webcam from gstreamer

v4l2src -> videoconvert -> glupload -> glcolorconvert -> qml6glsink

poc006/src/qt_gst_helpers.cpp

@@ -0,0 +1,95 @@
+// file: poc-qt/poc006/src/qt_gst_helpers.cpp
+
+#include "qt_gst_helpers.h"
+
+#include <QQuickItem>
+#include <QQuickWindow>
+#include <QQmlApplicationEngine>
+#include <QObject>
+#include <QRunnable>
+
+#include <gst/gst.h>
+
+class SetPlaying : public QRunnable
+{
+public:
+    explicit SetPlaying(GstElement* pipeline)
+        : pipeline_(pipeline ? GST_ELEMENT(gst_object_ref(pipeline)) : nullptr)
+    {
+    }
+
+    ~SetPlaying() override
+    {
+        if (pipeline_) {
+            gst_object_unref(pipeline_);
+            pipeline_ = nullptr;
+        }
+    }
+
+    void run() override
+    {
+        if (pipeline_) {
+            gst_element_set_state(pipeline_, GST_STATE_PLAYING);
+        }
+    }
+
+private:
+    GstElement* pipeline_;
+};
+
+QQuickItem* find_video_item(QQmlApplicationEngine& engine)
+{
+    const auto roots = engine.rootObjects();
+    if (roots.isEmpty()) {
+        return nullptr;
+    }
+
+    auto* root_window = qobject_cast<QQuickWindow*>(roots.first());
+    if (!root_window) {
+        return nullptr;
+    }
+
+    return root_window->findChild<QQuickItem*>("videoItem");
+}
+
+bool bind_sink_widget(std::uintptr_t sink_ptr, QQuickItem* item)
+{
+    if (sink_ptr == 0 || item == nullptr) {
+        return false;
+    }
+
+    auto* sink = reinterpret_cast<GstElement*>(sink_ptr);
+
+    g_object_set(sink, "widget", item, nullptr);
+
+    // Recommandé pour propager correctement le contexte GL Qt/GStreamer
+    gst_element_set_state(sink, GST_STATE_READY);
+
+    return true;
+}
+
+bool schedule_pipeline_play(QQmlApplicationEngine& engine, std::uintptr_t pipeline_ptr)
+{
+    if (pipeline_ptr == 0) {
+        return false;
+    }
+
+    const auto roots = engine.rootObjects();
+    if (roots.isEmpty()) {
+        return false;
+    }
+
+    auto* root_window = qobject_cast<QQuickWindow*>(roots.first());
+    if (!root_window) {
+        return false;
+    }
+
+    auto* pipeline = reinterpret_cast<GstElement*>(pipeline_ptr);
+
+    root_window->scheduleRenderJob(
+        new SetPlaying(pipeline),
+        QQuickWindow::BeforeSynchronizingStage
+    );
+
+    return true;
+}