QCustomPlot鼠标拖拽游标
我在y轴上添加了一个游标，想要通过鼠标来拖动游标在y轴上滑动
要实现在QCustomPlot上拖拽游标,可以这样做:
- 定义游标类,继承QGraphicsItem
cpp
class Cursor : public QGraphicsItem
{
public:
Cursor();
void paint(QPainter *painter, const QStyleOptionGraphicsItem *option, QWidget *widget);
};
- 重写sceneEvent方法,检测鼠标按下和移动事件
cpp
void Cursor::sceneEvent(QEvent *event)
{
switch (event->type()) {
case QEvent::GraphicsSceneMousePress:
mousePressPosition = static_cast<QGraphicsSceneMouseEvent*>(event)->pos();
break;
case QEvent::GraphicsSceneMouseMove:
if (static_cast<QGraphicsSceneMouseEvent*>(event)->buttons() & Qt::LeftButton) {
// 拖动游标
QPointF position = static_cast<QGraphicsSceneMouseEvent*>(event)->pos();
setPos(mapToParent(position - mousePressPosition));
}
break;
}
QGraphicsItem::sceneEvent(event);
}
- 重写mouseReleaseEvent结束拖拽
cpp
void Cursor::sceneEvent(QEvent *event)
{
if (event->type() == QEvent::GraphicsSceneMouseRelease) {
// 结束拖拽
mousePressPosition = QPointF();
}
}
- 将游标添加到QCustomPlot的scene中
cpp
Cursor *cursor = new Cursor;
customPlot->scene()->addItem(cursor);
- 重写QCustomPlot的mousePressEvent/MoveEvent/ReleaseEvent,转发给游标
cpp
void QCustomPlot::mousePressEvent(QMouseEvent *event)
{
if (cursor)
cursor->sceneEvent(event);
QCustomPlot::mousePressEvent(event);
}
void QCustomPlot::mouseMoveEvent(QMouseEvent *event)
{
if (cursor)
cursor->sceneEvent(event);
QCustomPlot::mouseMoveEvent(event);
}
void QCustomPlot::mouseReleaseEvent(QMouseEvent *event)
{
if (cursor)
cursor->sceneEvent(event);
QCustomPlot::mouseReleaseEvent(event);
}
这样,当用户在QCustomPlot上单击并拖动鼠标时,会触发游标的sceneEvent方法,从而实现游标的拖拽效果。
希望这个示例能帮助您实现QCustomPlot上拖拽游标的需求。如有任何其他问题,欢迎在评论中提出。
- 帮你找了个相似的问题, 你可以看下: https://ask.csdn.net/questions/7477975
- 你也可以参考下这篇文章：QCustomPlot详解第一章：绘制简单曲线
- 除此之外, 这篇博客: QCustomplot绘制动态曲线图-游标及鼠标跟踪显示数值中的 一.效果图 部分也许能够解决你的问题, 你可以仔细阅读以下内容或跳转源博客中阅读:
效果图如下：
引用chatGPT作答，你可以使用QCustomPlot提供的QCPItemTracer类来实现在y轴上拖拽游标。以下是实现的步骤：
1.创建一个QCPItemTracer对象并将其添加到图表中的y轴上，代码如下：
QCPItemTracer *tracer = new QCPItemTracer(customPlot);
customPlot->addItem(tracer);
tracer->setGraph(customPlot->graph(0)); // 设置关联的图形对象
tracer->setInterpolating(true); // 开启插值模式
tracer->setStyle(QCPItemTracer::tsCircle); // 设置游标的形状
tracer->setPen(QPen(Qt::red)); // 设置游标的边框颜色
tracer->setBrush(Qt::red); // 设置游标的填充颜色
tracer->setGraphKey(xValue); // 设置游标的横坐标位置
tracer->setGraphValue(yValue); // 设置游标的纵坐标位置
2.在QCustomPlot的mouseMoveEvent和mousePressEvent事件中，获取鼠标的纵坐标值，并将其设置为QCPItemTracer对象的纵坐标值，以实现在y轴上拖拽游标。具体代码如下：
void YourWidget::mousePressEvent(QMouseEvent *event)
{
if(event->button() == Qt::LeftButton)
{
double mouseY = customPlot->yAxis->pixelToCoord(event->pos().y());
tracer->setGraphValue(mouseY);
customPlot->replot();
event->accept();
}
}
void YourWidget::mouseMoveEvent(QMouseEvent *event)
{
double mouseY = customPlot->yAxis->pixelToCoord(event->pos().y());
tracer->setGraphValue(mouseY);
customPlot->replot();
event->accept();
}
在代码中，QCustomPlot的yAxis->pixelToCoord()方法可以将鼠标在y轴上的像素坐标转换为实际的坐标值。tracer->setGraphValue()方法则将转换后的坐标值设置为QCPItemTracer对象的纵坐标位置。最后，调用customPlot->replot()方法来重新绘制图表即可。
以下答案由GPT-3.5大模型与博主波罗歌共同编写：
对于QCustomPlot的鼠标拖拽游标操作，可以通过如下的步骤来实现：
1.创建一个QCPItemStraightLine来表示游标，并使用QCustomPlot的addItem方法将其添加到图形界面中。
2.为该直线添加可拖动的事件处理程序。
3.在事件处理函数中，确定新的直线位置，更新直线，并重新绘制QCustomPlot
下面的代码提供一个简单的实现方法，该方法可以在y轴上添加可拖动的游标线：
// 创建一个QCPItemStraightLine对象
QCPItemStraightLine *m_cursorLine = new QCPItemStraightLine(customPlot);
// 设置起始点和终止点
m_cursorLine->setPen(QPen(Qt::red));
m_cursorLine->point1->setCoords(0, 0.5);
m_cursorLine->point2->setCoords(1, 0.5);
// 设置拖动事件处理程序
m_cursorLine->setSelectable(true);
m_cursorLine->setSelected(true);
m_cursorLine->setMovable(true);
m_cursorLine->setClipToAxisRect(false);
connect(customPlot, &QCustomPlot::mouseMove, this, [=](QMouseEvent *event) {
if (m_cursorLine->selected() && customPlot->xAxis->selectedParts().testFlag(QCPAxis::spAxis)) {
double posY = customPlot->yAxis->pixelToCoord(event->pos().y());
m_cursorLine->point1->setCoords(0, posY);
m_cursorLine->point2->setCoords(1, posY);
customPlot->replot();
}
