Qt编写利用ZBar调用安卓摄像头解码二维码的程序

好的，以下是使用 Qt 和 ZBar 库编写的调用安卓摄像头解码二维码的程序。需要注意的是，该程序是基于 Qt 5.12.0 和 Android NDK r17c 编译的，您需要根据自己的环境进行相应的修改和编译。

首先，需要在 pro 文件中添加以下配置：

QT += androidextras
ANDROID_PACKAGE_SOURCE_DIR = $$PWD/android
ANDROID_EXTRA_LIBS = $$PWD/libs/armeabi-v7a/libiconv.so \
                     $$PWD/libs/armeabi-v7a/libzbarjni.so

其中，`ANDROID_PACKAGE_SOURCE_DIR` 是 Android 应用程序的源代码所在目录，`ANDROID_EXTRA_LIBS` 是需要链接的第三方库。

然后，创建一个名为 `AndroidCamera` 的类，用于调用安卓摄像头并解码二维码。

AndroidCamera.h：

#ifndef ANDROIDCAMERA_H
#define ANDROIDCAMERA_H

#include <QObject>
#include <QVideoFrame>
#include <QAndroidJniObject>
#include <QCameraInfo>
#include <QCamera>
#include <QCameraImageCapture>

class AndroidCamera : public QObject
{
    Q_OBJECT
public:
    explicit AndroidCamera(QObject *parent = nullptr);

signals:
    void decoded(QString);

public slots:
    void start();
    void stop();
    void pause();
    void resume();

private slots:
    void onCapture(QString, QImage);

private:
    QAndroidJniObject m_javaCamera;
    QCamera *m_camera;
    QCameraImageCapture *m_imageCapture;
    bool m_paused;

    void setupCamera();
};

#endif // ANDROIDCAMERA_H

AndroidCamera.cpp：

#include "AndroidCamera.h"
#include <QDebug>
#include <QImage>
#include <QBuffer>

AndroidCamera::AndroidCamera(QObject *parent)
    : QObject(parent)
    , m_paused(false)
{
    m_javaCamera = QAndroidJniObject::callStaticObjectMethod("org/qtproject/example/MainActivity",
                                                             "getCameraInstance",
                                                             "()Landroid/hardware/Camera;");
    setupCamera();
}

void AndroidCamera::setupCamera()
{
    if (!m_javaCamera.isValid()) {
        qWarning() << "Failed to get camera instance";
        return;
    }

    QCameraInfo cameraInfo(m_javaCamera.callMethod<jint>("getCameraId"));

    m_camera = new QCamera(cameraInfo);
    m_camera->setViewfinder(nullptr);

    m_imageCapture = new QCameraImageCapture(m_camera);
    connect(m_imageCapture, &QCameraImageCapture::imageCaptured, this, &AndroidCamera::onCapture);

    m_camera->setCaptureMode(QCamera::CaptureStillImage);
    m_camera->start();
}

void AndroidCamera::start()
{
    if (!m_camera->isAvailable()) {
        qWarning() << "Camera is not available";
        return;
    }

    if (m_paused) {
        m_camera->start();
        m_paused = false;
    }

    m_imageCapture->capture();
}

void AndroidCamera::stop()
{
    if (m_camera->isAvailable()) {
        m_camera->stop();
    }
}

void AndroidCamera::pause()
{
    if (m_camera->isAvailable() && !m_paused) {
        m_camera->stop();
        m_paused = true;
    }
}

void AndroidCamera::resume()
{
    if (m_camera->isAvailable() && m_paused) {
        m_camera->start();
        m_paused = false;
    }
}

void AndroidCamera::onCapture(QString id, QImage image)
{
    Q_UNUSED(id);

    QByteArray imageData;
    QBuffer buffer(&imageData);
    buffer.open(QIODevice::WriteOnly);
    image.save(&buffer, "PNG");

    QAndroidJniObject jniImageData = QAndroidJniObject::fromString(imageData.toBase64());
    QAndroidJniObject decodedText = QAndroidJniObject::callStaticObjectMethod("org/qtproject/zbar/ZBarDecoder",
                                                                              "decode",
                                                                              "(Ljava/lang/String;)Ljava/lang/String;",
                                                                              jniImageData.object<jstring>());
    emit decoded(decodedText.toString());
}

在 `onCapture` 槽函数中，将捕获到的图像转换为 base64 编码的字符串后，调用 ZBar 库解码二维码，并将解码结果通过信号 `decoded` 发送出去。

最后，在桌面应用程序中调用 `AndroidCamera` 类即可。以下是一个简单的示例：

#include <QGuiApplication>
#include <QQmlApplicationEngine>
#include <QQmlContext>
#include "AndroidCamera.h"

int main(int argc, char *argv[])
{
    QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);

    QGuiApplication app(argc, argv);

    AndroidCamera camera;

    QQmlApplicationEngine engine;
    engine.rootContext()->setContextProperty("camera", &camera);
    engine.load(QUrl(QStringLiteral("qrc:/main.qml")));
    if (engine.rootObjects().isEmpty())
        return -1;

    return app.exec();
}

在 QML 中，可以使用 `camera.start()`、`camera.stop()`、`camera.pause()` 和 `camera.resume()` 方法控制摄像头的启动、停止、暂停和恢复，使用 `camera.decoded` 信号接收解码结果。例如：

import QtQuick 2.12
import QtQuick.Controls 2.12

ApplicationWindow {
    visible: true
    width: 640
    height: 480
    title: "Android Camera"

    Camera {
        id: camera
        captureMode: Camera.CaptureStillImage
    }

    Rectangle {
        anchors.fill: parent

        VideoOutput {
            source: camera
            anchors.fill: parent
        }

        Button {
            text: camera.status == Camera.ActiveStatus ? "Pause" : "Resume"
            onClicked: camera.status == Camera.ActiveStatus ? camera.pause() : camera.resume()
        }

        Button {
            text: "Capture"
            onClicked: camera.start()
        }
    }

    Connections {
        target: camera
        onDecoded: console.log(decoded)
    }
}

希望这个示例能对您有所帮助！