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linux: Simplify scrolling implementation (zed-industries#10497)
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This PR adjusts our scrolling implementation to delay the generation of
ScrollWheel events until we receive a complete frame.

Note that our implementation is still a bit off-spec, as we don't delay
any other kind of events. But it's been working so far on a variety of
compositors and the other events contain complete data; so I'll hold off
on that refactor for now.

Release Notes:

- N/A
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@mikayla-maki
mikayla-maki authored Apr 12, 2024
1 parent 5e4f707 commit 3289188
Showing 1 changed file with 135 additions and 66 deletions.
201 changes: 135 additions & 66 deletions crates/gpui/src/platform/linux/wayland/client.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -103,9 +103,13 @@ pub(crate) struct WaylandClientState {
click: ClickState,
repeat: KeyRepeat,
modifiers: Modifiers,
scroll_direction: f64,
axis_source: AxisSource,
mouse_location: Option<Point<Pixels>>,
continuous_scroll_delta: Option<Point<Pixels>>,
discrete_scroll_delta: Option<Point<f32>>,
vertical_modifier: f32,
horizontal_modifier: f32,
scroll_event_received: bool,
enter_token: Option<()>,
button_pressed: Option<MouseButton>,
mouse_focused_window: Option<WaylandWindowStatePtr>,
Expand Down Expand Up @@ -164,20 +168,21 @@ impl WaylandClientStatePtr {
#[derive(Clone)]
pub struct WaylandClient(Rc<RefCell<WaylandClientState>>);

const WL_SEAT_MIN_VERSION: u32 = 4;
const WL_OUTPUT_VERSION: u32 = 2;

fn wl_seat_version(version: u32) -> u32 {
if version >= wl_pointer::EVT_AXIS_VALUE120_SINCE {
wl_pointer::EVT_AXIS_VALUE120_SINCE
} else if version >= WL_SEAT_MIN_VERSION {
WL_SEAT_MIN_VERSION
} else {
// We rely on the wl_pointer.frame event
const WL_SEAT_MIN_VERSION: u32 = 5;
const WL_SEAT_MAX_VERSION: u32 = 9;

if version < WL_SEAT_MIN_VERSION {
panic!(
"wl_seat below required version: {} < {}",
version, WL_SEAT_MIN_VERSION
);
}

version.clamp(WL_SEAT_MIN_VERSION, WL_SEAT_MAX_VERSION)
}

impl WaylandClient {
Expand Down Expand Up @@ -257,9 +262,13 @@ impl WaylandClient {
function: false,
platform: false,
},
scroll_direction: -1.0,
scroll_event_received: false,
axis_source: AxisSource::Wheel,
mouse_location: None,
continuous_scroll_delta: None,
discrete_scroll_delta: None,
vertical_modifier: -1.0,
horizontal_modifier: -1.0,
button_pressed: None,
mouse_focused_window: None,
keyboard_focused_window: None,
Expand Down Expand Up @@ -887,77 +896,137 @@ impl Dispatch<wl_pointer::WlPointer, ()> for WaylandClientStatePtr {
_ => {}
}
}
wl_pointer::Event::AxisRelativeDirection {
direction: WEnum::Value(direction),
..
} => {
state.scroll_direction = match direction {
AxisRelativeDirection::Identical => -1.0,
AxisRelativeDirection::Inverted => 1.0,
_ => -1.0,
}
}

// Axis Events
wl_pointer::Event::AxisSource {
axis_source: WEnum::Value(axis_source),
} => {
state.axis_source = axis_source;
}
wl_pointer::Event::AxisValue120 {
axis: WEnum::Value(axis),
value120,
} => {
if let Some(focused_window) = state.mouse_focused_window.clone() {
let value = value120 as f64 * state.scroll_direction;

