Use XInput2 for event handling

This provides smooth scrolling for touchpad devices and will
enable support for touch events etc. in future.

1 files changed, 337 insertions, 0 deletions

diff --git a/src/api/x11/input.rs b/src/api/x11/input.rs
new file mode 100644
index 0000000..6b6d24d
--- /dev/null
+++ b/src/api/x11/input.rs
@@ -0,0 +1,337 @@
+use std::sync::Arc;
+
+use libc;
+use std::{mem, ptr};
+use std::ffi::CString;
+use std::slice::from_raw_parts;
+
+use events::Event;
+
+use super::{events, ffi};
+use super::XConnection;
+
+#[derive(Debug)]
+enum AxisType {
+    HorizontalScroll,
+    VerticalScroll,
+    Other
+}
+
+#[derive(Debug)]
+struct Axis {
+    id: i32,
+    device_id: i32,
+    axis_number: i32,
+    axis_type: AxisType
+}
+
+#[derive(Debug)]
+struct AxisValue {
+    device_id: i32,
+    axis_number: i32,
+    value: f64
+}
+
+struct InputState {
+    cursor_pos: (f64, f64),
+    axis_values: Vec<AxisValue>
+}
+
+pub struct XInputEventHandler {
+    display: Arc<XConnection>,
+    window: ffi::Window,
+    ic: ffi::XIC,
+    axis_list: Vec<Axis>,
+    current_state: InputState
+}
+
+impl XInputEventHandler {
+    pub fn new(display: &Arc<XConnection>, window: ffi::Window, ic: ffi::XIC) -> XInputEventHandler {
+        // query XInput support
+        let mut opcode: libc::c_int = 0;
+        let mut event: libc::c_int = 0;
+        let mut error: libc::c_int = 0;
+        let xinput_str = CString::new("XInputExtension").unwrap();
+
+        unsafe {
+            if (display.xlib.XQueryExtension)(display.display, xinput_str.as_ptr(), &mut opcode, &mut event, &mut error) == ffi::False {
+                panic!("XInput not available")
+            }
+        }
+
+        let mut xinput_major_ver = ffi::XI_2_Major;
+        let mut xinput_minor_ver = ffi::XI_2_Minor;
+
+        unsafe {
+            if (display.xinput2.XIQueryVersion)(display.display, &mut xinput_major_ver, &mut xinput_minor_ver) != ffi::Success as libc::c_int {
+                panic!("Unable to determine XInput version");
+            }
+        }
+
+        // specify the XInput events we want to receive
+        let mut mask: [libc::c_uchar; 1] = [0];
+        let mut input_event_mask = ffi::XIEventMask {
+            deviceid: ffi::XIAllDevices,
+            mask_len: mask.len() as i32,
+            mask: mask.as_mut_ptr()
+        };
+        let events = &[
+            ffi::XI_ButtonPress,
+            ffi::XI_ButtonRelease,
+            ffi::XI_Motion
+        ];
+        for event in events {
+            ffi::XISetMask(&mut mask, *event);
+        }
+
+        unsafe {
+            match (display.xinput2.XISelectEvents)(display.display, window, &mut input_event_mask, 1) {
+                status if status as u8 == ffi::Success => (),
+                err => panic!("Failed to select events {:?}", err)
+            }
+        }
+
+        XInputEventHandler {
+            display: display.clone(),
+            window: window,
+            ic: ic,
+            axis_list: read_input_axis_info(display),
+            current_state: InputState {
+                cursor_pos: (0.0, 0.0),
+                axis_values: Vec::new()
+            }
+        }
+    }
+
+    pub fn translate_key_event(&self, event: &mut ffi::XKeyEvent) -> Vec<Event> {
+        use events::Event::{KeyboardInput, ReceivedCharacter};
+        use events::ElementState::{Pressed, Released};
+
+        let mut translated_events = Vec::new();
+
+        let state;
+        if event.type_ == ffi::KeyPress {
+            let raw_ev: *mut ffi::XKeyEvent = event;
+            unsafe { (self.display.xlib.XFilterEvent)(mem::transmute(raw_ev), self.window) };
+            state = Pressed;
+        } else {
+            state = Released;
+        }
+
+        let mut kp_keysym = 0;
+
+        let written = unsafe {
+            use std::str;
+
+            let mut buffer: [u8; 16] = [mem::uninitialized(); 16];
+            let raw_ev: *mut ffi::XKeyEvent = event;
+            let count = (self.display.xlib.Xutf8LookupString)(self.ic, mem::transmute(raw_ev),
+            mem::transmute(buffer.as_mut_ptr()),
+            buffer.len() as libc::c_int, &mut kp_keysym, ptr::null_mut());
