Cursor: apply x/y change during resize on commit

This fixes issues with resizing clients that stick to a fixed aspect
ratio during resize such as mpv.

river/Cursor.zig

@@ -131,6 +131,12 @@ const log = std.log.scoped(.cursor);
 /// Current cursor mode as well as any state needed to implement that mode
 mode: Mode = .passthrough,
 
+/// Set to whatever the current mode is when a transaction is started.
+/// This is necessary to handle termination of move/resize modes properly
+/// since the termination is not complete until a transaction completes and
+/// View.resizeUpdatePosition() is called.
+inflight_mode: Mode = .passthrough,
+
 seat: *Seat,
 wlr_cursor: *wlr.Cursor,
 pointer_gestures: *wlr.PointerGesturesV1,
@@ -334,7 +340,22 @@ fn handleButton(listener: *wl.Listener(*wlr.Pointer.event.Button), event: *wlr.P
         assert(self.pressed_count > 0);
         self.pressed_count -= 1;
         if (self.pressed_count == 0 and self.mode != .passthrough) {
-            self.leaveMode(event);
+            log.debug("leaving {s} mode", .{@tagName(self.mode)});
+
+            switch (self.mode) {
+                .passthrough => unreachable,
+                .down => {
+                    // If we were in down mode, we need pass along the release event
+                    _ = self.seat.wlr_seat.pointerNotifyButton(event.time_msec, event.button, event.state);
+                },
+                .move => {},
+                .resize => |data| data.view.pending.resizing = false,
+            }
+
+            self.mode = .passthrough;
+            self.passthrough(event.time_msec);
+
+            server.root.applyPending();
         } else {
             _ = self.seat.wlr_seat.pointerNotifyButton(event.time_msec, event.button, event.state);
         }
@@ -785,24 +806,6 @@ fn enterMode(cursor: *Self, mode: Mode, view: *View, image: Image) void {
     server.root.applyPending();
 }
 
-/// Return from down/move/resize to passthrough
-fn leaveMode(self: *Self, event: *wlr.Pointer.event.Button) void {
-    log.debug("leave {s} mode", .{@tagName(self.mode)});
-
-    switch (self.mode) {
-        .passthrough => unreachable,
-        .down => {
-            // If we were in down mode, we need pass along the release event
-            _ = self.seat.wlr_seat.pointerNotifyButton(event.time_msec, event.button, event.state);
-        },
-        .move => {},
-        .resize => |resize| resize.view.pending.resizing = false,
-    }
-
-    self.mode = .passthrough;
-    self.passthrough(event.time_msec);
-}
-
 fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64, delta_y: f64, unaccel_dx: f64, unaccel_dy: f64) void {
     self.unhide();
 
@@ -852,25 +855,18 @@ fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64,
                 constraint.maybeActivate();
             }
         },
-        .move => |*data| {
+        inline .move, .resize => |*data, tag| {
             dx += data.delta_x;
             dy += data.delta_y;
             data.delta_x = dx - @trunc(dx);
             data.delta_y = dy - @trunc(dy);
 
-            const view = data.view;
+            if (tag == .move) {
-            view.pending.move(@floatToInt(i32, dx), @floatToInt(i32, dy));
+                data.view.pending.move(@floatToInt(i32, dx), @floatToInt(i32, dy));
-
+            } else {
-            server.root.applyPending();
+                // Modify width/height of the pending box, taking constraints into account
-        },
+                // The x/y coordinates of the view will be adjusted as needed in View.resizeCommit()
-        .resize => |*data| {
+                // based on the dimensions actually committed by the client.
-            dx += data.delta_x;
-            dy += data.delta_y;
-            data.delta_x = dx - @trunc(dx);
-            data.delta_y = dy - @trunc(dy);
-
-            {
-                // Modify the pending box, taking constraints into account
                 const border_width = if (data.view.pending.ssd) server.config.border_width else 0;
 
                 var output_width: i32 = undefined;
@@ -881,12 +877,13 @@ fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64,
                 const box = &data.view.pending.box;
 
