output: split into multiple files

This organizes the wlr_output implementation into separate files.
This avoids having a single mega-file with lots of unrelated parts
and makes it more obvious what the interactions between all the
parts are.

No functional changes, just moving code around.

include/types/wlr_output.h

@@ -0,0 +1,15 @@
+#ifndef TYPES_WLR_OUTPUT_H
+#define TYPES_WLR_OUTPUT_H
+
+#include <wlr/render/drm_format_set.h>
+#include <wlr/types/wlr_output.h>
+
+void output_pending_resolution(struct wlr_output *output, int *width,
+	int *height);
+
+struct wlr_drm_format *output_pick_format(struct wlr_output *output,
+	const struct wlr_drm_format_set *display_formats);
+void output_clear_back_buffer(struct wlr_output *output);
+bool output_ensure_buffer(struct wlr_output *output);
+
+#endif

types/meson.build

@@ -3,6 +3,10 @@ wlr_files += files(
 	'data_device/wlr_data_offer.c',
 	'data_device/wlr_data_source.c',
 	'data_device/wlr_drag.c',
+	'output/cursor.c',
+	'output/output.c',
+	'output/render.c',
+	'output/transform.c',
 	'scene/subsurface_tree.c',
 	'scene/wlr_scene.c',
 	'scene/output_layout.c',
@@ -43,7 +47,6 @@ wlr_files += files(
 	'wlr_output_layout.c',
 	'wlr_output_management_v1.c',
 	'wlr_output_power_management_v1.c',
-	'wlr_output.c',
 	'wlr_pointer_constraints_v1.c',
 	'wlr_pointer_gestures_v1.c',
 	'wlr_pointer.c',

types/output/cursor.c

@@ -0,0 +1,573 @@
+#include <assert.h>
+#include <drm_fourcc.h>
+#include <stdlib.h>
+#include <wlr/interfaces/wlr_output.h>
+#include <wlr/render/wlr_renderer.h>
+#include <wlr/types/wlr_matrix.h>
+#include <wlr/types/wlr_surface.h>
+#include <wlr/util/log.h>
+#include "backend/backend.h"
+#include "render/allocator/allocator.h"
+#include "render/swapchain.h"
+#include "types/wlr_output.h"
+#include "util/signal.h"
+
+static void output_cursor_damage_whole(struct wlr_output_cursor *cursor);
+
+void wlr_output_lock_software_cursors(struct wlr_output *output, bool lock) {
+	if (lock) {
+		++output->software_cursor_locks;
+	} else {
+		assert(output->software_cursor_locks > 0);
+		--output->software_cursor_locks;
+	}
+	wlr_log(WLR_DEBUG, "%s hardware cursors on output '%s' (locks: %d)",
+		lock ? "Disabling" : "Enabling", output->name,
+		output->software_cursor_locks);
+
+	if (output->software_cursor_locks > 0 && output->hardware_cursor != NULL) {
+		assert(output->impl->set_cursor);
+		output->impl->set_cursor(output, NULL, 0, 0);
+		output_cursor_damage_whole(output->hardware_cursor);
+		output->hardware_cursor = NULL;
+	}
+
+	// If it's possible to use hardware cursors again, don't switch immediately
+	// since a recorder is likely to lock software cursors for the next frame
+	// again.
+}
+
+static void output_scissor(struct wlr_output *output, pixman_box32_t *rect) {
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	assert(renderer);
+
+	struct wlr_box box = {
+		.x = rect->x1,
+		.y = rect->y1,
+		.width = rect->x2 - rect->x1,
+		.height = rect->y2 - rect->y1,
+	};
+
+	int ow, oh;
+	wlr_output_transformed_resolution(output, &ow, &oh);
+
+	enum wl_output_transform transform =
+		wlr_output_transform_invert(output->transform);
+	wlr_box_transform(&box, &box, transform, ow, oh);
+
+	wlr_renderer_scissor(renderer, &box);
+}
+
+/**
+ * Returns the cursor box, scaled for its output.
+ */
+static void output_cursor_get_box(struct wlr_output_cursor *cursor,
+		struct wlr_box *box) {
+	box->x = cursor->x - cursor->hotspot_x;
+	box->y = cursor->y - cursor->hotspot_y;
+	box->width = cursor->width;
+	box->height = cursor->height;
+}
+
+static void output_cursor_render(struct wlr_output_cursor *cursor,
+		pixman_region32_t *damage) {
+	struct wlr_renderer *renderer =
+		wlr_backend_get_renderer(cursor->output->backend);
+	assert(renderer);
+
+	struct wlr_texture *texture = cursor->texture;
+	if (cursor->surface != NULL) {
+		texture = wlr_surface_get_texture(cursor->surface);
+	}
+	if (texture == NULL) {
+		return;
+	}
+
+	struct wlr_box box;
+	output_cursor_get_box(cursor, &box);
+
+	pixman_region32_t surface_damage;
+	pixman_region32_init(&surface_damage);
+	pixman_region32_union_rect(&surface_damage, &surface_damage, box.x, box.y,
+		box.width, box.height);
+	pixman_region32_intersect(&surface_damage, &surface_damage, damage);
+	if (!pixman_region32_not_empty(&surface_damage)) {
+		goto surface_damage_finish;
+	}
+
+	float matrix[9];
+	wlr_matrix_project_box(matrix, &box, WL_OUTPUT_TRANSFORM_NORMAL, 0,
+		cursor->output->transform_matrix);
+
+	int nrects;
+	pixman_box32_t *rects = pixman_region32_rectangles(&surface_damage, &nrects);
+	for (int i = 0; i < nrects; ++i) {
+		output_scissor(cursor->output, &rects[i]);
+		wlr_render_texture_with_matrix(renderer, texture, matrix, 1.0f);
+	}
+	wlr_renderer_scissor(renderer, NULL);
+
+surface_damage_finish:
+	pixman_region32_fini(&surface_damage);
+}
+
+void wlr_output_render_software_cursors(struct wlr_output *output,
+		pixman_region32_t *damage) {
+	int width, height;
+	wlr_output_transformed_resolution(output, &width, &height);
+
+	pixman_region32_t render_damage;
+	pixman_region32_init(&render_damage);
+	pixman_region32_union_rect(&render_damage, &render_damage, 0, 0,
+		width, height);
+	if (damage != NULL) {
+		// Damage tracking supported
+		pixman_region32_intersect(&render_damage, &render_damage, damage);
+	}
+
+	if (pixman_region32_not_empty(&render_damage)) {
+		struct wlr_output_cursor *cursor;
+		wl_list_for_each(cursor, &output->cursors, link) {
+			if (!cursor->enabled || !cursor->visible ||
+					output->hardware_cursor == cursor) {
+				continue;
+			}
+			output_cursor_render(cursor, &render_damage);
+		}
+	}
+
+	pixman_region32_fini(&render_damage);
+}
+
+static void output_cursor_damage_whole(struct wlr_output_cursor *cursor) {
+	struct wlr_box box;
+	output_cursor_get_box(cursor, &box);
+
+	pixman_region32_t damage;
+	pixman_region32_init_rect(&damage, box.x, box.y, box.width, box.height);
+
+	struct wlr_output_event_damage event = {
+		.output = cursor->output,
+		.damage = &damage,
+	};
+	wlr_signal_emit_safe(&cursor->output->events.damage, &event);
+
+	pixman_region32_fini(&damage);
+}
+
+static void output_cursor_reset(struct wlr_output_cursor *cursor) {
+	if (cursor->output->hardware_cursor != cursor) {
+		output_cursor_damage_whole(cursor);
+	}
+	if (cursor->surface != NULL) {
+		wl_list_remove(&cursor->surface_commit.link);
+		wl_list_remove(&cursor->surface_destroy.link);
+		if (cursor->visible) {
+			wlr_surface_send_leave(cursor->surface, cursor->output);
+		}
+		cursor->surface = NULL;
+	}
+}
+
+static void output_cursor_update_visible(struct wlr_output_cursor *cursor) {
+	struct wlr_box output_box;
+	output_box.x = output_box.y = 0;
+	wlr_output_transformed_resolution(cursor->output, &output_box.width,
+		&output_box.height);
+
+	struct wlr_box cursor_box;
+	output_cursor_get_box(cursor, &cursor_box);
+
+	struct wlr_box intersection;
+	bool visible =
+		wlr_box_intersection(&intersection, &output_box, &cursor_box);
