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The QAbstractItemModel class provides the abstract interface for item model classes. More...
#include <QAbstractItemModel>
Inherits QObject.
Inherited by QAbstractTableModel, QAbstractListModel, QDirModel, QProxyModel, and QStandardItemModel.
The QAbstractItemModel class provides the abstract interface for item model classes.
The QAbstractItemModel class defines the standard interface that item models must use to be able to interoperate with other components in the model/view architecture. It is not supposed to be instantiated directly. Instead, you should subclass it to create new models.
If you need a model to use with a QListView or a QTableView, you should consider subclassing QAbstractListModel or QAbstractTableModel instead of this class.
The underlying data model is exposed to views and delegates as a hierarchy of tables. If you don't make use of the hierarchy, then the model is a simple table of rows and columns. Each item has a unique index specified by a QModelIndex.
Every item has an index(), and possibly a sibling() index; child items have a parent() index. hasChildren() is true for items that have children. Each item has a number of data elements associated with them, each with a particular Role. Data elements are set individually with setData(), or for all roles with setItemData(). Data is retrieved from an item with data() (for a single role), or with itemData() (for every role). Items can be queried with flags() (see {QAbstractTableModel::ItemFlag}) to see if they are selectable, dragable etc. An item can be searched for using match().
The model has a rowCount() and a columnCount() for each level of the hierarchy. Rows and columns can be inserted and removed with insertRows(), insertColumns(), removeRows(), and removeColumns().
The model emits signals to indicate changes. For example, dataChanged() is emitted whenever the contents of the model are changed; rowsInserted(), columnsInserted(), rowsRemoved(), and columnsRemoved() are emitted when the model's dimensions are changed.
If the model isSortable(), it can be sorted with sort(). To customize sorting and searching, comparison functions can be reimplemented; for example, lessThan(), equal(), and greaterThan().
When subclassing QAbstractItemModel, at the very least you must implement index(), parent(), rowCount(), columnCount(), and data(). To enable editing in your model, you must also implement flags() to return ItemIsEditable and setData().
See also Model/View Programming, QModelIndex, and QAbstractItemView.
This enum describes the properties of an item:
QAbstractItemModel::ItemIsSelectable | It can be selected. |
QAbstractItemModel::ItemIsEditable | It can be edited. |
QAbstractItemModel::ItemIsDragEnabled | It can be dragged. |
QAbstractItemModel::ItemIsDropEnabled | It can be used as a drop target. |
QAbstractItemModel::ItemIsCheckable | It can be checked. |
QAbstractItemModel::ItemIsEnabled | The user can interact with the item. |
The ItemFlags typedef can store a combination of ItemFlag values.
QAbstractItemModel::MatchContains | The value is contained in the item. |
QAbstractItemModel::MatchFromStart | The value matches the start of the item. |
QAbstractItemModel::MatchFromEnd | The value matches the end of the item. |
QAbstractItemModel::MatchExactly | The value matches the item exactly. |
QAbstractItemModel::MatchCase | The search is case sensitive. |
QAbstractItemModel::MatchWrap | The search wraps around. |
QAbstractItemModel::MatchDefault | The default match, which is MatchFromStart|MatchWrap. |
The MatchFlags typedef can store a combination of MatchFlag values.
Each item in the model has a set of data elements associated with it, each with its own role. The roles are used by the view to indicate to the model which type of data it needs.
The general purpose roles are:
QAbstractItemModel::DisplayRole | The key data to be rendered (usually text). |
QAbstractItemModel::DecorationRole | The data to be rendered as a decoration (usually an icon). |
QAbstractItemModel::EditRole | The data in a form suitable for editing in an editor. |
QAbstractItemModel::ToolTipRole | The data displayed in the item's tooltip. |
QAbstractItemModel::StatusTipRole | The data displayed in the status bar. |
QAbstractItemModel::WhatsThisRole | The data displayed for the item in "What's This?" mode. |
Roles describing appearance and meta data:
QAbstractItemModel::FontRole | The font used for items rendered with the default delegate. |
QAbstractItemModel::TextAlignmentRole | The alignment of the text for items rendered with the default delegate. |
QAbstractItemModel::BackgroundColorRole | The background color used for items rendered with the default delegate. |
QAbstractItemModel::TextColorRole | The text color used for items rendered with the default delegate. |
QAbstractItemModel::CheckStateRole | Whether the item can be checked. |
Accessibility roles:
QAbstractItemModel::AccessibleTextRole | The text to be used by accessibility extensions and plugins, such as screen readers. |
QAbstractItemModel::AccessibleDescriptionRole | A description of the item for accessibility purposes. |
QAbstractItemModel::UserRole | The first role that can be used for application-specific purposes. |
Constructs an abstract item model with the given parent.
