我来自C#和WPF,那里有一种将集合绑定(bind)到 View 的不错的方法,可以通过当前DataContext填充数据。
我一直在学习Qt,我知道有一种方法可以为 View 提供模型(QAbstractItemModel),然后通过修改模型可以自动更新 View ,这很不错,而且是我想要的。
我当前的问题是我想为以下类Definition
创建一个编辑器 View
class Definition
{
public:
vector<Step*> Steps;
bool SomeBoolMember1;
bool SomeBoolMember2;
int SomeIntMember1;
int SomeIntMember2;
}
Step
是class Step
{
public:
vector<Requirement*> Requirements;
bool SomeBoolMember1;
bool SomeBoolMember2;
int SomeIntMember1;
int SomeIntMember2;
}
Requirement
是class Requirement
{
public:
RequirementType Type;
}
我的目标是建立一个 View ,以便能够修改
Definition
的集合。可能的 View 可能是这样的:当不同的定义选择的选择项目 View 被更新(选定定义的负载数据),然后我们有以下步骤的列表的滚动 View 。每个步骤都带有要求列表。
如您所见,这不是火箭科学,但我知道这可能很乏味。关于如何构造模型/ View 模型以实现所需功能的任何提示?
最佳答案
您的问题很广泛。 Qt的模型非常笼统,有很多方法可以构造它们以实现相同的行为。我创建了一个简化的示例,说明如何构建它们。我只用了Definition
和Step
,将Requirement
添加到Step
类似于将Step
添加到Definition
...
struct Step
{
bool SomeBoolMember1 {false};
int SomeIntMember1 {0};
};
struct Definition
{
std::vector<std::shared_ptr<Step>> Steps;
bool SomeBoolMember1 {false};
int SomeIntMember1 {0};
};
struct Data
{
std::vector<std::shared_ptr<Definition>> definitions;
};
模型非常简单,我为
Definition
创建了一个模型,为Step
创建了一个模型。每个模型都有代表这些对象属性的列,模型的行代表对象的一个实例。 Definition
的模型有一个Step
的列,该列返回给定Step
的Definition
的模型。class StepModel : public QAbstractItemModel
{
Q_OBJECT
using BaseClass = QAbstractItemModel;
public:
enum Columns
{
E_BOOL_1,
E_INT_1,
E_REQUIREMENT,
_END
};
StepModel(Definition* definition, QObject* parent) :
BaseClass(parent),
definition(definition)
{
}
virtual QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override
{
return createIndex(row, column, nullptr);
}
virtual QModelIndex parent(const QModelIndex &child) const override
{
return QModelIndex();
}
virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override
{
return definition->Steps.size();
}
virtual int columnCount(const QModelIndex &parent = QModelIndex()) const override
{
return _END;
}
virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override
{
if (role != Qt::DisplayRole) return QVariant();
const auto& step = definition->Steps.at(index.row());
switch (index.column())
{
case E_BOOL_1:
return step->SomeBoolMember1;
case E_INT_1:
return step->SomeIntMember1;
case E_REQUIREMENT:
return QVariant();
}
}
virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override
{
if (role != Qt::EditRole) return false;
auto& step = definition->Steps.at(index.row());
switch (index.column())
{
case E_BOOL_1:
step->SomeBoolMember1 = value.toBool();
return true;
case E_INT_1:
step->SomeIntMember1 = value.toInt();
return true;
case E_REQUIREMENT:
assert(false);
return false;
}
}
virtual bool insertRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
{
assert(count == 1);
beginInsertRows(parent, row, row);
definition->Steps.push_back(std::make_shared<Step>());
endInsertRows();
return true;
}
virtual bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
{
assert(count == 1);
beginRemoveRows(parent, row, row);
definition->Steps.erase(definition->Steps.begin() + row);
endRemoveRows();
return true;
}
private:
Definition* definition;
};
Q_DECLARE_METATYPE(StepModel*)
class DefinitionModel : public QAbstractItemModel
{
Q_OBJECT
using BaseClass = QAbstractItemModel;
public:
enum Columns
{
E_NAME,
E_BOOL_1,
E_INT_1,
E_STEPS,
_END
};
DefinitionModel(QObject* parent) :
BaseClass(parent)
{
}
virtual QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const override
{
return createIndex(row, column, nullptr);
}
virtual QModelIndex parent(const QModelIndex &child) const override
{
return QModelIndex();
}
virtual int rowCount(const QModelIndex &parent = QModelIndex()) const override
{
return definitionData.definitions.size();
}
virtual int columnCount(const QModelIndex &parent = QModelIndex()) const override
{
return _END;
}
virtual QVariant data(const QModelIndex &index, int role = Qt::DisplayRole) const override
{
if (role != Qt::DisplayRole) return QVariant();
