Implementing QML's TreeView Model using C (2)_PHP Tutorial

Use C to implement QML’s TreeView Model (2)

We have introduced the implementation of the two-dimensional table model above, and then share the implementation of the hierarchical model. First, implement a node class for saving Node data and node relationships of the tree data model:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>class TreeNode;<br /> </li><li><br /></li><li>typedef TreeNode* TreeNodePtr;<br /></li><li><br /></li><li>class TreeNode<br /></li><li>{<br /></li><li>public:<br /></li><li>explicit TreeNode();<br /></li><li>TreeNodePtr parent() const;<br /></li><li>void setParent(const TreeNodePtr p); //设置父节点，根节点的父节点为NULL<br /></li><li>void appendNode(TreeNodePtr node);<br /></li><li>void removeNode(int row);<br /></li><li>void setData(int role,QVariant value);  </li><li>QList<TreeNodePtr>childs;  //用于保存子节点指针，把childs放到public不好，仅仅是为了方便，不要学。<br /></li><li><br /></li><li>private:<br /></li><li>TreeNodePtr mParent=NULL;  //父节点<br /></li><li>QHash<int,QVariant>mRecord; //一个节点可以保存一行数据，哈希表的key是整型，用于保存role，QVariant保存数据<br /></li><li><br /></li><li>}; </li></ol>

The implementation of TreeNode is also quite simple:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>TreeNodePtr TreeNode::parent() const<br /> </li><li>{<br /></li><li>return mParent;<br /></li><li>}<br /></li><li><br /></li><li>void TreeNode::setParent(const TreeNodePtr p)<br /></li><li>{<br /></li><li>this->mParent = p;<br /></li><li>}<br /></li><li><br /></li><li>void TreeNode::appendNode(TreeNodePtr node)<br /></li><li>{<br /></li><li>childs.append(node);<br /></li><li>}<br /></li><li><br /></li><li>void TreeNode::removeNode(int row)<br /></li><li>{<br /></li><li>childs.removeAt(row);<br /></li><li>}<br /></li><li><br /></li><li><br /></li><li>QVariant TreeNode::data(int role)<br /></li><li>{<br /></li><li>return mRecord[role];<br /></li><li>}<br /></li><li><br /></li><li>void TreeNode::setData(int role, QVariant value)<br /></li><li>{<br /></li><li>mRecord[role] = value;<br /></li><li>} </li></ol>

Next, start the operation on SqlMenuEntryModel:

The implementation of

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>class SqlMenuEntry:public QAbstractItemModel,public QQmlParserStatus<br /> </li><li>{<br /></li><li>Q_OBJECT<br /></li><li>public:<br /></li><li>explicit SqlMenuEntry(QObject *parent=0);<br /></li><li>~SqlMenuEntry();<br /></li><li>enum MenuEntryRoles{idRole=Qt::UserRole+1,nameRole,defaultEntryRole,customEntryRole,iconRole,iconHoverRole};<br /></li><li>int rowCount(const QModelIndex &parent=QModelIndex()) const;<br /></li><li>int columnCount(const QModelIndex &parent=QModelIndex()) const;<br /></li><li>QModelIndex index(int row, int column, const QModelIndex &parent=QModelIndex()) const;<br /></li><li>QVariant data(const QModelIndex &index, int role=Qt::DisplayRole) const;<br /></li><li>QModelIndex parent(const QModelIndex &child) const;<br /></li><li>QHash<int,QByteArray>roleNames() const;<br /></li><li>private:<br /></li><li>QHash<int,QByteArray> mRoleNames;<br /></li><li>  <s>QList</s><s><</s><s>QHash</s><s><</s><s>int</s><s>,</s><s>QVariant</s><s>></s><s>></s><s> mRecords</s><s>;</s> //QList不能保存树状数据，干掉<br /></li><li>  QList mRootEntrys;   //用于保存根节点 </li><li>  void _addEntryNode(TreeNodePtr node,TreeNodePtr parent=0); //用于向树添加节点 </li><li>}; </li></ol>

_addEntryNode is as follows:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>void SqlMenuEntry::_addEntryNode(TreeNodePtr node, TreeNodePtr parent)<br /> </li><li>{<br /></li><li>if(parent == NULL)<br /></li><li>{<br /></li><li>mRootEntrys.append(node);<br /></li><li>}else{<br /></li><li>node->setParent(parent);<br /></li><li>parent->appendNode(node);<br /></li><li>}<br /></li><li>} </li><li><br /> </li></ol>

