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+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 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/. */
+
+#include "nsISupports.idl"
+
+interface nsIObserver;
+
+/**
+ * The nsIPrefBranch interface is used to manipulate the preferences data. This
+ * object may be obtained from the preferences service (nsIPrefService) and
+ * used to get and set default and/or user preferences across the application.
+ *
+ * This object is created with a "root" value which describes the base point in
+ * the preferences "tree" from which this "branch" stems. Preferences are
+ * accessed off of this root by using just the final portion of the preference.
+ * For example, if this object is created with the root "browser.startup.",
+ * the preferences "browser.startup.page", "browser.startup.homepage",
+ * and "browser.startup.homepage_override" can be accessed by simply passing
+ * "page", "homepage", or "homepage_override" to the various Get/Set methods.
+ *
+ * @see nsIPrefService
+ */
+
+[scriptable, uuid(55d25e49-793f-4727-a69f-de8b15f4b985)]
+interface nsIPrefBranch : nsISupports
+{
+
+ /**
+ * Values describing the basic preference types.
+ *
+ * @see getPrefType
+ */
+ const long PREF_INVALID = 0;
+ const long PREF_STRING = 32;
+ const long PREF_INT = 64;
+ const long PREF_BOOL = 128;
+
+ /**
+ * Called to get the root on which this branch is based, such as
+ * "browser.startup."
+ */
+ readonly attribute string root;
+
+ /**
+ * Called to determine the type of a specific preference.
+ *
+ * @param aPrefName The preference to get the type of.
+ *
+ * @return long A value representing the type of the preference. This
+ * value will be PREF_STRING, PREF_INT, or PREF_BOOL.
+ */
+ long getPrefType(in string aPrefName);
+
+ /**
+ * Called to get the state of an individual boolean preference.
+ *
+ * @param aPrefName The boolean preference to get the state of.
+ *
+ * @return boolean The value of the requested boolean preference.
+ *
+ * @see setBoolPref
+ */
+ boolean getBoolPref(in string aPrefName);
+
+ /**
+ * Called to set the state of an individual boolean preference.
+ *
+ * @param aPrefName The boolean preference to set the state of.
+ * @param aValue The boolean value to set the preference to.
+ *
+ * @throws Error if setting failed or the preference has a default
+ value of a type other than boolean.
+ *
+ * @see getBoolPref
+ */
+ void setBoolPref(in string aPrefName, in boolean aValue);
+
+ /**
+ * Called to get the state of an individual floating-point preference.
+ * "Floating point" preferences are really string preferences that
+ * are converted to floating point numbers.
+ *
+ * @param aPrefName The floating point preference to get the state of.
+ *
+ * @return float The value of the requested floating point preference.
+ *
+ * @see setCharPref
+ */
+ float getFloatPref(in string aPrefName);
+
+ /**
+ * Called to get the state of an individual string preference.
+ *
+ * @param aPrefName The string preference to retrieve.
+ *
+ * @return string The value of the requested string preference.
+ *
+ * @see setCharPref
+ */
+ string getCharPref(in string aPrefName);
+
+ /**
+ * Called to set the state of an individual string preference.
+ *
+ * @param aPrefName The string preference to set.
+ * @param aValue The string value to set the preference to.
+ *
+ * @throws Error if setting failed or the preference has a default
+ value of a type other than string.
+ *
+ * @see getCharPref
+ */
+ void setCharPref(in string aPrefName, in string aValue);
+
+ /**
+ * Called to get the state of an individual integer preference.
+ *
+ * @param aPrefName The integer preference to get the value of.
+ *
+ * @return long The value of the requested integer preference.
+ *
+ * @see setIntPref
+ */
+ long getIntPref(in string aPrefName);
+
+ /**
+ * Called to set the state of an individual integer preference.
+ *
+ * @param aPrefName The integer preference to set the value of.
+ * @param aValue The integer value to set the preference to.
+ *
+ * @throws Error if setting failed or the preference has a default
+ value of a type other than integer.
+ *
+ * @see getIntPref
+ */
+ void setIntPref(in string aPrefName, in long aValue);
+
+ /**
+ * Called to get the state of an individual complex preference. A complex
+ * preference is a preference which represents an XPCOM object that can not
+ * be easily represented using a standard boolean, integer or string value.
+ *
+ * @param aPrefName The complex preference to get the value of.
+ * @param aType The XPCOM interface that this complex preference
+ * represents. Interfaces currently supported are:
+ * - nsIFile
+ * - nsISupportsString (UniChar)
+ * - nsIPrefLocalizedString (Localized UniChar)
+ * @param aValue The XPCOM object into which to the complex preference
+ * value should be retrieved.
