QT += concurrent

#include <QtConcurrent>

int compute(int a, int b) {
    QThread::msleep(500);
    return a + b;
}

void MainWindow::on_btn_thread_start_3_clicked()
{
    static int a = 10, b = 20;
    a++;
    b++;

    // 1?? 啟動(dòng)異步任務(wù)
    QFuture<int> future = QtConcurrent::run(compute, a, b);

    // 2?? 創(chuàng)建 watcher 監(jiān)聽(tīng)完成事件
    QFutureWatcher<int> *watcher = new QFutureWatcher<int>(this);
    
    // 3?? 連接 finished 信號(hào)（在主線(xiàn)程觸發(fā)?。?
    connect(watcher, &QFutureWatcher<int>::finished, this, [watcher]() {
        qDebug() << "Result:" << watcher->result();
        watcher->deleteLater(); // 自動(dòng)清理內(nèi)存
    });

    // 4?? 將 future 綁定到 watcher
    watcher->setFuture(future);
}

QFuture<int> future = QtConcurrent::run(compute, a, b);

QImage convertToGrayscale(const QString& filePath)
{
    // 模擬阻塞
    QThread::msleep(2000);
    QImage img(filePath);
    if (img.isNull()) {
        qWarning() << "Failed to load:" << filePath;
        return QImage(); // 返回空?qǐng)D
    }
    // 轉(zhuǎn)為黑白（灰度）
    return img.convertToFormat(QImage::Format_Grayscale8);
}

void MainWindow::on_btn_thread_start_3_1_clicked()
{
    // 1. 選擇多個(gè)圖片文件（最多10個(gè)）
    QStringList filePaths = QFileDialog::getOpenFileNames(
        this,
        "選擇圖片（最多10張）",
        QDir::homePath(),
        "Images (*.png *.jpg *.jpeg *.bmp *.gif)"
        );

    if (filePaths.isEmpty()) {
        return;
    }

    if (filePaths.size() > 10) {
        QMessageBox::warning(this, "警告", "最多只能選擇10張圖片！");
        filePaths = filePaths.mid(0, 10);
    }

    // 2. 禁用按鈕，防止重復(fù)點(diǎn)擊
    // m_convertButton->setEnabled(false);

    // 3. 啟動(dòng)并發(fā)轉(zhuǎn)換
    QFuture<QImage> future = QtConcurrent::mapped(filePaths, convertToGrayscale);

    // 4. 設(shè)置 watcher 監(jiān)聽(tīng)完成
    if (!m_watcher) {
        m_watcher = new QFutureWatcher<QImage>(this);
        connect(m_watcher, &QFutureWatcher<QImage>::finished,
                this, &MainWindow::onConversionFinished);
    }
    m_watcher->setFuture(future);
}

void MainWindow::onConversionFinished()
{
    // 5. 獲取所有結(jié)果（順序與輸入 filePaths 一致）
    QList<QImage> results = m_watcher->future().results();

    // 6. 為每張有效圖片彈窗顯示
    int validCount = 0;
    for (int i = 0; i < results.size(); ++i) {
        if (!results[i].isNull()) {
            QString title = QString("結(jié)果 %1").arg(++validCount);
            showImageInDialog(results[i], title);
        }
    }

    // 7. 恢復(fù)按鈕
    // m_convertButton->setEnabled(true);

    if (validCount == 0) {
        QMessageBox::information(this, "提示", "沒(méi)有成功加載任何圖片。");
    }
}

void MainWindow::showImageInDialog(const QImage &img, const QString &title)
{
    QDialog* dialog = new QDialog(this);
    dialog->setAttribute(Qt::WA_DeleteOnClose); // 關(guān)閉時(shí)自動(dòng) delete
    dialog->setWindowTitle(title);
    dialog->resize(600, 400);

    QLabel* label = new QLabel(dialog);
    label->setPixmap(QPixmap::fromImage(img).scaled(
        dialog->size(), Qt::KeepAspectRatio, Qt::SmoothTransformation));
    label->setAlignment(Qt::AlignCenter);

    QVBoxLayout* layout = new QVBoxLayout(dialog);
    layout->addWidget(label);
    dialog->setLayout(layout);

    dialog->show();
}

QFuture<QImage> future = QtConcurrent::mapped(filePaths, convertToGrayscale);

QList<QImage> results = m_watcher->future().results();