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实现效果：（确认按钮固定，上方内容右侧有滚动条可上下滑动）
1因为初学小白异想天开，想通过QVboxLayout在上面做一个固定QWidget，限制其高度，让他达到滚动的目的，做成了下面这个模样
2通过网上查找方法知道了滚动区QScrollArea可以实现区域内容滚动效果
/*添加窗体内部滚动布局*/
void addTrunk()
{
scrollArea = new QScrollArea(this);
scrollArea->setGeometry(0, 50, 360, 450);/*左上长宽*/
QFrame * widget = new QFrame(this);
widget->setContentsMargins(0, 0, 0, 0);
widget->setFixedSize(350, 590);
m_pTrunk = new QVBoxLayout(widget);
m_pTrunk->setContentsMargins(15, 0, 20, 10);
m_pTrunk->setSpacing(10);
QLabel *roomName = new QLabel;
roomName->setText(u8"房间名:");
roomName->setObjectName("editroom_topic");
QTextEdit *roomNameEdit = new QTextEdit;
roomNameEdit->setFixedWidth(331);
roomNameEdit->setFixedHeight(54);
roomNameEdit->setPlaceholderText(QStringLiteral("请输入房间名"));
roomNameEdit->setObjectName("grey_4r_textedit");
QLabel *roomNoticeTitle = new QLabel;
roomNoticeTitle->setText(u8"公告标题(限10个字):");
roomNoticeTitle->setObjectName("editroom_topic");
m_pNoticeTitleRegister = new QLabel(); //计数器
m_pNoticeTitleRegister->setGeometry(100, 250, 58, 18);
m_pNoticeTitleRegister->setStyleSheet("QLabel{color:#95949D;font:14px;}");
roomNoticeTitleEdit = new QLineEdit;
roomNoticeTitleEdit->setFixedWidth(250);
roomNoticeTitleEdit->setFixedHeight(30);
roomNoticeTitleEdit->setPlaceholderText(QStringLiteral("请输入公告标题"));
roomNoticeTitleEdit->setObjectName("grey_4r_lineedit_register");
roomNoticeTitleEdit->setMaxLength(10);
connect(roomNoticeTitleEdit, SIGNAL(textEdited()), this, SLOT(slot_scalerNoticeTitleText()));
QLabel *roomNotice = new QLabel;
roomNotice->setText(u8"房间公告(限300个字):");
roomNotice->setObjectName("editroom_topic");
m_pNoticeRegister = new QLabel(); //计数器
m_pNoticeRegister->setGeometry(100, 450, 58, 18);
m_pNoticeRegister->setStyleSheet("QLabel{color:#95949D;font:14px;}");
roomNoticeEdit = new QTextEdit;
roomNoticeEdit->setFixedWidth(314);
roomNoticeEdit->setFixedHeight(110);
roomNoticeEdit->setPlaceholderText(QStringLiteral("请输入房间公告..."));
roomNoticeEdit->setObjectName("grey_4r_textedit_Register");
roomNoticeEdit->setMaximumWidth(10);
connect(roomNoticeEdit, SIGNAL(textChanged()), this, SLOT(slot_scalerNoticeText()));
QLabel *roomWelcome = new QLabel;
roomWelcome->setText(u8"欢迎语(限300个字):");
roomWelcome->setObjectName("editroom_topic");
m_pWelcomeRegister = new QLabel(); //计数器
m_pWelcomeRegister->setGeometry(100, 650, 58, 18);
m_pWelcomeRegister->setStyleSheet("QLabel{color:#95949D;font:14px;}");
roomWelcomeEdit = new QTextEdit;
roomWelcomeEdit->setFixedWidth(314);
roomWelcomeEdit->setFixedHeight(110);
roomWelcomeEdit->setPlaceholderText(QStringLiteral("请输入欢迎语..."));
//roomWelcomeEdit->setHtml(QString("<font color=\"#95949D\">%1</font>").arg(QStringLiteral(" 请输入欢迎语...")));
roomWelcomeEdit->setObjectName("grey_4r_textedit_Register");
connect(roomWelcomeEdit, SIGNAL(textChanged()), this, SLOT(slot_scalerWelcomeText()));
QLabel *roomKey = new QLabel;
roomKey->setText(u8"房间密码:");
roomKey->setObjectName("editroom_topic");
