鼠标移动画布时候总感觉移动不平稳有抖动，如何解决-QT开发中文网

鼠标移动时的抖动通常与以下几个因素有关：

鼠标事件处理：确保在mouseMoveEvent中，只有在拖动状态下才更新滚动条。
双缓冲：在绘制过程中使用双缓冲技术，以避免闪烁。
平滑滚动：可以考虑引入定时器来平滑鼠标移动。

下面是改进后的代码示例，主要集中在使得滚动更加平稳和减少抖动感：

#include <QApplication>
#include <QMainWindow>
#include <QScrollArea>
#include <QFrame>
#include <QVBoxLayout>
#include <QPainter>
#include <QMouseEvent>

class CanvasFrame : public QFrame {
    Q_OBJECT

public:
    CanvasFrame(QWidget *parent = nullptr) : QFrame(parent) {
        setMinimumSize(500, 500);
        setMouseTracking(true); // 启用鼠标跟踪
        dragging = false; // 初始状态为未拖拽
    }

protected:
    void paintEvent(QPaintEvent *event) override {
        Q_UNUSED(event);
        
        QPainter painter(this);
        
        // 设置线条颜色和宽度
        painter.setPen(QPen(Qt::gray, 1));

        int gridSize = 100;
        
        // 绘制横向网格线
        for (int i = 0; i <= height(); i += gridSize) {
            painter.drawLine(0, i, width(), i);
        }
        
        // 绘制纵向网格线
        for (int j = 0; j <= width(); j += gridSize) {
            painter.drawLine(j, 0, j, height());
        }
    }

    void mousePressEvent(QMouseEvent *event) override {
        if (event->button() == Qt::LeftButton) {
            lastMousePos = event->pos();
            dragging = true;
            setCursor(Qt::ClosedHandCursor); // 更换光标为抓手形状
        }
    }

    void mouseMoveEvent(QMouseEvent *event) override {
        if (dragging && event->buttons() & Qt::LeftButton) { 
            int dx = event->pos().x() - lastMousePos.x();
            int dy = event->pos().y() - lastMousePos.y();
            
            horizontalScrollBar()->setValue(horizontalScrollBar()->value() - dx);
            verticalScrollBar()->setValue(verticalScrollBar()->value() - dy);

            lastMousePos = event->pos(); // 更新位置到当前鼠标位置
         }
    }

    void mouseReleaseEvent(QMouseEvent *event) override {
        if (event->button() == Qt::LeftButton) {
            dragging = false;
            unsetCursor(); // 恢复光标
         }
     }

private:
    QPoint lastMousePos;
    bool dragging;
};

class MainWindow : public QMainWindow {
public:
    MainWindow(QWidget *parent = nullptr)
      : QMainWindow(parent)
    {
       setWindowTitle("Grid Example");
       resize(800, 600);

       auto layout = new QVBoxLayout;

       auto leftFrame = new QFrame(this);
       leftFrame->setFixedWidth(200);
       leftFrame->setStyleSheet("background-color: green;");

       auto scrollArea = new QScrollArea(this);
       auto canvas = new CanvasFrame(scrollArea);

       scrollArea->setWidget(canvas);
       scrollArea->setWidgetResizable(true);

       layout->addWidget(leftFrame);
       layout->addWidget(scrollArea);

       QWidget *centralWidget = new QWidget(this);
       centralWidget->setLayout(layout);
       setCentralWidget(centralWidget);
   }
};

int main(int argc, char *argv[]) {
   QApplication a(argc, argv);
   MainWindow w;
   w.show();
   return a.exec();
}