});
在上述代码中，我们首先创建了一个QCPItemStraightLine对象，然后设置其起始点和终止点，将它添加到QCustomPlot中。然后，我们将其设置为可拖动，并将其连接到QCustomPlot对象的mouseMove事件处理程序中。在事件处理函数中，我们获取y轴上的新位置，根据这个新位置的更新QCPItemStraightLine对象的位置，并重新绘制QCustomPlot图形界面。
希望这个解答对你有帮助！
如果我的回答解决了您的问题，请采纳！
引用new bing部分回答作答：
要在QCustomPlot中实现拖动游标，您需要以下步骤：
1 在y轴上创建一个游标，可以使用QCPItemStraightLine类实现：
QCPItemStraightLine *cursor = new QCPItemStraightLine(customPlot->yAxis);
cursor->setPen(QPen(Qt::black));
cursor->point1->setCoords(0, 0);
cursor->point2->setCoords(1, 1);
2 为了让游标可以拖动，您需要在QCustomPlot的鼠标事件处理函数中处理拖动事件：
void MainWindow::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
{
// Check if cursor is being clicked on
QCPItemStraightLine *cursor = qobject_cast<QCPItemStraightLine *>(ui->customPlot->plottable(0));
if (cursor && cursor->selectTest(event->pos(), false) >= 0)
{
// Cursor is being clicked on, start dragging
m_draggingCursor = true;
m_cursorDragStart = event->pos();
}
}
}
void MainWindow::mouseMoveEvent(QMouseEvent *event)
{
if (m_draggingCursor)
{
// Calculate the cursor's new position
double pixelDiff = event->pos().y() - m_cursorDragStart.y();
double valueDiff = ui->customPlot->yAxis->pixelToCoord(pixelDiff);
// Set the cursor's new position
QCPItemStraightLine *cursor = qobject_cast<QCPItemStraightLine *>(ui->customPlot->plottable(0));
if (cursor)
{
double newValue = cursor->point1->coords().y() - valueDiff;
cursor->point1->setCoords(0, newValue);
cursor->point2->setCoords(1, newValue);
ui->customPlot->replot();
}
}
}
void MainWindow::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
{
// Cursor drag has ended
m_draggingCursor = false;
}
}
3 在类的成员变量中添加以下变量：在类的成员变量中添加以下变量：
bool m_draggingCursor;
QPoint m_cursorDragStart;
完整代码如下：
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include "qcustomplot.h"
MainWindow::MainWindow(QWidget *parent)
: QMainWindow(parent)
, ui(new Ui::MainWindow)
, m_draggingCursor(false)
{
ui->setupUi(this);
// Add a graph to the plot
ui->customPlot->addGraph();
// Add a cursor to the plot
QCPItemStraightLine *cursor = new QCPItemStraightLine(ui->customPlot);
cursor->setPen(QPen(Qt::red));
cursor->point1->setCoords(0, 0);
cursor->point2->setCoords(1, 0);
// Connect mouse events to plot
ui->customPlot->setInteractions(QCP::iRangeDrag | QCP::iRangeZoom);
ui->customPlot->installEventFilter(this);
}
MainWindow::~MainWindow()
{
delete ui;
}
bool MainWindow::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::MouseButtonPress)
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
mousePressEvent(mouseEvent);
return true;
}
else if (event->type() == QEvent::MouseMove)
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
mouseMoveEvent(mouseEvent);
return true;
}
else if (event->type() == QEvent::MouseButtonRelease)
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
mouseReleaseEvent(mouseEvent);
return true;
}
else
{
return QObject::eventFilter(obj, event);
}
}
void MainWindow::mousePressEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
{
// Check if cursor is being clicked on
QCPItemStraightLine *cursor = qobject_cast<QCPItemStraightLine *>(ui->customPlot->plottable(0));
if (cursor && cursor->selectTest(event->pos(), false) >= 0)
{
// Cursor is being clicked on, start dragging
m_draggingCursor = true;
m_cursorDragStart = event->pos();
}
}
}
void MainWindow::mouseMoveEvent(QMouseEvent *event)
{
if (m_draggingCursor)
{
// Calculate the cursor's new position
double pixelDiff = event->pos().y() - m_cursorDragStart.y();
double valueDiff = ui->customPlot->yAxis->pixelToCoord(pixelDiff);
// Set the cursor's new position
QCPItemStraightLine *cursor = qobject_cast<QCPItemStraightLine *>(ui->customPlot->plottable(0));
if (cursor)
{
double newValue = cursor->point1->coords().y() - valueDiff;
cursor->point1->setCoords(0, newValue);
cursor->point2->setCoords(1, newValue);
ui->customPlot->replot();
}
}
}
void MainWindow::mouseReleaseEvent(QMouseEvent *event)
{
if (event->button() == Qt::LeftButton)
{
// Cursor drag has ended
m_draggingCursor = false;
}
}