output-swapchain: new helper

Closes: swaywm#3079

include/types/wlr_output_swapchain.h

@@ -0,0 +1,9 @@
+#ifndef TYPES_WLR_OUTPUT_SWAPCHAIN_H
+#define TYPES_WLR_OUTPUT_SWAPCHAIN_H
+
+#include <wlr/types/wlr_output_swapchain.h>
+
+struct wlr_output_swapchain_manager *wlr_output_swapchain_manager_create(
+	struct wlr_renderer *renderer, struct wlr_allocator *allocator);
+
+#endif

include/wlr/types/wlr_output_swapchain.h

@@ -0,0 +1,48 @@
+/*
+ * This an unstable interface of wlroots. No guarantees are made regarding the
+ * future consistency of this API.
+ */
+#ifndef WLR_USE_UNSTABLE
+#error "Add -DWLR_USE_UNSTABLE to enable unstable wlroots features"
+#endif
+
+#ifndef WLR_TYPES_WLR_OUTPUT_SWAPCHAIN_H
+#define WLR_TYPES_WLR_OUTPUT_SWAPCHAIN_H
+
+#include <wayland-util.h>
+
+struct wlr_output;
+
+struct wlr_output_swapchain_manager {
+	struct wlr_renderer *renderer;
+
+	// private state
+
+	struct wlr_allocator *allocator;
+};
+
+struct wlr_output_swapchain {
+	struct wlr_output *output;
+	struct wlr_output_swapchain_manager *manager;
+	struct wlr_swapchain *swapchain;
+
+	// private state
+
+	struct wlr_buffer *back_buffer;
+
+	struct wl_listener output_destroy;
+};
+
+struct wlr_output_swapchain_manager *wlr_output_swapchain_manager_autocreate(
+	struct wlr_backend *backend);
+void wlr_output_swapchain_manager_destroy(
+	struct wlr_output_swapchain_manager *manager);
+
+struct wlr_output_swapchain *wlr_output_swapchain_create(
+	struct wlr_output_swapchain_manager *manager, struct wlr_output *output);
+void wlr_output_swapchain_destroy(struct wlr_output_swapchain *output_swapchain);
+bool wlr_output_swapchain_begin(struct wlr_output_swapchain *output_swapchain,
+	int *buffer_age);
+void wlr_output_swapchain_end(struct wlr_output_swapchain *output_swapchain);
+
+#endif

types/meson.build

@@ -43,6 +43,7 @@ wlr_files += files(
 	'wlr_output_layout.c',
 	'wlr_output_management_v1.c',
 	'wlr_output_power_management_v1.c',
+	'wlr_output_swapchain.c',
 	'wlr_output.c',
 	'wlr_pointer_constraints_v1.c',
 	'wlr_pointer_gestures_v1.c',

