QT学习_string转换和显示组件

Posted 2021-06-26 Leslie X徐

QT例子

string转换

创建一个btnCal(pushbutton)，三个lineEdit，计算购买水果价钱
右键btnCal，选择"go to slot…" -> “clicked()”，编写下列代码

void Widget::on_btnCal_clicked()
{
    QString str = ui->editNum->text();
    int num = str.toInt();
    str = ui->editPrice->text();
    float price = str.toFloat();
    float total = num*price;
    str = str.sprintf("%.2f",total);
    ui->editTotal->setText(str);
}

进制转换

void Widget::on_btnDec_clicked()
{
    QString str = ui->editDec->text();
    int val = str.toInt();

    str = str.setNum(val,16);//to hex
    str = str.toUpper();
    ui->editHex->setText(str);

    str = str.setNum(val,2);
    ui->editBin->setText(str);
}

void Widget::on_btnBin_clicked()
{
    QString str = ui->editBin->text();
    bool ok;
    int val = str.toInt(&ok,2);

    str = str.setNum(val,16);//to hex
    str = str.toUpper();
    ui->editHex->setText(str);

    str = QString::number(val,10);
    ui->editDec->setText(str);
}

void Widget::on_btnHex_clicked()
{
    QString str = ui->editHex->text();
    bool ok;
    int val = str.toInt(&ok,16);

    str = str.setNum(val,10);
    ui->editDec->setText(str);

    str = str.setNum(val,2);
    ui->editBin->setText(str);
}

各种组件及其属性

• QGroupBox
• QAbstractSlider
  • QSlider
  • QScrollBar
  • QDial
• QProgressBar
• QLCDNumber
  

源文件：

1. 滑动RGB颜色滑动条设置textEdit底色

#include "widget.h"
#include "ui_widget.h"

Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    //将其他滑动条的valueChanged信号与槽函数相关联
    //则当4个滑动条任一滑动时，都调用这个槽函数
    QObject::connect(ui->SliderBlue,SIGNAL(valueChanged(int)),
                     this,SLOT(on_SliderRed_valueChanged(int)));
    QObject::connect(ui->SliderGreen,SIGNAL(valueChanged(int)),
                     this,SLOT(on_SliderRed_valueChanged(int)));
    QObject::connect(ui->SliderAlpha,SIGNAL(valueChanged(int)),
                     this,SLOT(on_SliderRed_valueChanged(int)));
}

Widget::~Widget()
{
    delete ui;
}

void Widget::on_SliderRed_valueChanged(int value)
{
    Q_UNUSED(value);
    QColor color;
    int R = ui->SliderRed->value();
    int G = ui->SliderGreen->value();
    int B = ui->SliderBlue->value();
    int alpha = ui->SliderAlpha->value();

    color.setRgb(R,G,B,alpha); //use setRgb to get color

    QPalette pal = ui->textEdit->palette();
    pal.setColor(QPalette::Base,color);
    ui->textEdit->setPalette(pal);
}

拖动dial组件，在LCD组件显示，旁边radio按钮选择数据的进制模式

void Widget::on_dial_valueChanged(int value)
{
    ui->lcdNumber->display(value);
}

void Widget::on_radioBtnDec_clicked()
{
    ui->lcdNumber->setDigitCount(3);
    ui->lcdNumber->setDecMode();
}

void Widget::on_radioBtnBin_clicked()
{
    ui->lcdNumber->setDigitCount(8);
    ui->lcdNumber->setBinMode();
}

void Widget::on_radioBtnOct_clicked()
{
    ui->lcdNumber->setDigitCount(4);
    ui->lcdNumber->setOctMode();
}

void Widget::on_radioBtnHex_clicked()
{
    ui->lcdNumber->setDigitCount(3);
    ui->lcdNumber->setHexMode();
}

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 = nullptr);
    ~Widget();

private slots:
    void on_SliderRed_valueChanged(int value);

    void on_dial_valueChanged(int value);

    void on_radioBtnDec_clicked();

    void on_radioBtnBin_clicked();

     void on_radioBtnOct_clicked();

     void on_radioBtnHex_clicked();

private:
    Ui::Widget *ui;
};

#endif // WIDGET_H