QDial设置范围从0.00到10.00至小部件显示

Question

I have a class that connects a Lcd display with a dial and when you rotate the dial you get values on the lcd like this

#ifndef SLIDELCD_H
#define SLIDELCD_H

#include <QDial>
#include <QVBoxLayout>
#include <QLCDNumber>
#include "CustomDial.h"
class SlideLcd: public QWidget
{
Q_OBJECT
public:
SlideLcd(QWidget *parent=nullptr);
private:
CustomDial *dial;
QLCDNumber *lcd;
QVBoxLayout *layout;
};

SlideLcd::SlideLcd(QWidget *parent)
               :QWidget(parent)
{
dial = new CustomDial;
dial->setNotchesVisible(true);
lcd = new QLCDNumber;
connect(dial, SIGNAL(valueChanged(int)), lcd , SLOT(display(int)));
layout = new QVBoxLayout;
layout->addWidget(lcd);
layout->addWidget(dial);
setLayout(layout);
}

I know that with QDial::setRange(0,100) you can set the range from 0-100 but is there any way to set ranges like 0.00 to 100.00

Answer 1

Given that there's no way to specify QDial range using double , you should provide an extra slot to catch the valueChanged signal, edit the value there and pass the edited value to display method of lcd .

So, in your widget class:

private slots:
  void dialValueChanged(int value);

Set dial range to 0-10000 in constructor:

dial->setMinimum(0);
dial->setMaximum(10000);

then connect the new slot:

connect(dial, SIGNAL(valueChanged(int)), this , SLOT(dialValueChanged(int)));

The slot definition is like this:

void SlideLcd::dialValueChanged(int value)
{
  double v = (double)((double)value / 100);
  lcd->display(v);
}

This way, as the dial value changes from 0 to 10000, your lcd will display numbers in range 0.00 to 100.00, accordingly.