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https://gitlab.freedesktop.org/gstreamer/gstreamer-rs.git
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examples: Make use of glib::closure! for the overlay-composition example
This commit is contained in:
Sebastian Dröge
Sebastian Dröge
parent
eecce101da
commit
1ebfaee644
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@ -116,7 +116,6 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
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info: None,
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}));
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let drawer_clone = drawer.clone();
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// Connect to the overlaycomposition element's "draw" signal, which is emitted for
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// each videoframe piped through the element. The signal handler needs to
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// return a gst_video::VideoOverlayComposition to be drawn on the frame
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@ -128,126 +127,124 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
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//
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// In this case, the signal passes the gst::Element and a gst::Sample with
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// the current buffer
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overlay.connect("draw", false, move |args| {
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use std::f64::consts::PI;
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overlay.connect_closure(
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"draw",
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false,
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glib::closure!(@strong drawer => move |_overlay: &gst::Element,
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sample: &gst::Sample| {
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use std::f64::consts::PI;
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let drawer = &drawer_clone;
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let drawer = drawer.lock().unwrap();
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let drawer = drawer.lock().unwrap();
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// Get the signal's arguments
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let _overlay = args[0].get::<gst::Element>().unwrap();
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let sample = args[1].get::<gst::Sample>().unwrap();
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let buffer = sample.buffer().unwrap();
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let timestamp = buffer.pts().unwrap();
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let buffer = sample.buffer().unwrap();
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let timestamp = buffer.pts().unwrap();
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let info = drawer.info.as_ref().unwrap();
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let layout = drawer.layout.borrow();
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let info = drawer.info.as_ref().unwrap();
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let layout = drawer.layout.borrow();
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let angle = 2.0 * PI * (timestamp % (10 * gst::ClockTime::SECOND)).nseconds() as f64
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/ (10.0 * gst::ClockTime::SECOND.nseconds() as f64);
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let angle = 2.0 * PI * (timestamp % (10 * gst::ClockTime::SECOND)).nseconds() as f64
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/ (10.0 * gst::ClockTime::SECOND.nseconds() as f64);
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/* Create a Cairo image surface to draw into and the context around it. */
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let surface = cairo::ImageSurface::create(
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cairo::Format::ARgb32,
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info.width() as i32,
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info.height() as i32,
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)
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.unwrap();
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let cr = cairo::Context::new(&surface).expect("Failed to create cairo context");
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/* Create a Cairo image surface to draw into and the context around it. */
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let surface = cairo::ImageSurface::create(
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cairo::Format::ARgb32,
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info.width() as i32,
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info.height() as i32,
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)
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.unwrap();
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let cr = cairo::Context::new(&surface).expect("Failed to create cairo context");
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cr.save().expect("Failed to save state");
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cr.set_operator(cairo::Operator::Clear);
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cr.paint().expect("Failed to clear background");
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cr.restore().expect("Failed to restore state");
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// The image we draw (the text) will be static, but we will change the
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// transformation on the drawing context, which rotates and shifts everything
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// that we draw afterwards. Like this, we have no complicated calulations
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// in the actual drawing below.
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// Calling multiple transformation methods after each other will apply the
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// new transformation on top. If you repeat the cr.rotate(angle) line below
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// this a second time, everything in the canvas will rotate twice as fast.
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cr.translate(
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f64::from(info.width()) / 2.0,
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f64::from(info.height()) / 2.0,
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);
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cr.rotate(angle);
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// This loop will render 10 times the string "GStreamer" in a circle
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for i in 0..10 {
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// Cairo, like most rendering frameworks, is using a stack for transformations
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// with this, we push our current transformation onto this stack - allowing us
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// to make temporary changes / render something / and then returning to the
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// previous transformations.
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cr.save().expect("Failed to save state");
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let angle = (360. * f64::from(i)) / 10.0;
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let red = (1.0 + f64::cos((angle - 60.0) * PI / 180.0)) / 2.0;
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cr.set_source_rgb(red, 0.0, 1.0 - red);
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cr.rotate(angle * PI / 180.0);
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// Update the text layout. This function is only updating pango's internal state.
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// So e.g. that after a 90 degree rotation it knows that what was previously going
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// to end up as a 200x100 rectangle would now be 100x200.
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pangocairo::functions::update_layout(&cr, &**layout);
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let (width, _height) = layout.size();
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// Using width and height of the text, we can properly possition it within
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// our canvas.
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cr.move_to(
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-(f64::from(width) / f64::from(pango::SCALE)) / 2.0,
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-(f64::from(info.height())) / 2.0,
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);
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// After telling the layout object where to draw itself, we actually tell
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// it to draw itself into our cairo context.
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pangocairo::functions::show_layout(&cr, &**layout);
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// Here we go one step up in our stack of transformations, removing any
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// changes we did to them since the last call to cr.save();
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cr.set_operator(cairo::Operator::Clear);
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cr.paint().expect("Failed to clear background");
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cr.restore().expect("Failed to restore state");
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}
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/* Drop the Cairo context to release the additional reference to the data and
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* then take ownership of the data. This only works if we have the one and only
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* reference to the image surface */
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drop(cr);
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let stride = surface.stride();
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let data = surface.take_data().unwrap();
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// The image we draw (the text) will be static, but we will change the
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// transformation on the drawing context, which rotates and shifts everything
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// that we draw afterwards. Like this, we have no complicated calulations
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// in the actual drawing below.
