QModelIndex 类用于在数据模型中定位数据。 更多...
The QModelIndex class is used to locate data in a data model.
此类被用作项模型的索引，派生自 QAbstractItemModel . The index is used by item views, delegates, and selection models to locate an item in the model.
New QModelIndex objects are created by the model using the QAbstractItemModel.createIndex () function. An invalid model index can be constructed with the QModelIndex constructor. Invalid indexes are often used as parent indexes when referring to top-level items in a model.
Model indexes refer to items in models, and contain all the information required to specify their locations in those models. Each index is located in a given row and column, and may have a parent index; use row (), column ()，和 parent () to obtain this information. Each top-level item in a model is represented by a model index that does not have a parent index - in this case, parent () will return an invalid model index, equivalent to an index constructed with the zero argument form of the QModelIndex () constructor.
To obtain a model index that refers to an existing item in a model, call QAbstractItemModel.index () with the required row and column values, and the model index of the parent. When referring to top-level items in a model, supply QModelIndex () as the parent index.
model () function returns the model that the index references as a QAbstractItemModel 。 child () function is used to examine items held under the index in the model. The sibling () function allows you to traverse items in the model on the same level as the index.
注意： Model indexes should be used immediately and then discarded. You should not rely on indexes to remain valid after calling model functions that change the structure of the model or delete items. If you need to keep a model index over time use a QPersistentModelIndex .
Creates a new empty model index. This type of model index is used to indicate that the position in the model is invalid.
另请参阅 isValid () and QAbstractItemModel .
Creates a new model index that is a copy of the other model index.
Returns the child of the model index that is stored in the given row and column .
注意： This function does not work for an invalid model index which is often used as the root index.
另请参阅 parent () and sibling ().
Returns the column this model index refers to.
返回数据为给定 role for the item referred to by the index.
Returns the flags for the item referred to by the index.
该函数在 Qt 4.2 引入。
返回 long used by the model to associate the index with the internal data structure.
另请参阅 QAbstractItemModel.createIndex ().
返回 void * pointer used by the model to associate the index with the internal data structure.
另请参阅 QAbstractItemModel.createIndex ().
Returns true if this model index is valid; otherwise returns false.
A valid index belongs to a model, and has non-negative row and column numbers.
另请参阅 model (), row ()，和 column ().
Returns a pointer to the model containing the item that this index refers to.
A const pointer to the model is returned because calls to non-const functions of the model might invalidate the model index and possibly crash your application.
Returns the parent of the model index, or QModelIndex () if it has no parent.
另请参阅 child (), sibling ()，和 model ().
Returns the row this model index refers to.
Returns the sibling at row and column . If there is no sibling at this position, an invalid QModelIndex 被返回。