+
+	if (cursor->surface != NULL) {
+		if (cursor->visible && !visible) {
+			wlr_surface_send_leave(cursor->surface, cursor->output);
+		}
+		if (!cursor->visible && visible) {
+			wlr_surface_send_enter(cursor->surface, cursor->output);
+		}
+	}
+
+	cursor->visible = visible;
+}
+
+static struct wlr_drm_format *output_pick_cursor_format(struct wlr_output *output) {
+	struct wlr_allocator *allocator = backend_get_allocator(output->backend);
+	assert(allocator != NULL);
+
+	const struct wlr_drm_format_set *display_formats = NULL;
+	if (output->impl->get_cursor_formats) {
+		display_formats =
+			output->impl->get_cursor_formats(output, allocator->buffer_caps);
+		if (display_formats == NULL) {
+			wlr_log(WLR_ERROR, "Failed to get cursor display formats");
+			return NULL;
+		}
+	}
+
+	return output_pick_format(output, display_formats);
+}
+
+static struct wlr_buffer *render_cursor_buffer(struct wlr_output_cursor *cursor) {
+	struct wlr_output *output = cursor->output;
+
+	float scale = output->scale;
+	enum wl_output_transform transform = WL_OUTPUT_TRANSFORM_NORMAL;
+	struct wlr_texture *texture = cursor->texture;
+	if (cursor->surface != NULL) {
+		texture = wlr_surface_get_texture(cursor->surface);
+		scale = cursor->surface->current.scale;
+		transform = cursor->surface->current.transform;
+	}
+	if (texture == NULL) {
+		return NULL;
+	}
+
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	if (renderer == NULL) {
+		wlr_log(WLR_ERROR, "Failed to get backend renderer");
+		return NULL;
+	}
+
+	struct wlr_allocator *allocator = backend_get_allocator(output->backend);
+	if (allocator == NULL) {
+		wlr_log(WLR_ERROR, "Failed to get backend allocator");
+		return NULL;
+	}
+
+	int width = texture->width;
+	int height = texture->height;
+	if (output->impl->get_cursor_size) {
+		// Apply hardware limitations on buffer size
+		output->impl->get_cursor_size(cursor->output, &width, &height);
+		if ((int)texture->width > width || (int)texture->height > height) {
+			wlr_log(WLR_DEBUG, "Cursor texture too large (%dx%d), "
+				"exceeds hardware limitations (%dx%d)", texture->width,
+				texture->height, width, height);
+			return NULL;
+		}
+	}
+
+	if (output->cursor_swapchain == NULL ||
+			output->cursor_swapchain->width != width ||
+			output->cursor_swapchain->height != height) {
+		struct wlr_drm_format *format =
+			output_pick_cursor_format(output);
+		if (format == NULL) {
+			wlr_log(WLR_ERROR, "Failed to pick cursor format");
+			return NULL;
+		}
+
+		wlr_swapchain_destroy(output->cursor_swapchain);
+		output->cursor_swapchain = wlr_swapchain_create(allocator,
+			width, height, format);
+		if (output->cursor_swapchain == NULL) {
+			wlr_log(WLR_ERROR, "Failed to create cursor swapchain");
+			return NULL;
+		}
+	}
+
+	struct wlr_buffer *buffer =
+		wlr_swapchain_acquire(output->cursor_swapchain, NULL);
+	if (buffer == NULL) {
+		return NULL;
+	}
+
+	struct wlr_box cursor_box = {
+		.width = texture->width * output->scale / scale,
+		.height = texture->height * output->scale / scale,
+	};
+
+	float output_matrix[9];
+	wlr_matrix_identity(output_matrix);
+	if (output->transform != WL_OUTPUT_TRANSFORM_NORMAL) {
+		struct wlr_box tr_size = {
+			.width = buffer->width,
+			.height = buffer->height,
+		};
+		wlr_box_transform(&tr_size, &tr_size, output->transform, 0, 0);
+
+		wlr_matrix_translate(output_matrix, buffer->width / 2.0,
+			buffer->height / 2.0);
+		wlr_matrix_transform(output_matrix, output->transform);
+		wlr_matrix_translate(output_matrix, - tr_size.width / 2.0,
+			- tr_size.height / 2.0);
+	}
+
+	float matrix[9];
+	wlr_matrix_project_box(matrix, &cursor_box, transform, 0, output_matrix);
+
+	if (!wlr_renderer_begin_with_buffer(renderer, buffer)) {
+		wlr_buffer_unlock(buffer);
+		return NULL;
+	}
+
+	wlr_renderer_clear(renderer, (float[]){ 0.0, 0.0, 0.0, 0.0 });
+	wlr_render_texture_with_matrix(renderer, texture, matrix, 1.0);
+
+	wlr_renderer_end(renderer);
+
+	return buffer;
+}
+
+static bool output_cursor_attempt_hardware(struct wlr_output_cursor *cursor) {
+	struct wlr_output *output = cursor->output;
+
+	if (!output->impl->set_cursor ||
+			output->software_cursor_locks > 0) {
+		return false;
+	}
+
+	struct wlr_output_cursor *hwcur = output->hardware_cursor;
+	if (hwcur != NULL && hwcur != cursor) {
+		return false;
+	}
+
+	struct wlr_texture *texture = cursor->texture;
+	if (cursor->surface != NULL) {
+		// TODO: try using the surface buffer directly
+		texture = wlr_surface_get_texture(cursor->surface);
+	}
+
+	// If the cursor was hidden or was a software cursor, the hardware
+	// cursor position is outdated
+	output->impl->move_cursor(cursor->output,
+		(int)cursor->x, (int)cursor->y);
+
+	struct wlr_buffer *buffer = NULL;
+	if (texture != NULL) {
+		buffer = render_cursor_buffer(cursor);
+		if (buffer == NULL) {
+			wlr_log(WLR_ERROR, "Failed to render cursor buffer");
+			return false;
+		}
+	}
+
+	struct wlr_box hotspot = {
+		.x = cursor->hotspot_x,
+		.y = cursor->hotspot_y,
+	};
+	wlr_box_transform(&hotspot, &hotspot,
+		wlr_output_transform_invert(output->transform),
+		buffer ? buffer->width : 0, buffer ? buffer->height : 0);
+
+	bool ok = output->impl->set_cursor(cursor->output, buffer,
+		hotspot.x, hotspot.y);
+	if (ok) {
+		wlr_buffer_unlock(output->cursor_front_buffer);
+		output->cursor_front_buffer = buffer;
+		output->hardware_cursor = cursor;
+	} else {
+		wlr_buffer_unlock(buffer);
+	}
+	return ok;
+}
+
+bool wlr_output_cursor_set_image(struct wlr_output_cursor *cursor,
+		const uint8_t *pixels, int32_t stride, uint32_t width, uint32_t height,
+		int32_t hotspot_x, int32_t hotspot_y) {
+	struct wlr_renderer *renderer =
+		wlr_backend_get_renderer(cursor->output->backend);
+	if (!renderer) {
+		// if the backend has no renderer, we can't draw a cursor, but this is
+		// actually okay, for ex. with the noop backend
+		return true;
+	}
+
+	output_cursor_reset(cursor);
+
+	cursor->width = width;
+	cursor->height = height;
+	cursor->hotspot_x = hotspot_x;
+	cursor->hotspot_y = hotspot_y;
+	output_cursor_update_visible(cursor);
+
+	wlr_texture_destroy(cursor->texture);
+	cursor->texture = NULL;
+
+	cursor->enabled = false;
+	if (pixels != NULL) {
+		cursor->texture = wlr_texture_from_pixels(renderer,
+			DRM_FORMAT_ARGB8888, stride, width, height, pixels);
+		if (cursor->texture == NULL) {
+			return false;
+		}
+		cursor->enabled = true;
+	}
+
+	if (output_cursor_attempt_hardware(cursor)) {
+		return true;
+	}
+
+	wlr_log(WLR_DEBUG, "Falling back to software cursor on output '%s'",
+		cursor->output->name);
+	output_cursor_damage_whole(cursor);
+	return true;
+}
+
+static void output_cursor_commit(struct wlr_output_cursor *cursor,
+		bool update_hotspot) {
+	if (cursor->output->hardware_cursor != cursor) {
+		output_cursor_damage_whole(cursor);
+	}
+
+	struct wlr_surface *surface = cursor->surface;
+	assert(surface != NULL);
+
+	// Some clients commit a cursor surface with a NULL buffer to hide it.