Destroys the abstract item model.
Returns the buddy of the item represented by index. When the user wants to edit an item the delegate will ask for the item's buddy, and item instead. In the default implementation an item is it's own buddy.
Returns the number of columns for the given parent.
This signal is emitted after columns have been inserted into the model. The new items are those between start and end inclusive, under the given parent item.
See also insertColumns().
Creates a model index for the given row and column that points to the given data.
This function provides a consistent interface that model subclasses must use to create model indexes.
Returns the data stored under the given role for the item referred to by the index.
This signal is emitted whenever the data in an existing item changes. The affected items are those between topLeft and bottomRight inclusive.
See also rowsInserted(), rowsRemoved(), columnsInserted(), columnsRemoved(), and setData().
Fetches any available data for the items with the parent specified by the parent index.
Returns the item flags for the given index.
The base class implementation returns a combination of flags that enables the item (ItemIsEnabled) and allows it to be selected (ItemIsSelectable).
See also ItemFlag.
Returns true if the model returns a valid QModelIndex for row and column with parent, otherwise returns false.
Returns the data for the given role and section in the header with the specified orientation.
This signal is emitted whenever a header is changed. The orientation indicates whether the horizontal or vertical header has changed. The sections in the header from the first to the last need to be updated.
See also headerData() and setHeaderData().
Returns the index of the item in the model specified by the given row, column and parent index.
Inserts a single column before the given column in the child items of the parent specified. Returns true if the column is inserted; otherwise returns false.
See also insertColumns(), insertRow(), and removeColumn().
Inserts count new columns in the model before the given column. The items in each new column will be children of the item represented by the parent model index.
If column is 0, the columns are prepended to any existing columns. If column is columnCount(), the columns are appended to any existing columns. If parent has no children, a single row with count columns is inserted.
Returns true if the columns were successfully inserted; otherwise returns false.
The base class implementation does nothing and returns false. If you want to be able to insert columns you must reimplement this function.
Inserts a single row before the given row in the child items of the parent specified. Returns true if the row is inserted; otherwise returns false.
See also insertRows(), insertColumn(), and removeRow().
Inserts count rows into the model before the given row. The items in the new row will be children of the item represented by the parent model index.
If row is 0, the rows are prepended to any existing rows in the parent. If row is rowCount(), the rows are appended to any existing rows in the parent. If parent has no children, a single column with count rows is inserted.
Returns true if the rows were successfully inserted; otherwise returns false.
The base class implementation does nothing and returns false. If you want to be able to insert rows you must reimplement this function.
Returns a map with values for all predefined roles in the model for the item at the given index.
This must be reimplemented if you want to extend the model with custom roles.
Returns a list of indexes for the items where the data stored under the given role matches the specified value. The way the search is performed is defined by the flags given. The list that is returned may be empty.
The search starts from the start index, and continues until the number of matching data items equals hits, the search reaches the last row, or the search reaches start again, depending on whether MatchWrap is specified in flags.
See also QAbstractItemModel::MatchFlag.
Returns the parent of the model item with the given index.
Removes the given column from the child items of the parent specified. Returns true if the column is removed; otherwise returns false.
See also removeColumns(), removeRow(), and insertColumn().
Removes count columns starting with column column under parent parent from the model. Returns true if the columns were successfully removed; otherwise returns false.
The base class implementation does nothing and returns false.
Removes the given row from the child items of the parent specified. Returns true if the row is removed; otherwise returns false.
See also removeRows(), removeColumn(), and insertRow().
Removes count rows starting with row row under parent parent from the model. Returns true if the rows were successfully removed; otherwise returns false.
The base class implementation does nothing and returns false.
Called to let the model know that it should discart whatever it has cached. Typically used for row editing.
Returns the number of rows under the given parent.
This signal is emitted after rows have been inserted into the model. The new items are those between start and end inclusive, under the given parent item.
See also insertRows().
Sets the role data for the item at index to value. Returns true if successful; otherwise returns false.
The base class implementation returns false. This function and data() must be reimplemented for editable models.
See also data() and itemData().
Sets the role for the header section to value. The orientation gives the orientation of the header.
See also headerData().
For every Role in roles, sets the role data for the item at index to the associated value in roles. Returns true if successful; otherwise returns false.
See also setData(), data(), and itemData().
Returns the model index of the sibling of the item specified by the given row, column, and index.
Sorts the model by column in the given order.
The base class implementation does nothing.
See also isSortable().
Returns the row and column span of the item represented by index.
Called to let the model know that it should submit whatever it has cached to the permanent storage. Typically used for row editing.
Returns false on error, otherwise true.
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