From 9a2e0d97d71720fdb752a5d375aac7c579e67ccf Mon Sep 17 00:00:00 2001
From: Isaac Freund <mail@isaacfreund.com>
Date: Tue, 7 Mar 2023 23:43:23 +0100
Subject: layer-shell: apply exclusive zones in separate pass

This brings the behavior closer to what we had before the scene
graph refactor.

The main difference now is that the order has changed from background to
overlay instead of from overlay to background. This ordering seems to
make more sense in the cases I've tested and the old ordering was just
cargo-cult anyways.
---
 river/Output.zig | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/river/Output.zig b/river/Output.zig
index 7a94275..15c2be4 100644
--- a/river/Output.zig
+++ b/river/Output.zig
@@ -297,26 +297,44 @@ pub fn layerSurfaceTree(self: Self, layer: zwlr.LayerShellV1.Layer) *wlr.SceneTr
 /// Arrange all layer surfaces of this output and adjust the usable area.
 /// Will arrange views as well if the usable area changes.
 /// Requires a call to Root.applyPending()
-pub fn arrangeLayers(self: *Self) void {
+pub fn arrangeLayers(output: *Self) void {
     var full_box: wlr.Box = .{
         .x = 0,
         .y = 0,
         .width = undefined,
         .height = undefined,
     };
-    self.wlr_output.effectiveResolution(&full_box.width, &full_box.height);
+    output.wlr_output.effectiveResolution(&full_box.width, &full_box.height);
 
     // This box is modified as exclusive zones are applied
     var usable_box = full_box;
 
-    for ([_]zwlr.LayerShellV1.Layer{ .overlay, .top, .bottom, .background }) |layer| {
-        const tree = self.layerSurfaceTree(layer);
+    // Ensure all exclusive zones are applied before arranging surfaces
+    // without exclusive zones.
+    output.sendLayerConfigures(full_box, &usable_box, .exclusive);
+    output.sendLayerConfigures(full_box, &usable_box, .non_exclusive);
+
+    output.usable_box = usable_box;
+}
+
+fn sendLayerConfigures(
+    output: *Self,
+    full_box: wlr.Box,
+    usable_box: *wlr.Box,
+    mode: enum { exclusive, non_exclusive },
+) void {
+    for ([_]zwlr.LayerShellV1.Layer{ .background, .bottom, .top, .overlay }) |layer| {
+        const tree = output.layerSurfaceTree(layer);
         var it = tree.children.iterator(.forward);
         while (it.next()) |node| {
             assert(node.type == .tree);
             if (@intToPtr(?*SceneNodeData, node.data)) |node_data| {
                 const layer_surface = node_data.data.layer_surface;
-                layer_surface.scene_layer_surface.configure(&full_box, &usable_box);
+
+                const exclusive = layer_surface.wlr_layer_surface.current.exclusive_zone > 0;
+                if (exclusive != (mode == .exclusive)) continue;
+
+                layer_surface.scene_layer_surface.configure(&full_box, usable_box);
                 layer_surface.popup_tree.node.setPosition(
                     layer_surface.scene_layer_surface.tree.node.x,
                     layer_surface.scene_layer_surface.tree.node.y,
@@ -324,8 +342,6 @@ pub fn arrangeLayers(self: *Self) void {
             }
         }
     }
-
-    self.usable_box = usable_box;
 }
 
 fn handleDestroy(listener: *wl.Listener(*wlr.Output), _: *wlr.Output) void {
-- 
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