+	cursor->enabled = wlr_surface_has_buffer(surface);
+	cursor->width = surface->current.width * cursor->output->scale;
+	cursor->height = surface->current.height * cursor->output->scale;
+	output_cursor_update_visible(cursor);
+	if (update_hotspot) {
+		cursor->hotspot_x -= surface->current.dx * cursor->output->scale;
+		cursor->hotspot_y -= surface->current.dy * cursor->output->scale;
+	}
+
+	if (output_cursor_attempt_hardware(cursor)) {
+		return;
+	}
+
+	// Fallback to software cursor
+	output_cursor_damage_whole(cursor);
+}
+
+static void output_cursor_handle_commit(struct wl_listener *listener,
+		void *data) {
+	struct wlr_output_cursor *cursor =
+		wl_container_of(listener, cursor, surface_commit);
+	output_cursor_commit(cursor, true);
+}
+
+static void output_cursor_handle_destroy(struct wl_listener *listener,
+		void *data) {
+	struct wlr_output_cursor *cursor = wl_container_of(listener, cursor,
+		surface_destroy);
+	output_cursor_reset(cursor);
+}
+
+void wlr_output_cursor_set_surface(struct wlr_output_cursor *cursor,
+		struct wlr_surface *surface, int32_t hotspot_x, int32_t hotspot_y) {
+	hotspot_x *= cursor->output->scale;
+	hotspot_y *= cursor->output->scale;
+
+	if (surface && surface == cursor->surface) {
+		// Only update the hotspot: surface hasn't changed
+
+		if (cursor->output->hardware_cursor != cursor) {
+			output_cursor_damage_whole(cursor);
+		}
+		cursor->hotspot_x = hotspot_x;
+		cursor->hotspot_y = hotspot_y;
+		if (cursor->output->hardware_cursor != cursor) {
+			output_cursor_damage_whole(cursor);
+		} else {
+			struct wlr_buffer *buffer = cursor->output->cursor_front_buffer;
+
+			struct wlr_box hotspot = {
+				.x = cursor->hotspot_x,
+				.y = cursor->hotspot_y,
+			};
+			wlr_box_transform(&hotspot, &hotspot,
+				wlr_output_transform_invert(cursor->output->transform),
+				buffer ? buffer->width : 0, buffer ? buffer->height : 0);
+
+			assert(cursor->output->impl->set_cursor);
+			cursor->output->impl->set_cursor(cursor->output,
+				buffer, hotspot.x, hotspot.y);
+		}
+		return;
+	}
+
+	output_cursor_reset(cursor);
+
+	cursor->surface = surface;
+	cursor->hotspot_x = hotspot_x;
+	cursor->hotspot_y = hotspot_y;
+
+	if (surface != NULL) {
+		wl_signal_add(&surface->events.commit, &cursor->surface_commit);
+		wl_signal_add(&surface->events.destroy, &cursor->surface_destroy);
+
+		cursor->visible = false;
+		output_cursor_commit(cursor, false);
+	} else {
+		cursor->enabled = false;
+		cursor->width = 0;
+		cursor->height = 0;
+
+		if (cursor->output->hardware_cursor == cursor) {
+			assert(cursor->output->impl->set_cursor);
+			cursor->output->impl->set_cursor(cursor->output, NULL, 0, 0);
+		}
+	}
+}
+
+bool wlr_output_cursor_move(struct wlr_output_cursor *cursor,
+		double x, double y) {
+	if (cursor->x == x && cursor->y == y) {
+		return true;
+	}
+
+	if (cursor->output->hardware_cursor != cursor) {
+		output_cursor_damage_whole(cursor);
+	}
+
+	bool was_visible = cursor->visible;
+	x *= cursor->output->scale;
+	y *= cursor->output->scale;
+	cursor->x = x;
+	cursor->y = y;
+	output_cursor_update_visible(cursor);
+
+	if (!was_visible && !cursor->visible) {
+		// Cursor is still hidden, do nothing
+		return true;
+	}
+
+	if (cursor->output->hardware_cursor != cursor) {
+		output_cursor_damage_whole(cursor);
+		return true;
+	}
+
+	assert(cursor->output->impl->move_cursor);
+	return cursor->output->impl->move_cursor(cursor->output, (int)x, (int)y);
+}
+
+struct wlr_output_cursor *wlr_output_cursor_create(struct wlr_output *output) {
+	struct wlr_output_cursor *cursor =
+		calloc(1, sizeof(struct wlr_output_cursor));
+	if (cursor == NULL) {
+		return NULL;
+	}
+	cursor->output = output;
+	wl_signal_init(&cursor->events.destroy);
+	wl_list_init(&cursor->surface_commit.link);
+	cursor->surface_commit.notify = output_cursor_handle_commit;
+	wl_list_init(&cursor->surface_destroy.link);
+	cursor->surface_destroy.notify = output_cursor_handle_destroy;
+	wl_list_insert(&output->cursors, &cursor->link);
+	cursor->visible = true; // default position is at (0, 0)
+	return cursor;
+}
+
+void wlr_output_cursor_destroy(struct wlr_output_cursor *cursor) {
+	if (cursor == NULL) {
+		return;
+	}
+	output_cursor_reset(cursor);
+	wlr_signal_emit_safe(&cursor->events.destroy, cursor);
+	if (cursor->output->hardware_cursor == cursor) {
+		// If this cursor was the hardware cursor, disable it
+		if (cursor->output->impl->set_cursor) {
+			cursor->output->impl->set_cursor(cursor->output, NULL, 0, 0);
+		}
+		cursor->output->hardware_cursor = NULL;
+	}
+	wlr_texture_destroy(cursor->texture);
+	wl_list_remove(&cursor->link);
+	free(cursor);
+}

types/output/output.c

@@ -0,0 +1,818 @@
+#define _POSIX_C_SOURCE 200809L
+#include <assert.h>
+#include <stdlib.h>
+#include <wlr/interfaces/wlr_output.h>
+#include <wlr/types/wlr_matrix.h>
+#include <wlr/types/wlr_surface.h>
+#include <wlr/util/log.h>
+#include "render/swapchain.h"
+#include "types/wlr_output.h"
+#include "util/global.h"
+#include "util/signal.h"
+
+#define OUTPUT_VERSION 3
+
+static void send_geometry(struct wl_resource *resource) {
+	struct wlr_output *output = wlr_output_from_resource(resource);
+	wl_output_send_geometry(resource, 0, 0,
+		output->phys_width, output->phys_height, output->subpixel,
+		output->make, output->model, output->transform);
+}
+
+static void send_current_mode(struct wl_resource *resource) {
+	struct wlr_output *output = wlr_output_from_resource(resource);
+	if (output->current_mode != NULL) {
+		struct wlr_output_mode *mode = output->current_mode;
+		wl_output_send_mode(resource, WL_OUTPUT_MODE_CURRENT,
+			mode->width, mode->height, mode->refresh);
+	} else {
+		// Output has no mode
+		wl_output_send_mode(resource, WL_OUTPUT_MODE_CURRENT, output->width,
+			output->height, output->refresh);
+	}
+}
+
+static void send_scale(struct wl_resource *resource) {
+	struct wlr_output *output = wlr_output_from_resource(resource);
+	uint32_t version = wl_resource_get_version(resource);
+	if (version >= WL_OUTPUT_SCALE_SINCE_VERSION) {
+		wl_output_send_scale(resource, (uint32_t)ceil(output->scale));
+	}
+}
+
+static void send_done(struct wl_resource *resource) {
+	uint32_t version = wl_resource_get_version(resource);
+	if (version >= WL_OUTPUT_DONE_SINCE_VERSION) {
+		wl_output_send_done(resource);
+	}
+}
+
+static void output_handle_resource_destroy(struct wl_resource *resource) {
+	wl_list_remove(wl_resource_get_link(resource));
+}
+
+static void output_handle_release(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static const struct wl_output_interface output_impl = {
