要c++实现-QT开发中文网

下面是一个使用 C++ 和 Qt 框架实现的示例，演示如何在 QGraphicsView 中移动图片，并与水平滚动条（QScrollBar）限制结合。

示例代码

#include <QApplication>
#include <QMainWindow>
#include <QGraphicsView>
#include <QGraphicsScene>
#include <QGraphicsPixmapItem>
#include <QSlider>
#include <QVBoxLayout>
#include <QWidget>

class ImageMover : public QMainWindow {
    Q_OBJECT

public:
    ImageMover() {
        setWindowTitle("Image Mover with Scrollbar");
        setGeometry(100, 100, 600, 500);

        // 创建场景和视图
        scene = new QGraphicsScene(this);
        view = new QGraphicsView(scene);

        // 加载图像并添加到场景中
        pixmapItem = new QGraphicsPixmapItem(QPixmap("your-image-url.jpg"));
        scene->addItem(pixmapItem);

        // 设置视图属性
        view->setRenderHint(QPainter::Antialiasing);

        // 创建滚动条
        scrollbar = new QSlider(Qt::Horizontal);
        scrollbar->setMinimum(-300);  // 根据需要设置最小值
        scrollbar->setMaximum(0);      // 根据需要设置最大值
        connect(scrollbar, &QSlider::valueChanged, this, &ImageMover::updateImagePosition);

        // 布局设置
        QVBoxLayout *layout = new QVBoxLayout();
        layout->addWidget(view);
        layout->addWidget(scrollbar);

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

protected:
    void mousePressEvent(QMouseEvent *event) override {
            if (event->button() == Qt::LeftButton) {
                QPointF scenePos = view->mapToScene(event->pos());
                if (pixmapItem->isUnderMouse()) {
                    offsetX = scenePos.x() - pixmapItem->x();
                    offsetY = scenePos.y() - pixmapItem->y();

                    dragging = true;
                }
            }
            event->accept();
    }

    void mouseMoveEvent(QMouseEvent *event) override {
            if (dragging) {
                QPointF newScenePos = view->mapToScene(event->pos());
                qreal newX = newScenePos.x() - offsetX;
                qreal newY = newScenePos.y() - offsetY;

                // 更新图片位置，限制在滚动条范围内
                qreal limitedX = std::max(newX, -300.0);  // 最小限制为-300，根据你的需求调整 
                limitedX = std::min(limitedX, 0.0);       // 最大限制为0

                pixmapItem->setPos(limitedX, newY);
            }
            event->accept();
    }

    void mouseReleaseEvent(QMouseEvent *event) override {
            if (event->button() == Qt::LeftButton) {
                 dragging = false;   
             }
             event-accept();   
     }

private slots:
    void updateImagePosition() {
         qreal value = scrollbar.value();
         pixmapItem-setX(value);
     }

private:
   QGraphicsView *view;
   QGraphicsScene *scene;
   QGraphicsPixmapItem *pixmapItem;
   QSlider *scrollbar;

   bool dragging{false};
   qreal offsetX{0}, offsetY{0};
};

int main(int argc, char *argv[]) {
    QApplication app(argc, argv);
    
    ImageMover window;
    window.show();

    return app.exec();
}

#include "main.moc"