Example #1
0
class Video(QWidget):
    def __init__(self):
        # init the widget
        QWidget.__init__(self)

        # set up the scene
        self.scene=QGraphicsScene()
        self.scene.setSceneRect(0,0,800,600)

        # add a view of that scene
        self.view = QGraphicsView()
        self.view.setScene(self.scene)
        self.view.setRenderHint(QPainter.Antialiasing)
        self.view.setFixedSize(800,600)
        self.view.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.view.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)

        # set the screen sync
        val = "1"
        # Set for nVidia linux
        os.environ["__GL_SYNC_TO_VBLANK"] = val
        # Set for recent linux Mesa DRI Radeon
        os.environ["LIBGL_SYNC_REFRESH"] = val

        qglf = QGLFormat()
        qglf.setSampleBuffers(True)
        #qglf.setSwapInterval(1)
        self.glw = QGLWidget(qglf)
        self.glw.setAutoBufferSwap(False)
        self.view.setViewport(self.glw)
        
        QTimer.singleShot(0,self.glw.swapBuffers)

    def swapBuffers(self):
        # first call the swap on the QGLWidget
        self.glw.swapBuffers()

        self.glw.makeCurrent()

        # The following is taken from the PsychToolbox
        # Draw a single pixel in left-top area of back-buffer. 
        # This will wait/stall the rendering pipeline
        # until the buffer flip has happened, aka immediately after the VBL has started.
        # We need the pixel as "synchronization token", so the following glFinish() really
        # waits for VBL instead of just "falling through" due to the asynchronous nature of
        # OpenGL:
        glDrawBuffer(GL_BACK)
        # We draw our single pixel with an alpha-value of zero - so effectively it doesn't
        # change the color buffer - just the z-buffer if z-writes are enabled...
        glColor4f(0.0,0.0,0.0,0.0)
        glBegin(GL_POINTS)
        glVertex2i(10,10)
        glEnd()
        # This glFinish() will wait until point drawing is finished, ergo backbuffer was ready
        # for drawing, ergo buffer swap in sync with start of VBL has happened.
        glFinish()

    def show(self):
        # shows the viewer widget
        self.view.show()
Example #2
0
class GUI():
    def __init__(self):
        # init the widget
        #QWidget.__init__(self, parent)

        # set up the scene
        self.scene = QGraphicsScene()
        self.scene.setSceneRect(0, 0, 800, 600)

        # add a view of that scene
        self.view = QGraphicsView()
        self.view.setScene(self.scene)
        self.view.setRenderHint(QPainter.Antialiasing)
        self.view.setFixedSize(800, 600)
        self.view.setHorizontalScrollBarPolicy(Qt.ScrollBarAlwaysOff)
        self.view.setVerticalScrollBarPolicy(Qt.ScrollBarAlwaysOff)

        # set the screen sync to vertical retrace
        val = "1"
        # Set for nVidia linux
        os.environ["__GL_SYNC_TO_VBLANK"] = val
        # Set for recent linux Mesa DRI Radeon
        os.environ["LIBGL_SYNC_REFRESH"] = val

        qglf = QGLFormat()
        qglf.setSampleBuffers(True)
        self.glw = QGLWidget(qglf)
        self.glw.setAutoBufferSwap(False)
        self.view.setViewport(self.glw)

        #self.view.showFullScreen()
        self.view.show()

        self.last_finish = 0

        QTimer.singleShot(0, self.glw.swapBuffers)

    def swapBuffers(self):
        # first call the swap on the QGLWidget
        start = long(now() * 1000)

        self.glw.swapBuffers()

        #self.glw.makeCurrent()

        # The following is taken from the PsychToolbox
        # Draw a single pixel in left-top area of back-buffer.
        # This will wait/stall the rendering pipeline
        # until the buffer flip has happened, aka immediately after the VBL has started.
        # We need the pixel as "synchronization token", so the following glFinish() really
        # waits for VBL instead of just "falling through" due to the asynchronous nature of
        # OpenGL:
        glDrawBuffer(GL_BACK)
        # We draw our single pixel with an alpha-value of zero - so effectively it doesn't
        # change the color buffer - just the z-buffer if z-writes are enabled...
        glColor4f(0.0, 0.0, 0.0, 0.0)
        glBegin(GL_POINTS)
        glVertex2i(10, 10)
        glEnd()
        # This glFinish() will wait until point drawing is finished, ergo backbuffer was ready
        # for drawing, ergo buffer swap in sync with start of VBL has happened.
        glFinish()

        finish = long(now() * 1000)
        fdiff = finish - self.last_finish
        self.last_finish = finish
        return (start, finish - start, fdiff)