Maintainer	gtk2hs-users@lists.sourceforge.net
Stability	provisional
Portability	portable (depends on GHC)
Safe Haskell	None
Language	Haskell98

Graphics.UI.Gtk.ModelView.TreeModel

Contents

Detail
Class Hierarchy
Types
Constructors
Methods
Signals

Description

The tree interface used by TreeView.

Synopsis

Detail

The TreeModel interface defines a generic storage object for use by the TreeView and similar widgets. Specifically, the functions in defined here are used by Gtk's widgets to access the stored data. Thus, rather than calling these functions, an application programmer has to implement them. While the module Graphics.UI.Gtk.ModelView.CustomStore provides the necessary functions to implement the TreeMode interface, it is often sufficient to use the wo implementations that come with Gtk2Hs, namely are ListStore and TreeStore.

The model is represented as a hierarchical tree of values. It is important to note that this interface only provides a way of examining a model and observing changes. The implementation of each individual model decides how and if changes are made.

Two generic models are provided that implement the TreeModel interface: the TreeStore and the ListStore. To use these, the developer simply inserts data into these models as necessary. These models provide the data structure as well as the TreeModel interface. In fact, they implement other interfaces, making drag and drop and storing data trivial.

A TreeModel stores records of the same type. Each record is referred to as row, just like in a relational database. Defining how the information of a row is displayed can be done in two ways: If the widget displays data using CellRenderer or one of its derivatives, it is possible to state how a row is mapped to the attributes of a renderer using the cellLayoutSetAttributes function. Some widgets do not use CellRenderers to display their data. In this case an extraction function can be defined that maps a row to one of a few basic types (like Strings or Ints). This extraction function is associated with a ColumnId using treeModelSetColumn. The latter can be set in the widget for the property that should be set. The widget then uses the function treeModelGetValue and the ColumnId to extract the value from the model. As the name suggests, using ColumnIds creates a view of the data as if each row were divided into a well-defined set of columns, again, like a relational database.

Models are accessed on a node level of granularity. There are two index types used to reference a particular node in a model. They are the TreePath and the TreeIter. Most of the interface consists of operations on a TreeIter.

A path is essentially a potential node. It is a location on a model that may or may not actually correspond to a node on a specific model. A TreePath is in fact a synonym for a list of Ints and hence are easy to manipulate. Each number refers to the offset at that level. Thus, the path [0] refers to the root node and the path [2,4] refers to the fifth child of the third node.

By contrast, a TreeIter is a reference to a specific node on a specific model. It is an abstract data type filled in by the model. One can convert a path to an iterator by calling treeModelGetIter. These iterators are the primary way of accessing a model and are similar to the iterators used by TextBuffer. The model interface defines a set of operations using them for navigating the model. Iterators are expected to always be valid for as long as the model is unchanged (and doesn't emit a signal).

Class Hierarchy

| GInterface
| +----TreeModel
| +--------TypedTreeModel

Types

data TreeModel Source

Instances

Eq TreeModel Source
Ord TreeModel Source
GObjectClass TreeModel Source
TreeModelClass TreeModel Source

class GObjectClass o => TreeModelClass o Source

Instances

TreeModelClass TreeModel Source
TreeModelClass (ListStore a) Source
TreeModelClass (TreeStore a) Source
TreeModelClass (CustomStore private row) Source

castToTreeModel :: GObjectClass obj => obj -> TreeModel Source

gTypeTreeModel :: GType Source

toTreeModel :: TreeModelClass o => o -> TreeModel Source

data TypedTreeModel row Source

Instances

TypedTreeModelClass TypedTreeModel Source

class TypedTreeModelClass model Source

Instances

TypedTreeModelClass TypedTreeModelFilter Source
TypedTreeModelClass TypedTreeModelSort Source
TypedTreeModelClass TypedTreeModel Source
TypedTreeModelClass ListStore Source
TypedTreeModelClass TreeStore Source

toTypedTreeModel :: TypedTreeModelClass model => model row -> TypedTreeModel row Source

data TreeIter Source

Tree Iterator: a pointer to an entry in a TreeModel. The constructor of this structure is public for the sake of creating custom tree models. The first value is a time stamp that is handled by the functions that interface with Gtk. The time stamps are used to print warnings if programmers use an iter to a model that has changed meanwhile. The other three fields are used by the custom model implementation to implement an indexing scheme. The precise use of the three words is therefore implementation specific. See also TreePath.