QLineEdit *roomKeyEdit = new QLineEdit;
roomKeyEdit->setFixedWidth(331);
roomKeyEdit->setFixedHeight(30);
roomKeyEdit->setPlaceholderText(QStringLiteral("请输入4位房间密码..."));
roomKeyEdit->setObjectName("grey_4r_lineedit");
QRegExp regx("[0-9]+$");
QValidator *validator = new QRegExpValidator(regx, roomKeyEdit);
roomKeyEdit->setValidator(validator);
roomKeyEdit->setMaxLength(4);
/*结合计数器和edit*/
QWidget *m_pNoticeTitleBar = new QWidget;
m_pNoticeTitleBar->setContentsMargins(0, 0, 0, 0);
m_pNoticeTitleBar->setFixedWidth(330);
m_pNoticeTitleBar->setFixedHeight(30);
m_pNoticeTitleBar->setObjectName("edit_Register_bar");
QVBoxLayout *m_pNoticeTitleBox = new QVBoxLayout(m_pNoticeTitleBar);
m_pNoticeTitleBox->addWidget(roomNoticeTitleEdit, 0, Qt::AlignLeft);
QWidget *m_pNoticeBar = new QWidget;
m_pNoticeBar->setFixedHeight(120);
m_pNoticeBar->setFixedWidth(330);
m_pNoticeBar->setObjectName("edit_Register_bar");
QVBoxLayout *m_pNoticeBox = new QVBoxLayout(m_pNoticeBar);
m_pNoticeBox->addWidget(roomNoticeEdit, 0, Qt::AlignTop | Qt::AlignLeft);
m_pNoticeBox->addWidget(m_pNoticeRegister, 0, Qt::AlignTrailing | Qt::AlignRight);
m_pNoticeBox->addSpacing(2);
QWidget *m_pWelcomeBar = new QWidget;
m_pWelcomeBar->setFixedHeight(120);
m_pWelcomeBar->setFixedWidth(330);
m_pWelcomeBar->setObjectName("edit_Register_bar");
QVBoxLayout *m_pNoticeWelcomeBox = new QVBoxLayout(m_pWelcomeBar);
m_pNoticeWelcomeBox->addSpacing(-6);
m_pNoticeWelcomeBox->addWidget(roomWelcomeEdit, 0, Qt::AlignTop | Qt::AlignLeft);
m_pNoticeWelcomeBox->addWidget(m_pWelcomeRegister, 0, Qt::AlignTrailing | Qt::AlignRight);
m_pNoticeWelcomeBox->addSpacing(2);
m_pTrunk->addWidget(roomName, 0, Qt::AlignLeft);
m_pTrunk->addWidget(roomNameEdit, 0, Qt::AlignLeft);
m_pTrunk->addWidget(roomNoticeTitle, 0, Qt::AlignLeft);
m_pTrunk->addWidget(m_pNoticeTitleBar, 0, Qt::AlignLeft);
m_pTrunk->addWidget(roomNotice, 0, Qt::AlignLeft);
m_pTrunk->addWidget(m_pNoticeBar, 0, Qt::AlignLeft);
m_pTrunk->addWidget(roomWelcome, 0, Qt::AlignLeft);
m_pTrunk->addWidget(m_pWelcomeBar, 0, Qt::AlignLeft);
m_pTrunk->addWidget(roomKey, 0, Qt::AlignLeft);
m_pTrunk->addWidget(roomKeyEdit, 0, Qt::AlignLeft);
widget->setLayout(m_pTrunk);
scrollArea->setWidget(widget);
widget->setObjectName("we");
widget->setStyleSheet("QFrame#we{background:white;}");
}
*QFrame与QWidget的区别：
QFrame是基本控件的基类，QWidget是QFrame基类，关系如下：
QPushButton,QLabel… -> QFrame ->QWidget
*QScrollArea布局是出现滚动条的原因，主要是因为其中包含了一个子类scrllAreaWidgetContents，是小widget套一个大widget实现内部装不下而出现滚动效果。
步骤如下：
1）new QScrollArea;
2）new QFrame;
3）new QLabel,QPushButton等内部布局控件;
4）将内部控件装入内部布局QFrame;
5）将QFrame内部布局装入QScrollArea
3.无法改变滚动区背景颜色
QScrollArea 是无法通过样式表来改变背景色的，只能设置加入到QScrollArea里面的QWidget的样式，这样才能改变背景色。
当然也可以通过函数来设置QScollArea的背景色。
scrollArea->setBackgroundRole(QPalette::Dark); // 背景色
参照其他博主原文：https://blog.csdn.net/woniulx2014/article/details/83176220
https://blog.csdn.net/panghaichun/article/details/50781681
4.setVerticalScrollMode(QAbstractItemView::ScrollMode::ScrollPerPixel);
5.QListWidgetItem按照像素滚动到底部