haiku/docs/user/storage/NodeInfo.dox

/*
 * Copyright 2013 Haiku Inc. All rights reserved.
 * Distributed under the terms of the MIT License.
 *
 * Authors:
 *		Axel Dörfler, axeld@pinc-software.de
 *		John Scipione, jscipione@gmail.com
 *		Ingo Weinhold, bonefish@users.sf.net
 *
 * Corresponds to:
 *		headers/os/storage/NodeInfo.h	hrev45253
 *		src/kits/storage/NodeInfo.cpp	hrev45253
 */


/*!
	\file NodeInfo.h
	\ingroup storage
	\ingroup libbe
	\brief Provides the BNodeInfo class.
*/


/*!
	\class BNodeInfo
	\ingroup storage
	\ingroup libbe
	\brief Provides access to file type meta data on a node.

	BNodeInfo provides a nice wrapper to all sorts of useful meta data such as
	the MIME-type, the file's icon and the application that will open
	the file.
*/


/*!
	\fn BNodeInfo::BNodeInfo()
	\brief Creates an uninitialized BNodeInfo object.

	After created a BNodeInfo with this, you should call SetTo().

	\see SetTo(BNode *node)
*/


/*!
	\fn BNodeInfo::BNodeInfo(BNode *node)
	\brief Creates a BNodeInfo object and initializes it to the supplied
	       \a node.

	\param node The \a node to gather information on.
*/


/*!
	\fn BNodeInfo::~BNodeInfo()
	\brief Frees the object and associated resources.

	The internal BNode object is not deleted.
*/


/*!
	\name Constructor helper methods
*/


//! @{


/*!
	\fn status_t BNodeInfo::SetTo(BNode *node)
	\brief Initializes the BNodeInfo to the supplied \a node.

	The BNodeInfo object does not copy the supplied \a node object, it uses it
	directly instead. You must not delete the supply \a node while the
	BNodeInfo object exists. The BNodeInfo does not take over ownership of the
	\a node and it doesn't delete it on destruction either.

	\param node The \a node to gather information on.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_BAD_VALUE The node was not properly initialized.
*/


/*!
	\fn status_t BNodeInfo::InitCheck() const
	\brief Checks whether or not the object has been properly initialized.

	\returns A status code.
	\retval B_OK The object was properly initialized.
	\retval B_BAD_VALUE The object was \b not properly initialized.
*/


//! @}


/*!
	\name MIME-type methods
*/


//! @{


/*!
	\fn status_t BNodeInfo::GetType(char *type) const
	\brief Writes the MIME-type of the node into \a type.

	The source of the type information is the \c BEOS:TYPE attribute of the
	node. The \a type buffer should be pre-allocated before it is passed into
	GetType(), it should be at least \c B_MIME_TYPE_LENGTH in length.

	\param type A pointer to a pre-allocated char buffer of at least
	       \c B_MIME_TYPE_LENGTH length into which the MIME-type of the
	       node is written.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object is not properly initialized.
	\retval B_BAD_VALUE \c NULL \a type or the type string stored in the
	        attribute is longer than \c B_MIME_TYPE_LENGTH.
	\retval B_BAD_TYPE The stored type string attribute has the wrong type.
	\retval B_ENTRY_NOT_FOUND No type is set on the node.
*/


/*!
	\fn status_t BNodeInfo::SetType(const char *type)
	\brief Sets the MIME-type of the node. If \a type is \c NULL the
	       \c BEOS:TYPE attribute is removed instead.

	The \a type string is written into the \c BEOS:TYPE attribute of the node.
	If \a type is \c NULL, the \c BEOS:TYPE attribute is removed instead. The
	\a type parameter may not by longer than \c B_MIME_TYPE_LENGTH in length
	including the terminating \c NUL character.

	\param type The MIME-type to be assigned to the \a node. Must not be
	       longer than \c B_MIME_TYPE_LENGTH (including the terminating
	       \c NUL). May be \c NULL to remove the attribute.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object was not properly initialized.
	\retval B_BAD_VALUE \a type is longer than \c B_MIME_TYPE_LENGTH.
*/


//! @}


/*!
	\name Icon methods
*/


//! @{


/*!
	\fn status_t BNodeInfo::GetIcon(BBitmap *icon, icon_size k) const
	\brief Gets the icon of the node.

	The icon stored in the \c BEOS:L:STD_ICON attribute (large) or
	\c BEOS:M:STD_ICON attribute (mini) is retrieved.