+	.release = output_handle_release,
+};
+
+static void output_bind(struct wl_client *wl_client, void *data,
+		uint32_t version, uint32_t id) {
+	// `output` can be NULL if the output global is being destroyed
+	struct wlr_output *output = data;
+
+	struct wl_resource *resource = wl_resource_create(wl_client,
+		&wl_output_interface, version, id);
+	if (resource == NULL) {
+		wl_client_post_no_memory(wl_client);
+		return;
+	}
+	wl_resource_set_implementation(resource, &output_impl, output,
+		output_handle_resource_destroy);
+
+	if (output == NULL) {
+		wl_list_init(wl_resource_get_link(resource));
+		return;
+	}
+
+	wl_list_insert(&output->resources, wl_resource_get_link(resource));
+
+	send_geometry(resource);
+	send_current_mode(resource);
+	send_scale(resource);
+	send_done(resource);
+
+	struct wlr_output_event_bind evt = {
+		.output = output,
+		.resource = resource,
+	};
+
+	wlr_signal_emit_safe(&output->events.bind, &evt);
+}
+
+void wlr_output_create_global(struct wlr_output *output) {
+	if (output->global != NULL) {
+		return;
+	}
+	output->global = wl_global_create(output->display,
+		&wl_output_interface, OUTPUT_VERSION, output, output_bind);
+	if (output->global == NULL) {
+		wlr_log(WLR_ERROR, "Failed to allocate wl_output global");
+	}
+}
+
+void wlr_output_destroy_global(struct wlr_output *output) {
+	if (output->global == NULL) {
+		return;
+	}
+
+	// Make all output resources inert
+	struct wl_resource *resource, *tmp;
+	wl_resource_for_each_safe(resource, tmp, &output->resources) {
+		wl_resource_set_user_data(resource, NULL);
+		wl_list_remove(wl_resource_get_link(resource));
+		wl_list_init(wl_resource_get_link(resource));
+	}
+
+	wlr_global_destroy_safe(output->global, output->display);
+	output->global = NULL;
+}
+
+static void schedule_done_handle_idle_timer(void *data) {
+	struct wlr_output *output = data;
+	output->idle_done = NULL;
+
+	struct wl_resource *resource;
+	wl_resource_for_each(resource, &output->resources) {
+		uint32_t version = wl_resource_get_version(resource);
+		if (version >= WL_OUTPUT_DONE_SINCE_VERSION) {
+			wl_output_send_done(resource);
+		}
+	}
+}
+
+void wlr_output_schedule_done(struct wlr_output *output) {
+	if (output->idle_done != NULL) {
+		return; // Already scheduled
+	}
+
+	struct wl_event_loop *ev = wl_display_get_event_loop(output->display);
+	output->idle_done =
+		wl_event_loop_add_idle(ev, schedule_done_handle_idle_timer, output);
+}
+
+struct wlr_output *wlr_output_from_resource(struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource, &wl_output_interface,
+		&output_impl));
+	return wl_resource_get_user_data(resource);
+}
+
+void wlr_output_update_enabled(struct wlr_output *output, bool enabled) {
+	if (output->enabled == enabled) {
+		return;
+	}
+
+	output->enabled = enabled;
+	wlr_signal_emit_safe(&output->events.enable, output);
+}
+
+static void output_update_matrix(struct wlr_output *output) {
+	wlr_matrix_identity(output->transform_matrix);
+	if (output->transform != WL_OUTPUT_TRANSFORM_NORMAL) {
+		int tr_width, tr_height;
+		wlr_output_transformed_resolution(output, &tr_width, &tr_height);
+
+		wlr_matrix_translate(output->transform_matrix,
+			output->width / 2.0, output->height / 2.0);
+		wlr_matrix_transform(output->transform_matrix, output->transform);
+		wlr_matrix_translate(output->transform_matrix,
+			- tr_width / 2.0, - tr_height / 2.0);
+	}
+}
+
+void wlr_output_enable(struct wlr_output *output, bool enable) {
+	if (output->enabled == enable) {
+		output->pending.committed &= ~WLR_OUTPUT_STATE_ENABLED;
+		return;
+	}
+
+	output->pending.committed |= WLR_OUTPUT_STATE_ENABLED;
+	output->pending.enabled = enable;
+}
+
+static void output_state_clear_mode(struct wlr_output_state *state) {
+	if (!(state->committed & WLR_OUTPUT_STATE_MODE)) {
+		return;
+	}
+
+	state->mode = NULL;
+
+	state->committed &= ~WLR_OUTPUT_STATE_MODE;
+}
+
+void wlr_output_set_mode(struct wlr_output *output,
+		struct wlr_output_mode *mode) {
+	output_state_clear_mode(&output->pending);
+
+	if (output->current_mode == mode) {
+		return;
+	}
+
+	output->pending.committed |= WLR_OUTPUT_STATE_MODE;
+	output->pending.mode_type = WLR_OUTPUT_STATE_MODE_FIXED;
+	output->pending.mode = mode;
+}
+
+void wlr_output_set_custom_mode(struct wlr_output *output, int32_t width,
+		int32_t height, int32_t refresh) {
+	output_state_clear_mode(&output->pending);
+
+	if (output->width == width && output->height == height &&
+			output->refresh == refresh) {
+		return;
+	}
+
+	output->pending.committed |= WLR_OUTPUT_STATE_MODE;
+	output->pending.mode_type = WLR_OUTPUT_STATE_MODE_CUSTOM;
+	output->pending.custom_mode.width = width;
+	output->pending.custom_mode.height = height;
+	output->pending.custom_mode.refresh = refresh;
+}
+
+void wlr_output_update_mode(struct wlr_output *output,
+		struct wlr_output_mode *mode) {
+	output->current_mode = mode;
+	if (mode != NULL) {
+		wlr_output_update_custom_mode(output, mode->width, mode->height,
+			mode->refresh);
+	} else {
+		wlr_output_update_custom_mode(output, 0, 0, 0);
+	}
+}
+
+void wlr_output_update_custom_mode(struct wlr_output *output, int32_t width,
+		int32_t height, int32_t refresh) {
+	if (output->width == width && output->height == height &&
+			output->refresh == refresh) {
+		return;
+	}
+
+	output->width = width;
+	output->height = height;
+	output_update_matrix(output);
+
+	output->refresh = refresh;
+
+	if (output->swapchain != NULL &&
+			(output->swapchain->width != output->width ||
+			output->swapchain->height != output->height)) {
+		wlr_swapchain_destroy(output->swapchain);
+		output->swapchain = NULL;
+	}
+
+	struct wl_resource *resource;
+	wl_resource_for_each(resource, &output->resources) {
+		send_current_mode(resource);
+	}
+	wlr_output_schedule_done(output);
+
+	wlr_signal_emit_safe(&output->events.mode, output);
+}
+
+void wlr_output_set_transform(struct wlr_output *output,
+		enum wl_output_transform transform) {
+	if (output->transform == transform) {
+		output->pending.committed &= ~WLR_OUTPUT_STATE_TRANSFORM;
+		return;
+	}
+
+	output->pending.committed |= WLR_OUTPUT_STATE_TRANSFORM;
+	output->pending.transform = transform;
+}
+
+void wlr_output_set_scale(struct wlr_output *output, float scale) {
+	if (output->scale == scale) {
+		output->pending.committed &= ~WLR_OUTPUT_STATE_SCALE;
+		return;
+	}
+
+	output->pending.committed |= WLR_OUTPUT_STATE_SCALE;
+	output->pending.scale = scale;
+}
+