types/wlr_output_swapchain.c

@@ -0,0 +1,254 @@
+#include <assert.h>
+#include <drm_fourcc.h>
+#include <stdlib.h>
+#include <wlr/backend.h>
+#include <wlr/interfaces/wlr_output.h>
+#include <wlr/render/wlr_renderer.h>
+#include <wlr/types/wlr_output.h>
+#include <wlr/types/wlr_output_swapchain.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_swapchain.h"
+
+struct wlr_output_swapchain_manager *wlr_output_swapchain_manager_create(
+		struct wlr_renderer *renderer, struct wlr_allocator *allocator) {
+	struct wlr_output_swapchain_manager *manager = calloc(1, sizeof(*manager));
+	if (manager == NULL) {
+		return NULL;
+	}
+
+	manager->renderer = renderer;
+	manager->allocator = allocator;
+
+	return manager;
+}
+
+struct wlr_output_swapchain_manager *wlr_output_swapchain_manager_autocreate(
+		struct wlr_backend *backend) {
+	struct wlr_renderer *renderer = wlr_renderer_autocreate(backend);
+	if (renderer == NULL) {
+		return NULL;
+	}
+
+	struct wlr_allocator *allocator = wlr_allocator_autocreate(backend, renderer);
+	if (allocator == NULL) {
+		wlr_renderer_destroy(renderer);
+		return NULL;
+	}
+
+	struct wlr_output_swapchain_manager *manager =
+		wlr_output_swapchain_manager_create(renderer, allocator);
+	if (manager == NULL) {
+		wlr_allocator_destroy(allocator);
+		wlr_renderer_destroy(renderer);
+		return NULL;
+	}
+
+	return manager;
+}
+
+void wlr_output_swapchain_manager_destroy(
+		struct wlr_output_swapchain_manager *manager) {
+	wlr_allocator_destroy(manager->allocator);
+	wlr_renderer_destroy(manager->renderer);
+	free(manager);
+}
+
+static 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 struct wlr_drm_format *pick_format(
+		struct wlr_output_swapchain *output_swapchain,
+		const struct wlr_drm_format_set *display_formats) {
+	struct wlr_renderer *renderer = output_swapchain->manager->renderer;
+
+	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_swapchain->output->name);
+		return NULL;
+	}
+
+	return format;
+}
+
+static bool update_swapchain(struct wlr_output_swapchain *output_swapchain,
+		bool allow_modifiers) {
+	struct wlr_output *output = output_swapchain->output;
+
+	int width, height;
+	output_pending_resolution(output, &width, &height);
+
+	if (output_swapchain->swapchain != NULL &&
+			output_swapchain->swapchain->width == width &&
+			output_swapchain->swapchain->height == height &&
+			(allow_modifiers || output->swapchain->format->len == 0)) {
+		return true;
+	}
+
+	struct wlr_allocator *allocator = output_swapchain->manager->allocator;
+	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 =
+		pick_format(output_swapchain, 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->swapchain);
+	output_swapchain->swapchain = swapchain;
+	return true;
+}
+
+static void handle_output_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_output_swapchain *output_swapchain =
+		wl_container_of(listener, output_swapchain, output_destroy);
+	wlr_output_swapchain_destroy(output_swapchain);
+}
+
+struct wlr_output_swapchain *wlr_output_swapchain_create(
+		struct wlr_output_swapchain_manager *manager,
+		struct wlr_output *output) {
+	struct wlr_output_swapchain *output_swapchain =
+		calloc(1, sizeof(*output_swapchain));
+	if (output_swapchain == NULL) {
+		return NULL;
+	}
+
+	output_swapchain->output = output;
+	output_swapchain->manager = manager;
+
+	output_swapchain->output_destroy.notify = handle_output_destroy;
+	wl_signal_add(&output->events.destroy, &output_swapchain->output_destroy);
+
+	return output_swapchain;
+}
+
+void wlr_output_swapchain_destroy(struct wlr_output_swapchain *output_swapchain) {
+	wl_list_remove(&output_swapchain->output_destroy.link);
+	free(output_swapchain);
+}
+
+bool wlr_output_swapchain_begin(struct wlr_output_swapchain *output_swapchain,
+		int *buffer_age) {
+	assert(output_swapchain->back_buffer == NULL);
+
+	if (!update_swapchain(output_swapchain, true)) {
+		return false;
+	}
+
+	struct wlr_buffer *buffer =
+		wlr_swapchain_acquire(output_swapchain->swapchain, buffer_age);
+	if (buffer == NULL) {
+		return false;
+	}
+
+	if (!wlr_renderer_begin_with_buffer(output_swapchain->manager->renderer,
+			buffer)) {
+		wlr_buffer_unlock(buffer);
+		return false;
+	}
+
+	output_swapchain->back_buffer = buffer;
+	return true;
+}
+
+void wlr_output_swapchain_end(struct wlr_output_swapchain *output_swapchain) {
+	assert(output_swapchain->back_buffer != NULL);
+
+	wlr_renderer_end(output_swapchain->manager->renderer);
+
+	wlr_output_attach_buffer(output_swapchain->output,
+		output_swapchain->back_buffer);
+
+	wlr_buffer_unlock(output_swapchain->back_buffer);
+	output_swapchain->back_buffer = NULL;
+}