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#[macro_use]
extern crate glium;
use std::thread;
#[allow(unused_imports)]
use glium::{glutin, Surface};
use glium::index::PrimitiveType;
mod screenshot {
use glium::Surface;
use std::collections::VecDeque;
use std::vec::Vec;
use std::borrow::Cow;
// Container that holds image data as vector of (u8, u8, u8, u8).
// This is used to take data from PixelBuffer and move it to another thread
// with minimum conversions done on main thread.
pub struct RGBAImageData {
pub data: Vec<(u8, u8, u8, u8)>,
pub width: u32,
pub height: u32,
}
impl glium::texture::Texture2dDataSink<(u8, u8, u8, u8)> for RGBAImageData {
fn from_raw(data: Cow<'_, [(u8, u8, u8, u8)]>, width: u32, height: u32) -> Self {
RGBAImageData {
data: data.into_owned(),
width,
height,
}
}
}
struct AsyncScreenshotTask {
pub target_frame: u64,
pub pixel_buffer: glium::texture::pixel_buffer::PixelBuffer<(u8, u8, u8, u8)>,
}
impl AsyncScreenshotTask {
fn new(facade: &dyn glium::backend::Facade, target_frame: u64) -> Self {
// Get information about current framebuffer
let dimensions = facade.get_context().get_framebuffer_dimensions();
let rect = glium::Rect {
left: 0,
bottom: 0,
width: dimensions.0,
height: dimensions.1,
};
let blit_target = glium::BlitTarget {
left: 0,
bottom: 0,
width: dimensions.0 as i32,
height: dimensions.1 as i32,
};
// Create temporary texture and blit the front buffer to it
let texture = glium::texture::Texture2d::empty(facade, dimensions.0, dimensions.1)
.unwrap();
let framebuffer = glium::framebuffer::SimpleFrameBuffer::new(facade, &texture).unwrap();
framebuffer.blit_from_frame(&rect,
&blit_target,
glium::uniforms::MagnifySamplerFilter::Nearest);
// Read the texture into new pixel buffer
let pixel_buffer = texture.read_to_pixel_buffer();
AsyncScreenshotTask {
target_frame,
pixel_buffer,
}
}
fn read_image_data(self) -> RGBAImageData {
self.pixel_buffer.read_as_texture_2d().unwrap()
}
}
pub struct ScreenshotIterator<'a>(&'a mut AsyncScreenshotTaker);
impl<'a> Iterator for ScreenshotIterator<'a> {
type Item = RGBAImageData;
fn next(&mut self) -> Option<RGBAImageData> {
if self.0.screenshot_tasks.front().map(|task| task.target_frame) == Some(self.0.frame) {
let task = self.0.screenshot_tasks.pop_front().unwrap();
Some(task.read_image_data())
} else {
None
}
}
}
pub struct AsyncScreenshotTaker {
screenshot_delay: u64,
frame: u64,
screenshot_tasks: VecDeque<AsyncScreenshotTask>,
}
impl AsyncScreenshotTaker {
pub fn new(screenshot_delay: u64) -> Self {
AsyncScreenshotTaker {
screenshot_delay,
frame: 0,
screenshot_tasks: VecDeque::new(),
}
}
pub fn next_frame(&mut self) {
self.frame += 1;
}
pub fn pickup_screenshots(&mut self) -> ScreenshotIterator<'_> {
ScreenshotIterator(self)
}
pub fn take_screenshot(&mut self, facade: &dyn glium::backend::Facade) {
self.screenshot_tasks
.push_back(AsyncScreenshotTask::new(facade, self.frame + self.screenshot_delay));
}
}
}
fn main() {
// building the display, ie. the main object
let event_loop = glutin::event_loop::EventLoop::new();
let wb = glutin::window::WindowBuilder::new().with_title("Press S to take screenshot");
let cb = glutin::ContextBuilder::new();
let display = glium::Display::new(wb, cb, &event_loop).unwrap();
// building the vertex buffer, which contains all the vertices that we will draw
let vertex_buffer = {
#[derive(Copy, Clone)]
struct Vertex {
position: [f32; 2],
color: [f32; 3],
}
implement_vertex!(Vertex, position, color);
glium::VertexBuffer::new(&display,
&[Vertex {
position: [-0.5, -0.5],