+void wlr_output_enable_adaptive_sync(struct wlr_output *output, bool enabled) {
+	bool currently_enabled =
+		output->adaptive_sync_status != WLR_OUTPUT_ADAPTIVE_SYNC_DISABLED;
+	if (currently_enabled == enabled) {
+		output->pending.committed &= ~WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED;
+		return;
+	}
+
+	output->pending.committed |= WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED;
+	output->pending.adaptive_sync_enabled = enabled;
+}
+
+void wlr_output_set_subpixel(struct wlr_output *output,
+		enum wl_output_subpixel subpixel) {
+	if (output->subpixel == subpixel) {
+		return;
+	}
+
+	output->subpixel = subpixel;
+
+	struct wl_resource *resource;
+	wl_resource_for_each(resource, &output->resources) {
+		send_geometry(resource);
+	}
+	wlr_output_schedule_done(output);
+}
+
+void wlr_output_set_description(struct wlr_output *output, const char *desc) {
+	if (output->description != NULL && desc != NULL &&
+			strcmp(output->description, desc) == 0) {
+		return;
+	}
+
+	free(output->description);
+	if (desc != NULL) {
+		output->description = strdup(desc);
+	} else {
+		output->description = NULL;
+	}
+
+	wlr_signal_emit_safe(&output->events.description, output);
+}
+
+static void handle_display_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_output *output =
+		wl_container_of(listener, output, display_destroy);
+	wlr_output_destroy_global(output);
+}
+
+void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,
+		const struct wlr_output_impl *impl, struct wl_display *display) {
+	assert(impl->commit);
+	if (impl->set_cursor || impl->move_cursor) {
+		assert(impl->set_cursor && impl->move_cursor);
+	}
+	output->backend = backend;
+	output->impl = impl;
+	output->display = display;
+	wl_list_init(&output->modes);
+	output->transform = WL_OUTPUT_TRANSFORM_NORMAL;
+	output->scale = 1;
+	output->commit_seq = 0;
+	wl_list_init(&output->cursors);
+	wl_list_init(&output->resources);
+	wl_signal_init(&output->events.frame);
+	wl_signal_init(&output->events.damage);
+	wl_signal_init(&output->events.needs_frame);
+	wl_signal_init(&output->events.precommit);
+	wl_signal_init(&output->events.commit);
+	wl_signal_init(&output->events.present);
+	wl_signal_init(&output->events.bind);
+	wl_signal_init(&output->events.enable);
+	wl_signal_init(&output->events.mode);
+	wl_signal_init(&output->events.description);
+	wl_signal_init(&output->events.destroy);
+	pixman_region32_init(&output->pending.damage);
+
+	const char *no_hardware_cursors = getenv("WLR_NO_HARDWARE_CURSORS");
+	if (no_hardware_cursors != NULL && strcmp(no_hardware_cursors, "1") == 0) {
+		wlr_log(WLR_DEBUG,
+			"WLR_NO_HARDWARE_CURSORS set, forcing software cursors");
+		output->software_cursor_locks = 1;
+	}
+
+	wlr_addon_set_init(&output->addons);
+
+	output->display_destroy.notify = handle_display_destroy;
+	wl_display_add_destroy_listener(display, &output->display_destroy);
+}
+
+void wlr_output_destroy(struct wlr_output *output) {
+	if (!output) {
+		return;
+	}
+
+	wlr_buffer_unlock(output->front_buffer);
+	output->front_buffer = NULL;
+
+	wl_list_remove(&output->display_destroy.link);
+	wlr_output_destroy_global(output);
+	output_clear_back_buffer(output);
+
+	wlr_signal_emit_safe(&output->events.destroy, output);
+	wlr_addon_set_finish(&output->addons);
+
+	// The backend is responsible for free-ing the list of modes
+
+	struct wlr_output_cursor *cursor, *tmp_cursor;
+	wl_list_for_each_safe(cursor, tmp_cursor, &output->cursors, link) {
+		wlr_output_cursor_destroy(cursor);
+	}
+
+	wlr_swapchain_destroy(output->cursor_swapchain);
+	wlr_buffer_unlock(output->cursor_front_buffer);
+
+	wlr_swapchain_destroy(output->swapchain);
+
+	if (output->idle_frame != NULL) {
+		wl_event_source_remove(output->idle_frame);
+	}
+
+	if (output->idle_done != NULL) {
+		wl_event_source_remove(output->idle_done);
+	}
+
+	free(output->description);
+
+	pixman_region32_fini(&output->pending.damage);
+
+	if (output->impl && output->impl->destroy) {
+		output->impl->destroy(output);
+	} else {
+		free(output);
+	}
+}
+
+void wlr_output_transformed_resolution(struct wlr_output *output,
+		int *width, int *height) {
+	if (output->transform % 2 == 0) {
+		*width = output->width;
+		*height = output->height;
+	} else {
+		*width = output->height;
+		*height = output->width;
+	}
+}
+
+void wlr_output_effective_resolution(struct wlr_output *output,
+		int *width, int *height) {
+	wlr_output_transformed_resolution(output, width, height);
+	*width /= output->scale;
+	*height /= output->scale;
+}
+
+struct wlr_output_mode *wlr_output_preferred_mode(struct wlr_output *output) {
+	if (wl_list_empty(&output->modes)) {
+		return NULL;
+	}
+
+	struct wlr_output_mode *mode;
+	wl_list_for_each(mode, &output->modes, link) {
+		if (mode->preferred) {
+			return mode;
+		}
+	}
+
+	// No preferred mode, choose the first one
+	return wl_container_of(output->modes.next, mode, link);
+}
+
+static void output_state_clear_buffer(struct wlr_output_state *state) {
+	if (!(state->committed & WLR_OUTPUT_STATE_BUFFER)) {
+		return;
+	}
+
+	wlr_buffer_unlock(state->buffer);
+	state->buffer = NULL;
+
+	state->committed &= ~WLR_OUTPUT_STATE_BUFFER;
+}
+
+void wlr_output_set_damage(struct wlr_output *output,
+		pixman_region32_t *damage) {
+	pixman_region32_intersect_rect(&output->pending.damage, damage,
+		0, 0, output->width, output->height);
+	output->pending.committed |= WLR_OUTPUT_STATE_DAMAGE;
+}
+
+static void output_state_clear_gamma_lut(struct wlr_output_state *state) {
+	free(state->gamma_lut);
+	state->gamma_lut = NULL;
+	state->committed &= ~WLR_OUTPUT_STATE_GAMMA_LUT;
+}
+
+static void output_state_clear(struct wlr_output_state *state) {
+	output_state_clear_buffer(state);
+	output_state_clear_gamma_lut(state);
+	pixman_region32_clear(&state->damage);
+	state->committed = 0;
+}
+
+void output_pending_resolution(struct wlr_output *output, int *width,
+		int *height) {
+	if (output->pending.committed & WLR_OUTPUT_STATE_MODE) {
+		switch (output->pending.mode_type) {
+		case WLR_OUTPUT_STATE_MODE_FIXED:
+			*width = output->pending.mode->width;
+			*height = output->pending.mode->height;
+			return;
+		case WLR_OUTPUT_STATE_MODE_CUSTOM:
+			*width = output->pending.custom_mode.width;
+			*height = output->pending.custom_mode.height;
+			return;
+		}
+		abort();
+	} else {
+		*width = output->width;
+		*height = output->height;
+	}
+}
+
+static bool output_basic_test(struct wlr_output *output) {
+	if (output->pending.committed & WLR_OUTPUT_STATE_BUFFER) {
