gst-qt6/QQuickGstreamerItem.cpp at main · Deep-In-Sight/gst-qt6 · GitHub

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#include "QQuickGstreamerItem.h"

#include <QQmlEngine>
#include <QQuickWindow>
#include <QGuiApplication>
#include <QRunnable>
#include <QDebug>

#include <gst/gst.h>

QQuickGstreamerItem::QQuickGstreamerItem(QQuickItem *parent)
    : QQuickItem(parent)
{
    connect(this, &QQuickGstreamerItem::windowChanged, this, &QQuickGstreamerItem::onWindowChanged);
}

QQuickGstreamerItem::~QQuickGstreamerItem()
{
    teardownPipeline();
}

void QQuickGstreamerItem::setPipelineDesc(const QString &desc)
{
    if (m_pipelineDesc == desc)
        return;
    m_pipelineDesc = desc;
    m_readyWidgets.clear();
    m_needsSetup = true;

    emit pipelineDescChanged();
}

void QQuickGstreamerItem::setVideoObject(QObject *obj)
{
    if (m_videoItem == obj)
        return;

    m_videoItem = qobject_cast<QQuickItem*>(obj);
    if (m_pipeline && m_readyWidgets.contains(m_videoItem) && m_readyWidgets[m_videoItem])
        ensureSinkBound();
    else {
        m_needsSetup = true;
    }

    emit videoObjectChanged();
}

void QQuickGstreamerItem::onWindowChanged(QQuickWindow *win)
{
    connect(win, &QQuickWindow::beforeSynchronizing, this, &QQuickGstreamerItem::onBeforeSynchronizing);
}

void QQuickGstreamerItem::onBeforeSynchronizing()
{
    if (!m_needsSetup)
        return;
    teardownPipeline();
    createPipeline();
    ensureSinkBound();
    gst_element_set_state(m_pipeline, GST_STATE_PLAYING);
    m_needsSetup = false;
    m_readyWidgets[m_videoItem] = true;
}


void QQuickGstreamerItem::teardownPipeline()
{
    if (m_pipeline) {
        gst_element_set_state(m_pipeline, GST_STATE_NULL);
        gst_object_unref(m_pipeline);
        m_pipeline = nullptr;
    }
}

void QQuickGstreamerItem::ensureSinkBound()
{
    if (!m_videoItem || !m_pipeline)
        return;
    GstElement *sink = gst_bin_get_by_name(GST_BIN(m_pipeline), "sink");
    if (!sink)
        return;
    g_object_set(G_OBJECT(sink), "widget", m_videoItem.data(), nullptr);
    gst_object_unref(sink);
}

void QQuickGstreamerItem::createPipeline()
{
    if (m_pipelineDesc.isEmpty())
        return;

    GError *err = nullptr;
    m_pipeline = gst_parse_launch(m_pipelineDesc.toUtf8().constData(), &err);

    if (err) {
        qDebug() << "Failed to create pipeline: " << err->message;
        g_error_free(err);
        if (m_pipeline) {
            gst_object_unref(m_pipeline);
            m_pipeline = nullptr;
        }
    }
}