QCombobox应用QStyledItemDelegate小Demo

效果是这样的：

QComboBox是个很基础的控件，也是继承自QWidget。

①我们先建立代理类，继承自QStyledItemDelegate：

1、头文件：

#ifndef ITEMDELEGATE_H
 #define ITEMDELEGATE_H

 #include <QStyledItemDelegate>
 class ItemDelegate : public QStyledItemDelegate
 {
   Q_OBJECT
 signals:
     void deleteItem(const QModelIndex &index);
 public:
     ItemDelegate(QObject * parent=0);
     virtual ~ItemDelegate(){}
     void paint(QPainter * painter,const QStyleOptionViewItem & option,const QModelIndex & index) const;
     bool editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index);
 };

 #endif // ITEMDELEGATE_H

2、源文件：

#include "ItemDelegate.h"
 #include <QPainter>
 #include <QMouseEvent>
 #include <QStyledItemDelegate>
 #include <QToolTip>
 #include <QApplication>
 ItemDelegate::ItemDelegate(QObject * parent)
     : QStyledItemDelegate(parent)
 {
 }

 void ItemDelegate::paint(QPainter *painter, const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
     QStyleOptionViewItem  viewOption(option);
     if (viewOption.state & QStyle::State_HasFocus)
     {
         viewOption.state = viewOption.state ^ QStyle::State_HasFocus;
     }
     QStyledItemDelegate::paint(painter, viewOption, index);
     int height = (viewOption.rect.height() - 9) / 2;
     QPixmap pixmap = QPixmap(":/delete");
     QRect decorationRect = QRect(viewOption.rect.left() + viewOption.rect.width() - 30, viewOption.rect.top() + height, 9, 9);
     painter->drawPixmap(decorationRect, pixmap);
 }

 bool ItemDelegate::editorEvent(QEvent *event, QAbstractItemModel *model, const QStyleOptionViewItem &option, const QModelIndex &index)
 {
     int height = (option.rect.height() - 9) / 2;
     QRect decorationRect = QRect(option.rect.left() + option.rect.width() - 30, option.rect.top() + height, 9, 9);
     QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
     if (event->type() == QEvent::MouseButtonPress && decorationRect.contains(mouseEvent->pos()))
     {
         emit deleteItem(index);
     }
     if (event->type() == QEvent::MouseMove && decorationRect.contains(mouseEvent->pos()))
     {
         QCursor cursor(Qt::PointingHandCursor);
         QApplication::setOverrideCursor(cursor);
         QString strText = QStringLiteral("删除账号信息");
         QToolTip::showText(mouseEvent->globalPos(), strText);
     }
     else
     {
         QCursor cursor(Qt::ArrowCursor);
         QApplication::setOverrideCursor(cursor);
     }
     return QStyledItemDelegate::editorEvent(event, model, option, index);
 }

②在我们的程序中应用这个代理：

1、头文件：

#ifndef WIDGET_H
 #define WIDGET_H

 #include <QWidget>
 namespace Ui {
 class Widget;
 }
 class Widget : public QWidget
 {
     Q_OBJECT
 public:
     explicit Widget(QWidget *parent = 0);
     ~Widget();
 private slots:
     void deleteItem(const QModelIndex &index);
 private:
     Ui::Widget *ui;
 };
 #endif // WIDGET_H

2、源文件：

#include "widget.h"
 #include "ui_Widget.h"
 #include "ItemDelegate.h"
 #include <QMessageBox>
 Widget::Widget(QWidget *parent) :
     QWidget(parent),
     ui(new Ui::Widget)
 {
     ui->setupUi(this);
     ItemDelegate *pDelegate = new ItemDelegate(this);
     ui->comboBox->addItem(QPixmap(":/shasha.png"), QStringLiteral("沙师弟"));
     ui->comboBox->addItem(QPixmap(":/jiejie.png"), QStringLiteral("二师兄"));
     ui->comboBox->addItem(QPixmap(":/kongkong.png"), QStringLiteral("猴哥"));
     ui->comboBox->addItem(QPixmap(":/tangtang.png"), QStringLiteral("师傅"));
     ui->comboBox->setItemDelegate(pDelegate);
     connect(pDelegate, SIGNAL(deleteItem(QModelIndex)), this, SLOT(deleteItem(QModelIndex)));
 }
 Widget::~Widget()
 {
     delete ui;
 }
 void Widget::deleteItem(const QModelIndex &index)
 {
     if (QMessageBox::question(this, QStringLiteral("提示"), QStringLiteral("确认要删除所选账号吗？"),
                      QMessageBox::Yes | QMessageBox::No, QMessageBox::Yes) == QMessageBox::Yes)
     {
         ui->comboBox->removeItem(index.row());
     }
 }