tiling: groundwork for resize grab

src/shell/layout/tiling/grabs.rs

@@ -0,0 +1,83 @@
+// SPDX-License-Identifier: GPL-3.0-only
+use super::{Data, Orientation, OutputInfo};
+use id_tree::{NodeId, Tree};
+use smithay::{
+    desktop::layer_map_for_output,
+    reexports::wayland_server::protocol::{wl_pointer::ButtonState, wl_surface},
+    utils::{Logical, Point},
+    wayland::{
+        output::Output,
+        seat::{AxisFrame, PointerGrab, PointerGrabStartData, PointerInnerHandle},
+        Serial,
+    },
+};
+use std::cell::RefCell;
+
+pub struct ResizeForkGrab {
+    pub start_data: PointerGrabStartData,
+    pub node_id: NodeId,
+    pub initial_ratio: f64,
+    pub idx: u8,
+    pub output: Output,
+}
+
+impl PointerGrab for ResizeForkGrab {
+    fn motion(
+        &mut self,
+        handle: &mut PointerInnerHandle<'_>,
+        location: Point<f64, Logical>,
+        _focus: Option<(wl_surface::WlSurface, Point<i32, Logical>)>,
+        serial: Serial,
+        time: u32,
+    ) {
+        // While the grab is active, no client has pointer focus
+        handle.motion(location, None, serial, time);
+
+        let delta = location - self.start_data.location;
+
+        let mut output_info = self
+            .output
+            .user_data()
+            .get::<RefCell<OutputInfo>>()
+            .unwrap()
+            .borrow_mut();
+        let tree = &mut output_info.trees.entry(self.idx).or_insert_with(Tree::new);
+        if let Some(&mut Data::Fork {
+            ref mut ratio,
+            ref orientation,
+        }) = tree.get_mut(&self.node_id).map(|x| x.data_mut()).ok()
+        {
+            let size = layer_map_for_output(&self.output).non_exclusive_zone().size;
+            let delta = match orientation {
+                Orientation::Vertical => delta.x / size.w as f64,
+                Orientation::Horizontal => delta.y / size.h as f64,
+            };
+            *ratio = 0.9f64.min(0.1f64.max(self.initial_ratio + delta));
+        } else {
+            handle.unset_grab(serial, time);
+        }
+    }
+
+    fn button(
+        &mut self,
+        handle: &mut PointerInnerHandle<'_>,
+        button: u32,
+        state: ButtonState,
+        serial: Serial,
+        time: u32,
+    ) {
+        handle.button(button, state, serial, time);
+        if handle.current_pressed().is_empty() {
+            // No more buttons are pressed, release the grab.
+            handle.unset_grab(serial, time);
+        }
+    }
+
+    fn axis(&mut self, handle: &mut PointerInnerHandle<'_>, details: AxisFrame) {
+        handle.axis(details)
+    }
+
+    fn start_data(&self) -> &PointerGrabStartData {
+        &self.start_data
+    }
+}