当前位置： 代码迷 >> 综合 >> 关于重写 QComboBox 后下拉菜单显示不正常的问题
  详细解决方案

关于重写 QComboBox 后下拉菜单显示不正常的问题

热度：47   发布时间：2023-10-14 22:04:34.0

文章目录

    • 问题描述
    • 问题分析
    • 临时解决方案
    • 代码整理
      • 1. 错误案例：Qt 组合框QComboBox定制颜色选择框
      • 2. 错误案例：自定义多选QComboBox
      • 3. 正确案例：教你如何实现带复选框的ComboBox（自定义QComboBox）

问题描述

这两天在开发过程中，重写了 QComboBox 这个控件，参考这篇博客 Qt 组合框QComboBox定制颜色选择框 实现的

关于重写 QComboBox 后下拉菜单显示不正常的问题

但是发现了一个奇怪的问题，就是在加载数据后，初始化是正确的

但是在多次点击下拉按钮后，或者是从某次点击某一 item 开始，下拉菜单的显示便开始错乱，如下图所示

关于重写 QComboBox 后下拉菜单显示不正常的问题
这个图显示的是末尾几项缺失

再或者如下图

关于重写 QComboBox 后下拉菜单显示不正常的问题

这个图显示的是开始几项缺失

与这个类似的，自定义多选QComboBox 这篇博客也存在同样的问题

问题分析

导致出现该问题可能的操作：多次点击下拉菜单 或者是 从某一次点击开始后就错乱

但是这两个操作都是最普通不过的操作，所以感觉很诡异

猜测可能是因为 QListWidget 的问题，换成 QListView 好像就没问题了

但是核心问题是什么，尚且不清楚，欢迎读者指出问题所在

临时解决方案

好在网上大神多，我又找了几篇博客，找到了一篇刻印临时解决的方案

具体见博客 教你如何实现带复选框的ComboBox（自定义QComboBox）

或者采用以下简单的方法，在不提升 QComboBox 的情况下直接使用

QPixmap image(30, 30);
image.fill(QColor(255, 0, 0));
combobox->addItem(QIcon(image),QString::fromLocal8Bit("Content"));

代码整理

以下类的使用都相同，都是首先在界面拖拽一个 QComboBox，然后将其提升为以下类中的某一个，然后添加数据进行测试

1. 错误案例：Qt 组合框QComboBox定制颜色选择框

QColorCombobox.h

#pragma once
#include <QLineEdit>
#include <QCombobox>class QLabel;
class QListWidget;class QColorWidget : public QLineEdit {
    Q_OBJECT
public:QColorWidget(QWidget *parent = Q_NULLPTR);~QColorWidget();void updateColor(const QColor &color);void mousePressEvent(QMouseEvent *event);signals:void click(const QColor &color);
private:QLabel *m_pLabel;QLabel *m_pRgbLabel;QColor m_color;
};class QColorCombobox : public QComboBox {
    Q_OBJECT
public:QColorCombobox(QWidget *parent = Q_NULLPTR);~QColorCombobox();void appendItem(const QColor &color);private slots:void onClickColorWidget(const QColor &color);
private:QColorWidget *m_pLineEdit;QListWidget *m_pListWidget;
};

