view: save and restore floating dimensions

When a floating view is fullscreened and returned to floating, it should
remember its previous floating size/position.

river/View.zig

@@ -85,9 +85,9 @@ saved_surface_box: Box,
 /// These are what we render while a transaction is in progress
 saved_buffers: std.ArrayList(SavedBuffer),
 
-/// The dimensions the view would have taken if we didn't force it to tile
+/// The floating dimensions the view, saved so that they can be restored if the
-natural_width: u32,
+/// view returns to floating mode.
-natural_height: u32,
+float_box: Box,
 
 pub fn init(self: *Self, output: *Output, tags: u32, surface: var) void {
     self.output = output;
@@ -259,19 +259,6 @@ pub fn getTitle(self: Self) [*:0]const u8 {
     };
 }
 
-/// Return a box centered on the usable area of the current output and with
-/// the natural width/height of the view.
-pub fn getDefaultFloatBox(self: Self) Box {
-    return .{
-        .x = std.math.max(0, @divTrunc(@intCast(i32, self.output.usable_box.width) -
-            @intCast(i32, self.natural_width), 2)),
-        .y = std.math.max(0, @divTrunc(@intCast(i32, self.output.usable_box.height) -
-            @intCast(i32, self.natural_height), 2)),
-        .width = self.natural_width,
-        .height = self.natural_height,
-    };
-}
-
 /// Called by the impl when the surface is ready to be displayed
 pub fn map(self: *Self) void {
     const root = self.output.root;

river/XdgToplevel.zig

@@ -155,8 +155,14 @@ fn handleMap(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
 
     view.wlr_surface = self.wlr_xdg_surface.surface;
 
-    view.natural_width = @intCast(u32, self.wlr_xdg_surface.geometry.width);
+    // Use the view's "natural" size centered on the output as the default
-    view.natural_height = @intCast(u32, self.wlr_xdg_surface.geometry.height);
+    // floating dimensions
+    view.float_box.width = @intCast(u32, self.wlr_xdg_surface.geometry.width);
+    view.float_box.height = @intCast(u32, self.wlr_xdg_surface.geometry.height);
+    view.float_box.x = std.math.max(0, @divTrunc(@intCast(i32, view.output.usable_box.width) -
+        @intCast(i32, view.float_box.width), 2));
+    view.float_box.y = std.math.max(0, @divTrunc(@intCast(i32, view.output.usable_box.height) -
+        @intCast(i32, view.float_box.height), 2));
 
     const wlr_xdg_toplevel: *c.wlr_xdg_toplevel = @field(
         self.wlr_xdg_surface,
@@ -170,13 +176,13 @@ fn handleMap(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
     if (wlr_xdg_toplevel.parent != null or has_fixed_size) {
         // If the toplevel has a parent or has a fixed size make it float
         view.pending.float = true;
-        view.pending.box = view.getDefaultFloatBox();
+        view.pending.box = view.float_box;
     } else {
         // Make views with app_ids listed in the float filter float
         for (root.server.config.float_filter.items) |filter_app_id| {
             if (std.mem.eql(u8, std.mem.span(app_id), std.mem.span(filter_app_id))) {
                 view.pending.float = true;
-                view.pending.box = view.getDefaultFloatBox();
+                view.pending.box = view.float_box;
                 break;
             }
         }

river/XwaylandView.zig

@@ -142,8 +142,14 @@ fn handleMap(listener: ?*c.wl_listener, data: ?*c_void) callconv(.C) void {
 
     view.wlr_surface = self.wlr_xwayland_surface.surface;
 
-    view.natural_width = self.wlr_xwayland_surface.width;
+    // Use the view's "natural" size centered on the output as the default
-    view.natural_height = self.wlr_xwayland_surface.height;
+    // floating dimensions
+    view.float_box.width = self.wlr_xwayland_surface.width;
+    view.float_box.height = self.wlr_xwayland_surface.height;
+    view.float_box.x = std.math.max(0, @divTrunc(@intCast(i32, view.output.usable_box.width) -
+        @intCast(i32, view.float_box.width), 2));
+    view.float_box.y = std.math.max(0, @divTrunc(@intCast(i32, view.output.usable_box.height) -
+        @intCast(i32, view.float_box.height), 2));
 
     view.map();
 }

river/command/toggle_float.zig

@@ -34,7 +34,7 @@ pub fn toggleFloat(
         // Don't float fullscreen views
         if (view.pending.fullscreen) return;
 
-        if (!view.pending.float) view.pending.box = view.getDefaultFloatBox();
+        if (!view.pending.float) view.pending.box = view.float_box;
         view.pending.float = !view.pending.float;
         view.output.root.arrange();
     }

river/command/toggle_fullscreen.zig

@@ -30,6 +30,9 @@ pub fn toggleFullscreen(
     if (args.len > 1) return Error.TooManyArguments;
 
     if (seat.focused_view) |view| {
+        // If transitionng from fullscreen -> float, return to the saved
+        // floating dimensions.
+        if (view.pending.fullscreen and view.pending.float) view.pending.box = view.float_box;
         view.setFullscreen(!view.pending.fullscreen);
         view.output.root.arrange();
     }