+
+            str::from_utf8(&buffer[..count as usize]).unwrap_or("").to_string()
+        };
+
+        {
+            for chr in written.chars() {
+                translated_events.push(ReceivedCharacter(chr));
+            }
+        }
+
+        let mut keysym = unsafe {
+            (self.display.xlib.XKeycodeToKeysym)(self.display.display, event.keycode as ffi::KeyCode, 0)
+        };
+
+        if (ffi::XK_KP_Space as libc::c_ulong <= keysym) && (keysym <= ffi::XK_KP_9 as libc::c_ulong) {
+            keysym = kp_keysym
+        };
+
+        let vkey = events::keycode_to_element(keysym as libc::c_uint);
+
+        translated_events.push(KeyboardInput(state, event.keycode as u8, vkey));
+        translated_events
+    }
+
+    pub fn translate_event(&mut self, cookie: &ffi::XGenericEventCookie) -> Option<Event> {
+        use events::Event::{MouseInput, MouseMoved, MouseWheel};
+        use events::ElementState::{Pressed, Released};
+        use events::MouseButton::{Left, Right, Middle};
+        use events::MouseScrollDelta::{PixelDelta, LineDelta};
+
+        match cookie.evtype {
+            ffi::XI_KeyPress | ffi::XI_KeyRelease => {
+                let event_data: &ffi::XIDeviceEvent = unsafe{mem::transmute(cookie.data)};
+                if cookie.evtype == ffi::XI_KeyPress {
+                    if event_data.flags & ffi::XIKeyRepeat == 0 {
+                        println!("XInput Key {} pressed", event_data.detail);
+                        None
+                    } else {
+                        None
+                    }
+                } else {
+                    None
+                }
+            },
+            ffi::XI_ButtonPress | ffi::XI_ButtonRelease => {
+                let event_data: &ffi::XIDeviceEvent = unsafe{mem::transmute(cookie.data)};
+                let state = if cookie.evtype == ffi::XI_ButtonPress {
+                    Pressed
+                } else {
+                    Released
+                };
+                match event_data.detail as u32 {
+                    ffi::Button1 => Some(MouseInput(state, Left)),
+                    ffi::Button2 => Some(MouseInput(state, Middle)),
+                    ffi::Button3 => Some(MouseInput(state, Right)),
+                    ffi::Button4 => {
+                        if event_data.flags & ffi::XIPointerEmulated == 0 {
+                            Some(MouseWheel(LineDelta(0.0, 1.0)))
+                        } else {
+                            // emulated button event from a touch/smooth-scroll
+                            // event. Scrolling is instead reported via the
+                            // XI_Motion event handler
+                            None
+                        }
+                    },
+                    ffi::Button5 => {
+                        if event_data.flags & ffi::XIPointerEmulated == 0 {
+                            Some(MouseWheel(LineDelta(0.0, -1.0)))
+                        } else {
+                            None
+                        }
+                    },
+                    _ => None
+                }
+            },
+            ffi::XI_Motion => {
+                let event_data: &ffi::XIDeviceEvent = unsafe{mem::transmute(cookie.data)};
+                let axis_state = event_data.valuators;
+                let mask = unsafe{ from_raw_parts(axis_state.mask, axis_state.mask_len as usize) };
+                let mut axis_count = 0;
+
+                let mut scroll_delta = (0.0, 0.0);
+                for axis_id in 0..axis_state.mask_len {
+                    if ffi::XIMaskIsSet(&mask, axis_id) {
+                        let axis_value = unsafe{*axis_state.values.offset(axis_count)};
+                        let delta = calc_scroll_deltas(event_data, axis_id, axis_value, &self.axis_list, 
+                                                       &mut self.current_state.axis_values);
+                        scroll_delta.0 += delta.0;
+                        scroll_delta.1 += delta.1;
+                        axis_count += 1;
+                    }
+                }
+
+                if scroll_delta.0.abs() > 0.0 || scroll_delta.1.abs() > 0.0 {
