效果如下:

#ifndef QTLCDLABEL_H
#define QTLCDLABEL_H

#include
#include
#include
#include
#include

class QtLCDLabel : public QLabel
{
Q_OBJECT
public:
QtLCDLabel(QWidget *parent = nullptr);
~QtLCDLabel();

void setText(QString text);
void setPixelSize(int size) { m_pixelSize = size; this->update();}
void setSpacingSize(int size) { m_spacingSize = size; this->update();}
void setTextColor(QColor color) { m_textColor = color; this->update();}
void setPixelColor(QColor color) { m_pixelColor = color; this->update();}
void setBackgroundColor(QColor color) { m_backgroundColor = color; this->update();}
void setAutoScroll(bool flags);

protected:
void paintEvent(QPaintEvent *pEvent);
void resizeEvent(QResizeEvent *pEvent);
QImage generateDotMatrix(const QString &text);
QImage generateBackgroundDotMatrixImage();
QImage generateDotMatrixImage(const QImage& source);

private:
int m_scrollOffset = 0;
QTimer *m_timer = nullptr;
QImage m_textImage;
QImage m_textDotMatrixImage; // 绿色文字点阵图（提前生成好）
QImage m_backgroundDotMatrixImage; // 灰色背景点阵图（只在resize时候生成一次）

int m_pixelSize = 2;
int m_spacingSize = 1;

QColor m_textColor = Qt::red;
QColor m_pixelColor = QColor::fromRgb(32, 32, 32);
QColor m_backgroundColor = Qt::black;

bool m_IsAutoScroll = false;
};

#endif // QTLCDLABEL_H

#include "qtlcdlabel.h"
#include

QtLCDLabel::QtLCDLabel(QWidget *parent)
: QLabel(parent)
{

}

void QtLCDLabel::setAutoScroll(bool flags){
if(flags){
if(nullptr == m_timer){
m_timer = new QTimer(this);
connect(m_timer, &QTimer::timeout, this, () {
m_scrollOffset += 4;
// 重绘
update();
});
}
m_timer->start(50);
}else{
if(nullptr != m_timer){
m_timer->stop();
}
}
}

QtLCDLabel::~QtLCDLabel(){

}

void QtLCDLabel::setText(QString text){
m_textImage = generateDotMatrix(text);
// 清空点阵图，表示需要重新生成
m_textDotMatrixImage = QImage();
update();
}
void QtLCDLabel::resizeEvent(QResizeEvent *pEvent){
m_backgroundDotMatrixImage = generateBackgroundDotMatrixImage();
QLabel::resizeEvent(pEvent);
}

QImage QtLCDLabel::generateBackgroundDotMatrixImage()
{
QImage image(width(), height(), QImage::Format_ARGB32);
image.fill(m_backgroundColor);

QPainter painter(&image);
painter.setRenderHint(QPainter::Antialiasing);

for (int y = 0; y < height(); y += (m_pixelSize + m_spacingSize))
{
for (int x = 0; x < width(); x += (m_pixelSize + m_spacingSize))
{
QRect rect(x, y, m_pixelSize, m_pixelSize);
painter.fillRect(rect, m_pixelColor);
}
}

return image;
}

QImage QtLCDLabel::generateDotMatrix(const QString &text){

// 1. 基础设置
QFont font;
font.setFamily("宋体");
font.setBold(true);
// font.setItalic(true);

// 2. 先粗略估计字体大小，让它能填满控件宽度一定比例
// 让字体高度大概是控件高度的60%
// 字号和像素高度大致比例调整一下
int targetHeight = height() * 0.2;
int pointSize= targetHeight / 2.0;
font.setPointSize(pointSize);

QFontMetrics fm(font);
int textWidth = fm.horizontalAdvance(text);
int textHeight = fm.height();

if(textWidth width())
{
startX = -m_scrollOffset;
if (m_scrollOffset > matrixWidth)
m_scrollOffset = 0;
}

int offsetY = (height() - m_textDotMatrixImage.height()) / 2;
painter.drawImage(startX, offsetY, m_textDotMatrixImage);
}
}
码云地址：https://gitee.com/miaoxingxing/qt-lcd---display-control.git