From d8c20ddac2a58bf3256ed77881b94030211fa080 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Thu, 12 Dec 2019 23:22:18 +0100
Subject: [PATCH] Don't re-use prev alloc on composition layer change

---
 include/private.h   | 3 ++-
 output.c            | 3 +++
 test/meson.build    | 1 +
 test/test_dynamic.c | 3 +++
 4 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/private.h b/include/private.h
index 0bcd154..abd0040 100644
--- a/include/private.h
+++ b/include/private.h
@@ -30,7 +30,8 @@ struct liftoff_output {
 	struct liftoff_layer *composition_layer;
 
 	struct liftoff_list layers; /* liftoff_layer.link */
-	bool layers_changed; /* layer added or removed */
+	/* layer added or removed, or composition layer changed */
+	bool layers_changed;
 };
 
 struct liftoff_layer {
diff --git a/output.c b/output.c
index 462f103..7b1b372 100644
--- a/output.c
+++ b/output.c
@@ -44,5 +44,8 @@ void liftoff_output_set_composition_layer(struct liftoff_output *output,
 					  struct liftoff_layer *layer)
 {
 	assert(layer->output == output);
+	if (layer != output->composition_layer) {
+		output->layers_changed = true;
+	}
 	output->composition_layer = layer;
 }
diff --git a/test/meson.build b/test/meson.build
index e8df7cf..e4727cf 100644
--- a/test/meson.build
+++ b/test/meson.build
@@ -47,6 +47,7 @@ tests = {
 		'fb',
 		'add-layer',
 		'remove-layer',
+		'change-composition-layer',
 	],
 	'priority': [
 		#'basic',
diff --git a/test/test_dynamic.c b/test/test_dynamic.c
index 7532425..c960075 100644
--- a/test/test_dynamic.c
+++ b/test/test_dynamic.c
@@ -91,6 +91,9 @@ int main(int argc, char *argv[]) {
 		liftoff_layer_destroy(other_layer);
 		other_layer = NULL;
 		want_reuse_prev_alloc = false;
+	} else if (strcmp(test_name, "change-composition-layer") == 0) {
+		liftoff_output_set_composition_layer(output, layer);
+		want_reuse_prev_alloc = false;
 	} else {
 		fprintf(stderr, "no such test: %s\n", test_name);
 		return 1;