QColorCombobox.cpp

#include "QColorCombobox.h"
#include <QLabel>
#include <QHBoxLayout>
#include <QListWidget>QColorWidget::QColorWidget(QWidget *parent /*= Q_NULLPTR*/): QLineEdit(parent), m_color(255, 0, 0) {
    m_pLabel = new QLabel(this);m_pRgbLabel = new QLabel(this);m_pLabel->setFixedSize(15, 15);QHBoxLayout *layout = new QHBoxLayout();layout->addWidget(m_pLabel);layout->addWidget(m_pRgbLabel);layout->setContentsMargins(5, 0, 0, 2);setLayout(layout);setReadOnly(true);setStyleSheet("QLineEdit{border: none;}QLineEdit:hover{background-color:rgb(0,125,255);}");
}QColorWidget::~QColorWidget() {
    }void QColorWidget::updateColor(const QColor &color) {
    m_color = color;QString strstyle = QString("border:1px solid black;background-color:rgb(%1,%2,%3);").arg(QString::number(color.red()), QString::number(color.green()), QString::number(color.blue()));QString strText = QString("%1,%2,%3").arg(QString::number(color.red()), QString::number(color.green()), QString::number(color.blue()));m_pLabel->setStyleSheet(strstyle);m_pRgbLabel->setText(strText);
}void QColorWidget::mousePressEvent(QMouseEvent *event) {
    emit click(m_color);
}QColorCombobox::QColorCombobox(QWidget *parent /*= Q_NULLPTR*/): QComboBox(parent) {
    m_pLineEdit = new QColorWidget(this);m_pListWidget = new QListWidget(this);    m_pLineEdit->setStyleSheet("");setContextMenuPolicy(Qt::NoContextMenu);//禁用菜单m_pListWidget->setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);//禁用垂直滚动条m_pListWidget->setStyleSheet("QListWidget::Item:hover{background-color:rgb(0,125,255);}");setLineEdit(m_pLineEdit);setModel(m_pListWidget->model());setView(m_pListWidget);}QColorCombobox::~QColorCombobox() {
    
}void QColorCombobox::appendItem(const QColor &color) {
    QColorWidget *pWid = new QColorWidget(this);pWid->updateColor(color);connect(pWid, SIGNAL(click(const QColor &)), this, SLOT(onClickColorWidget(const QColor &)));QListWidgetItem *pItem = new QListWidgetItem(m_pListWidget);m_pListWidget->addItem(pItem);m_pListWidget->setItemWidget(pItem, pWid);}void QColorCombobox::onClickColorWidget(const QColor &color) {
    m_pLineEdit->updateColor(color);hidePopup();
}

MainWindow.cpp

ui.comboBox->appendItem(QColor(255, 0, 0));
ui.comboBox->appendItem(QColor(255, 255, 0));
ui.comboBox->appendItem(QColor(255, 0, 255));
ui.comboBox->appendItem(QColor(0, 255, 255));
ui.comboBox->appendItem(QColor(0, 255, 0));

2. 错误案例：自定义多选QComboBox

MutiComboBox.h

#ifndef MUTICOMBOBOX_H
#define MUTICOMBOBOX_H#include <QWidget>
#include <QListWidget>
#include <QLineEdit>
#include <QComboBox>class  MutiComboBox : public QComboBox
{
    Q_OBJECTpublic:MutiComboBox(QWidget *parent = 0);MutiComboBox(const QMap<int,QString> &mapData,QWidget *parent = 0);~MutiComboBox();public:void setModelData(const QMap<int,QString> &mapData);void setCheckedItems(const QString &data);QString getSelectedItemDatas();private slots:void stateChanged(int state);void textChanged(const QString &text);private:void clear();private:QListWidget *pListWidget;QLineEdit *pLineEdit;QString strSelectedText;bool bSelected;
};#endif // MUTICOMBOBOX_H

