Do not update unrelated layer surface settings on configure event

Before this patch, wlclock would always update all layer surface settings on
every configure event. This is known to create a feedback loop with faulty
compositors (see https://github.com/swaywm/sway/pull/6709). While wlclock did
nothing wrong before, not updating these settings is more idiomatic.

4 files changed, 53 insertions, 54 deletions

diff --git a/src/output.c b/src/output.c
index 708c98f..e9c5f51 100644
--- a/src/output.c
+++ b/src/output.c
@@ -39,8 +39,6 @@ static void output_update_surface (struct Wlclock_output *output)
 		if ( context.output == NULL || ! strcmp(context.output, output->name) )
 			create_surface(output);
 	}
-	else
-		update_surface(output->surface);
 }
 
 static void output_handle_done (void *data, struct wl_output *wl_output)
diff --git a/src/render.c b/src/render.c
index cecb829..9ed1963 100644
--- a/src/render.c
+++ b/src/render.c
@@ -260,4 +260,3 @@ void render_hands_frame (struct Wlclock_surface *surface)
 	wl_surface_damage_buffer(surface->hands_surface, 0, 0, INT32_MAX, INT32_MAX);
 	wl_surface_attach(surface->hands_surface, surface->current_hands_buffer->buffer, 0, 0);
 }
-
diff --git a/src/surface.c b/src/surface.c
index f736504..79c8b6b 100644
--- a/src/surface.c
+++ b/src/surface.c
@@ -21,16 +21,30 @@
 #include"buffer.h"
 #include"render.h"
 
+
 static void layer_surface_handle_configure (void *data,
 		struct zwlr_layer_surface_v1 *layer_surface, uint32_t serial,
 		uint32_t w, uint32_t h)
 {
 	struct Wlclock_surface *surface = (struct Wlclock_surface *)data;
-	clocklog(1, "[surface] Layer surface configure request: global_name=%d w=%d h=%d serial=%d\n",
+	clocklog(1, "[surface] Layer surface configure request: output=%d w=%d h=%d serial=%d\n",
 			surface->output->global_name, w, h, serial);
+
 	zwlr_layer_surface_v1_ack_configure(layer_surface, serial);
-	if ( (w != (uint32_t)surface->dimensions.w || h != (uint32_t)surface->dimensions.h)
-			&& (w > 0 && h > 0) )
+
+	bool dimensions_changed = false;
+	if ( w != (uint32_t)surface->dimensions.w )
+	{
+		surface->dimensions.w =  w == 0 ? context.dimensions.w : (int32_t)w;
+		dimensions_changed = true;
+	}
+	if ( h != (uint32_t)surface->dimensions.h )
+	{
+		surface->dimensions.h =  h == 0 ? context.dimensions.h : (int32_t)h;
+		dimensions_changed = true;
+	}
+
+	if (dimensions_changed)
 	{
 		/* Try to fit into the space the compositor wants us to occupy
 		 * while also keeping the center square and not changing the
@@ -41,10 +55,22 @@ static void layer_surface_handle_configure (void *data,
 		surface->dimensions.center_size = size_a < size_b ? size_a : size_b;
 		if ( surface->dimensions.center_size < 10 )
 			surface->dimensions.center_size = 10;
+
+		zwlr_layer_surface_v1_set_size(surface->layer_surface,
+				surface->dimensions.w, surface->dimensions.h);
+		wl_subsurface_set_position(surface->subsurface,
+				surface->dimensions.center_x, surface->dimensions.center_y);
 	}
 
-	surface->configured = true;
-	update_surface(surface);
+	if ( dimensions_changed || !surface->configured )
+	{
+		surface->configured = true;
+
+		render_background_frame(surface);
+		render_hands_frame(surface);
+		wl_surface_commit(surface->hands_surface);
+		wl_surface_commit(surface->background_surface);
+	}
 }
 
 static void layer_surface_handle_closed (void *data, struct zwlr_layer_surface_v1 *layer_surface)
@@ -79,37 +105,6 @@ static int32_t get_exclusive_zone (struct Wlclock_surface *surface)
 		return context.exclusive_zone;
 }
 
