output: get rid of active field

The less state that needs to be maintained, the better

river/Output.zig

@@ -76,10 +76,6 @@ attach_mode: AttachMode = .top,
 /// List of status tracking objects relaying changes to this output to clients.
 status_trackers: std.SinglyLinkedList(OutputStatus) = .{},
 
-/// Whether or not the output is active
-/// An active output can have focus (e.g. an output turned off by dpms is active)
-active: bool = false,
-
 destroy: wl.Listener(*wlr.Output) = undefined,
 enable: wl.Listener(*wlr.Output) = undefined,
 frame: wl.Listener(*wlr.Output) = undefined,
@@ -496,10 +492,7 @@ fn handleDestroy(listener: *wl.Listener(*wlr.Output), wlr_output: *wlr.Output) v
     log.debug(.server, "output '{}' destroyed", .{self.wlr_output.name});
 
     // Remove the destroyed output from root if it wasn't already removed
-    const node = @fieldParentPtr(std.TailQueue(Self).Node, "data", self);
-    if (self.active) {
-        root.removeOutput(node);
-    }
+    root.removeOutput(self);
 
     var it = root.all_outputs.first;
     while (it) |all_node| : (it = all_node.next) {
@@ -518,16 +511,17 @@ fn handleDestroy(listener: *wl.Listener(*wlr.Output), wlr_output: *wlr.Output) v
     // Free all memory and clean up the wlr.Output
     self.wlr_output.data = undefined;
     util.gpa.free(self.layout);
+
+    const node = @fieldParentPtr(std.TailQueue(Self).Node, "data", self);
     util.gpa.destroy(node);
 }
 
 fn handleEnable(listener: *wl.Listener(*wlr.Output), wlr_output: *wlr.Output) void {
     const self = @fieldParentPtr(Self, "enable", listener);
 
-    if (wlr_output.enabled and !self.active) {
-        const node = @fieldParentPtr(std.TailQueue(Self).Node, "data", self);
-        self.root.addOutput(node);
-    }
+    // Add the output to root.outputs and the output layout if it has not
+    // already been added.
+    if (wlr_output.enabled) self.root.addOutput(self);
 }
 
 fn handleFrame(listener: *wl.Listener(*wlr.Output), wlr_output: *wlr.Output) void {

river/OutputManager.zig

@@ -95,7 +95,7 @@ fn handleNewOutput(listener: *wl.Listener(*wlr.Output), wlr_output: *wlr.Output)
     ptr_node.data = &node.data;
 
     self.root.all_outputs.append(ptr_node);
-    self.root.addOutput(node);
+    self.root.addOutput(&node.data);
 }
 
 /// Send the new output configuration to all wlr-output-manager clients
@@ -192,8 +192,7 @@ fn applyOutputConfig(self: *Self, config: *wlr.OutputConfigurationV1) bool {
         }
 
         if (disable) {
-            const node = @fieldParentPtr(std.TailQueue(Output).Node, "data", output);
-            self.root.removeOutput(node);
+            self.root.removeOutput(output);
             self.root.output_layout.remove(output.wlr_output);
         }
 

river/Root.zig

@@ -90,12 +90,18 @@ pub fn deinit(self: *Self) void {
     self.transaction_timer.remove();
 }
 
-/// Removes the output in node.data from self.outputs
-/// The node is not freed
-pub fn removeOutput(self: *Self, node: *std.TailQueue(Output).Node) void {
-    const output = &node.data;
+/// Remove the output from self.outputs and evacuate views if it is a member of
+/// the list. The node is not freed
+pub fn removeOutput(self: *Self, output: *Output) void {
+    const node = @fieldParentPtr(std.TailQueue(Output).Node, "data", output);
+
+    // If the node has already been removed, do nothing
+    var output_it = self.outputs.first;
+    while (output_it) |n| : (output_it = n.next) {
+        if (n == node) break;
+    } else return;
+
     self.outputs.remove(node);
-    output.active = false;
 
     // Use the first output in the list as fallback.
     // If there is no other real output, use the noop output.
@@ -137,11 +143,16 @@ pub fn removeOutput(self: *Self, node: *std.TailQueue(Output).Node) void {
     self.startTransaction();
 }
 
-/// Adds the output in node.data to self.outputs
-/// The Output in node.data must be initalized
-pub fn addOutput(self: *Self, node: *std.TailQueue(Output).Node) void {
+/// Add the output to self.outputs and the output layout if it has not
+/// already been added.
+pub fn addOutput(self: *Self, output: *Output) void {
+    const node = @fieldParentPtr(std.TailQueue(Output).Node, "data", output);
+
+    // If we have already added the output, do nothing and return
+    var output_it = self.outputs.first;
+    while (output_it) |n| : (output_it = n.next) if (n == node) return;
+
     self.outputs.append(node);
-    node.data.active = true;
 
     // Add the new output to the layout. The add_auto function arranges outputs
     // from left-to-right in the order they appear. A more sophisticated