MutiComboBox.cpp

#include "muticombobox.h"#include <QCheckBox>
#include <QDebug>MutiComboBox::MutiComboBox(QWidget *parent): QComboBox(parent)
{
    pListWidget = new QListWidget(this);pListWidget->setObjectName("MutiComboBoxListWidget");pLineEdit = new QLineEdit(this);//this->setModel(pListWidget->model());//this->setView(pListWidget);this->setLineEdit(pLineEdit);pLineEdit->setReadOnly(true);connect(pLineEdit,SIGNAL(textChanged(const QString &)),this,SLOT(textChanged(const QString &)));
}MutiComboBox::MutiComboBox(const QMap<int,QString> &mapData,QWidget *parent)
:QComboBox(parent)
{
    pListWidget = new QListWidget(this);pLineEdit = new QLineEdit(this);QMapIterator<int,QString> it(mapData);while(it.hasNext()){
    it.next();QListWidgetItem *pItem = new QListWidgetItem(pListWidget);pListWidget->addItem(pItem);pItem->setData(Qt::UserRole,it.key());QCheckBox *pCheckBox = new QCheckBox(this);pCheckBox->setText(it.value());pListWidget->addItem(pItem);pListWidget->setItemWidget(pItem,pCheckBox);connect(pCheckBox,SIGNAL(stateChanged(int)),this,SLOT(stateChanged(int)));}this->setModel(pListWidget->model());this->setView(pListWidget);this->setLineEdit(pLineEdit);pLineEdit->setReadOnly(true);connect(pLineEdit,SIGNAL(textChanged(const QString &)),this,SLOT(textChanged(const QString &)));
}MutiComboBox::~MutiComboBox()
{
    delete pListWidget;delete pLineEdit;
}
void MutiComboBox::setModelData(const QMap<int,QString> &mapData)
{
    int count = pListWidget->count();for (int row = 0; row < count;++row){
    QListWidgetItem *pItem = pListWidget->takeItem(0);delete pItem;}QMapIterator<int,QString> it(mapData);while(it.hasNext()){
    it.next();QListWidgetItem *pItem = new QListWidgetItem(pListWidget);pListWidget->addItem(pItem);pItem->setData(Qt::UserRole,it.key());QCheckBox *pCheckBox = new QCheckBox(this);pCheckBox->setText(it.value());pListWidget->addItem(pItem);pListWidget->setItemWidget(pItem,pCheckBox);connect(pCheckBox,SIGNAL(stateChanged(int)),this,SLOT(stateChanged(int)));}this->setModel(pListWidget->model());this->setView(pListWidget);
}void MutiComboBox::setCheckedItems(const QString &data)
{
    clear();if(data.isEmpty())return;int count = pListWidget->count();QStringList list(data.split(";"));QStringListIterator it(list);while(it.hasNext()){
    QString da = it.next();for(int i=0;i<count;++i){
    QListWidgetItem *pItem = pListWidget->item(i);if(pItem->data(Qt::UserRole).toString() == da){
    QWidget *pWidget = pListWidget->itemWidget(pItem);QCheckBox *pCheckBox = (QCheckBox*) pWidget;pCheckBox->setChecked(true);break;}}}
}
QString MutiComboBox::getSelectedItemDatas()
{
    int nCount = pListWidget->count();QString strSeltectedData("");for(int i=0; i < nCount; ++i){
    QListWidgetItem *pItem = pListWidget->item(i);QWidget *pWidget = pListWidget->itemWidget(pItem);QCheckBox *pCheckBox = (QCheckBox*) pWidget;if(pCheckBox->isChecked()){
    QString strText = pItem->data(Qt::UserRole).toString().trimmed();strSeltectedData.append(strText).append(";");}}if(strSeltectedData.endsWith(";")){
    strSeltectedData.remove(strSeltectedData.count()-1,1);}return strSeltectedData;
}void MutiComboBox::stateChanged(int state)
{
    bSelected = true;QString strSelectedData("");strSelectedText.clear();QObject *object= QObject::sender();QCheckBox *pSenderCheckBox = static_cast<QCheckBox*>(object);int nCount = pListWidget->count();for(int i=0; i < nCount; ++i){
    QListWidgetItem *pItem = pListWidget->item(i);QWidget *pWidget = pListWidget->itemWidget(pItem);QCheckBox *pCheckBox = (QCheckBox*) pWidget;if(pCheckBox->isChecked()){
    QString strText = pCheckBox->text();strSelectedData.append(strText).append(";");}}if(strSelectedData.endsWith(";")){
    strSelectedData.remove(strSelectedData.count()-1,1);}if(!strSelectedData.isEmpty()){
    strSelectedText = strSelectedData;pLineEdit->setText(strSelectedData);pLineEdit->setToolTip(strSelectedData);}else{
    pLineEdit->clear();}bSelected = false;
}void MutiComboBox::textChanged(const QString &text)
{
    if(!bSelected){
    pLineEdit->setText(strSelectedText);}
}void MutiComboBox::clear(){
    int nCount = pListWidget->count();for(int i=0; i < nCount; ++i){
    QListWidgetItem *pItem = pListWidget->item(i);QWidget *pWidget = pListWidget->itemWidget(pItem);QCheckBox *pCheckBox = (QCheckBox*) pWidget;if(pCheckBox->isChecked()){
    pCheckBox->setChecked(false);}}strSelectedText = "";pLineEdit->setText("");
}

