内容

• 特性
• 方法
• 详细描述

VisualDataModel QML Element

The VisualDataModel encapsulates a model and delegate 更多...

• 所有成员列表，包括继承成员

特性

• delegate : Component
• model : model
• parts : object
• rootIndex : QModelIndex

方法

• QModelIndex modelIndex (int index )
• QModelIndex parentModelIndex ()

详细描述

A VisualDataModel encapsulates a model and the delegate that will be instantiated for items in the model.

It is usually not necessary to create VisualDataModel elements. However, it can be useful for manipulating and accessing the modelIndex when a QAbstractItemModel subclass is used as the model. Also, VisualDataModel is used together with Package to provide delegates to multiple views.

The example below illustrates using a VisualDataModel 采用 ListView .

import QtQuick 1.0
Rectangle {
    width: 200; height: 100
    VisualDataModel {
        id: visualModel
        model: ListModel {
            ListElement { name: "Apple" }
            ListElement { name: "Orange" }
        }
        delegate: Rectangle {
            height: 25
            width: 100
            Text { text: "Name: " + name}
        }
    }
    ListView {
        anchors.fill: parent
        model: visualModel
    }
}
					

特性文档编制

delegate : Component

The delegate provides a template defining each item instantiated by a view. The index is exposed as an accessible index property. Properties of the model are also available depending upon the type of Data Model .

model : model

This property holds the model providing data for the VisualDataModel .

The model provides a set of data that is used to create the items for a view. For large or dynamic datasets the model is usually provided by a C++ model object. The C++ model object must be a QAbstractItemModel subclass or a simple list.

Models can also be created directly in QML, using a ListModel or XmlListModel .

另请参阅 数据模型 .

parts : 对象

The parts property selects a VisualDataModel which creates delegates from the part named. This is used in conjunction with the Package 元素。

For example, the code below selects a model which creates delegates named list 从 Package :

VisualDataModel {
    id: visualModel
    delegate: Package {
        Item { Package.name: "list" }
    }
    model: myModel
}
ListView {
    width: 200; height:200
    model: visualModel.parts.list
}
								

另请参阅 Package .

rootIndex : QModelIndex

QAbstractItemModel provides a hierarchical tree of data, whereas QML only operates on list data. rootIndex allows the children of any node in a QAbstractItemModel to be provided by this model.

This property only affects models of type QAbstractItemModel that are hierarchical (e.g, a tree model).

For example, here is a simple interactive file system browser. When a directory name is clicked, the view's rootIndex is set to the QModelIndex node of the clicked directory, thus updating the view to show the new directory's contents.

main.cpp :

int main(int argc, char ** argv)
{
    QApplication app(argc, argv);
    QDeclarativeView view;
    QDirModel model;
    view.rootContext()->setContextProperty("dirModel", &model);
    view.setSource(QUrl::fromLocalFile("view.qml"));
    view.show();
    return app.exec();
}
									

view.qml :

import QtQuick 1.0
ListView {
    id: view
    width: 300
    height: 400
    model: VisualDataModel {
        model: dirModel
        delegate: Rectangle {
            width: 200; height: 25
            Text { text: filePath }
            MouseArea {
                anchors.fill: parent
                onClicked: {
                    if (model.hasModelChildren)
                        view.model.rootIndex = view.model.modelIndex(index)
                }
            }
        }
    }
}
									

若 model 是 QAbstractItemModel subclass, the delegate can also reference a hasModelChildren property (optionally qualified by a model . prefix) that indicates whether the delegate's model item has any child nodes.

另请参阅 modelIndex() and parentModelIndex() .

方法文档编制

QModelIndex modelIndex ( int index )

QAbstractItemModel provides a hierarchical tree of data, whereas QML only operates on list data. This function assists in using tree models in QML.

返回 QModelIndex for the specified index. This value can be assigned to rootIndex .

另请参阅 rootIndex .

QModelIndex parentModelIndex ()

QAbstractItemModel provides a hierarchical tree of data, whereas QML only operates on list data. This function assists in using tree models in QML.

返回 QModelIndex for the parent of the current rootIndex . This value can be assigned to rootIndex .

另请参阅 rootIndex .