
                                    nsIAccessibleTableCell *aCell,
                                    PRInt32 aRowOrColHeaderCells,
                                    nsIArray **aCells);
};

#endif