Add first simple triable animation based on fractionals

@@ -6,3 +6,7 @@ edition = "2018"
 
 [dependencies]
 lazy_static = "1.4.0"
+libc = "0.2"
+gl = "0.5.2"
+x11 = { version = "2.3", features = ["glx"] }
+xcb = { version = "0.8", features = ["dri2", "randr", "thread", "xlib_xcb", "shm"] }

@@ -20,13 +20,19 @@
 //
 use std::cmp;
 use std::fmt::{Formatter, Display, Result};
+use std::sync::mpsc;
 
 pub trait Easel {
-    fn canvas(self) -> dyn Canvas;
+    //fn canvas(&mut self, width :u16, height :u16) -> Option<&dyn Canvas>;
 }
 
 pub trait Canvas {
-    fn draw(self, c :&dyn Drawable, ofs :Coordinate);
+    fn init_events(&self);
+    fn start_events(&self, tx :mpsc::Sender<i32>);
+
+    fn clear(&mut self);
+    fn draw(&mut self, c :&dyn Drawable, ofs :Coordinate);
+    fn show(&self);
 }
 
 pub trait Drawable {

@@ -28,6 +28,7 @@ pub mod fractional;
 pub mod transform;
 pub mod trigonometry;
 pub mod vector;
+pub mod xcb;
 
 use fractional::Fractional;
 use vector::Vector;

@@ -23,6 +23,9 @@ use std::f64::consts::PI as FPI;
 use std::fmt::Display;
 use std::num::TryFromIntError;
 use std::ops::{Add,Sub,Neg,Mul,Div};
+use std::sync::mpsc;
+use std::time;
+use std::thread;
 
 use fractional::continuous::Continuous;
 use fractional::easel::{ Coordinate, Coordinates, Drawable, Line, Polyline
@@ -32,6 +35,9 @@ use fractional::trigonometry::Trig;
 use fractional::vector::{Vector};
 use fractional::transform::{TMatrix, translate, rotate_x, rotate_y, rotate_z, rotate_v};
 
+use fractional::xcb::XcbEasel;
+use fractional::easel::Canvas;
+
 fn mean(v: &Vec<i64>) -> Result<Fractional, TryFromIntError> {
     let r = v.iter().fold(0, |acc, x| acc + x);
     let l = i64::try_from(v.len())?;
@@ -325,4 +331,54 @@ fn main() {
     _transform2();
     println!();
     _line();
+
+    let xcb = XcbEasel::new().unwrap();
+    let mut canvas = xcb.canvas(151, 151).unwrap();
+
+    canvas.set_title("Something...");
+    canvas.init_events();
+
+    let (tx, rx) = mpsc::channel();
+    let tx1 = mpsc::Sender::clone(&tx);
+    canvas.start_events(tx);
+
+    let i = Vector(Fractional(  0,1), Fractional(-35,1), Fractional(0,1));
+    let j = Vector(Fractional( 30,1), Fractional( 17,1), Fractional(0,1));
+    let k = Vector(Fractional(-30,1), Fractional( 17,1), Fractional(0,1));
+
+    fn to_i32(x :Fractional) -> i32 {
+        let Fractional(n, d) = x;
+        (n / d + if (n % d).abs() < (n / 2).abs() { 0 } else { 1 }) as i32
+    }
+
+    thread::spawn(move || {
+        loop {
+            tx1.send(0).unwrap();
+            thread::sleep(time::Duration::from_millis(10));
+        }
+    });
+
+    let mut deg :i32 = 0;
+
+    for x in rx {
+        match x {
+            1 => break,
+            _ => {
+                let rot :TMatrix<Fractional> = rotate_z(deg);
+                let Vector(ix, iy, _) = rot.apply(&i);
+                let Vector(jx, jy, _) = rot.apply(&j);
+                let Vector(kx, ky, _) = rot.apply(&k);
+
+                let pg = Polygon(
+                    Coordinates(vec!( Coordinate(to_i32(ix), to_i32(iy))
+                                    , Coordinate(to_i32(jx), to_i32(jy))
+                                    , Coordinate(to_i32(kx), to_i32(ky)) )));
+
+                canvas.clear();
+                canvas.draw(&pg, Coordinate(75,75));
+                canvas.show();
+                deg = (deg + 3) % 359;
+            },
+        }
+    }
 }

