我有一个 QML ListView,它使用 QAbstractListModel 子类作为模型。
ListView {
id: myListView
x: 208
y: 19
width: 110
height: 160
delegate: myListDelegate {}
model: MyListModel
opacity: 0
}
模型是 MyListItem
的列表。
class MyListModel : public QAbstractListModel
{
Q_OBJECT
public:
enum MyRoles {
HeadingRole = Qt::UserRole + 1,
DescriptionRole,
QuantityRole
};
explicit MyListModel(QObject *parent = 0);
void addMyListItem(const MyListItem &item);
int rowCount(const QModelIndex & parent = QModelIndex()) const;
QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const;
void dropList();
private:
QList<MyListItem> m_list;
};
在委托(delegate)中我有一个鼠标区域。
我如何拦截鼠标区域上的点击并从我的 QList 模型中选择 那个 MyListItem
并将它发送到应用程序的 C++ 部分内的某处?
最佳答案
评论提到从 data()
返回指向 MyListItem
的指针到 QML 并在 QML 中访问和修改它。这需要您的 MyListItem
继承自 QObject
并为您要在 QML 中访问的每个成员添加一个 Q_PROPERTY
。它还需要密切关注对象所有权 (QQmlEngine::ObjectOwnership
)。
还有一种方式:实现QAbstractListModel::setData()
和QAbstractListModel::roleNames()
,模型内容可以从QML改变,比如model.roleName = foo
.
下面的最小工作示例,每次单击委托(delegate)时数量都会加倍:
C++:
struct MyListItem
{
QString heading;
QString description;
int quantity;
};
class MyListModel : public QAbstractListModel
{
Q_OBJECT
Q_ENUMS(MyRoles)
public:
enum MyRoles {
HeadingRole = Qt::UserRole + 1,
DescriptionRole,
QuantityRole
};
using QAbstractListModel::QAbstractListModel;
QHash<int,QByteArray> roleNames() const override {
return { { HeadingRole, "heading" },
{ DescriptionRole, "description" },
{ QuantityRole, "quantity" },
};
}
int rowCount(const QModelIndex & parent = QModelIndex()) const override {
if (parent.isValid())
return 0;
return m_list.size();
}
bool setData(const QModelIndex &index, const QVariant &value, int role) override
{
if (!hasIndex(index.row(), index.column(), index.parent()) || !value.isValid())
return false;
MyListItem &item = m_list[index.row()];
if (role == DescriptionRole) item.description = value.toString();
else if (role == HeadingRole) item.heading = value.toString();
else if (role == QuantityRole) item.quantity = value.toInt();
else return false;
emit dataChanged(index, index, { role } );
return true ;
}
QVariant data(const QModelIndex & index, int role = Qt::DisplayRole) const override {
if (!hasIndex(index.row(), index.column(), index.parent()))
return {};
const MyListItem &item = m_list.at(index.row());
if (role == DescriptionRole) return item.description;
if (role == HeadingRole) return item.heading;
if (role == QuantityRole) return item.quantity;
return {};
}
private:
QVector<MyListItem> m_list = {
{ "heading 1", "description 1", 1 },
{ "heading 2", "description 2", 42 },
{ "heading 3", "description 3", 4711 }
};
};
QML:
ListView {
id: listView
anchors.fill: parent
model: MyListModel {}
delegate: Item {
implicitHeight: text.height
width: listView.width
Text {
id: text
text: model.heading + " " + model.description + " " + model.quantity
}
MouseArea {
anchors.fill: text
onClicked: {
model.quantity *= 2;
}
}
}
}
关于c++ - 从 QML ListView 操作 QAbstractListModel 中的数据,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/44777999/