Constructors

TreeIter !CInt !Word32 !Word32 !Word32

Instances

Show TreeIter Source
Storable TreeIter Source

type TreePath = [Int] Source

TreePath : a list of indices to specify a subtree or node in a TreeModel. The node that correspond to a given TreePath might change if nodes are removed or added and a TreePath may refer to a different or even non-existent node after a modification of the model. In contrast, a TreeIter is a more compact representation of a TreePath which becomes invalid after each modification of the underlying model. An intelligent index that is adjusted with each update of the model to point to the same node (whenever possible) is TreeRowReference.

data ColumnId row ty Source

The type of a tree column.

Constructors

makeColumnIdInt :: Int -> ColumnId row Int Source

Create a ColumnId to extract an integer.

makeColumnIdBool :: Int -> ColumnId row Bool Source

Create a ColumnId to extract an Boolean.

makeColumnIdString :: GlibString string => Int -> ColumnId row string Source

Create a ColumnId to extract an string.

makeColumnIdPixbuf :: Int -> ColumnId row Pixbuf Source

Create a ColumnId to extract an Pixbuf.

invalidColumnId :: ColumnId row ty Source

The invalid ColumnId. Widgets use this value if no column id has been set.

Methods

columnIdToNumber :: ColumnId row ty -> Int Source

Convert a ColumnId to a bare number.

stringToTreePath :: DefaultGlibString -> TreePath Source

Convert a comma or colon separated string into a TreePath. Any non-digit characters are assumed to separate indices, thus, the function always is always successful.

treeModelGetFlags :: TreeModelClass self => self -> IO [TreeModelFlags] Source

Returns a set of flags supported by this interface.

The flags supported should not change during the lifecycle of the tree_model.

treeModelGetIter Source

Arguments

:: TreeModelClass self
=> self
-> TreePath	`path` - The `TreePath`.
-> IO (Maybe TreeIter)

Turn a TreePath into a TreeIter.

Returns Nothing if the given TreePath was invalid. The empty list is always invalid. The root node of a tree can be accessed by passing [0] as path.

treeModelGetIterFromString Source

Arguments

:: (TreeModelClass self, GlibString string)
=> self
-> string	`pathString` - A string representation of a `TreePath`.
-> IO (Maybe TreeIter)

Turn a String into a TreeIter.

Returns Nothing if the string is not a colon separated list of numbers that references a valid node.

treeModelGetIterFirst :: TreeModelClass self => self -> IO (Maybe TreeIter) Source

Retrieves an TreeIter to the first entry.

Returns Nothing if the table is empty.

treeModelGetPath :: TreeModelClass self => self -> TreeIter -> IO TreePath Source

Turn an abstract TreeIter into a TreePath.

In case the given TreeIter was invalid, an empty list is returned.

treeModelGetValue Source

Arguments

:: TreeModelClass self
=> self
-> TreeIter
-> ColumnId row ty	`column` - The column to lookup the value at.
-> IO ty

Read the value of at a specific column and TreeIter.

treeModelIterNext :: TreeModelClass self => self -> TreeIter -> IO (Maybe TreeIter) Source

Retrieve an iterator to the node following it at the current level. If there is no next node, Nothing is returned.

treeModelIterChildren Source

Arguments

:: TreeModelClass self
=> self
-> TreeIter	`parent` - a pointer to the parent
-> IO (Maybe TreeIter)

Retrieve an iterator to the first child of parent. If parent has no children, Nothing.

treeModelIterHasChild Source

Arguments

:: TreeModelClass self
=> self
-> TreeIter	`iter` - The `TreeIter` to test for children.
-> IO Bool	returns `True` if `iter` has children.

Returns True if iter has children, False otherwise.

treeModelIterNChildren Source

Arguments

:: TreeModelClass self
=> self
-> Maybe TreeIter	`iter` - The `TreeIter`, or `Nothing`.
-> IO Int	returns The number of children of `iter`.

Returns the number of children that iter has. As a special case, if iter is Nothing, then the number of toplevel nodes is returned.

treeModelIterNthChild Source

Arguments

:: TreeModelClass self
=> self
-> Maybe TreeIter	`parent` - The `TreeIter` to get the child from, or `Nothing`.
-> Int	`n` - Then index of the desired child.
-> IO (Maybe TreeIter)

Retrieve the nth child of parent, counting from zero. If n is too big or parent has no children, Nothing is returned. If Nothing is specified for the parent argument, the function will return the nth root node.

treeModelIterParent :: TreeModelClass self => self -> TreeIter -> IO (Maybe TreeIter) Source

Retrieve the parent of this iterator.

treeModelForeach :: TreeModelClass self => self -> (TreeIter -> IO Bool) -> IO () Source

Maps a function over each node in model in a depth-first fashion. If it returns True, then the tree ceases to be walked, and treeModelForeach returns.

treeModelGetStringFromIter Source

Arguments

:: (TreeModelClass self, GlibString string)
=> self
-> TreeIter	`iter` - An `TreeIter`.
-> IO string	the returned string representation

Generates a string representation of the iter. This string is a ':' separated list of numbers. For example, "4:10:0:3" would be an acceptable return value for this string.

