Qt 使用 QFrame 实现 QScrollArea

#include "mainwindow.h"
#include "ui_mainwindow.h"

#include <QPushButton>
#include <QGridLayout>
#include <QPoint>
#include <QString>
#include <QFrame>
#include <QWheelEvent>
#include <QDebug>

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    QFrame *frmBody = new QFrame(ui->m_container);
    QGridLayout *bodyLayout = new QGridLayout();
    for (int i = 0; i < 20; ++i) {
        QPushButton *btn = new QPushButton(this);
        btn->setFixedSize(120, 80);
        btn->setText(QString::fromLocal8Bit("按钮%1").arg(i + 1));
        bodyLayout->addWidget(btn, 0, i);
    }

    frmBody->setLayout(bodyLayout);
    frmBody->setStyleSheet("QFrame { background-color: green; }");
    frmBody->move(ui->m_container->x(), ui->m_container->y());

    m_body = frmBody;
}

MainWindow::~MainWindow()
{
    delete ui;
}

void MainWindow::wheelEvent(QWheelEvent *event)
{
    QPoint numPixels = event->pixelDelta();
    QPoint numDegrees = event->angleDelta() / 8;
    QPoint numSteps = numDegrees / 15;

    int step = numSteps.y();
    int nextPos = m_body->x() + step * 10;
    if (nextPos < ui->m_container->width() - m_body->width()) {
        nextPos = ui->m_container->width() - m_body->width();
    }
    if (nextPos > 0) nextPos = 0;

    m_body->move(nextPos, 0);
}

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>

class QFrame;
class QWheelEvent;

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();

    void wheelEvent(QWheelEvent *event);

private:
    Ui::MainWindow *ui;

    QFrame *m_body = nullptr;
};

#endif // MAINWINDOW_H

链接：https://pan.baidu.com/s/1TDs5QEettIHPK3G_xXRttg
提取码：9mdq