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我写了一个派生自QAbstractModelItem的类。它在QTreeView上使用。令人遗憾的是,官方文档示例并未显示如何添加或删除模型上的项目。我认为这很容易做到,所以我闯入了它。问题是删除选定的对象会导致异常。例如:QTreeView/QAbstractItemModel - 删除导致异常
用户单击QTreeView上的一行,并希望将其与其所有子项(如果有)一起删除。这是一个被执行的代码:
MyModel.cpp:
// This gets called with the QModelIndex of the currently selected row.
void MyModel::remove(const QModelIndex &index) {
if (!index.isValid())
return;
MyItem * selectedItem = static_cast<MyItem*>(index.internalPointer());
beginRemoveRows(index, index.row(), index.row());
// Call the method on the selected row object that will delete itself and all its children:
selectedItem->destroy();
endRemoveRows();
}
MyItem.h:
// A pointer list with child items.
std::vector<MyItem*> children;
MyItem.cpp:
// Deletes all children of this object and itself.
void MyItem::destroy(bool isFirst) {
if (children.size() > 0) {
// Each child needs to run this function, to ensure that all nested objects are properly deleted:
for each (auto child in children)
child->destroy(false);
// Now that the children have been deleted from heap memory clear the child pointer list:
children.clear();
}
// This boolean determines wether this object is the selected row/highest object in the row hierachy. Remove this object from the parent's pointer list:
if(isFirst)
parent->removeChild(this);
// And lastly delete this instance:
if(!isFirst) // This will cause a memory leak, but it is necessary
delete this; // <- because this throws an exception if I run this on the first object.
}
// Removes a single child reference from this instance's pointer list.
void MyItem::removeChild(MyItem * child)
{
auto it = std::find(children.begin(), children.end(), child);
children.erase(it);
}
现在,如果我们不介意小的内存泄漏这工作得很好。 ^^
但是,如果我尝试的第一个/所选行对象运行delete命令 - 那么两个例外之一发生:
- 该行有孩子: 抛出异常:读访问冲突。这是0xDDDDDDDD。
- 该行没有子女: 抛出异常:写入访问冲突。 _Parent_proxy是0x64F30630。
我保持代码简短但希望它包含我的错误。或者有人知道一个很好的QTreeView/QAbstractItemModel示例,它显示了如何添加/删除项目?
亲切的问候 空
首先,我认为你必须使用在beginRemoveRows父指数调用:beginRemoveRows(index.parent(),index.row(),index.row( )) – Fabio
非常感谢! :)这是异常的原因,现在它工作。如果您重新发布您的答案,我会将其标记为已解决。 – Sora