1

我将 QTreeView 与 TreeModel（继承 QAbstractItemModel）一起使用。TreeModel::flags() 函数返回 Qt::ItemIsUserCheckable，因此在视图中的每个项目旁边都会显示一个复选框。我需要做的是在未选中父项但用户必须能够正常与其交互（必须启用复选框）时将复选框显示为禁用。

我尝试实现自定义 QStyledItemDelegate 并自己绘制复选框。但是，在委托的 draw() 函数中绘制复选框时，我不知道如何使用自定义图像。我什至不知道这是否是正确的方法。

我也想过以某种方式使用样式表，但复选框的显示取决于模型数据（是否选中父级）。

有任何想法吗？

这是我的 ItemDelegate::paint() 函数。

void ItemDelegate::paint(QPainter *painter,
                         const QStyleOptionViewItem &option,
                         const QModelIndex &index) const
{
    int value = index.model()->data(index, Qt::DisplayRole).toInt();

    QStyleOptionButton check_box_style_option;

    check_box_style_option.state |= QStyle::State_Enabled;

    if (value == 1)
        check_box_style_option.state |= QStyle::State_On;
    else
        check_box_style_option.state |= QStyle::State_Off;

    check_box_style_option.rect = option.rect;


    QApplication::style()->drawControl(QStyle::CE_CheckBox,
                                       &check_box_style_option, painter);
}

[编辑] TreeModel 代码。树模型基于“simpletreemodel”示例。我将 flags() 更改为还返回 Qt::ItemIsUserCheckable 和 data(), setData() 以启用复选框以选中和取消选中。

#include <QtGui>
#include <QDebug>
#include "treeitem.h"
#include "treemodel.h"

TreeModel::TreeModel(Container *data, QObject *parent)
    : QAbstractItemModel(parent)
{
    root_item_ = new TreeItem("");
    SetupModelData(data, root_item_);
}

TreeModel::~TreeModel()
{
    delete root_item_;
}

int TreeModel::columnCount(const QModelIndex &parent) const
{
    if (parent.isValid())
        return static_cast<TreeItem*>(parent.internalPointer())->columnCount();
    else
        return root_item_->columnCount();
}

QVariant TreeModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

    TreeItem *item = static_cast<TreeItem*>(index.internalPointer());

    if(role == Qt::CheckStateRole && index.column() == 0)
        return static_cast<int>(item->checked()) ? Qt::Checked : Qt::Unchecked;

    if(role != Qt::DisplayRole)
        return QVariant();

    return item->data(index.column());
}

bool TreeModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    TreeItem *item = static_cast<TreeItem*>(index.internalPointer());

    if(role == Qt::CheckStateRole)
        item->set_checked(!item->checked());

    if(role == Qt::EditRole)
    {
        qDebug() << "value:" << value.toString();
        item->set_data(value.toString());
    }

    emit dataChanged(index, index);

    return true;
}

Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return 0;

    return Qt::ItemIsEnabled | Qt::ItemIsSelectable | Qt::ItemIsUserCheckable;
}

QVariant TreeModel::headerData(int section, Qt::Orientation orientation,
                               int role) const
{
    if (orientation == Qt::Horizontal && role == Qt::DisplayRole)
        return root_item_->data(section);

    return QVariant();
}

QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent)
            const
{
    if (!hasIndex(row, column, parent))
        return QModelIndex();

    TreeItem *parentItem;

    if (!parent.isValid())
        parentItem = root_item_;
    else
        parentItem = static_cast<TreeItem*>(parent.internalPointer());

    TreeItem *childItem = parentItem->child(row);
    if (childItem)
        return createIndex(row, column, childItem);
    else
        return QModelIndex();
}

QModelIndex TreeModel::parent(const QModelIndex &index) const
{
    if (!index.isValid())
        return QModelIndex();

    TreeItem *childItem = static_cast<TreeItem*>(index.internalPointer());
    TreeItem *parentItem = childItem->parent();

    if (parentItem == root_item_)
        return QModelIndex();

    return createIndex(parentItem->row(), 0, parentItem);
}

int TreeModel::rowCount(const QModelIndex &parent) const
{
    TreeItem *parentItem;
    if (parent.column() > 0)
        return 0;

    if (!parent.isValid())
        parentItem = root_item_;
    else
        parentItem = static_cast<TreeItem*>(parent.internalPointer());

    return parentItem->childCount();
}

void TreeModel::SetupModelData(Container *data, TreeItem *parent)
{
    TreeItem *new_item = new TreeItem(data->id(), parent);
    data->set_tree_item(new_item);
    parent->appendChild(new_item);

    foreach(Container *child, data->children())
        SetupModelData(child, new_item);
}
4

0 回答 0