MainWindow.cpp

QMap<int, QString> qmap = {
    {
    1, "111"},{
    2, "222"},{
    3, "333"},{
    4, "444"},{
    5, "555"},{
    11, "111"},{
    12, "222"},{
    13, "333"},{
    14, "444"},{
    15, "555"},{
    21, "111"},{
    22, "222"},{
    23, "333"},{
    24, "444"},{
    25, "555"},
};ui->combobox->setModelData(qmap);

3. 正确案例：教你如何实现带复选框的ComboBox（自定义QComboBox）

XComboBox.h

#pragma once#include <QComboBox>
#include <QStandardItemModel>
#include <QListView>
#include <QKeyEvent>class QLineEdit;
class QListView;struct ItemInfo
{
    int idx;QString str;QVariant userData;bool bChecked;ItemInfo(){
    idx = -1;str = QString("");userData = QVariant();bChecked = false;}
};// 事件过滤器
class KeyPressEater : public QObject
{
    Q_OBJECT
public:KeyPressEater(QObject* parent=nullptr):QObject(parent) {
    }~KeyPressEater() {
    }
signals:void sigActivated(int idx);protected:bool eventFilter(QObject *obj, QEvent *event){
    if (event->type() == QEvent::KeyPress){
    QKeyEvent *keyEvent = static_cast<QKeyEvent *>(event);if (keyEvent->key() == Qt::Key_Space){
    QListView* lstV = qobject_cast<QListView*>(obj);if (nullptr != lstV){
    int idx = lstV->currentIndex().row();if (-1 != idx){
    emit sigActivated(idx);}}}else if (keyEvent->key() == Qt::Key_Up || keyEvent->key() == Qt::Key_Down){
    return QObject::eventFilter(obj, event);}return true;}else {
    // standard event processingreturn QObject::eventFilter(obj, event);}}
};class XComboBox : public QComboBox
{
    Q_OBJECTpublic:XComboBox(QWidget *parent = Q_NULLPTR);~XComboBox();// 添加itemvoid AddItem(const QString& str, bool bChecked = false, QVariant &userData = QVariant());void AddItems(const QList<ItemInfo>& lstItemInfo);void AddItems(const QMap<QString, bool>& mapStrChk);void AddItems(const QList<QString>& lstStr);// 删除itemvoid RemoveItem(int idx);// 清空itemvoid Clear();// 获取选中的数据字符串列表QStringList GetSelItemsText();// 获取选中item的信息QList<ItemInfo> GetSelItemsInfo();// 获取item文本QString GetItemText(int idx);// 获取item信息ItemInfo GetItemInfo(int idx);signals:// popup显示信号void showingPopup();// popup隐藏信号void hidingPopup();protected:void showPopup();// 重写QComboBox的hidePopup函数// 目的选择过程中，不隐藏listviewvoid hidePopup();virtual void mousePressEvent(QMouseEvent * event);virtual void mouseReleaseEvent(QMouseEvent * event);virtual void mouseMoveEvent(QMouseEvent * event);private:void UpdateText();private slots:void sltActivated(int idx);private:QLineEdit* pLineEdit;QListView* pListView;QStandardItemModel m_model;
};

XComboBox.cpp

#include "XComboBox.h"
#include <QLineEdit>
#include <QMouseEvent>
#include <QDebug>XComboBox::XComboBox(QWidget *parent): QComboBox(parent)
{
    pLineEdit = new QLineEdit(this);pLineEdit->setReadOnly(true);this->setLineEdit(pLineEdit);this->lineEdit()->disconnect();KeyPressEater *keyPressEater = new KeyPressEater(this);pListView = new QListView(this);pListView->installEventFilter(keyPressEater);this->setView(pListView);this->setModel(&m_model);connect(this, SIGNAL(activated(int)), this, SLOT(sltActivated(int)));connect(keyPressEater, SIGNAL(sigActivated(int)), this, SLOT(sltActivated(int)));
}XComboBox::~XComboBox()
{
    