+//
+// XCB implementation for drawing some stuff...
+//
+// Georg Hopp <georg@steffers.org>
+//
+// Copyright © 2019 Georg Hopp
+//
+// 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, either version 3 of the License, or
+// (at your option) any later version.
+//
+// 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 <http://www.gnu.org/licenses/>.
+//
+extern crate xcb;
+
+use std::sync::Arc;
+use std::ptr; //::{null, null_mut};
+use std::thread;
+use std::sync::mpsc;
+
+use crate::easel::{Easel, Canvas, Drawable, Coordinate, Coordinates};
+
+#[derive(Clone)]
+pub struct XcbEasel (Arc<xcb::Connection>, i32);
+
+pub struct XcbCanvas<'a> { conn   :Arc<xcb::Connection>
+                         , width  :u16
+                         , height :u16
+                         , window :u32
+                         , pixmap :u32
+                         , gc     :u32
+                         , shm    :&'a mut [u32] }
+
+impl XcbEasel {
+    pub fn new() -> Result<XcbEasel, xcb::ConnError> {
+        let (conn, num) = xcb::Connection::connect(None)?;
+
+        Ok(XcbEasel(Arc::new(conn), num))
+    }
+
+    pub fn setup(&self) -> xcb::Setup {
+        let XcbEasel(conn, _) = self;
+        conn.get_setup()
+    }
+
+    pub fn screen(&self) -> Option<xcb::Screen> {
+        let XcbEasel(_, num) = self;
+        self.setup().roots().nth(*num as usize)
+    }
+
+    pub fn canvas(&self, width :u16, height :u16) -> Option<XcbCanvas> {
+        let Self(conn, _) = self;
+        let conn          = conn.clone();
+        let screen        = match self.screen() {
+            None         => return None,
+            Some(screen) => screen,
+        };
+
+        let shmseg = conn.generate_id();
+        let gc     = conn.generate_id();
+        let pixmap = conn.generate_id();
+        let window = conn.generate_id();
+
+        xcb::create_window( &conn, xcb::COPY_FROM_PARENT as u8, window
+                          , screen.root(), 0, 0, width, width, 0
+                          , xcb::WINDOW_CLASS_INPUT_OUTPUT as u16
+                          , screen.root_visual()
+                          , &[(xcb::CW_BACK_PIXEL, screen.white_pixel())] );
+
+        xcb::create_gc( &conn, gc, screen.root()
+                      , &[ (xcb::GC_FOREGROUND, screen.black_pixel())
+                      , (xcb::GC_GRAPHICS_EXPOSURES, 0) ] );
+
+        let (shmid, shm) = getshm((width * height) as usize);
+        xcb::shm::attach(&conn, shmseg, shmid as u32, false);
+        unsafe { libc::shmctl(shmid, libc::IPC_RMID, ptr::null_mut()); }
+
+        xcb::shm::create_pixmap( &conn, pixmap, window, width, height
+                               , screen.root_depth(), shmseg, 0 );
+
+        xcb::map_window(&conn, window);
+        conn.flush();
+
+        Some(XcbCanvas{ conn:   conn
+                      , width:  width
+                      , height: height
+                      , window: window
+                      , pixmap: pixmap
+                      , gc:     gc
+                      , shm:    shm } )
+    }
+}
+
+impl<'a> XcbCanvas<'a> {
+    pub fn set_title(&self, title :&str) {
+        let c = xcb::change_property_checked( &self.conn
+                                            , xcb::PROP_MODE_REPLACE as u8
+                                            , self.window
+                                            , xcb::ATOM_WM_NAME
+                                            , xcb::ATOM_STRING
+                                            , 8
+                                            , title.as_bytes() );
+        if self.conn.has_error().is_err() || c.request_check().is_err() {
+            println!("Error setting title");
+        }
+    }
+}
+
+fn getshm<'a>(size :usize) -> (i32, &'a mut [u32]) {
+    use std::slice::from_raw_parts_mut;
+
+    unsafe {
+        let id = libc::shmget( libc::IPC_PRIVATE
+                               , size * 4
+                               , libc::IPC_CREAT | 0o744 );
+        let ptr = libc::shmat(id, ptr::null(), 0);
+        (id as i32, from_raw_parts_mut(ptr as *mut u32, size))
+    }
+}
+
+impl Easel for XcbEasel {}