const auto& definition = definitionData.definitions.at(index.row());
switch (index.column())
{
case E_NAME:
return QString("Definition %1").arg(index.row() + 1);
case E_BOOL_1:
return definition->SomeBoolMember1;
case E_INT_1:
return definition->SomeIntMember1;
case E_STEPS:
return QVariant::fromValue(new StepModel(definition.get(), nullptr));
}
}
virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole) override
{
if (role != Qt::EditRole) return false;
auto& definition = definitionData.definitions.at(index.row());
switch (index.column())
{
case E_BOOL_1:
definition->SomeBoolMember1 = value.toBool();
return true;
case E_INT_1:
definition->SomeIntMember1 = value.toInt();
return true;
default:
assert(false);
return false;
}
}
virtual bool insertRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
{
assert(count == 1);
beginInsertRows(parent, row, row);
definitionData.definitions.push_back(std::make_shared<Definition>());
endInsertRows();
return true;
}
virtual bool removeRows(int row, int count, const QModelIndex &parent = QModelIndex()) override
{
assert(count == 1);
beginRemoveRows(parent, row, row);
definitionData.definitions.pop_back();
endRemoveRows();
return true;
}
private:
Data definitionData;
};
在此示例中,
DefinitionModel
拥有Data
实例,这不是您在实际应用中想要执行的操作,只是为了简单起见。对话框有点复杂,因为在创建新实例时必须动态创建
Steps
的小部件。我为小部件创建了一个简单的映射,将其映射到其适当模型的列。每次选择新的定义时,都会通过此映射从模型中加载回数据。namespace Ui
{
class MainWindow;
}
class MainWindow : public QMainWindow
{
Q_OBJECT
public:
explicit MainWindow(QWidget *parent = 0) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
auto definitionModel = new DefinitionModel(this);
ui->definitionView->setModel(definitionModel);
connect(ui->definitionView->selectionModel(), &QItemSelectionModel::currentRowChanged, this, [=]
{
update();
}, Qt::QueuedConnection);
connect(ui->addDefinition, &QPushButton::pressed, this, [this]
{
auto* model = ui->definitionView->model();
model->insertRow(model->rowCount());
ui->definitionView->update();
ui->definitionView->setCurrentIndex(model->index(model->rowCount() - 1, 0));
});
connect(ui->removeDefinition, &QPushButton::pressed, this, [this]
{
auto* model = ui->definitionView->model();
if (model->rowCount() > 0)
{
const int row = model->rowCount() - 1;
for (const auto& widget : steps[row])
{
unmap(widget);
}
steps.erase(steps.find(row));
model->removeRow(row);
}
});
auto getCurrentDefinition = [this] { return ui->definitionView->currentIndex().row(); };
map(ui->definitionInt, definitionModel, DefinitionModel::E_INT_1, getCurrentDefinition);
map(ui->definitionBool, definitionModel, DefinitionModel::E_BOOL_1, getCurrentDefinition);
connect(ui->addStep, &QPushButton::pressed, this, [=]
{
if (getCurrentDefinition() == -1) return;
auto widget = new QWidget(this);
auto layout = new QHBoxLayout(widget);
auto checkBox = new QCheckBox(widget);
layout->addWidget(checkBox);
auto spinBox = new QSpinBox(widget);
layout->addWidget(spinBox);
auto removeButton = new QPushButton(widget);
removeButton->setText("remove");
layout->addWidget(removeButton);
ui->rightLayout->addWidget(widget);
const int currentDefinition = getCurrentDefinition();
steps[currentDefinition].push_back(widget);
auto model = definitionModel->data(definitionModel->index(currentDefinition, DefinitionModel::E_STEPS), Qt::DisplayRole).value<QAbstractItemModel*>();
model->setParent(widget);
const int rowCount = model->rowCount();
model->insertRow(rowCount);
auto getRow = [=]
{
auto it = std::find(steps[currentDefinition].begin(), steps[currentDefinition].end(), widget);
return std::distance(steps[currentDefinition].begin(), it);
};
map(checkBox, model, StepModel::E_BOOL_1, getRow);
map(spinBox, model, StepModel::E_INT_1, getRow);
connect(ui->definitionView->selectionModel(), &QItemSelectionModel::currentRowChanged, widget, [=] (const QModelIndex& current)
{
widget->setVisible(current.row() == currentDefinition);
});