You can add data to the model through the following code:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>beginResetModel();<br /> </li><li><br /></li><li>auto node = new TreeNode(); </li><li>node->setData(nameRole,"parent 1");<br /></li><li>node->setData(iconRole,"parenticon1"); </li><li>_addEntryNode(node);  //添加第一个根节点<br /></li><li>    </li><li>     auto subNode = new TreeNode(); </li><li>     subNode->setData(nameRole,"child1");<br /></li><li>     _addEntryNode(subNode,node)； //添加子节点 </li><li><br /> </li><li>endResetModel(); </li></ol>

The above code adds a root node parent1 and Child1, a child node of parent1, can then continue to improve the SqlMenuEntryModel so that the TreeView can smoothly display the correct data and data relationships. First, change int rowCount(const QModelIndex &parent) so that the model can correctly return the number of root nodes and child node rows:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>int SqlMenuEntry::rowCount(const QModelIndex &parent) const<br /> </li><li>{<br /></li><li>if(parent.isValid()) //parent不为空，则要获取的行数是某个节点的子节点行数<br /></li><li>{<br /></li><li>TreeNodePtr parentNode = (TreeNodePtr)parent.internalPointer(); //节点信息在index时被保存在QModelIndex的internalPointer中<br /></li><li>return parentNode->childs.size();<br /></li><li>} </li><li>return mRootEntrys.size(); //否则返回的是根节点行数<br /></li><li><br /></li><li>} </li></ol>

Implement the index interface function so that the model can return child nodes The modelIndex also saves the corresponding node pointer in the internalPointer of the modelIndex:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>QModelIndex SqlMenuEntry::index(int row, int column, const QModelIndex &parent) const<br /> </li><li>{<br /></li><li>if(!parent.isValid()) //parent为空，返回的是根节点的modelIndex，返回的同时，把节点数据指针(TreeNodePtr)保存在QModelIndex的internalPointer中，以便在其它函数中获取节点数据<br /></li><li>{<br /></li><li>if((row >= 0) && (row < mRootEntrys.size()))<br /></li><li>{<br /></li><li>return createIndex(row,column,mRootEntrys.at(row)); <br /></li><li>}<br /></li><li>}else{<br /></li><li>TreeNodePtr parentNode = (TreeNodePtr)parent.internalPointer(); //返回子节点的modelIndex<br /></li><li>return createIndex(row,column,parentNode->childs[row]);<br /></li><li>}<br /></li><li>return QModelIndex();<br /></li><li>} </li></ol>

parent(const QModelIndex &child) is used to return the parent node index of a node:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>QModelIndex SqlMenuEntry::parent(const QModelIndex &child) const<br /> </li><li>{<br /></li><li>TreeNodePtr node = (TreeNodePtr)child.internalPointer();<br /></li><li>if(node->parent() == NULL)<br /></li><li>{<br /></li><li>return QModelIndex(); //根节点没有parent<br /></li><li>}else{<br /></li><li>return createIndex(0,1,node->parent());<br /></li><li>} </li></ol>

implementation data(constQModelIndex&index,introle) returns the data in the node:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>QVariant SqlMenuEntry::data(const QModelIndex &index, int role) const<br /> </li><li>{<br /></li><li>TreeNodePtr node = (TreeNodePtr)index.internalPointer();<br /></li><li>return node->data(role);<br /></li><li>} </li></ol>

After the above creation, the model can already provide data for TreeView normally:

<ol style="margin:0 1px 0 0px;padding-left:40px;" start="1" class="dp-css"><li>TreeView{<br /> </li><li>anchors.fill: parent<br /></li><li>TableViewColumn {<br /></li><li>title: "Name"<br /></li><li>role: "name"<br /></li><li>}<br /></li><li><br /></li><li>TableViewColumn {<br /></li><li>title: "Entry"<br /></li><li>role: "icon"<br /></li><li>}<br /></li><li>model:MenuEntryModel{}<br /></li><li>} </li></ol>

Let’s continue working. Tomorrow I will continue to add related experience in adding, deleting and updating data.

http://www.bkjia.com/PHPjc/1120298.htmlwww.bkjia.comtruehttp: //www.bkjia.com/PHPjc/1120298.htmlTechArticleUsing C to implement QML’s TreeView Model (2) The implementation method of the two-dimensional table model has been introduced above. Next, To implement the shared hierarchical model, first implement a node class to save tree numbers...