基于QT繪制一個(gè)漂亮的預(yù)警儀表

更新時(shí)間：2023年04月06日 11:12:47 作者：音視頻開發(fā)老舅

這篇文章主要為大家詳細(xì)介紹了如何基于QT繪制一個(gè)漂亮的預(yù)警儀表，文中的示例代碼講解詳細(xì)，具有一定的學(xué)習(xí)價(jià)值，感興趣的可以了解一下

以下是用Qt實(shí)現(xiàn)漂亮預(yù)警儀表的步驟和代碼：

1.創(chuàng)建一個(gè)Qt項(xiàng)目，并添加一個(gè)主窗口。

2.在主窗口中添加QGraphicsView控件，用于繪制預(yù)警儀表。

3.創(chuàng)建一個(gè)QGraphicsScene對(duì)象，并將其設(shè)置為QGraphicsView的場(chǎng)景。

QGraphicsScene *scene = new QGraphicsScene(this);
ui->graphicsView->setScene(scene);

4.創(chuàng)建一個(gè)QGraphicsEllipseItem對(duì)象，用于表示預(yù)警儀表的外框。

QGraphicsEllipseItem *outerCircle = new QGraphicsEllipseItem(QRectF(-120,-120,240,240));
outerCircle->setPen(QPen(Qt::black, 4));
scene->addItem(outerCircle);

5.創(chuàng)建一個(gè)QGraphicsEllipseItem對(duì)象，用于表示預(yù)警儀表的中心點(diǎn)。

QGraphicsEllipseItem *centerCircle = new QGraphicsEllipseItem(QRectF(-15,-15,30,30));
centerCircle->setBrush(QBrush(Qt::red));
centerCircle->setPen(QPen(Qt::black, 2));
centerCircle->setZValue(1);
scene->addItem(centerCircle);

6.創(chuàng)建一些QGraphicsLineItem對(duì)象，用于表示預(yù)警儀表的刻度線。

for (int i = 0; i < 12; i++) {
    QGraphicsLineItem *line = new QGraphicsLineItem(-100, 0, -80, 0);
    line->setPen(QPen(Qt::black, 3));
    line->setRotation(i * 30);
    line->setPos(0, 0);
    scene->addItem(line);
}

7.創(chuàng)建一個(gè)QGraphicsPolygonItem對(duì)象，用于表示預(yù)警儀表的指針。

QPolygonF polygon;
polygon << QPointF(-10, 0) << QPointF(0, -120) << QPointF(10, 0);
QGraphicsPolygonItem *pointer = new QGraphicsPolygonItem(polygon);
pointer->setBrush(QBrush(Qt::red));
pointer->setPen(QPen(Qt::black, 2));
pointer->setZValue(2);
pointer->setPos(0, 0);
scene->addItem(pointer);

8.在主窗口的定時(shí)器中更新指針的旋轉(zhuǎn)角度。

void MainWindow::timerEvent(QTimerEvent *event)
{
    Q_UNUSED(event);
    int angle = ui->spinBox->value();
    QGraphicsItem *item = ui->graphicsView->scene()->items().at(3);
    item->setRotation(angle);
}

完整的代碼如下：

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include <QGraphicsScene>
#include <QGraphicsEllipseItem>
#include <QGraphicsPolygonItem>
#include <QGraphicsLineItem>
 
QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
 
protected:
    void timerEvent(QTimerEvent *event);
 
private:
    Ui::MainWindow *ui;
    QGraphicsScene *scene;
    QGraphicsEllipseItem *outerCircle;
    QGraphicsEllipseItem *centerCircle;
    QGraphicsPolygonItem *pointer;
    QList<QGraphicsLineItem*> lines;
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
 
MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
    // 創(chuàng)建場(chǎng)景
    scene = new QGraphicsScene(this);
    ui->graphicsView->setScene(scene);
 
    // 創(chuàng)建外框
    outerCircle = new QGraphicsEllipseItem(QRectF(-120,-120,240,240));
    outerCircle->setPen(QPen(Qt::black, 4));
    scene->addItem(outerCircle);
 
    // 創(chuàng)建中心點(diǎn)
    centerCircle = new QGraphicsEllipseItem(QRectF(-15,-15,30,30));
    centerCircle->setBrush(QBrush(Qt::red));
    centerCircle->setPen(QPen(Qt::black, 2));
    centerCircle->setZValue(1);
    scene->addItem(centerCircle);
 
    // 創(chuàng)建指針
    QPolygonF polygon;
    polygon << QPointF(-10, 0) << QPointF(0, -120) << QPointF(10, 0);
    pointer = new QGraphicsPolygonItem(polygon);
    pointer->setBrush(QBrush(Qt::red));
    pointer->setPen(QPen(Qt::black, 2));
    pointer->setZValue(2);
    pointer->setPos(0, 0);
    pointer->setRotation(0);
    scene->addItem(pointer);
 
    // 創(chuàng)建刻度線
    for (int i = 0; i < 12; i++) {
        QGraphicsLineItem *line = new QGraphicsLineItem(-100, 0, -80, 0);
        line->setPen(QPen(Qt::black, 3));
        line->setRotation(i * 30);
        line->setPos(0, 0);
        lines.append(line);
        scene->addItem(line);
    }
 
    // 啟動(dòng)定時(shí)器
    startTimer(100);
}
 
MainWindow::~MainWindow()
{
    delete ui;
}
 
void MainWindow::timerEvent(QTimerEvent *event)
{
    Q_UNUSED(event);
    int angle = ui->spinBox->value();
    QGraphicsItem *item = ui->graphicsView->scene()->items().at(3);
    pointer->setRotation(angle);
}

用Qt畫一個(gè)漂亮預(yù)警儀表，具有立體感，代碼，描述設(shè)計(jì)步驟