                 if (data.edges.left) {
+                    var x1 = box.x;
                     const x2 = box.x + box.width;
-                    box.x += @floatToInt(i32, dx);
+                    x1 += @floatToInt(i32, dx);
-                    box.x = math.max(box.x, border_width);
+                    x1 = math.max(x1, border_width);
-                    box.x = math.max(box.x, x2 - constraints.max_width);
+                    x1 = math.max(x1, x2 - constraints.max_width);
-                    box.x = math.min(box.x, x2 - constraints.min_width);
+                    x1 = math.min(x1, x2 - constraints.min_width);
-                    box.width = x2 - box.x;
+                    box.width = x2 - x1;
                 } else if (data.edges.right) {
                     box.width += @floatToInt(i32, dx);
                     box.width = math.max(box.width, constraints.min_width);
@@ -895,12 +892,13 @@ fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64,
                 }
 
                 if (data.edges.top) {
+                    var y1 = box.y;
                     const y2 = box.y + box.height;
-                    box.y += @floatToInt(i32, dy);
+                    y1 += @floatToInt(i32, dy);
-                    box.y = math.max(box.y, border_width);
+                    y1 = math.max(y1, border_width);
-                    box.y = math.max(box.y, y2 - constraints.max_height);
+                    y1 = math.max(y1, y2 - constraints.max_height);
-                    box.y = math.min(box.y, y2 - constraints.min_height);
+                    y1 = math.min(y1, y2 - constraints.min_height);
-                    box.height = y2 - box.y;
+                    box.height = y2 - y1;
                 } else if (data.edges.bottom) {
                     box.height += @floatToInt(i32, dy);
                     box.height = math.max(box.height, constraints.min_height);
@@ -984,12 +982,26 @@ pub fn updateState(self: *Self) void {
 
             // Keep the cursor locked to the original offset from the edges of the view.
             const box = &data.view.current.box;
-            const dx = data.offset_x;
+            const new_x = blk: {
-            const dy = data.offset_y;
+                if (mode == .move or data.edges.left) {
-            const lx = if (mode == .move or data.edges.left) dx + box.x else box.x + box.width - dx;
+                    break :blk @intToFloat(f64, data.offset_x + box.x);
-            const ly = if (mode == .move or data.edges.top) dy + box.y else box.y + box.height - dy;
+                } else if (data.edges.right) {
+                    break :blk @intToFloat(f64, box.x + box.width - data.offset_x);
+                } else {
+                    break :blk self.wlr_cursor.x;
+                }
+            };
+            const new_y = blk: {
+                if (mode == .move or data.edges.top) {
+                    break :blk @intToFloat(f64, data.offset_y + box.y);
+                } else if (data.edges.bottom) {
+                    break :blk @intToFloat(f64, box.y + box.height - data.offset_y);
+                } else {
+                    break :blk self.wlr_cursor.y;
+                }
+            };
 
-            self.wlr_cursor.warpClosest(null, @intToFloat(f64, lx), @intToFloat(f64, ly));
+            self.wlr_cursor.warpClosest(null, new_x, new_y);
         },
     }
 }

river/Root.zig

@@ -512,6 +512,8 @@ pub fn applyPending(root: *Self) void {
                     }
                 },
             }
+
+            cursor.inflight_mode = cursor.mode;
         }
     }
 

