＜QT基础(3)＞QLineEdit使用笔记-编程知识

＜QT基础(3)＞QLineEdit使用笔记

LineEdit

这次要用的是两个功能：初始化展示参数值，修改参数值。

初始化

将l_num的默认值显示

    ui.lineEdit->setText(QString::number(l_num));

信号

textChanged() 文本发生改变
textEdited() 文本编辑信号
cursorPositionChanged(）光标发生改变
returnPressed() 回车键或return按键按下信号
editingFinished() 回车键或return按键按下信号或者焦点丢失信号
selectionChanged() 只要选择改变这个信号就会被发射

目前觉得好用的是editingFinished和returnPressed，暂时使用editingFinished。

    connect(ui.lineEdit, SIGNAL(editingFinished()), this, SLOT(lineEditset()));
//textChanged   cursorPositionChanged//editingFinished  selectionChanged returnPressed()

槽函数

把键入lineedit的值赋给后台参数。

void DcmImgPro::lineEditset()
{l_num = ui.lineEdit->text().toInt();
}

当然这里没有针对键入值做异常判定，应该有。

void DcmImgPro::lineEditset() {bool ok;int new_num = ui.lineEdit->text().toInt(&ok);if (!ok) {QMessageBox::warning(this, "Error", "Invalid input! Please enter a valid integer.");} else {l_num = new_num;}
}

总体代码

实现了向ScrollArea内部填充指定数量的QLabel，作为Dicom图像的预览窗口。

#pragma once#include <QtWidgets/QMainWindow>
#include <QtWidgets>
#include "ui_dcmimgpro.h"class DcmImgPro : public QMainWindow
{Q_OBJECTpublic:DcmImgPro(QWidget *parent = nullptr);~DcmImgPro();private:Ui::DcmImgProClass ui;
private slots:void pushbtn();void lineEditset();
private:int l_num = 15;
};class ScrollableWidget:public QWidget
{
public:ScrollableWidget(int numWidgets){QVBoxLayout* layout = new QVBoxLayout(this);for (int i = 0; i < numWidgets; i++){QWidget* widget = new QWidget;QString msg = "Label_" + QString::number(i);QLabel* label = new QLabel(msg);QVBoxLayout* widgetlayout = new QVBoxLayout(widget);widgetlayout->addWidget(label);layout->addWidget(widget);}};};

#include "dcmimgpro.h"DcmImgPro::DcmImgPro(QWidget *parent): QMainWindow(parent)
{ui.setupUi(this);ui.scrollArea->setWidgetResizable(true);ScrollableWidget* scrollableWidget = new  ScrollableWidget(l_num);ui.scrollArea->setWidget(scrollableWidget);ui.lineEdit->setText(QString::number(l_num));connect(ui.pushButton, SIGNAL(clicked()), this, SLOT(pushbtn()));connect(ui.lineEdit, SIGNAL(editingFinished()), this, SLOT(lineEditset()));//textChanged   cursorPositionChanged//editingFinished  selectionChanged returnPressed() 
}void DcmImgPro::pushbtn()
{ui.scrollArea->setWidget(nullptr);ScrollableWidget* scrollableWidget = new  ScrollableWidget(l_num);ui.scrollArea->setWidget(scrollableWidget);
}void DcmImgPro::lineEditset()
{l_num = ui.lineEdit->text().toInt();
}
DcmImgPro::~DcmImgPro()
{}