-static void configure_subsurface (struct Wlclock_surface *surface)
-{
-	clocklog(1, "[surface] Configuring sub surface: global_name=%d\n",
-			surface->output->global_name);
-	wl_subsurface_set_position(surface->subsurface,
-			surface->dimensions.center_x, surface->dimensions.center_y);
-	struct wl_region *region = wl_compositor_create_region(context.compositor);
-	wl_surface_set_input_region(surface->hands_surface, region);
-	wl_region_destroy(region);
-}
-
-static void configure_layer_surface (struct Wlclock_surface *surface)
-{
-	clocklog(1, "[surface] Configuring layer surface: global_name=%d\n",
-			surface->output->global_name);
-	zwlr_layer_surface_v1_set_size(surface->layer_surface,
-			surface->dimensions.w, surface->dimensions.h);
-	zwlr_layer_surface_v1_set_anchor(surface->layer_surface, context.anchor);
-	zwlr_layer_surface_v1_set_margin(surface->layer_surface,
-			context.margin_top, context.margin_right,
-			context.margin_bottom, context.margin_left);
-	zwlr_layer_surface_v1_set_exclusive_zone(surface->layer_surface,
-			get_exclusive_zone(surface));
-	if (! context.input)
-	{
-		struct wl_region *region = wl_compositor_create_region(context.compositor);
-		wl_surface_set_input_region(surface->background_surface, region);
-		wl_region_destroy(region);
-	}
-}
-
 bool create_surface (struct Wlclock_output *output)
 {
 	clocklog(1, "[surface] Creating surface: global_name=%d\n", output->global_name);
@@ -158,8 +153,28 @@ bool create_surface (struct Wlclock_output *output)
 		return false;
 	}
 
-	configure_layer_surface(surface);
-	configure_subsurface(surface);
+	/* Set up layer surface. */
+	zwlr_layer_surface_v1_set_size(surface->layer_surface,
+			surface->dimensions.w, surface->dimensions.h);
+	zwlr_layer_surface_v1_set_anchor(surface->layer_surface, context.anchor);
+	zwlr_layer_surface_v1_set_margin(surface->layer_surface,
+			context.margin_top, context.margin_right,
+			context.margin_bottom, context.margin_left);
+	zwlr_layer_surface_v1_set_exclusive_zone(surface->layer_surface,
+			get_exclusive_zone(surface));
+	if (! context.input)
+	{
+		struct wl_region *region = wl_compositor_create_region(context.compositor);
+		wl_surface_set_input_region(surface->background_surface, region);
+		wl_region_destroy(region);
+	}
+
+	/* Set up subsurface. */
+	wl_subsurface_set_position(surface->subsurface,
+			surface->dimensions.center_x, surface->dimensions.center_y);
+	struct wl_region *region = wl_compositor_create_region(context.compositor);
+	wl_surface_set_input_region(surface->hands_surface, region);
+	wl_region_destroy(region);
 
 	wl_surface_commit(surface->hands_surface);
 	wl_surface_commit(surface->background_surface);
@@ -187,18 +202,6 @@ void destroy_surface (struct Wlclock_surface *surface)
 	free(surface);
 }
 
-void update_surface (struct Wlclock_surface *surface)
-{
-	if ( surface == NULL || ! surface->configured )
-		return;
-	configure_layer_surface(surface);
-	configure_subsurface(surface);
-	render_background_frame(surface);
-	render_hands_frame(surface);
-	wl_surface_commit(surface->hands_surface);
-	wl_surface_commit(surface->background_surface);
-}
-
 void update_all_hands (void)
 {
 	clocklog(1, "[surface] Updating all hands.\n");
diff --git a/src/surface.h b/src/surface.h
index 716697f..50e29b8 100644
--- a/src/surface.h
+++ b/src/surface.h
@@ -29,7 +29,6 @@ struct Wlclock_surface
 
 bool create_surface (struct Wlclock_output *output);
 void destroy_surface (struct Wlclock_surface *surface);
-void update_surface (struct Wlclock_surface *surface);
 void update_all_hands (void);
 
 #endif