在使用mvd時，我們可能會有這種需求，比如有一項的數據是文件類型，然后我們要彈出一個文件對話框，選擇一個文件路徑然后把文件路徑展示出來。
我們可能寫出如下代碼

#include "MyStyledItemDeletegate.h"
#include <QRect>
#include <QStyleOptionButton>
#include <QEvent>
#include <QMouseEvent>
#include <QFileDialog>
#include <QDebug>MyStyledItemDeletegate::MyStyledItemDeletegate(QObject *parent) : QStyledItemDelegate(parent)
{}void MyStyledItemDeletegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{QStyledItemDelegate::paint(painter, option, index);if(index.column() == 2){QPushButton btn(QStringLiteral("選擇路徑"));//通過sizeHint獲取btn的大小而不是顯式指定按鈕的大小，這樣如果字符串修改了我們不需要手動該大小QRect btnRect = QRect(0, 0, btn.sizeHint().width(), btn.sizeHint().height());btnRect.moveCenter(option.rect.center());btnRect.moveRight(option.rect.right());QStyleOptionButton btnOpt;btnOpt.init(&btn);btnOpt.rect = btnRect;btnOpt.text = btn.text();btn.style()->drawControl(QStyle::CE_PushButton, &btnOpt, painter, &btn);QStyleOptionViewItem& mutableOption = const_cast<QStyleOptionViewItem&>(option);mutableOption.rect = QRect(option.rect.x(), option.rect.y(), option.rect.width() - btnRect.width(), option.rect.height());}
}bool MyStyledItemDeletegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{if(index.column() == 2 && event->type() == QEvent::MouseButtonPress){QMouseEvent* mouseEvent = dynamic_cast<QMouseEvent*>(event);if(mouseEvent){QPushButton btn(QStringLiteral("選擇路徑"));QRect btnRect = QRect(0, 0, btn.sizeHint().width(), btn.sizeHint().height());btnRect.moveCenter(option.rect.center());btnRect.moveRight(option.rect.right());if(btnRect.contains(mouseEvent->pos())){QString filePath = QFileDialog::getOpenFileName(nullptr, QStringLiteral("選擇一個文件"));if(!filePath.isEmpty()){model->setData(index, filePath, Qt::DisplayRole);}}}return true;}return QStyledItemDelegate::editorEvent(event, model, option, index);
}

這樣導致的問題是，當文字超長時，不能夠很正確的顯示省略號，修改后如下。

#include "MyStyledItemDeletegate.h"
#include <QRect>
#include <QStyleOptionButton>
#include <QEvent>
#include <QMouseEvent>
#include <QFileDialog>
#include <QDebug>MyStyledItemDeletegate::MyStyledItemDeletegate(QObject *parent) : QStyledItemDelegate(parent)
{}void MyStyledItemDeletegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
{if(index.column() == 2){QPushButton btn(QStringLiteral("選擇路徑"));//通過sizeHint獲取btn的大小而不是顯式指定按鈕的大小，這樣如果字符串修改了我們不需要手動該大小QRect btnRect = QRect(0, 0, btn.sizeHint().width(), btn.sizeHint().height());btnRect.moveCenter(option.rect.center());btnRect.moveRight(option.rect.right());QStyleOptionButton btnOpt;btnOpt.init(&btn);btnOpt.rect = btnRect;btnOpt.text = btn.text();btn.style()->drawControl(QStyle::CE_PushButton, &btnOpt, painter, &btn);QStyleOptionViewItem& mutableOption = const_cast<QStyleOptionViewItem&>(option);mutableOption.rect = QRect(option.rect.x(), option.rect.y(), option.rect.width() - btnRect.width(), option.rect.height());}QStyledItemDelegate::paint(painter, option, index);
}bool MyStyledItemDeletegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
{if(index.column() == 2 && event->type() == QEvent::MouseButtonPress){QMouseEvent* mouseEvent = dynamic_cast<QMouseEvent*>(event);if(mouseEvent){QPushButton btn(QStringLiteral("選擇路徑"));QRect btnRect = QRect(0, 0, btn.sizeHint().width(), btn.sizeHint().height());btnRect.moveCenter(option.rect.center());btnRect.moveRight(option.rect.right());if(btnRect.contains(mouseEvent->pos())){QString filePath = QFileDialog::getOpenFileName(nullptr, QStringLiteral("選擇一個文件"));if(!filePath.isEmpty()){model->setData(index, filePath, Qt::DisplayRole);}}}return true;}return QStyledItemDelegate::editorEvent(event, model, option, index);
}

修正后效果如下

總結，一個好的軟件總是慢慢打磨細節的