fix: prevent stale blur surface after workspace switch

Author: dy-tea

TODO.md

@@ -7,7 +7,6 @@
 - Effects per window state (e.g. unfocused, focused, ...)
 - Inner glow effects on borders
 - Floating toplevels with mica are missing rounded border clip on their surface
-- Some layer surfaces with blur and a static position do not update the blur surface correctly (layer surface bar doesn't appear to track a toplevel behind it consistently; moving to an empty workspace from a non-empty workspace leaves behind some stale information in the blur surface)
 - Intel works perfectly but AMD has the following issues: gles2 non-protocol blur buffers render as black; vulkan has an abort when closing some toplevels, incorrectly clips surfaces with rounded borders and blur surfaces are missing
 - When shadow is enabled on a toplevel with rounded borders, the shadow seems to be clipped where the toplevel was clipped by the rounded border (either a layering or rendering issue)
 

include/effects.h

@@ -87,6 +87,8 @@ typedef struct effects_output_t {
 	uint32_t backdrop_gen;
 	uint32_t blur_gen;
 	uint32_t layer_blur_gen;
+
+	bool prev_workspace_switch;
 } effects_output_t;
 
 typedef struct effects_state_t {

src/effects.c

@@ -519,6 +519,7 @@ static uint64_t capture_bg_to_tex1_ex(output_t *output, effects_output_t *ctx, b
 			bool reaches_visible = damage_reaches_visible_surface(output, ctx, &ctx->scratch_region_b,
 				hide_blur_toplevels);
 			if (pixman_region32_empty(&ctx->scratch_region_c) && !reaches_visible) {
+				wlr_log(WLR_DEBUG, "effects: capture_bg_tex1 EARLY-RETURN stale backdrop");
 				wlr_scene_output_set_position(ctx->capture_scene_output, -0x7fff, -0x7fff);
 				if (changed)
 					*changed = false;
@@ -1078,10 +1079,6 @@ static bool rebuild_live_blur_layers(output_t *output, uint64_t bg_tex, pixman_r
 	if (ctx->layer_blur_buf && ctx->layer_blur_native[0] && ctx->layer_blur_gen == ctx->backdrop_gen)
 		return true;
 
-	if (!ensure_sized_buf(&ctx->layer_blur_buf, ctx->layer_blur_native, &ctx->layer_blur_buf_w,
-		&ctx->layer_blur_buf_h, ctx->blur_w, ctx->blur_h))
-		return false;
-
 	int n_scissor = 0;
 	const pixman_box32_t *scissor = blur_damage_boxes(ctx, damage, w, h, &n_scissor);
 	effects_backend->blur(&ctx->be_state, bg_tex, ctx->blur_w, ctx->blur_h, &bp,
@@ -2205,6 +2202,13 @@ void effects_output_frame(output_t *output, struct wlr_scene_output *scene_outpu
 
 	bool workspace_switch = animation_workspace_switch_active(output);
 	bool workspace_warmup = workspace_switch && workspace_effect_buffers_missing(output);
+	bool switch_just_ended = ctx->prev_workspace_switch && !workspace_switch;
+
+	ctx->prev_workspace_switch = workspace_switch;
+	if (switch_just_ended) {
+		ctx->shared_bg_valid = false;
+		ctx->combined_bg_valid = false;
+	}
 
 	// check if layer blur surfaces need rendering
 	bool has_layer_blur = false;
@@ -2265,9 +2269,9 @@ void effects_output_frame(output_t *output, struct wlr_scene_output *scene_outpu
 		ctx->blur_h != want_bh)
 		effects_output_resize(ctx, output->width, output->height, output);
 
-	bool bg_damaged = workspace_warmup || effect_regions_damaged(output,
+	bool bg_damaged = workspace_warmup || switch_just_ended || effect_regions_damaged(output,
 		scene_output) || effects_pending_update(output);
-	bool mica_dirty = mica_enabled && ctx->mica_dirty;
+	bool mica_dirty = mica_enabled && (ctx->mica_dirty || switch_just_ended);
 	bool effects_work = bg_damaged || mica_dirty;
 
 	if (!effects_work && !effects_border_pending(output) && !screen_shader_enabled)
@@ -2382,8 +2386,8 @@ void effects_output_frame(output_t *output, struct wlr_scene_output *scene_outpu
 			push_corner_masks_to_toplevels(output, any_cm_dirty);
 			goto cm_done;
 		}
-		bool any_layer_needs_blur = blur_enabled && layer_blur_needs_rebuild(output,
-			&scene_output->damage_ring.current);
+		bool any_layer_needs_blur = blur_enabled && (switch_just_ended || layer_blur_needs_rebuild(output,
+			&scene_output->damage_ring.current));
 
 		if (any_layer_needs_blur && any_cm) {
 			uint64_t bg_tex = capture_bg_combined(output, ctx);
@@ -2477,6 +2481,9 @@ void effects_output_frame(output_t *output, struct wlr_scene_output *scene_outpu
 			effects_output_resize(ctx, output->width, output->height, output);
 	}
 
+	ctx->shared_bg_valid = false;
+	ctx->combined_bg_valid = false;
+
 	effects_backend->frame_begin();
 
 	// apply corner masks and layer blur if needed