Merge branch 'damage-ring-swapchain-helper' into 'master'

swapchain: Introduce new helper for damage rings

See merge request wlroots/wlroots!4854

include/wlr/render/swapchain.h

@@ -1,12 +1,15 @@
 #ifndef WLR_RENDER_SWAPCHAIN_H
 #define WLR_RENDER_SWAPCHAIN_H
 
+#include <pixman.h>
 #include <stdbool.h>
 #include <wayland-server-core.h>
 #include <wlr/render/drm_format_set.h>
 
 #define WLR_SWAPCHAIN_CAP 4
 
+struct wlr_damage_ring;
+
 struct wlr_swapchain_slot {
 	struct wlr_buffer *buffer;
 	bool acquired; // waiting for release
@@ -33,13 +36,31 @@ struct wlr_swapchain *wlr_swapchain_create(
 	struct wlr_allocator *alloc, int width, int height,
 	const struct wlr_drm_format *format);
 void wlr_swapchain_destroy(struct wlr_swapchain *swapchain);
+
 /**
  * Acquire a buffer from the swap chain.
  *
+ * Can return NULL if the swapchain failed to acquire a buffer either because
+ * the swapchain is full, or the buffer couldn't be allocated.
+ *
  * The returned buffer is locked. When the caller is done with it, they must
  * unlock it by calling wlr_buffer_unlock.
  */
 struct wlr_buffer *wlr_swapchain_acquire(struct wlr_swapchain *swapchain);
+
+/**
+ * Acquire a buffer from the swap chain that is optimal for the damage ring.
+ * Will automatically rotate the swapchain.
+ *
+ * Can return NULL if the swapchain failed to acquire a buffer either because
+ * the swapchain is full, or the buffer couldn't be allocated.
+ *
+ * The returned buffer is locked. When the caller is done with it, they must
+ * unlock it by calling wlr_buffer_unlock.
+ */
+struct wlr_buffer *wlr_swapchain_acquire_from_damage_ring(struct wlr_swapchain *swapchain,
+	struct wlr_damage_ring *ring, pixman_region32_t *damage);
+
 /**
  * Returns true if this buffer has been created by this swapchain, and false
  * otherwise.

render/swapchain.c

@@ -3,6 +3,7 @@
 #include <wlr/util/log.h>
 #include <wlr/render/swapchain.h>
 #include <wlr/types/wlr_buffer.h>
+#include <wlr/types/wlr_damage_ring.h>
 #include "render/allocator/allocator.h"
 #include "render/drm_format_set.h"
 
@@ -108,6 +109,40 @@ struct wlr_buffer *wlr_swapchain_acquire(struct wlr_swapchain *swapchain) {
 	return slot_acquire(swapchain, free_slot);
 }
 
+struct wlr_buffer *wlr_swapchain_acquire_from_damage_ring(struct wlr_swapchain *swapchain,
+		struct wlr_damage_ring *ring, pixman_region32_t *damage) {
+	struct wlr_buffer *buffer = NULL;
+
+	struct wlr_damage_ring_buffer *entry;
+	wl_list_for_each(entry, &ring->buffers, link) {
+		for (size_t i = 0; i < WLR_SWAPCHAIN_CAP; i++) {
+			struct wlr_swapchain_slot *slot = &swapchain->slots[i];
+			if (slot->acquired) {
+				continue;
+			}
+
+			if (slot->buffer == entry->buffer) {
+				buffer = slot_acquire(swapchain, slot);
+				break;
+			}
+		}
+
+		if (buffer) {
+			break;
+		}
+	}
+
+	if (!buffer) {
+		buffer = wlr_swapchain_acquire(swapchain);
+		if (!buffer) {
+			return NULL;
+		}
+	}
+
+	wlr_damage_ring_rotate_buffer(ring, buffer, damage);
+	return buffer;
+}
+
 bool wlr_swapchain_has_buffer(struct wlr_swapchain *swapchain,
 		struct wlr_buffer *buffer) {
 	for (size_t i = 0; i < WLR_SWAPCHAIN_CAP; i++) {

types/scene/wlr_scene.c

@@ -2103,7 +2103,9 @@ bool wlr_scene_output_build_state(struct wlr_scene_output *scene_output,
 		swapchain = output->swapchain;
 	}
 
-	struct wlr_buffer *buffer = wlr_swapchain_acquire(swapchain);
+	pixman_region32_init(&render_data.damage);
+	struct wlr_buffer *buffer = wlr_swapchain_acquire_from_damage_ring(swapchain,
+		&scene_output->damage_ring, &render_data.damage);
 	if (buffer == NULL) {
 		return false;
 	}
@@ -2128,16 +2130,11 @@ bool wlr_scene_output_build_state(struct wlr_scene_output *scene_output,
 		.signal_point = scene_output->in_point,
 	});
 	if (render_pass == NULL) {
-		wlr_buffer_unlock(buffer);
-		return false;
+		goto fail;
 	}
 
 	render_data.render_pass = render_pass;
 
-	pixman_region32_init(&render_data.damage);
-	wlr_damage_ring_rotate_buffer(&scene_output->damage_ring, buffer,
-		&render_data.damage);
-
 	pixman_region32_t background;
 	pixman_region32_init(&background);
 	pixman_region32_copy(&background, &render_data.damage);
@@ -2219,12 +2216,7 @@ bool wlr_scene_output_build_state(struct wlr_scene_output *scene_output,
 	pixman_region32_fini(&render_data.damage);
 
 	if (!wlr_render_pass_submit(render_pass)) {
-		wlr_buffer_unlock(buffer);
-
-		// if we failed to render the buffer, it will have undefined contents
-		// Trash the damage ring
-		wlr_damage_ring_add_whole(&scene_output->damage_ring);
-		return false;
+		goto fail;
 	}
 
 	wlr_output_state_set_buffer(state, buffer);
@@ -2238,6 +2230,14 @@ bool wlr_scene_output_build_state(struct wlr_scene_output *scene_output,
 	scene_output_state_attempt_gamma(scene_output, state);
 
 	return true;
+
+	fail:
+		wlr_buffer_unlock(buffer);
+
+		// if we failed to render the buffer, it will have undefined contents
+		// Trash the damage ring
+		wlr_damage_ring_add_whole(&scene_output->damage_ring);
+		return false;
 }
 
 int64_t wlr_scene_timer_get_duration_ns(struct wlr_scene_timer *timer) {