+		if (output->frame_pending) {
+			wlr_log(WLR_DEBUG, "Tried to commit a buffer while a frame is pending");
+			return false;
+		}
+
+		if (output->back_buffer == NULL) {
+			if (output->attach_render_locks > 0) {
+				wlr_log(WLR_DEBUG, "Direct scan-out disabled by lock");
+				return false;
+			}
+
+			// If the output has at least one software cursor, refuse to attach the
+			// buffer
+			struct wlr_output_cursor *cursor;
+			wl_list_for_each(cursor, &output->cursors, link) {
+				if (cursor->enabled && cursor->visible &&
+						cursor != output->hardware_cursor) {
+					wlr_log(WLR_DEBUG,
+						"Direct scan-out disabled by software cursor");
+					return false;
+				}
+			}
+
+			// If the size doesn't match, reject buffer (scaling is not
+			// supported)
+			int pending_width, pending_height;
+			output_pending_resolution(output, &pending_width, &pending_height);
+			if (output->pending.buffer->width != pending_width ||
+					output->pending.buffer->height != pending_height) {
+				wlr_log(WLR_DEBUG, "Direct scan-out buffer size mismatch");
+				return false;
+			}
+		}
+	}
+
+	bool enabled = output->enabled;
+	if (output->pending.committed & WLR_OUTPUT_STATE_ENABLED) {
+		enabled = output->pending.enabled;
+	}
+
+	if (!enabled && output->pending.committed & WLR_OUTPUT_STATE_BUFFER) {
+		wlr_log(WLR_DEBUG, "Tried to commit a buffer on a disabled output");
+		return false;
+	}
+	if (!enabled && output->pending.committed & WLR_OUTPUT_STATE_MODE) {
+		wlr_log(WLR_DEBUG, "Tried to modeset a disabled output");
+		return false;
+	}
+	if (!enabled && output->pending.committed & WLR_OUTPUT_STATE_ADAPTIVE_SYNC_ENABLED) {
+		wlr_log(WLR_DEBUG, "Tried to enable adaptive sync on a disabled output");
+		return false;
+	}
+	if (!enabled && output->pending.committed & WLR_OUTPUT_STATE_GAMMA_LUT) {
+		wlr_log(WLR_DEBUG, "Tried to set the gamma lut on a disabled output");
+		return false;
+	}
+
+	return true;
+}
+
+bool wlr_output_test(struct wlr_output *output) {
+	if (!output_basic_test(output)) {
+		return false;
+	}
+	if (!output_ensure_buffer(output)) {
+		return false;
+	}
+	if (!output->impl->test) {
+		return true;
+	}
+	return output->impl->test(output);
+}
+
+bool wlr_output_commit(struct wlr_output *output) {
+	if (!output_basic_test(output)) {
+		wlr_log(WLR_ERROR, "Basic output test failed for %s", output->name);
+		return false;
+	}
+
+	if (!output_ensure_buffer(output)) {
+		return false;
+	}
+
+	if ((output->pending.committed & WLR_OUTPUT_STATE_BUFFER) &&
+			output->idle_frame != NULL) {
+		wl_event_source_remove(output->idle_frame);
+		output->idle_frame = NULL;
+	}
+
+	struct timespec now;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
+	struct wlr_output_event_precommit pre_event = {
+		.output = output,
+		.when = &now,
+	};
+	wlr_signal_emit_safe(&output->events.precommit, &pre_event);
+
+	// output_clear_back_buffer detaches the buffer from the renderer. This is
+	// important to do before calling impl->commit(), because this marks an
+	// implicit rendering synchronization point. The backend needs it to avoid
+	// displaying a buffer when asynchronous GPU work isn't finished.
+	struct wlr_buffer *back_buffer = NULL;
+	if ((output->pending.committed & WLR_OUTPUT_STATE_BUFFER) &&
+			output->back_buffer != NULL) {
+		back_buffer = wlr_buffer_lock(output->back_buffer);
+		output_clear_back_buffer(output);
+	}
+
+	if (!output->impl->commit(output)) {
+		wlr_buffer_unlock(back_buffer);
+		output_state_clear(&output->pending);
+		return false;
+	}
+
+	if (output->pending.committed & WLR_OUTPUT_STATE_BUFFER) {
+		struct wlr_output_cursor *cursor;
+		wl_list_for_each(cursor, &output->cursors, link) {
+			if (!cursor->enabled || !cursor->visible || cursor->surface == NULL) {
+				continue;
+			}
+			wlr_surface_send_frame_done(cursor->surface, &now);
+		}
+	}
+
+	output->commit_seq++;
+
+	bool scale_updated = output->pending.committed & WLR_OUTPUT_STATE_SCALE;
+	if (scale_updated) {
+		output->scale = output->pending.scale;
+	}
+
+	if (output->pending.committed & WLR_OUTPUT_STATE_TRANSFORM) {
+		output->transform = output->pending.transform;
+		output_update_matrix(output);
+	}
+
+	bool geometry_updated = output->pending.committed &
+		(WLR_OUTPUT_STATE_MODE | WLR_OUTPUT_STATE_TRANSFORM);
+	if (geometry_updated || scale_updated) {
+		struct wl_resource *resource;
+		wl_resource_for_each(resource, &output->resources) {
+			if (geometry_updated) {
+				send_geometry(resource);
+			}
+			if (scale_updated) {
+				send_scale(resource);
+			}
+		}
+		wlr_output_schedule_done(output);
+	}
+
+	// Unset the front-buffer when a new buffer will replace it or when the
+	// output is getting disabled
+	if ((output->pending.committed & WLR_OUTPUT_STATE_BUFFER) ||
+			((output->pending.committed & WLR_OUTPUT_STATE_ENABLED) &&
+				!output->pending.enabled)) {
+		wlr_buffer_unlock(output->front_buffer);
+		output->front_buffer = NULL;
+	}
+
+	if (output->pending.committed & WLR_OUTPUT_STATE_BUFFER) {
+		output->frame_pending = true;
+		output->needs_frame = false;
+	}
+
+	if (back_buffer != NULL) {
+		wlr_swapchain_set_buffer_submitted(output->swapchain, back_buffer);
+		wlr_buffer_unlock(output->front_buffer);
+		output->front_buffer = back_buffer;
+	}
+
+	uint32_t committed = output->pending.committed;
+	output_state_clear(&output->pending);
+
+	struct wlr_output_event_commit event = {
+		.output = output,
+		.committed = committed,
+		.when = &now,
+	};
+	wlr_signal_emit_safe(&output->events.commit, &event);
+
+	return true;
+}
+
+void wlr_output_rollback(struct wlr_output *output) {
+	output_clear_back_buffer(output);
+	output_state_clear(&output->pending);
+}
+
+void wlr_output_attach_buffer(struct wlr_output *output,
+		struct wlr_buffer *buffer) {
+	output_state_clear_buffer(&output->pending);
+	output->pending.committed |= WLR_OUTPUT_STATE_BUFFER;
+	output->pending.buffer = wlr_buffer_lock(buffer);
+}
+
+void wlr_output_send_frame(struct wlr_output *output) {
+	output->frame_pending = false;
+	if (output->enabled) {
+		wlr_signal_emit_safe(&output->events.frame, output);
+	}
+}
+
+static void schedule_frame_handle_idle_timer(void *data) {
+	struct wlr_output *output = data;
+	output->idle_frame = NULL;
+	if (!output->frame_pending) {
+		wlr_output_send_frame(output);
+	}
+}
+
+void wlr_output_schedule_frame(struct wlr_output *output) {
+	// Make sure the compositor commits a new frame. This is necessary to make
+	// clients which ask for frame callbacks without submitting a new buffer
+	// work.
