pica-client: VAAPI on X11, two codepaths

1 files changed, 97 insertions, 0 deletions

diff --git a/pica-client/vaapix11widget.h b/pica-client/vaapix11widget.h
new file mode 100644
index 0000000..53b6135
--- /dev/null
+++ b/pica-client/vaapix11widget.h
@@ -0,0 +1,97 @@
+/*
+	(c) Copyright  2012 - 2026 Anton Sviridenko
+	https://picapica.im
+
+	This program is free software: you can redistribute it and/or modify
+	it under the terms of the GNU General Public License as published by
+	the Free Software Foundation, version 3.
+
+	This program is distributed in the hope that it will be useful,
+	but WITHOUT ANY WARRANTY; without even the implied warranty of
+	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+	GNU General Public License for more details.
+
+	You should have received a copy of the GNU General Public License
+	along with this program.  If not, see <https://www.gnu.org/licenses/>.
+*/
+#ifndef VAAPIX11WIDGET_H
+#define VAAPIX11WIDGET_H
+
+#ifdef HAVE_VAAPI_X11
+
+#include "vaapi.h"
+
+#include <QWidget>
+#include <QString>
+
+// Draws decoded frames by handing the surface to the driver with the widget's
+// own X window as the target - vaPutSurface() - rather than going through
+// OpenGL at all. The picture never leaves the GPU; the driver does the colour
+// conversion and the scaling.
+//
+// This is the path for an X11 session, where Qt's OpenGL contexts come from
+// GLX and cannot import the DMA-BUF handles a surface is exported as. Since it
+// touches no OpenGL, it does not care which of the two Qt picked.
+//
+// The cost of drawing outside Qt is that Qt must be kept away from this
+// widget's area: it is given a native window of its own, Qt is told not to
+// paint or clear it (WA_PaintOnScreen, WA_NoSystemBackground, a null paint
+// engine), and anything drawn over it - a menu, a tooltip - will fight with
+// the video underneath.
+class VaapiX11Widget : public QWidget, public VaapiRenderWidget
+{
+	Q_OBJECT
+public:
+	explicit VaapiX11Widget(QWidget *parent = nullptr);
+	~VaapiX11Widget() override;
+
+	virtual QWidget *widget() override { return this; }
+	virtual bool isWorking() const override { return m_working; }
+
+public slots:
+	virtual void setFrame(AVFramePtr frame) override;
+	virtual void clearFrame() override;
+
+signals:
+	// Raised once if a frame cannot be put on screen, carrying the reason.
+	// The widget stops trying after that.
+	void renderingFailed(QString message);
+
+protected:
+	// Nothing about this widget is painted by Qt, so it has no paint engine to
+	// offer. Returning one would have Qt draw over the video.
+	QPaintEngine *paintEngine() const override { return nullptr; }
+
+	void paintEvent(QPaintEvent *event) override;
+	void resizeEvent(QResizeEvent *event) override;
+	void showEvent(QShowEvent *event) override;
+
+private:
+	// Puts the current frame on the window, letterboxed to keep its aspect
+	// ratio. Returns false if the driver would not draw it.
+	bool putFrame();
+
+	// Paints the whole window black, so that the bars beside a letterboxed
+	// picture are not left holding whatever was there before.
+	void clearWindow();
+
+	void reportFailure(const QString &message);
+
+	AVFramePtr m_frame;
+	bool m_working;
+	bool m_reportedFailure;
+	bool m_describedSurface;
+	bool m_everDrew;
+
+	// Putting a surface on a window can fail for reasons that pass - the
+	// window not being mapped yet at the moment the first frame arrives, most
+	// obviously - so unlike an EGL import, which either works or never will,
+	// this one is worth retrying. Only a long run of failures means the path
+	// is really unusable.
+	int m_failuresInARow;
+	static const int kMaxFailuresInARow = 30;
+};
+
+#endif // HAVE_VAAPI_X11
+
+#endif // VAAPIX11WIDGET_H