+
+impl<'a> Canvas for XcbCanvas<'a> {
+    fn init_events(&self) {
+        let mask = [( xcb::CW_EVENT_MASK, xcb::EVENT_MASK_EXPOSURE
+                                        | xcb::EVENT_MASK_KEY_PRESS
+                                        | xcb::EVENT_MASK_STRUCTURE_NOTIFY
+                                        | xcb::EVENT_MASK_PROPERTY_CHANGE )];
+        xcb::change_window_attributes(&self.conn, self.window, &mask);
+        self.conn.flush();
+    }
+
+    fn start_events(&self, tx :mpsc::Sender<i32>) {
+        let conn   = self.conn.clone();
+        let window = self.window;
+        let pixmap = self.pixmap;
+        let gc     = self.gc;
+        let width  = self.width;
+        let height = self.height;
+
+        thread::spawn(move || {
+            loop {
+                let event = conn.wait_for_event();
+
+                match event {
+                    None        => break,
+                    Some(event) => {
+                        match event.response_type() & !0x80 {
+                            xcb::PROPERTY_NOTIFY => {
+                                let prop_notify :&xcb::PropertyNotifyEvent
+                                    = unsafe { xcb::cast_event(&event) };
+
+                                if prop_notify.atom() == xcb::ATOM_WM_NAME {
+                                    // retrieving title
+                                    let cookie
+                                        = xcb::get_property( &conn
+                                                           , false
+                                                           , window
+                                                           , xcb::ATOM_WM_NAME
+                                                           , xcb::ATOM_STRING
+                                                           , 0, 1024 );
+
+                                    if let Ok(reply) = cookie.get_reply() {
+                                        let r = reply.value();
+                                        let r = std::str::from_utf8(r).unwrap();
+
+                                        println!("title changed to: {}", r);
+                                    }
+                                }
+                            },
+
+                            xcb::EXPOSE => {
+                                xcb::copy_area( &conn, pixmap, window, gc
+                                                , 0, 0, 0, 0
+                                                , width, height );
+                                conn.flush();
+                            },
+
+                            xcb::KEY_PRESS => {
+                                let key_press: &xcb::KeyPressEvent
+                                    = unsafe { xcb::cast_event(&event) };
+
+                                println!( "Key '{}' pressed"
+                                          , key_press.detail() );
+
+                                // Q (on qwerty)
+                                if key_press.detail() == 0x18 {
+                                    tx.send(1).unwrap();
+                                    break;
+                                }
+                            },
+
+                            _ => {},
+                        }
+                    },
+                }
+            }
+        });
+    }
+
+    fn clear(&mut self) {
+        unsafe {
+            let ptr = self.shm.as_mut_ptr();
+            ptr::write_bytes( ptr, 0
+                            , self.width as usize * self.height as usize);
+        }
+    }
+
+    fn draw(&mut self, d :&dyn Drawable, ofs :Coordinate) {
+        let Coordinates(c)         = d.plot();
+        let Coordinate(xofs, yofs) = ofs;
+
+        for Coordinate(x, y) in c {
+            let idx :usize = ((y+yofs)*(self.width as i32)+x+xofs) as usize;
+            self.shm[idx] = 0xFFFFFF;
+        }
+    }
+
+    fn show(&self) {
+        xcb::copy_area( &self.conn, self.pixmap, self.window, self.gc
+                        , 0, 0, 0, 0
+                        , self.width, self.height );
+        self.conn.flush();
+    }
+}