	\param icon A pointer to a pre-allocated BBitmap object of the correct
		   dimension to store the requested icon: 16x16 for the mini or
		   32x32 for the large icon.
	\param k The size of the icon to be retrieved: \c B_MINI_ICON for a 16x16
	       icon and \c B_LARGE_ICON for a 32x32 icon.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object was not properly initialized.
	\retval B_BAD_VALUE \c NULL \a icon, unsupported icon size \a k or bitmap
		    dimensions (\a icon) and icon size (\a k) do not match.
*/


/*!
	\fn status_t BNodeInfo::SetIcon(const BBitmap *icon, icon_size k)
	\brief Sets the icon of the node. If \a icon is \c NULL, the attribute is
		   removed instead.

	The icon is stored in the \c BEOS:L:STD_ICON attribute (large) or
	\c BEOS:M:STD_ICON attribute (mini). If \a icon is \c NULL the respective
	attribute is removed instead.

	\param icon A pointer to a BBitmap object containing the icon to be set.
		   May be \c NULL.
	\param k The size of the icon to be set: \c B_MINI_ICON for the mini or
	       \c B_LARGE_ICON for the large icon.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object is not properly initialized.
	\retval B_BAD_VALUE Unknown icon size \a k or bitmap dimensions (\a icon)
		    and icon size (\a k) do not match.
*/


/*!
	\fn status_t BNodeInfo::GetIcon(uint8** data, size_t* size,
		type_code* type) const
	\brief Gets the icon of the node.

	The icon stored in the \c BEOS:ICON attribute of the node is retrieved.
	The caller is responsible to <tt>delete[]</tt> the data if the icon was
	retrieved.

	\param data A pointer in which a pointer to the icon data
		   will be returned.
	\param size A pointer in which the size of the found icon data
		   will be returned.
	\param type A pointer in which the type of the found icon data
		   will be returned.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object was not properly initialized.
	\retval B_BAD_VALUE \c NULL \a data, \c NULL \a size or \c NULL \a type.
	\retval B_NO_MEMORY No memory to allocate the \a data buffer.
*/


/*!
	\fn status_t BNodeInfo::SetIcon(const uint8* data, size_t size)
	\brief Sets the node icon of the node. If \a data is \c NULL or \a size
	       is 0, the \c BEOS:ICON attribute is removed instead.

	The icon is stored in the \c BEOS:ICON attribute of the node.

	\param data A pointer to valid icon data. May be \c NULL.
	\param size The size of the provided data buffer. May be 0.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object was not properly initialized.
*/


/*!
	\fn status_t BNodeInfo::GetTrackerIcon(BBitmap *icon,
		icon_size iconSize) const
	\brief Gets the icon displayed by Tracker for the icon.

	This method tries really hard to find an icon for the node:
	- If the node has no type this method returns the icon for
	  \c B_FILE_MIME_TYPE if it's a regular file or
	  \c B_DIRECTORY_MIME_TYPE if it's a directory, even if the node has its
	  own icon!
	- Next it will ask GetIcon() for an icon.
	- If this fails it will get the preferred application and ask the MIME
	  database if the application has an icon for the file type of the
	  node.
	- Next it will ask the MIME database whether there is an icon for the file
	  type of the node.
	- Then it will ask the MIME database for the preferred application for
	  the file type of the node and whether this application has a special
	  icon for the type.
	- Finally it will return a generic icon for whatever type of file type
	  (file/dir/etc.) the node is from the MIME database.

	The first action that provides an icon is used. In the case that none of
	them yield an icon this method fails, this is very unlikely though.

	\remarks You can set \a iconSize to get a scaled icon instead of using
	         a predefined icon_size constant, pass in an integer casted
	         to icon_size. For example to get a 64x64 icon pass in:
\code
(icon_size)64
\endcode

	\param icon A pointer to a pre-allocated BBitmap of the correct dimension
		   to store the requested icon (16x16 for the mini and 32x32 for the
		   large icon).
	\param iconSize The size of the icon to be retrieved: \c B_MINI_ICON
		   for a 16x16 icon or \c B_LARGE_ICON for a 32x32 icon.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object was not properly initialized.
	\retval B_BAD_VALUE \c NULL \a icon, unsupported icon size \a iconSize
	        or bitmap dimensions (\a icon) and icon size (\a iconSize) do
	        not match.
*/


/*!
	\fn status_t BNodeInfo::GetTrackerIcon(const entry_ref *ref,
		BBitmap *icon, icon_size iconSize)
	\brief Gets the icon displayed by Tracker for the node referred to by
	       \a ref.