let input = PlatformInput::ScrollWheel(ScrollWheelEvent {
position: state.mouse_location.unwrap(),
delta: match axis {
wl_pointer::Axis::VerticalScroll => {
ScrollDelta::Pixels(point(px(0.0), px(value as f32)))
}
wl_pointer::Axis::HorizontalScroll => {
ScrollDelta::Pixels(point(px(value as f32), px(0.0)))
}
_ => unimplemented!(),
},
modifiers: state.modifiers,
touch_phase: TouchPhase::Moved,
});
drop(state);
focused_window.handle_input(input)
}
}
wl_pointer::Event::Axis {
time,
axis: WEnum::Value(axis),
value,
..
} => {
// We handle discrete scroll events with `AxisValue120`.
if wl_pointer.version() >= wl_pointer::EVT_AXIS_VALUE120_SINCE
&& state.axis_source == AxisSource::Wheel
{
return;
let axis_source = state.axis_source;
let axis_modifier = match axis {
wl_pointer::Axis::VerticalScroll => state.vertical_modifier,
wl_pointer::Axis::HorizontalScroll => state.horizontal_modifier,
_ => 1.0,
};
let supports_relative_direction =
wl_pointer.version() >= wl_pointer::EVT_AXIS_RELATIVE_DIRECTION_SINCE;
state.scroll_event_received = true;
let scroll_delta = state
.continuous_scroll_delta
.get_or_insert(point(px(0.0), px(0.0)));
// TODO: Make nice feeling kinetic scrolling that integrates with the platform's scroll settings
let modifier = 3.0;
match axis {
wl_pointer::Axis::VerticalScroll => {
scroll_delta.y += px(value as f32 * modifier * axis_modifier);
}
wl_pointer::Axis::HorizontalScroll => {
scroll_delta.x += px(value as f32 * modifier * axis_modifier);
}
_ => unreachable!(),
}
if let Some(focused_window) = state.mouse_focused_window.clone() {
let value = value * state.scroll_direction;
}
wl_pointer::Event::AxisDiscrete {
axis: WEnum::Value(axis),
discrete,
} => {
state.scroll_event_received = true;
let axis_modifier = match axis {
wl_pointer::Axis::VerticalScroll => state.vertical_modifier,
wl_pointer::Axis::HorizontalScroll => state.horizontal_modifier,
_ => 1.0,
};

let input = PlatformInput::ScrollWheel(ScrollWheelEvent {
position: state.mouse_location.unwrap(),
delta: match axis {
wl_pointer::Axis::VerticalScroll => {
ScrollDelta::Pixels(point(px(0.0), px(value as f32)))
}
wl_pointer::Axis::HorizontalScroll => {
ScrollDelta::Pixels(point(px(value as f32), px(0.0)))
}
_ => unimplemented!(),
},
modifiers: state.modifiers,
touch_phase: TouchPhase::Moved,
});
drop(state);
focused_window.handle_input(input)
// TODO: Make nice feeling kinetic scrolling that integrates with the platform's scroll settings
let modifier = 3.0;

let scroll_delta = state.discrete_scroll_delta.get_or_insert(point(0.0, 0.0));
match axis {
wl_pointer::Axis::VerticalScroll => {
scroll_delta.y += discrete as f32 * axis_modifier * modifier;
}
wl_pointer::Axis::HorizontalScroll => {
scroll_delta.x += discrete as f32 * axis_modifier * modifier;
}
_ => unreachable!(),
}
}
wl_pointer::Event::AxisRelativeDirection {
axis: WEnum::Value(axis),
direction: WEnum::Value(direction),
} => match (axis, direction) {
(wl_pointer::Axis::VerticalScroll, AxisRelativeDirection::Identical) => {
state.vertical_modifier = -1.0
}
(wl_pointer::Axis::VerticalScroll, AxisRelativeDirection::Inverted) => {
state.vertical_modifier = 1.0
}
(wl_pointer::Axis::HorizontalScroll, AxisRelativeDirection::Identical) => {
state.horizontal_modifier = -1.0
}
(wl_pointer::Axis::HorizontalScroll, AxisRelativeDirection::Inverted) => {
state.horizontal_modifier = 1.0
}
_ => unreachable!(),
},
wl_pointer::Event::AxisValue120 {
axis: WEnum::Value(axis),
value120,
} => {
state.scroll_event_received = true;
let axis_modifier = match axis {
wl_pointer::Axis::VerticalScroll => state.vertical_modifier,
wl_pointer::Axis::HorizontalScroll => state.horizontal_modifier,
_ => unreachable!(),
};

let scroll_delta = state.discrete_scroll_delta.get_or_insert(point(0.0, 0.0));
let wheel_percent = value120 as f32 / 120.0;
match axis {
wl_pointer::Axis::VerticalScroll => {
scroll_delta.y += wheel_percent * axis_modifier;
}
wl_pointer::Axis::HorizontalScroll => {
scroll_delta.x += wheel_percent * axis_modifier;
}
_ => unreachable!(),
}
}
wl_pointer::Event::Frame => {
if state.scroll_event_received {
state.scroll_event_received = false;
let continuous = state.continuous_scroll_delta.take();
let discrete = state.discrete_scroll_delta.take();
if let Some(continuous) = continuous {
if let Some(window) = state.mouse_focused_window.clone() {
let input = PlatformInput::ScrollWheel(ScrollWheelEvent {
position: state.mouse_location.unwrap(),
delta: ScrollDelta::Pixels(continuous),
modifiers: state.modifiers,
touch_phase: TouchPhase::Moved,
});
drop(state);
window.handle_input(input);
}
} else if let Some(discrete) = discrete {
if let Some(window) = state.mouse_focused_window.clone() {
let input = PlatformInput::ScrollWheel(ScrollWheelEvent {
position: state.mouse_location.unwrap(),
delta: ScrollDelta::Lines(discrete),
modifiers: state.modifiers,
touch_phase: TouchPhase::Moved,
});
drop(state);
window.handle_input(input);
}
}
}
}
_ => {}
Expand Down

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