From 6e0c1037059e113b4173be094f3ad07fc0a81924 Mon Sep 17 00:00:00 2001
From: Isaac Freund <mail@isaacfreund.com>
Date: Mon, 1 Jul 2024 12:27:16 +0200
Subject: [PATCH] Output: fix Wayland backend support

The wlroots Wayland backend does not support gamma LUT application and
will currently fail to render anything if river commits a gamma LUT.

To fix this, test the state when applying a gamma LUT and fall back to a
state with no gamma LUT set if that fails.

This problem was revealed by 2e09b66 which flags gamma as dirty on all
outputs when they are enabled.

(cherry picked from commit a80e0f7322b1f9f8b091a327aaea366b615042c8)
---
 build.zig.zon    |  4 ++--
 river/Output.zig | 15 ++++++++++-----
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/build.zig.zon b/build.zig.zon
index 01d58d8..fc5de55 100644
--- a/build.zig.zon
+++ b/build.zig.zon
@@ -12,8 +12,8 @@
             .hash = "1220687c8c47a48ba285d26a05600f8700d37fc637e223ced3aa8324f3650bf52242",
         },
         .@"zig-wlroots" = .{
-            .url = "https://codeberg.org/ifreund/zig-wlroots/archive/v0.17.1.tar.gz",
-            .hash = "1220c65ab884c236cc950b564c70f6cd04046d86485ee76e0cde886cef7438021b4f",
+            .url = "https://codeberg.org/ifreund/zig-wlroots/archive/v0.17.2.tar.gz",
+            .hash = "1220bb5e5c802c517425bc1d8d8d43d7b7fe5eb81ce4c46b15ce829d67ddadc55418",
         },
         .@"zig-xkbcommon" = .{
             .url = "https://codeberg.org/ifreund/zig-xkbcommon/archive/v0.2.0.tar.gz",
diff --git a/river/Output.zig b/river/Output.zig
index 518bfc6..c9d8add 100644
--- a/river/Output.zig
+++ b/river/Output.zig
@@ -540,18 +540,23 @@ fn renderAndCommit(output: *Output, scene_output: *wlr.SceneOutput) !void {
         var state = wlr.Output.State.init();
         defer state.finish();
 
-        if (server.root.gamma_control_manager.getControl(output.wlr_output)) |control| {
-            log.info("applying gamma settings from client", .{});
-            if (!control.apply(&state)) return error.OutOfMemory;
-        } else {
-            log.info("clearing gamma settings from client", .{});
+        const control = server.root.gamma_control_manager.getControl(output.wlr_output);
+        if (!wlr.GammaControlV1.apply(control, &state)) return error.OutOfMemory;
+
+        if (!output.wlr_output.testState(&state)) {
+            wlr.GammaControlV1.sendFailedAndDestroy(control);
             state.clearGammaLut();
+            // If the backend does not support gamma LUTs it will reject any
+            // state with the gamma LUT committed bit set even if the state
+            // has a null LUT. The wayland backend for example has this behavior.
+            state.committed.gamma_lut = false;
         }
 
         if (!scene_output.buildState(&state, null)) return error.CommitFailed;
 
         if (!output.wlr_output.commitState(&state)) return error.CommitFailed;
 
+        // TODO(wlroots) remove this rotate() call when updating to wlroots 0.18
         scene_output.damage_ring.rotate();
         output.gamma_dirty = false;
     } else {