+                    Some(MouseWheel(PixelDelta(scroll_delta.0 as f32, scroll_delta.1 as f32)))
+                } else {
+                    let new_cursor_pos = (event_data.event_x, event_data.event_y);
+                    if new_cursor_pos != self.current_state.cursor_pos {
+                        self.current_state.cursor_pos = new_cursor_pos;
+                        Some(MouseMoved((new_cursor_pos.0 as i32, new_cursor_pos.1 as i32)))
+                    } else {
+                        None
+                    }
+                }
+            },
+            _ => None
+        }
+    }
+}
+
+fn read_input_axis_info(display: &Arc<XConnection>) -> Vec<Axis> {
+    let mut axis_list = Vec::new();
+    let mut device_count = 0;
+
+    // only get events from the master devices which are 'attached'
+    // to the keyboard or cursor
+    let devices = unsafe{
+        (display.xinput2.XIQueryDevice)(display.display, ffi::XIAllMasterDevices, &mut device_count)
+    };
+    for i in 0..device_count {
+        let device = unsafe { *(devices.offset(i as isize)) };
+        for k in 0..device.num_classes {
+            let class = unsafe { *(device.classes.offset(k as isize)) };
+            match unsafe { (*class)._type } {
+                ffi::XIScrollClass => {
+                    let scroll_class: &ffi::XIScrollClassInfo = unsafe{mem::transmute(class)};
+                    axis_list.push(Axis{
+                        id: scroll_class.sourceid,
+                        device_id: device.deviceid,
+                        axis_number: scroll_class.number,
+                        axis_type: match scroll_class.scroll_type {
+                            ffi::XIScrollTypeHorizontal => AxisType::HorizontalScroll,
+                            ffi::XIScrollTypeVertical => AxisType::VerticalScroll,
+                            _ => { unreachable!() }
+                        }
+                    })
+                },
+                ffi::XIValuatorClass => {
+                    let valuator_class: &ffi::XIValuatorClassInfo = unsafe{mem::transmute(class)};
+                    axis_list.push(Axis{
+                        id: valuator_class.sourceid,
+                        device_id: device.deviceid,
+                        axis_number: valuator_class.number,
+                        axis_type: AxisType::Other
+                    })
+                },
+                _ => {}
+            }
+        }
+    }
+
+    axis_list.sort_by(|a, b| {
+        if a.device_id != b.device_id {
+            a.device_id.cmp(&b.device_id)
+        } else if a.id != b.id {
+            a.id.cmp(&b.id)
+        } else {
+            a.axis_number.cmp(&b.axis_number)
+        }
+    });
+    axis_list
+}
+
+/// Given an input motion event for an axis and the previous
+/// state of the axises, return the horizontal/vertical
+/// scroll deltas
+fn calc_scroll_deltas(event: &ffi::XIDeviceEvent,
+                     axis_id: i32,
+                     axis_value: f64,
+                     axis_list: &[Axis],
+                     prev_axis_values: &mut Vec<AxisValue>) -> (f64, f64) {
+    let prev_value_pos = prev_axis_values.iter().position(|prev_axis| {
+        prev_axis.device_id == event.sourceid &&
+            prev_axis.axis_number == axis_id
+    });
+    let delta = match prev_value_pos {
+        Some(idx) => axis_value - prev_axis_values[idx].value,
+        None => 0.0
+    };
+
+    let new_axis_value = AxisValue{
+        device_id: event.sourceid,
+        axis_number: axis_id,
+        value: axis_value
+    };
+
+    match prev_value_pos {
+        Some(idx) => prev_axis_values[idx] = new_axis_value,
+        None => prev_axis_values.push(new_axis_value)
+    }
+
+    let mut scroll_delta = (0.0, 0.0);
+
+    for axis in axis_list.iter() {
+        if axis.id == event.sourceid &&
+            axis.axis_number == axis_id {
+                match axis.axis_type {
+                    AxisType::HorizontalScroll => scroll_delta.0 = delta,
+                    AxisType::VerticalScroll => scroll_delta.1 = delta,
+                    _ => {}
+                }
+            }
+    }
+
+    scroll_delta
+}
+