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// Calling multiple transformation methods after each other will apply the
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// new transformation on top. If you repeat the cr.rotate(angle) line below
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// this a second time, everything in the canvas will rotate twice as fast.
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cr.translate(
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f64::from(info.width()) / 2.0,
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f64::from(info.height()) / 2.0,
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);
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cr.rotate(angle);
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/* Create an RGBA buffer, and add a video meta that the videooverlaycomposition expects */
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let mut buffer = gst::Buffer::from_mut_slice(data);
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// This loop will render 10 times the string "GStreamer" in a circle
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for i in 0..10 {
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// Cairo, like most rendering frameworks, is using a stack for transformations
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// with this, we push our current transformation onto this stack - allowing us
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// to make temporary changes / render something / and then returning to the
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// previous transformations.
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cr.save().expect("Failed to save state");
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gst_video::VideoMeta::add_full(
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buffer.get_mut().unwrap(),
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gst_video::VideoFrameFlags::empty(),
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gst_video::VideoFormat::Bgra,
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info.width(),
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info.height(),
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&[0],
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&[stride],
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)
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.unwrap();
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let angle = (360. * f64::from(i)) / 10.0;
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let red = (1.0 + f64::cos((angle - 60.0) * PI / 180.0)) / 2.0;
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cr.set_source_rgb(red, 0.0, 1.0 - red);
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cr.rotate(angle * PI / 180.0);
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/* Turn the buffer into a VideoOverlayRectangle, then place
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* that into a VideoOverlayComposition and return it.
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*
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* A VideoOverlayComposition can take a Vec of such rectangles
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* spaced around the video frame, but we're just outputting 1
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* here */
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let rect = gst_video::VideoOverlayRectangle::new_raw(
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&buffer,
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0,
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0,
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info.width(),
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info.height(),
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gst_video::VideoOverlayFormatFlags::PREMULTIPLIED_ALPHA,
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);
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// Update the text layout. This function is only updating pango's internal state.
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// So e.g. that after a 90 degree rotation it knows that what was previously going
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// to end up as a 200x100 rectangle would now be 100x200.
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pangocairo::functions::update_layout(&cr, &**layout);
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let (width, _height) = layout.size();
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// Using width and height of the text, we can properly possition it within
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// our canvas.
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cr.move_to(
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-(f64::from(width) / f64::from(pango::SCALE)) / 2.0,
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-(f64::from(info.height())) / 2.0,
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);
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// After telling the layout object where to draw itself, we actually tell
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// it to draw itself into our cairo context.
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pangocairo::functions::show_layout(&cr, &**layout);
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// Here we go one step up in our stack of transformations, removing any
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// changes we did to them since the last call to cr.save();
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cr.restore().expect("Failed to restore state");
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}
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/* Drop the Cairo context to release the additional reference to the data and
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* then take ownership of the data. This only works if we have the one and only
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* reference to the image surface */
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drop(cr);
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let stride = surface.stride();
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let data = surface.take_data().unwrap();
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/* Create an RGBA buffer, and add a video meta that the videooverlaycomposition expects */
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let mut buffer = gst::Buffer::from_mut_slice(data);
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gst_video::VideoMeta::add_full(
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buffer.get_mut().unwrap(),
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gst_video::VideoFrameFlags::empty(),
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gst_video::VideoFormat::Bgra,
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info.width(),
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info.height(),
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&[0],
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&[stride],
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)
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.unwrap();
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/* Turn the buffer into a VideoOverlayRectangle, then place
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* that into a VideoOverlayComposition and return it.
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*
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* A VideoOverlayComposition can take a Vec of such rectangles
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* spaced around the video frame, but we're just outputting 1
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* here */
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let rect = gst_video::VideoOverlayRectangle::new_raw(
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&buffer,
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0,
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0,
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info.width(),
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info.height(),
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gst_video::VideoOverlayFormatFlags::PREMULTIPLIED_ALPHA,
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);
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Some(
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gst_video::VideoOverlayComposition::new(Some(&rect))
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.unwrap()
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.to_value(),
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)
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});
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}),
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);
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// Add a signal handler to the overlay's "caps-changed" signal. This could e.g.
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// be called when the sink that we render to does not support resizing the image
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@ -256,15 +253,17 @@ fn create_pipeline() -> Result<gst::Pipeline, Error> {
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// resize our canvas's size.
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// Another possibility for when this might happen is, when our video is a network
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// stream that dynamically changes resolution when enough bandwith is available.
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overlay.connect("caps-changed", false, move |args| {
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let _overlay = args[0].get::<gst::Element>().unwrap();
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let caps = args[1].get::<gst::Caps>().unwrap();
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let mut drawer = drawer.lock().unwrap();
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drawer.info = Some(gst_video::VideoInfo::from_caps(&caps).unwrap());
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None
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});
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overlay.connect_closure(
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"caps-changed",
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false,
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glib::closure!(move |_overlay: &gst::Element,
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caps: &gst::Caps,
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_width: u32,
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_height: u32| {
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let mut drawer = drawer.lock().unwrap();
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drawer.info = Some(gst_video::VideoInfo::from_caps(caps).unwrap());
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}),
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);
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Ok(pipeline)
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}
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