view: unify clamped move logic, fix overflow

river/Cursor.zig

@@ -19,6 +19,7 @@ const Self = @This();
 
 const build_options = @import("build_options");
 const std = @import("std");
+const math = std.math;
 const wlr = @import("wlroots");
 const wayland = @import("wayland");
 const wl = wayland.server.wl;
@@ -468,8 +469,6 @@ fn leaveMode(self: *Self, event: *wlr.Pointer.event.Button) void {
 }
 
 fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64, delta_y: f64) void {
-    const config = self.seat.input_manager.server.config;
-
     switch (self.mode) {
         .passthrough => {
             self.wlr_cursor.move(device, delta_x, delta_y);
@@ -484,42 +483,28 @@ fn processMotion(self: *Self, device: *wlr.InputDevice, time: u32, delta_x: f64,
             );
         },
         .move => |view| {
-            const border_width = if (view.draw_borders) config.border_width else 0;
+            view.move(@floatToInt(i32, delta_x), @floatToInt(i32, delta_y));
-
-            // Set x/y of cursor and view, clamp to output dimensions
-            const output_resolution = view.output.getEffectiveResolution();
-            view.pending.box.x = std.math.clamp(
-                view.pending.box.x + @floatToInt(i32, delta_x),
-                @intCast(i32, border_width),
-                @intCast(i32, output_resolution.width - view.pending.box.width - border_width),
-            );
-            view.pending.box.y = std.math.clamp(
-                view.pending.box.y + @floatToInt(i32, delta_y),
-                @intCast(i32, border_width),
-                @intCast(i32, output_resolution.height - view.pending.box.height - border_width),
-            );
-
             self.wlr_cursor.move(
                 device,
                 @intToFloat(f64, view.pending.box.x - view.current.box.x),
                 @intToFloat(f64, view.pending.box.y - view.current.box.y),
             );
-
             view.applyPending();
         },
         .resize => |data| {
+            const config = &self.seat.input_manager.server.config;
             const border_width = if (data.view.draw_borders) config.border_width else 0;
 
             // Set width/height of view, clamp to view size constraints and output dimensions
             const box = &data.view.pending.box;
-            box.width = @intCast(u32, std.math.max(0, @intCast(i32, box.width) + @floatToInt(i32, delta_x)));
+            box.width = @intCast(u32, math.max(0, @intCast(i32, box.width) + @floatToInt(i32, delta_x)));
-            box.height = @intCast(u32, std.math.max(0, @intCast(i32, box.height) + @floatToInt(i32, delta_y)));
+            box.height = @intCast(u32, math.max(0, @intCast(i32, box.height) + @floatToInt(i32, delta_y)));
 
             data.view.applyConstraints();
 
             const output_resolution = data.view.output.getEffectiveResolution();
-            box.width = std.math.min(box.width, output_resolution.width - border_width - @intCast(u32, box.x));
+            box.width = math.min(box.width, output_resolution.width - border_width - @intCast(u32, box.x));
-            box.height = std.math.min(box.height, output_resolution.height - border_width - @intCast(u32, box.y));
+            box.height = math.min(box.height, output_resolution.height - border_width - @intCast(u32, box.y));
 
             data.view.applyPending();
 

river/View.zig

@@ -19,6 +19,7 @@ const Self = @This();
 
 const build_options = @import("build_options");
 const std = @import("std");
+const math = std.math;
 const os = std.os;
 const wlr = @import("wlroots");
 const wl = @import("wayland").server.wl;
@@ -380,6 +381,26 @@ pub fn getConstraints(self: Self) Constraints {
     };
 }
 
+/// Modify the pending x/y of the view by the given deltas, clamping to the
+/// bounds of the output.
+pub fn move(self: *Self, delta_x: i32, delta_y: i32) void {
+    const config = &self.output.root.server.config;
+    const border_width = if (self.draw_borders) @intCast(i32, config.border_width) else 0;
+    const output_resolution = self.output.getEffectiveResolution();
+
+    const max_x = @intCast(i32, output_resolution.width) - @intCast(i32, self.pending.box.width) - border_width;
+    self.pending.box.x += delta_x;
+    self.pending.box.x = math.max(self.pending.box.x, border_width);
+    self.pending.box.x = math.min(self.pending.box.x, max_x);
+    self.pending.box.x = math.max(self.pending.box.x, 0);
+
+    const max_y = @intCast(i32, output_resolution.height) - @intCast(i32, self.pending.box.height) - border_width;
+    self.pending.box.y += delta_y;
+    self.pending.box.y = math.max(self.pending.box.y, border_width);
+    self.pending.box.y = math.min(self.pending.box.y, max_y);
+    self.pending.box.y = math.max(self.pending.box.y, 0);
+}
+
 /// Find and return the view corresponding to a given surface, if any
 pub fn fromWlrSurface(surface: *wlr.Surface) ?*Self {
     if (surface.isXdgSurface()) {

river/command/move.zig

@@ -41,10 +41,10 @@ pub fn move(
 
     const view = getView(seat) orelse return;
     switch (direction) {
-        .up => moveVertical(view, -1 * delta),
+        .up => view.move(0, -delta),
-        .down => moveVertical(view, delta),
+        .down => view.move(0, delta),
-        .left => moveHorizontal(view, -1 * delta),
+        .left => view.move(-delta, 0),
-        .right => moveHorizontal(view, delta),
+        .right => view.move(delta, 0),
     }
 
     apply(view);
@@ -110,7 +110,7 @@ pub fn resize(
                 output_box.width - @intCast(u32, 2 * border_width),
             );
             real_delta -= @intCast(i32, view.pending.box.width);
-            moveHorizontal(view, @divFloor(real_delta, 2));
+            view.move(@divFloor(real_delta, 2), 0);
         },
         .vertical => {
             var real_delta: i32 = @intCast(i32, view.pending.box.height);
@@ -128,7 +128,7 @@ pub fn resize(
                 output_box.height - @intCast(u32, 2 * border_width),
             );
             real_delta -= @intCast(i32, view.pending.box.height);
-            moveVertical(view, @divFloor(real_delta, 2));
+            view.move(0, @divFloor(real_delta, 2));
         },
     }
 
@@ -155,23 +155,3 @@ fn getView(seat: *Seat) ?*View {
 
     return view;
 }
-
-fn moveVertical(view: *View, delta: i32) void {
-    const output_box = view.output.getEffectiveResolution();
-    const border_width = @intCast(i32, view.output.root.server.config.border_width);
-    view.pending.box.y = std.math.clamp(
-        view.pending.box.y + delta,
-        border_width,
-        @intCast(i32, output_box.height - view.pending.box.height) - border_width,
-    );
-}
-
-fn moveHorizontal(view: *View, delta: i32) void {
-    const output_box = view.output.getEffectiveResolution();
-    const border_width = @intCast(i32, view.output.root.server.config.border_width);
-    view.pending.box.x = std.math.clamp(
-        view.pending.box.x + delta,
-        border_width,
-        @intCast(i32, output_box.width - view.pending.box.width) - border_width,
-    );
-}