+ *
+ * @throws Error The value does not exist or is the wrong type.
+ *
+ * @see setComplexValue
+ */
+ void getComplexValue(in string aPrefName, in nsIIDRef aType,
+ [iid_is(aType), retval] out nsQIResult aValue);
+
+ /**
+ * Called to set the state of an individual complex preference. A complex
+ * preference is a preference which represents an XPCOM object that can not
+ * be easily represented using a standard boolean, integer or string value.
+ *
+ * @param aPrefName The complex preference to set the value of.
+ * @param aType The XPCOM interface that this complex preference
+ * represents. Interfaces currently supported are:
+ * - nsIFile
+ * - nsISupportsString (UniChar)
+ * - nsIPrefLocalizedString (Localized UniChar)
+ * @param aValue The XPCOM object from which to set the complex preference
+ * value.
+ *
+ * @throws Error if setting failed or the value is the wrong type.
+ *
+ * @see getComplexValue
+ */
+ void setComplexValue(in string aPrefName, in nsIIDRef aType, in nsISupports aValue);
+
+ /**
+ * Called to clear a user set value from a specific preference. This will, in
+ * effect, reset the value to the default value. If no default value exists
+ * the preference will cease to exist.
+ *
+ * @param aPrefName The preference to be cleared.
+ *
+ * @note
+ * This method does nothing if this object is a default branch.
+ */
+ void clearUserPref(in string aPrefName);
+
+ /**
+ * Called to lock a specific preference. Locking a preference will cause the
+ * preference service to always return the default value regardless of
+ * whether there is a user set value or not.
+ *
+ * @param aPrefName The preference to be locked.
+ *
+ * @note
+ * This method can be called on either a default or user branch but, in
+ * effect, always operates on the default branch.
+ *
+ * @throws Error The preference does not exist or an error occurred.
+ *
+ * @see unlockPref
+ */
+ void lockPref(in string aPrefName);
+
+ /**
+ * Called to check if a specific preference has a user value associated to
+ * it.
+ *
+ * @param aPrefName The preference to be tested.
+ *
+ * @note
+ * This method can be called on either a default or user branch but, in
+ * effect, always operates on the user branch.
+ *
+ * @note
+ * If a preference was manually set to a value that equals the default value,
+ * then the preference no longer has a user set value, i.e. it is
+ * considered reset to its default value.
+ * In particular, this method will return false for such a preference and
+ * the preference will not be saved to a file by nsIPrefService.savePrefFile.
+ *
+ * @return boolean true The preference has a user set value.
+ * false The preference only has a default value.
+ */
+ boolean prefHasUserValue(in string aPrefName);
+
+ /**
+ * Called to check if a specific preference is locked. If a preference is
+ * locked calling its Get method will always return the default value.
+ *
+ * @param aPrefName The preference to be tested.
+ *
+ * @note
+ * This method can be called on either a default or user branch but, in
+ * effect, always operates on the default branch.
+ *
+ * @return boolean true The preference is locked.
+ * false The preference is not locked.
+ *
+ * @see lockPref
+ * @see unlockPref
+ */
+ boolean prefIsLocked(in string aPrefName);
+
+ /**
+ * Called to unlock a specific preference. Unlocking a previously locked
+ * preference allows the preference service to once again return the user set
+ * value of the preference.
+ *
+ * @param aPrefName The preference to be unlocked.
+ *
+ * @note
+ * This method can be called on either a default or user branch but, in
+ * effect, always operates on the default branch.
+ *
+ * @throws Error The preference does not exist or an error occurred.
+ *
+ * @see lockPref
+ */
+ void unlockPref(in string aPrefName);
+
+
+ /**
+ * Called to remove all of the preferences referenced by this branch.
+ *
+ * @param aStartingAt The point on the branch at which to start the deleting
+ * preferences. Pass in "" to remove all preferences
+ * referenced by this branch.
+ *
+ * @note
+ * This method can be called on either a default or user branch but, in
+ * effect, always operates on both.
+ *
+ * @throws Error The preference(s) do not exist or an error occurred.
+ */
+ void deleteBranch(in string aStartingAt);
+
+ /**
+ * Returns an array of strings representing the child preferences of the
+ * root of this branch.
+ *
+ * @param aStartingAt The point on the branch at which to start enumerating
+ * the child preferences. Pass in "" to enumerate all
+ * preferences referenced by this branch.
+ * @param aCount Receives the number of elements in the array.
+ * @param aChildArray Receives the array of child preferences.