}void XComboBox::AddItem(const QString& str, bool bChecked /*= false*/, QVariant &userData /*= QVariant()*/)
{
    QStandardItem* item = new QStandardItem(str);item->setCheckable(true);item->setCheckState(bChecked ? Qt::Checked : Qt::Unchecked);item->setData(userData, Qt::UserRole + 1);m_model.appendRow(item);UpdateText();
}void XComboBox::AddItems(const QList<ItemInfo>& lstItemInfo)
{
    for (auto a : lstItemInfo){
    AddItem(a.str, a.bChecked, a.userData);}
}void XComboBox::AddItems(const QMap<QString, bool>& mapStrChk)
{
    for (auto it = mapStrChk.begin(); it != mapStrChk.end(); ++it){
    AddItem(it.key(), it.value());}
}void XComboBox::AddItems(const QList<QString>& lstStr)
{
    for (auto a : lstStr){
    AddItem(a, false);}
}void XComboBox::RemoveItem(int idx)
{
    m_model.removeRow(idx);UpdateText();
}void XComboBox::Clear()
{
    m_model.clear();UpdateText();
}QStringList XComboBox::GetSelItemsText()
{
    QStringList lst;QString str = pLineEdit->text();if (str.isEmpty()){
    return lst;}else{
    return pLineEdit->text().split(",");}
}QList<ItemInfo> XComboBox::GetSelItemsInfo()
{
    QList<ItemInfo> lstInfo;for (int i = 0; i < m_model.rowCount(); i++){
    QStandardItem* item = m_model.item(i);if (item->checkState() == Qt::Unchecked) continue;ItemInfo info;info.idx = i;info.str = item->text();info.bChecked = true;info.userData = item->data(Qt::UserRole + 1);lstInfo << info;}return lstInfo;
}QString XComboBox::GetItemText(int idx)
{
    if (idx < 0 || idx >= m_model.rowCount()){
    return QString("");}return m_model.item(idx)->text();
}ItemInfo XComboBox::GetItemInfo(int idx)
{
    ItemInfo info;if (idx < 0 || idx >= m_model.rowCount()){
    return info;}QStandardItem* item = m_model.item(idx);info.idx = idx;info.str = item->text();info.bChecked = (item->checkState() == Qt::Checked);info.userData = item->data(Qt::UserRole + 1);return info;
}void XComboBox::showPopup()
{
    emit showingPopup();QComboBox::showPopup();
}void XComboBox::hidePopup()
{
    int width = this->view()->width();int height = this->view()->height();int x = QCursor::pos().x() - mapToGlobal(geometry().topLeft()).x() + geometry().x();int y = QCursor::pos().y() - mapToGlobal(geometry().topLeft()).y() + geometry().y();QRect rectView(0, this->height(), width, height);if (!rectView.contains(x, y)){
    emit hidingPopup();QComboBox::hidePopup();}
}void XComboBox::mousePressEvent(QMouseEvent * event)
{
    QComboBox::mousePressEvent(event);event->accept();
}void XComboBox::mouseReleaseEvent(QMouseEvent * event)
{
    QComboBox::mouseReleaseEvent(event);event->accept();
}void XComboBox::mouseMoveEvent(QMouseEvent * event)
{
    QComboBox::mouseMoveEvent(event);event->accept();
}void XComboBox::UpdateText()
{
    QStringList lstTxt;for (int i = 0; i < m_model.rowCount(); ++i){
    QStandardItem* item = m_model.item(i);if (item->checkState() == Qt::Unchecked) continue;lstTxt << item->text();}pLineEdit->setText(lstTxt.join(","));pLineEdit->setToolTip(lstTxt.join("\n"));
}void XComboBox::sltActivated(int idx)
{
    QStandardItem* item = m_model.item(idx);if (nullptr == item) return;Qt::CheckState state = (item->checkState() == Qt::Checked) ? Qt::Unchecked : Qt::Checked;item->setCheckState(state);UpdateText();
}

MainWindow.cpp

QStringList lstStr;
for (int i = 0; i < 20; ++i) {
    lstStr << QString("item %1").arg(i);
}ui->combobox->AddItems(lstStr);
  相关解决方案

代码迷 - 您身边的软件异常，代码异常，编程异常助手（发现，解决，分享）
Copyright © 2009-2013 DAIMAMI.COM. All rights reserved.