	This methods works similarly to the non-static version but \a ref
	identifies the node. \a icon must be pre-allocated to the size requested
	using \a iconSize before being passed to this method.

	\param ref An entry_ref referring to the node for which the icon is
	       retrieved.
	\param icon A pointer to a pre-allocated BBitmap object of the correct
	       dimension to store the requested icon (16x16 for the mini and 32x32
	       for the large icon).
	\param iconSize The size of the icon to be retrieved: \c B_MINI_ICON
	       for a 16x16 icon or \c B_LARGE_ICON for a 32x32 icon.

	\returns A status code.
	\retval B_OK: Everything went fine.
	\retval B_NO_INIT: The object is not properly initialized.
	\retval B_BAD_VALUE: \c NULL ref or \a icon, unsupported icon size
	        \a iconSize or bitmap dimensions (\a icon) and icon size
	        (\a iconSize) do not match.
*/


//! @}


/*!
	\name Preferred application methods
*/


//! @{


/*!
	\fn status_t BNodeInfo::GetPreferredApp(char *signature,
		app_verb verb) const
	\brief Gets the preferred application of the node.

	Writes the contents of the \c BEOS:PREF_APP attribute into the
	\a signature buffer. The preferred application can be identified by its
	signature. \a signature should be at least \c B_MIME_TYPE_LENGTH or
	longer and pre-allocated before it is passed into this method.

	\param signature A pointer to a pre-allocated character buffer of size
	       \c B_MIME_TYPE_LENGTH or larger into which the MIME-type of the
	       preferred application is written.
	\param verb The type of access the preferred application is requested.
	       Currently \c B_OPEN is the only meaningful option.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object was not properly initialized.
	\retval B_BAD_VALUE \c NULL \a signature or bad app_verb.
*/


/*!
	\fn status_t BNodeInfo::SetPreferredApp(const char *signature,
		app_verb verb)
	\brief Sets the preferred application of the node. If \a signature is
	       \c NULL, the \c BEOS:PREF_APP attribute is removed instead.

	The supplied string is written into the \c BEOS:PREF_APP attribute of the
	node. If \a signature is \c NULL, the respective attribute is removed
	instead. \a signature must not be longer than \c B_MIME_TYPE_LENGTH
	       (including the terminating \c NUL).

	\param signature The signature of the preferred application to be set.
	       May be \c NULL.
	\param verb The type of access set to the preferred application.
	       Currently only \c B_OPEN is meaningful.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_NO_INIT The object is not properly initialized.
	\retval B_BAD_VALUE \c NULL \a signature, \a signature is longer than
	        \c B_MIME_TYPE_LENGTH or bad app_verb.
*/


//! @}


/*!
	\name Application hint methods
*/


//! @{


/*!
	\fn status_t BNodeInfo::GetAppHint(entry_ref *ref) const
	\brief Fills out \a ref with a pointer to a hint about the application
	       that will open this node.

	The path contained in the \c BEOS:PPATH attribute of the node is converted
	into an entry_ref and returned. \a ref should be pre-allocated before being
	passed into this method.

	\param ref A pointer to a pre-allocated entry_ref into which the app hint
	       is written.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_BAD_DATA Attribute size greater than \c B_PATH_NAME_LENGTH.
	\retval B_BAD_TYPE The stored type string attribute has the wrong type.
	\retval B_BAD_VALUE The \a ref object passed in was \c NULL.
	\retval B_ERROR Unable to read \c BEOS:PPATH attribute.
	\retval B_NO_INIT The object was not properly initialized.
*/


/*!
	\fn status_t BNodeInfo::SetAppHint(const entry_ref *ref)
	\brief Sets the application that will open the file type of the node. If
	       \a ref is \c NULL, the \c BEOS:PPATH attribute is removed instead.

	\a ref is converted into a path and stored in the \c BEOS:PPATH attribute
	of the node. If \a ref is NULL \c BEOS:PPATH is removed instead.

	\param ref A pointer to an entry_ref referring to the application.
	       May be \c NULL.

	\returns A status code.
	\retval B_OK Everything went fine.
	\retval B_BAD_VALUE The \a ref object passed in was \c NULL.
	\retval B_ENTRY_NOT_FOUND \c BEOS:PPATH attribute not found.
	\retval B_ERROR Unable to write \c BEOS:PPATH attribute.
	\retval B_NO_INIT The object was not properly initialized.
*/


//! @}