Qt Charts 折线图纵坐标长度调整

#include 'information.h' #include 'ui_information.h' #include 'sqlite.h' #include <QtCharts/QChartView> #include <QtCharts/QLineSeries> #include <QtCharts/QValueAxis> #include #include #include

Information::Information(QWidget *parent) : QWidget(parent), ui(new Ui::Information) { ui->setupUi(this); setWindowTitle('家居状态'); setFixedSize(600,400);

QVBoxLayout *layout = new QVBoxLayout(this); // 创建一个垂直布局对象

// 创建温度折线图
QtCharts::QChartView *temperatureChartView = new QtCharts::QChartView(this);
QtCharts::QLineSeries *temperatureSeries = new QtCharts::QLineSeries();

Sqlite::sqlite_init();
QSqlQuery temperatureQuery;
temperatureQuery.exec("SELECT value FROM Status WHERE device_name = '空调' AND device_state = '开启'");
while (temperatureQuery.next())
{
    double temperature = temperatureQuery.value(0).toDouble();
    temperatureSeries->append(temperatureSeries->count(), temperature);
}

QtCharts::QChart *temperatureChart = new QtCharts::QChart();
temperatureChart->addSeries(temperatureSeries);

QtCharts::QValueAxis *temperatureAxisY = new QtCharts::QValueAxis();
temperatureAxisY->setRange(-50, 50); // 设置纵坐标范围为-50~50
temperatureChart->addAxis(temperatureAxisY, Qt::AlignLeft);
temperatureSeries->attachAxis(temperatureAxisY);

temperatureChart->setTitle('空调温度变化表'); // 设置折线图名

temperatureChartView->setChart(temperatureChart);
temperatureChartView->setRenderHint(QPainter::Antialiasing);
temperatureChartView->setMinimumSize(600, 200);

layout->addWidget(temperatureChartView); // 使用布局对象的addWidget()函数添加chartView

temperatureChartView->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::MinimumExpanding);

// 创建湿度折线图
QtCharts::QChartView *humidityChartView = new QtCharts::QChartView(this);
QtCharts::QLineSeries *humiditySeries = new QtCharts::QLineSeries();

QSqlQuery humidityQuery;
humidityQuery.exec("SELECT value FROM Status WHERE device_name = '加湿器' AND device_state = '开启'");
while (humidityQuery.next())
{
    double humidity = humidityQuery.value(0).toDouble();
    humiditySeries->append(humiditySeries->count(), humidity);
}

QtCharts::QChart *humidityChart = new QtCharts::QChart();
humidityChart->addSeries(humiditySeries);

QtCharts::QValueAxis *humidityAxisY = new QtCharts::QValueAxis();
humidityAxisY->setRange(0, 200); // 设置纵坐标范围为0~200
humidityChart->addAxis(humidityAxisY, Qt::AlignLeft);
humiditySeries->attachAxis(humidityAxisY);

humidityChart->setTitle('加湿器湿度变化表'); // 设置折线图名

humidityChartView->setChart(humidityChart);
humidityChartView->setRenderHint(QPainter::Antialiasing);
humidityChartView->setMinimumSize(600, 200);

layout->addWidget(humidityChartView); // 使用布局对象的addWidget()函数添加chartView

humidityChartView->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::MinimumExpanding);

setLayout(layout); // 将布局对象设置为窗口的布局

}

Information::~Information() { delete ui; } 折线图的纵坐标长度在（600,400）界面上非常小内容：，可以尝试将折线图的纵坐标长度调大一些，例如将纵坐标范围设置为-50到50，或者更大一些的范围。可以修改代码中的以下部分：

temperatureAxisY->setRange(-50, 50); // 设置纵坐标范围为-50~50

humidityAxisY->setRange(0, 200); // 设置纵坐标范围为0~200

调整纵坐标范围后，重新编译运行程序，查看折线图的纵坐标长度是否满足要求。