+	wlr_output_update_needs_frame(output);
+
+	if (output->frame_pending || output->idle_frame != NULL) {
+		return;
+	}
+
+	// We're using an idle timer here in case a buffer swap happens right after
+	// this function is called
+	struct wl_event_loop *ev = wl_display_get_event_loop(output->display);
+	output->idle_frame =
+		wl_event_loop_add_idle(ev, schedule_frame_handle_idle_timer, output);
+}
+
+void wlr_output_send_present(struct wlr_output *output,
+		struct wlr_output_event_present *event) {
+	assert(event);
+	event->output = output;
+
+	if (event->presented && event->when == NULL) {
+		struct timespec now;
+		clockid_t clock = wlr_backend_get_presentation_clock(output->backend);
+		errno = 0;
+		if (clock_gettime(clock, &now) != 0) {
+			wlr_log_errno(WLR_ERROR, "failed to send output present event: "
+				"failed to read clock");
+			return;
+		}
+		event->when = &now;
+	}
+
+	wlr_signal_emit_safe(&output->events.present, event);
+}
+
+void wlr_output_set_gamma(struct wlr_output *output, size_t size,
+		const uint16_t *r, const uint16_t *g, const uint16_t *b) {
+	output_state_clear_gamma_lut(&output->pending);
+
+	output->pending.gamma_lut_size = size;
+	output->pending.gamma_lut = malloc(3 * size * sizeof(uint16_t));
+	if (output->pending.gamma_lut == NULL) {
+		wlr_log_errno(WLR_ERROR, "Allocation failed");
+		return;
+	}
+	memcpy(output->pending.gamma_lut, r, size * sizeof(uint16_t));
+	memcpy(output->pending.gamma_lut + size, g, size * sizeof(uint16_t));
+	memcpy(output->pending.gamma_lut + 2 * size, b, size * sizeof(uint16_t));
+
+	output->pending.committed |= WLR_OUTPUT_STATE_GAMMA_LUT;
+}
+
+size_t wlr_output_get_gamma_size(struct wlr_output *output) {
+	if (!output->impl->get_gamma_size) {
+		return 0;
+	}
+	return output->impl->get_gamma_size(output);
+}
+
+bool wlr_output_export_dmabuf(struct wlr_output *output,
+		struct wlr_dmabuf_attributes *attribs) {
+	if (output->front_buffer == NULL) {
+		return false;
+	}
+
+	struct wlr_dmabuf_attributes buf_attribs = {0};
+	if (!wlr_buffer_get_dmabuf(output->front_buffer, &buf_attribs)) {
+		return false;
+	}
+	return wlr_dmabuf_attributes_copy(attribs, &buf_attribs);
+}
+
+void wlr_output_update_needs_frame(struct wlr_output *output) {
+	if (output->needs_frame) {
+		return;
+	}
+	output->needs_frame = true;
+	wlr_signal_emit_safe(&output->events.needs_frame, output);
+}
+
+void wlr_output_damage_whole(struct wlr_output *output) {
+	int width, height;
+	wlr_output_transformed_resolution(output, &width, &height);
+
+	pixman_region32_t damage;
+	pixman_region32_init_rect(&damage, 0, 0, width, height);
+
+	struct wlr_output_event_damage event = {
+		.output = output,
+		.damage = &damage,
+	};
+	wlr_signal_emit_safe(&output->events.damage, &event);
+
+	pixman_region32_fini(&damage);
+}

types/output/render.c

@@ -0,0 +1,281 @@
+#include <assert.h>
+#include <drm_fourcc.h>
+#include <stdlib.h>
+#include <wlr/interfaces/wlr_output.h>
+#include <wlr/render/interface.h>
+#include <wlr/util/log.h>
+#include "backend/backend.h"
+#include "render/allocator/allocator.h"
+#include "render/drm_format_set.h"
+#include "render/swapchain.h"
+#include "render/wlr_renderer.h"
+#include "types/wlr_output.h"
+
+/**
+ * Ensure the output has a suitable swapchain. The swapchain is re-created if
+ * necessary.
+ *
+ * If allow_modifiers is set to true, the swapchain's format may use modifiers.
+ * If set to false, the swapchain's format is guaranteed to not use modifiers.
+ */
+static bool output_create_swapchain(struct wlr_output *output,
+		bool allow_modifiers) {
+	int width, height;
+	output_pending_resolution(output, &width, &height);
+
+	if (output->swapchain != NULL && output->swapchain->width == width &&
+			output->swapchain->height == height &&
+			(allow_modifiers || output->swapchain->format->len == 0)) {
+		return true;
+	}
+
+	struct wlr_allocator *allocator = backend_get_allocator(output->backend);
+	if (allocator == NULL) {
+		wlr_log(WLR_ERROR, "Failed to get backend allocator");
+		return false;
+	}
+
+	const struct wlr_drm_format_set *display_formats = NULL;
+	if (output->impl->get_primary_formats) {
+		display_formats =
+			output->impl->get_primary_formats(output, allocator->buffer_caps);
+		if (display_formats == NULL) {
+			wlr_log(WLR_ERROR, "Failed to get primary display formats");
+			return false;
+		}
+	}
+
+	struct wlr_drm_format *format = output_pick_format(output, display_formats);
+	if (format == NULL) {
+		wlr_log(WLR_ERROR, "Failed to pick primary buffer format for output '%s'",
+			output->name);
+		return false;
+	}
+	wlr_log(WLR_DEBUG, "Choosing primary buffer format 0x%"PRIX32" for output '%s'",
+		format->format, output->name);
+
+	if (!allow_modifiers && (format->len != 1 || format->modifiers[0] != DRM_FORMAT_MOD_LINEAR)) {
+		format->len = 0;
+	}
+
+	struct wlr_swapchain *swapchain =
+		wlr_swapchain_create(allocator, width, height, format);
+	free(format);
+	if (swapchain == NULL) {
+		wlr_log(WLR_ERROR, "Failed to create output swapchain");
+		return false;
+	}
+
+	wlr_swapchain_destroy(output->swapchain);
+	output->swapchain = swapchain;
+
+	return true;
+}
+
+static bool output_attach_back_buffer(struct wlr_output *output,
+		int *buffer_age) {
+	assert(output->back_buffer == NULL);
+
+	if (!output_create_swapchain(output, true)) {
+		return false;
+	}
+
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	assert(renderer != NULL);
+
+	struct wlr_buffer *buffer =
+		wlr_swapchain_acquire(output->swapchain, buffer_age);
+	if (buffer == NULL) {
+		return false;
+	}
+
+	if (!renderer_bind_buffer(renderer, buffer)) {
+		wlr_buffer_unlock(buffer);
+		return false;
+	}
+
+	output->back_buffer = buffer;
+	return true;
+}
+
+void output_clear_back_buffer(struct wlr_output *output) {
+	if (output->back_buffer == NULL) {
+		return;
+	}
+
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	assert(renderer != NULL);
+
+	renderer_bind_buffer(renderer, NULL);
+
+	wlr_buffer_unlock(output->back_buffer);
+	output->back_buffer = NULL;
+}
+
+bool wlr_output_attach_render(struct wlr_output *output, int *buffer_age) {
+	if (!output_attach_back_buffer(output, buffer_age)) {
+		return false;
+	}
+	wlr_output_attach_buffer(output, output->back_buffer);
+	return true;
+}
+
+static bool output_attach_empty_buffer(struct wlr_output *output) {
+	assert(!(output->pending.committed & WLR_OUTPUT_STATE_BUFFER));
+
+	if (!wlr_output_attach_render(output, NULL)) {
+		return false;
+	}
+
+	int width, height;
+	output_pending_resolution(output, &width, &height);
+
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	wlr_renderer_begin(renderer, width, height);
+	wlr_renderer_clear(renderer, (float[]){0, 0, 0, 0});
+	wlr_renderer_end(renderer);
+
+	return true;
+}
+
+bool output_ensure_buffer(struct wlr_output *output) {
+	// If we're lighting up an output or changing its mode, make sure to
+	// provide a new buffer
+	bool needs_new_buffer = false;
+	if ((output->pending.committed & WLR_OUTPUT_STATE_ENABLED) &&
+			output->pending.enabled) {
+		needs_new_buffer = true;
+	}
+	if (output->pending.committed & WLR_OUTPUT_STATE_MODE) {
+		needs_new_buffer = true;
+	}
+	if (!needs_new_buffer ||
+			(output->pending.committed & WLR_OUTPUT_STATE_BUFFER)) {
+		return true;
+	}
+
+	// If the backend doesn't necessarily need a new buffer on modeset, don't
+	// bother allocating one.