+ *
+ * @note
+ * This method can be called on either a default or user branch but, in
+ * effect, always operates on both.
+ *
+ * @throws Error The preference(s) do not exist or an error occurred.
+ */
+ void getChildList(in string aStartingAt,
+ [optional] out unsigned long aCount,
+ [array, size_is(aCount), retval] out string aChildArray);
+
+ /**
+ * Called to reset all of the preferences referenced by this branch to their
+ * default values.
+ *
+ * @param aStartingAt The point on the branch at which to start the resetting
+ * preferences to their default values. Pass in "" to
+ * reset all preferences referenced by this branch.
+ *
+ * @note
+ * This method can be called on either a default or user branch but, in
+ * effect, always operates on the user branch.
+ *
+ * @throws Error The preference(s) do not exist or an error occurred.
+ */
+ void resetBranch(in string aStartingAt);
+
+ /**
+ * Add a preference change observer. On preference changes, the following
+ * arguments will be passed to the nsIObserver.observe() method:
+ * aSubject - The nsIPrefBranch object (this)
+ * aTopic - The string defined by NS_PREFBRANCH_PREFCHANGE_TOPIC_ID
+ * aData - The name of the preference which has changed, relative to
+ * the |root| of the aSubject branch.
+ *
+ * aSubject.get*Pref(aData) will get the new value of the modified
+ * preference. For example, if your observer is registered with
+ * addObserver("bar.", ...) on a branch with root "foo.", modifying
+ * the preference "foo.bar.baz" will trigger the observer, and aData
+ * parameter will be "bar.baz".
+ *
+ * @param aDomain The preference on which to listen for changes. This can
+ * be the name of an entire branch to observe.
+ * e.g. Holding the "root" prefbranch and calling
+ * addObserver("foo.bar.", ...) will observe changes to
+ * foo.bar.baz and foo.bar.bzip
+ * @param aObserver The object to be notified if the preference changes.
+ * @param aHoldWeak true Hold a weak reference to |aObserver|. The object
+ * must implement the nsISupportsWeakReference
+ * interface or this will fail.
+ * false Hold a strong reference to |aObserver|.
+ *
+ * @note
+ * Registering as a preference observer can open an object to potential
+ * cyclical references which will cause memory leaks. These cycles generally
+ * occur because an object both registers itself as an observer (causing the
+ * branch to hold a reference to the observer) and holds a reference to the
+ * branch object for the purpose of getting/setting preference values. There
+ * are 3 approaches which have been implemented in an attempt to avoid these
+ * situations.
+ * 1) The nsPrefBranch object supports nsISupportsWeakReference. Any consumer
+ * may hold a weak reference to it instead of a strong one.
+ * 2) The nsPrefBranch object listens for xpcom-shutdown and frees all of the
+ * objects currently in its observer list. This ensures that long lived
+ * objects (services for example) will be freed correctly.
+ * 3) The observer can request to be held as a weak reference when it is
+ * registered. This insures that shorter lived objects (say one tied to an
+ * open window) will not fall into the cyclical reference trap.
+ *
+ * @note
+ * The list of registered observers may be changed during the dispatch of
+ * nsPref:changed notification. However, the observers are not guaranteed
+ * to be notified in any particular order, so you can't be sure whether the
+ * added/removed observer will be called during the notification when it
+ * is added/removed.
+ *
+ * @note
+ * It is possible to change preferences during the notification.
+ *
+ * @note
+ * It is not safe to change observers during this callback in Gecko
+ * releases before 1.9. If you want a safe way to remove a pref observer,
+ * please use an nsITimer.
+ *
+ * @see nsIObserver
+ * @see removeObserver
+ */
+ void addObserver(in string aDomain, in nsIObserver aObserver,
+ in boolean aHoldWeak);
+
+ /**
+ * Remove a preference change observer.
+ *
+ * @param aDomain The preference which is being observed for changes.
+ * @param aObserver An observer previously registered with addObserver().
+ *
+ * @note
+ * Note that you must call removeObserver() on the same nsIPrefBranch
+ * instance on which you called addObserver() in order to remove aObserver;
+ * otherwise, the observer will not be removed.
+ *
+ * @see nsIObserver
+ * @see addObserver
+ */
+ void removeObserver(in string aDomain, in nsIObserver aObserver);
+};
+
+
+%{C++
+
+#define NS_PREFBRANCH_CONTRACTID "@mozilla.org/preferencesbranch;1"
+/**
+ * Notification sent when a preference changes.
+ */
+#define NS_PREFBRANCH_PREFCHANGE_TOPIC_ID "nsPref:changed"
+
+%}