Available since Gtk+ version 2.2

treeModelRefNode Source

Arguments

:: TreeModelClass self
=> self
-> TreeIter	`iter` - The `TreeIter`.
-> IO ()

Lets the tree ref the node. This is an optional method for models to implement. To be more specific, models may ignore this call as it exists primarily for performance reasons.

This function is primarily meant as a way for views to let caching model know when nodes are being displayed (and hence, whether or not to cache that node.) For example, a file-system based model would not want to keep the entire file-hierarchy in memory, just the sections that are currently being displayed by every current view.

A model should be expected to be able to get an iter independent of its reffed state.

treeModelUnrefNode Source

Arguments

:: TreeModelClass self
=> self
-> TreeIter	`iter` - The `TreeIter`.
-> IO ()

Lets the tree unref the node. This is an optional method for models to implement. To be more specific, models may ignore this call as it exists primarily for performance reasons.

For more information on what this means, see treeModelRefNode. Please note that nodes that are deleted are not unreffed.

treeModelRowChanged Source

Arguments

:: TreeModelClass self
=> self
-> TreePath	`path` - A `TreePath` pointing to the changed row
-> TreeIter	`iter` - A valid `TreeIter` pointing to the changed row
-> IO ()

Emits the rowChanged signal on the model.

This function is only necessary to implement a custom tree model. When using ListStore or TreeStore, this function is called automatically.

treeModelRowInserted Source

Arguments

:: TreeModelClass self
=> self
-> TreePath	`path` - A `TreePath` pointing to the inserted row
-> TreeIter	`iter` - A valid `TreeIter` pointing to the inserted row
-> IO ()

Emits the rowInserted signal on the model.

This function is only necessary to implement a custom tree model. When using ListStore or TreeStore, this function is called automatically.

treeModelRowHasChildToggled Source

Arguments

:: TreeModelClass self
=> self
-> TreePath	`path` - A `TreePath` pointing to the changed row
-> TreeIter	`iter` - A valid `TreeIter` pointing to the changed row
-> IO ()

Emits the rowHasChildToggled signal on the model. This should be called by models after the child state of a node changes.

This function is only necessary to implement a custom tree model. When using ListStore or TreeStore, this function is called automatically.

treeModelRowDeleted Source

Arguments

:: TreeModelClass self
=> self
-> TreePath	`path` - A `TreePath` pointing to the previous location of the deleted row.
-> IO ()

Emits the rowDeleted signal on the model. This should be called by models after a row has been removed. The location pointed to by path should be the location that the row previously was at. It may not be a valid location anymore.

This function is only necessary to implement a custom tree model. When using ListStore or TreeStore, this function is called automatically.

treeModelRowsReordered Source

Arguments

:: TreeModelClass self
=> self
-> TreePath	`path` - A `TreePath` pointing to the tree node whose children have been reordered
-> Maybe TreeIter	`iter` - A valid `TreeIter` pointing to the node whose children have been reordered, or `Nothing` if `path` is `[]`.
-> [Int]	`newOrder` - a list of integers giving the previous position of each node at this hierarchy level.
-> IO ()

Emits the rowsReordered signal on the model. This should be called by models when their rows have been reordered. The length of newOrder must be equal to the value returned by treeModelIterNChildren self iter.

This function is only necessary to implement a custom tree model. When using ListStore or TreeStore, this function is called automatically.

Signals

rowChanged :: TreeModelClass self => Signal self (TreePath -> TreeIter -> IO ()) Source

This signal is emitted when a row in the model has changed.

rowInserted :: TreeModelClass self => Signal self (TreePath -> TreeIter -> IO ()) Source

This signal is emitted when a new row has been inserted in the model.

rowHasChildToggled :: TreeModelClass self => Signal self (TreePath -> TreeIter -> IO ()) Source

This signal is emitted when a row has gotten the first child row or lost its last child row.

rowDeleted :: TreeModelClass self => Signal self (TreePath -> IO ()) Source

This signal is emitted when a row has been deleted.

Note that no iterator is passed to the signal handler, since the row is already deleted.

Implementations of TreeModel must emit row-deleted before removing the node from its internal data structures. This is because models and views which access and monitor this model might have references on the node which need to be released in the rowDeleted handler.

rowsReordered :: TreeModelClass self => Signal self (TreePath -> Maybe TreeIter -> [Int] -> IO ()) Source

This signal is emitted when the children of a node in the TreeModel have been reordered. See treeModelRowsReordered for more information about the parameters that this signal carries.

Note that this signal is not emitted when rows are reordered by DND, since this is implemented by removing and then reinserting the row.