river/View.zig

@@ -244,14 +244,50 @@ pub fn destroy(view: *Self) void {
     }
 }
 
+/// The change in x/y position of the view during resize cannot be determined
+/// until the size of the buffer actually committed is known. Clients are permitted
+/// by the protocol to take a size smaller than that requested by the compositor in
+/// order to maintain an aspect ratio or similar (mpv does this for example).
+pub fn resizeUpdatePosition(view: *Self, width: i32, height: i32) void {
+    assert(view.inflight.resizing);
+
+    const data = blk: {
+        var it = server.input_manager.seats.first;
+        while (it) |node| : (it = node.next) {
+            const cursor = &node.data.cursor;
+            if (cursor.inflight_mode == .resize and cursor.inflight_mode.resize.view == view) {
+                break :blk cursor.inflight_mode.resize;
+            }
+        } else {
+            // The view resizing state should never be set when the view is
+            // not the target of an interactive resize.
+            unreachable;
+        }
+    };
+
+    if (data.edges.left) {
+        view.inflight.box.x += view.current.box.width - width;
+        view.pending.box.x = view.inflight.box.x;
+    }
+
+    if (data.edges.top) {
+        view.inflight.box.y += view.current.box.height - height;
+        view.pending.box.y = view.inflight.box.y;
+    }
+}
+
 pub fn updateCurrent(view: *Self) void {
     const config = &server.config;
 
-    if (view.impl == .xdg_toplevel) {
+    switch (view.impl) {
-        switch (view.impl.xdg_toplevel.configure_state) {
+        .xdg_toplevel => |*xdg_toplevel| {
+            switch (xdg_toplevel.configure_state) {
                 // If the configure timed out, don't update current to dimensions
                 // that have not been committed by the client.
                 .inflight, .acked => {
+                    if (view.inflight.resizing) {
+                        view.resizeUpdatePosition(view.current.box.width, view.current.box.height);
+                    }
                     view.inflight.box.width = view.current.box.width;
                     view.inflight.box.height = view.current.box.height;
                     view.pending.box.width = view.current.box.width;
@@ -259,7 +295,21 @@ pub fn updateCurrent(view: *Self) void {
                 },
                 .idle, .committed => {},
             }
-        view.impl.xdg_toplevel.configure_state = .idle;
+            xdg_toplevel.configure_state = .idle;
+        },
+        .xwayland_view => |xwayland_view| {
+            if (view.inflight.resizing) {
+                view.resizeUpdatePosition(
+                    xwayland_view.xwayland_surface.width,
+                    xwayland_view.xwayland_surface.height,
+                );
+            }
+            view.inflight.box.width = xwayland_view.xwayland_surface.width;
+            view.inflight.box.height = xwayland_view.xwayland_surface.height;
+            view.pending.box.width = xwayland_view.xwayland_surface.width;
+            view.pending.box.height = xwayland_view.xwayland_surface.height;
+        },
+        .none => {},
     }
 
     view.foreign_toplevel_handle.update();

river/XdgToplevel.zig

@@ -317,17 +317,20 @@ fn handleCommit(listener: *wl.Listener(*wlr.Surface), _: *wlr.Surface) void {
                 self.geometry.height != old_geometry.height;
             const no_layout = view.current.output != null and view.current.output.?.layout == null;
 
-            if (size_changed and (view.current.float or no_layout) and !view.current.fullscreen) {
+            if (size_changed) {
                 log.info(
                     "client initiated size change: {}x{} -> {}x{}",
                     .{ old_geometry.width, old_geometry.height, self.geometry.width, self.geometry.height },
                 );
-
+                if ((view.current.float or no_layout) and !view.current.fullscreen) {
                     view.current.box.width = self.geometry.width;
                     view.current.box.height = self.geometry.height;
                     view.pending.box.width = self.geometry.width;
                     view.pending.box.height = self.geometry.height;
                     server.root.applyPending();
+                } else {
+                    log.err("client is buggy and initiated size change while tiled or fullscreen", .{});
+                }
             }
         },
         // If the client has not yet acked our configure, we need to send a
@@ -338,6 +341,10 @@ fn handleCommit(listener: *wl.Listener(*wlr.Surface), _: *wlr.Surface) void {
         .acked => {
             self.configure_state = .committed;
 
+            if (view.inflight.resizing) {
+                view.resizeUpdatePosition(self.geometry.width, self.geometry.height);
+            }
+
             view.inflight.box.width = self.geometry.width;
             view.inflight.box.height = self.geometry.height;
             view.pending.box.width = self.geometry.width;