color: [0.0, 1.0, 0.0],
},
Vertex {
position: [0.0, 0.5],
color: [0.0, 0.0, 1.0],
},
Vertex {
position: [0.5, -0.5],
color: [1.0, 0.0, 0.0],
}])
.unwrap()
};
// building the index buffer
let index_buffer =
glium::IndexBuffer::new(&display, PrimitiveType::TrianglesList, &[0u16, 1, 2]).unwrap();
// compiling shaders and linking them together
let program = program!(&display,
140 => {
vertex: "
#version 140
uniform mat4 matrix;
in vec2 position;
in vec3 color;
out vec3 vColor;
void main() {
gl_Position = vec4(position, 0.0, 1.0) * matrix;
vColor = color;
}
",
fragment: "
#version 140
in vec3 vColor;
out vec4 f_color;
void main() {
f_color = vec4(vColor, 1.0);
}
"
},
110 => {
vertex: "
#version 110
uniform mat4 matrix;
attribute vec2 position;
attribute vec3 color;
varying vec3 vColor;
void main() {
gl_Position = vec4(position, 0.0, 1.0) * matrix;
vColor = color;
}
",
fragment: "
#version 110
varying vec3 vColor;
void main() {
gl_FragColor = vec4(vColor, 1.0);
}
",
},
)
.unwrap();
// drawing once
// building the uniforms
let uniforms = uniform! {
matrix: [
[1.0, 0.0, 0.0, 0.0],
[0.0, 1.0, 0.0, 0.0],
[0.0, 0.0, 1.0, 0.0],
[0.0, 0.0, 0.0, 1.0f32]
]
};
// The parameter sets the amount of frames between requesting the image
// transfer and picking it up. If the value is too small, the main thread
// will block waiting for the image to finish transferring. Tune it based on
// your requirements.
let mut screenshot_taker = screenshot::AsyncScreenshotTaker::new(5);
event_loop.run(move |event, _, control_flow| {
// React to events
use glium::glutin::event::{Event, WindowEvent, ElementState, VirtualKeyCode};
let mut take_screenshot = false;
let next_frame_time = std::time::Instant::now() +
std::time::Duration::from_nanos(16_666_667);
*control_flow = glutin::event_loop::ControlFlow::WaitUntil(next_frame_time);
match event {
Event::WindowEvent { event, .. } => match event {
WindowEvent::CloseRequested => {
*control_flow = glutin::event_loop::ControlFlow::Exit;
return;
},
WindowEvent::KeyboardInput { input, .. } => {
if let ElementState::Pressed = input.state {
if let Some(VirtualKeyCode::S) = input.virtual_keycode {
take_screenshot = true;
}
}
},
_ => return,
},
Event::NewEvents(cause) => match cause {
glutin::event::StartCause::ResumeTimeReached { .. } => (),
glutin::event::StartCause::Init => (),
_ => return,
},
_ => return,
}
// Tell Screenshot Taker to count next frame
screenshot_taker.next_frame();
// drawing a frame
let mut target = display.draw();
target.clear_color(0.0, 0.0, 0.0, 0.0);
target.draw(&vertex_buffer,
&index_buffer,
&program,
&uniforms,
&Default::default())
.unwrap();
target.finish().unwrap();
if take_screenshot {
// Take screenshot and queue it's delivery
screenshot_taker.take_screenshot(&display);
}
// Pick up screenshots that are ready this frame
for image_data in screenshot_taker.pickup_screenshots() {
// Process and write the image in separate thread to not block the rendering thread.
thread::spawn(move || {
// Convert (u8, u8, u8, u8) given by glium's PixelBuffer to flat u8 required by
// image's ImageBuffer.
let pixels = {
let mut v = Vec::with_capacity(image_data.data.len() * 4);
for (a, b, c, d) in image_data.data {
v.push(a);
v.push(b);
v.push(c);
v.push(d);
}
v
};
// Create ImageBuffer
let image_buffer =
image::ImageBuffer::from_raw(image_data.width, image_data.height, pixels)
.unwrap();
// Save the screenshot to file
let image = image::DynamicImage::ImageRgba8(image_buffer).flipv();
image.save("glium-example-screenshot.png").unwrap();
});
}
});
}