完整代码-QT开发中文网

以下是一个简单的Qt应用程序示例，演示了如何实现一个自定义的绘图区域，该区域在鼠标移动时显示网格并防止闪烁。这个示例使用双缓冲技术来避免重绘时出现闪烁。

#include <QApplication>
#include <QFrame>
#include <QPainter>
#include <QMouseEvent>
#include <QPixmap>
#include <QScrollBar>

class CanvasFrame : public QFrame {
    Q_OBJECT

public:
    CanvasFrame(QWidget *parent = nullptr) 
        : QFrame(parent), lastMousePos(0, 0) {
        setFixedSize(800, 600);
        buffer = QPixmap(size());
        buffer.fill(Qt::white); // 填充背景色
        drawGrid(); // 初始绘制网格
    }

protected:
    void paintEvent(QPaintEvent *event) override {
        Q_UNUSED(event);
        
        // 绘制缓冲区内容到窗口
        QPainter painter(this);
        painter.drawPixmap(0, 0, buffer);
    }

    void mouseMoveEvent(QMouseEvent *event) override {
        QPoint delta = event->pos() - lastMousePos;

        if (abs(delta.x()) > 5 || abs(delta.y()) > 5) { 
            horizontalScrollBar()->setValue(horizontalScrollBar()->value() - delta.x());
            verticalScrollBar()->setValue(verticalScrollBar()->value() - delta.y());
            
            lastMousePos = event->pos();
            
            update(); // 请求重新绘制
       }
    }

private:
    void drawGrid() {
        QPainter painter(&buffer);
        painter.setPen(QPen(Qt::gray, 1));
        
        int gridSize = 20; // 网格大小
        
        for (int i = 0; i <= height(); i += gridSize) {
            painter.drawLine(0, i, width(), i); // 横线
        }
        
        for (int j = 0; j <= width(); j += gridSize) {
            painter.drawLine(j, 0, j, height()); // 垂直线
        }
    }

private:
    QPoint lastMousePos;
    QPixmap buffer;
};

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);

    CanvasFrame frame;
    frame.show();

    return app.exec();
}

#include "main.moc"