connect(removeButton, &QPushButton::pressed, widget, [=]
{
model->removeRow(rowCount);
unmap(checkBox);
unmap(spinBox);
ui->rightLayout->removeWidget(widget);
auto it = std::find(steps[getCurrentDefinition()].begin(), steps[getCurrentDefinition()].end(), widget);
steps[currentDefinition].erase(it);
delete widget;
});
update();
});
}
~MainWindow()
{
delete ui;
}
private:
void map(QCheckBox* checkBox, QAbstractItemModel* model, int column, std::function<int()> getRow)
{
connect(checkBox, &QCheckBox::toggled, this, [=] (bool value)
{
model->setData(model->index(getRow(), column), value, Qt::EditRole);
});
auto update = [=]
{
checkBox->setChecked(model->data(model->index(getRow(), column), Qt::DisplayRole).toBool());
};
mapping.emplace(checkBox, update);
}
void map(QSpinBox* spinBox, QAbstractItemModel* model, int column, std::function<int()> getRow)
{
connect(spinBox, static_cast<void (QSpinBox::*)(int)>(&QSpinBox::valueChanged), this, [=] (int value)
{
model->setData(model->index(getRow(), column), value, Qt::EditRole);
});
auto update = [=]
{
spinBox->setValue(model->data(model->index(getRow(), column), Qt::DisplayRole).toInt());
};
mapping.emplace(spinBox, update);
}
void unmap(QWidget* widget)
{
mapping.erase(mapping.find(widget));
}
void update() const
{
for (const auto& pair : mapping)
{
pair.second();
}
}
Ui::MainWindow *ui;
std::map<QWidget*, std::function<void()>> mapping;
std::map<int, std::vector<QWidget*>> steps;
};
UI文件:
<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
<class>MainWindow</class>
<widget class="QMainWindow" name="MainWindow">
<property name="geometry">
<rect>
<x>0</x>
<y>0</y>
<width>800</width>
<height>600</height>
</rect>
</property>
<property name="windowTitle">
<string>MainWindow</string>
</property>
<widget class="QWidget" name="centralWidget">
<layout class="QHBoxLayout" name="verticalLayout" stretch="1,2">
<item>
<layout class="QVBoxLayout" name="verticalLayout_3">
<property name="spacing">
<number>0</number>
</property>
<property name="leftMargin">
<number>10</number>
</property>
<item>
<widget class="QListView" name="definitionView">
<property name="showDropIndicator" stdset="0">
<bool>false</bool>
</property>
<property name="selectionBehavior">
<enum>QAbstractItemView::SelectRows</enum>
</property>
</widget>
</item>
<item>
<layout class="QHBoxLayout" name="horizontalLayout">
<property name="topMargin">
<number>10</number>
</property>
<item>
<widget class="QPushButton" name="addDefinition">
<property name="text">
<string>add</string>
</property>
</widget>
</item>
<item>
<widget class="QPushButton" name="removeDefinition">
<property name="text">
<string>remove</string>
</property>
</widget>
</item>
</layout>
</item>
</layout>
</item>
<item>
<layout class="QVBoxLayout" name="verticalLayout_2">
<property name="rightMargin">
<number>10</number>
</property>
<item>
<layout class="QVBoxLayout" name="rightLayout">
<item>
<layout class="QHBoxLayout" name="horizontalLayout_2">
<item>
<widget class="QCheckBox" name="definitionBool">
<property name="text">
<string>CheckBox</string>
</property>
</widget>
</item>
<item>
<widget class="QSpinBox" name="definitionInt"/>
</item>
</layout>
</item>
<item>
<layout class="QHBoxLayout" name="horizontalLayout_3">
<property name="topMargin">
<number>10</number>
</property>
<item>
<widget class="QLabel" name="label">
<property name="text">
<string>Steps</string>
</property>
</widget>
</item>
<item>
<widget class="QPushButton" name="addStep">
<property name="text">
<string>add</string>
</property>
</widget>
</item>
</layout>
</item>
</layout>
</item>
<item>
<spacer name="verticalSpacer">
<property name="orientation">
<enum>Qt::Vertical</enum>
</property>
<property name="sizeHint" stdset="0">
<size>
<width>20</width>
<height>40</height>
</size>
</property>
</spacer>
</item>
</layout>
</item>
</layout>
</widget>
</widget>
<layoutdefault spacing="6" margin="11"/>
<resources/>
<connections/>
</ui>