+	if (!output->impl->test || output->impl->test(output)) {
+		return true;
+	}
+
+	wlr_log(WLR_DEBUG, "Attaching empty buffer to output for modeset");
+
+	if (!output_attach_empty_buffer(output)) {
+		goto error;
+	}
+	if (!output->impl->test || output->impl->test(output)) {
+		return true;
+	}
+
+	output_clear_back_buffer(output);
+	output->pending.committed &= ~WLR_OUTPUT_STATE_BUFFER;
+
+	if (output->swapchain->format->len == 0) {
+		return false;
+	}
+
+	// The test failed for a buffer which has modifiers, try disabling
+	// modifiers to see if that makes a difference.
+	wlr_log(WLR_DEBUG, "Output modeset test failed, retrying without modifiers");
+
+	if (!output_create_swapchain(output, false)) {
+		return false;
+	}
+	if (!output_attach_empty_buffer(output)) {
+		goto error;
+	}
+	if (!output->impl->test(output)) {
+		goto error;
+	}
+	return true;
+
+error:
+	output_clear_back_buffer(output);
+	output->pending.committed &= ~WLR_OUTPUT_STATE_BUFFER;
+	return false;
+}
+
+void wlr_output_lock_attach_render(struct wlr_output *output, bool lock) {
+	if (lock) {
+		++output->attach_render_locks;
+	} else {
+		assert(output->attach_render_locks > 0);
+		--output->attach_render_locks;
+	}
+	wlr_log(WLR_DEBUG, "%s direct scan-out on output '%s' (locks: %d)",
+		lock ? "Disabling" : "Enabling", output->name,
+		output->attach_render_locks);
+}
+
+struct wlr_drm_format *output_pick_format(struct wlr_output *output,
+		const struct wlr_drm_format_set *display_formats) {
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	struct wlr_allocator *allocator = backend_get_allocator(output->backend);
+	assert(renderer != NULL && allocator != NULL);
+
+	const struct wlr_drm_format_set *render_formats =
+		wlr_renderer_get_render_formats(renderer);
+	if (render_formats == NULL) {
+		wlr_log(WLR_ERROR, "Failed to get render formats");
+		return NULL;
+	}
+
+	struct wlr_drm_format *format = NULL;
+	const uint32_t candidates[] = { DRM_FORMAT_ARGB8888, DRM_FORMAT_XRGB8888 };
+	for (size_t i = 0; i < sizeof(candidates) / sizeof(candidates[0]); i++) {
+		uint32_t fmt = candidates[i];
+
+		const struct wlr_drm_format *render_format =
+			wlr_drm_format_set_get(render_formats, fmt);
+		if (render_format == NULL) {
+			wlr_log(WLR_DEBUG, "Renderer doesn't support format 0x%"PRIX32, fmt);
+			continue;
+		}
+
+		if (display_formats != NULL) {
+			const struct wlr_drm_format *display_format =
+				wlr_drm_format_set_get(display_formats, fmt);
+			if (display_format == NULL) {
+				wlr_log(WLR_DEBUG, "Output doesn't support format 0x%"PRIX32, fmt);
+				continue;
+			}
+			format = wlr_drm_format_intersect(display_format, render_format);
+		} else {
+			// The output can display any format
+			format = wlr_drm_format_dup(render_format);
+		}
+
+		if (format == NULL) {
+			wlr_log(WLR_DEBUG, "Failed to intersect display and render "
+				"modifiers for format 0x%"PRIX32, fmt);
+		} else {
+			break;
+		}
+	}
+	if (format == NULL) {
+		wlr_log(WLR_ERROR, "Failed to choose a format for output '%s'",
+			output->name);
+		return NULL;
+	}
+
+	return format;
+}
+
+uint32_t wlr_output_preferred_read_format(struct wlr_output *output) {
+	struct wlr_renderer *renderer = wlr_backend_get_renderer(output->backend);
+	if (!renderer->impl->preferred_read_format || !renderer->impl->read_pixels) {
+		return DRM_FORMAT_INVALID;
+	}
+
+	if (!output_attach_back_buffer(output, NULL)) {
+		return false;
+	}
+
+	uint32_t fmt = renderer->impl->preferred_read_format(renderer);
+
+	output_clear_back_buffer(output);
+
+	return fmt;
+}

types/output/transform.c

@@ -0,0 +1,25 @@
+#include <wlr/types/wlr_output.h>
+
+enum wl_output_transform wlr_output_transform_invert(
+		enum wl_output_transform tr) {
+	if ((tr & WL_OUTPUT_TRANSFORM_90) && !(tr & WL_OUTPUT_TRANSFORM_FLIPPED)) {
+		tr ^= WL_OUTPUT_TRANSFORM_180;
+	}
+	return tr;
+}
+
+enum wl_output_transform wlr_output_transform_compose(
+		enum wl_output_transform tr_a, enum wl_output_transform tr_b) {
+	uint32_t flipped = (tr_a ^ tr_b) & WL_OUTPUT_TRANSFORM_FLIPPED;
+	uint32_t rotation_mask = WL_OUTPUT_TRANSFORM_90 | WL_OUTPUT_TRANSFORM_180;
+	uint32_t rotated;
+	if (tr_b & WL_OUTPUT_TRANSFORM_FLIPPED) {
+		// When a rotation of k degrees is followed by a flip, the
+		// equivalent transform is a flip followed by a rotation of
+		// -k degrees.
+		rotated = (tr_b - tr_a) & rotation_mask;
+	} else {
+		rotated = (tr_a + tr_b) & rotation_mask;
+	}
+	return flipped | rotated;
+}