scaled-scene-buffer: restructure source files

- Rename `scaled_scene_buffer` to `scaled_buffer`. This makes it clear
  that `scaled_{font,img,icon}_buffers` are implementations of it.
- Move the files from `src/common` to `src/scaled-buffer` as
  `scaled_icon_buffer` heavily depends on `server` and `view` etc.

src/scaled-buffer/scaled-icon-buffer.c

@@ -0,0 +1,361 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define _POSIX_C_SOURCE 200809L
+#include "scaled-buffer/scaled-icon-buffer.h"
+#include <assert.h>
+#include <string.h>
+#include <wlr/util/log.h>
+#include "buffer.h"
+#include "common/macros.h"
+#include "common/mem.h"
+#include "common/string-helpers.h"
+#include "config.h"
+#include "config/rcxml.h"
+#include "desktop-entry.h"
+#include "img/img.h"
+#include "node.h"
+#include "scaled-buffer/scaled-buffer.h"
+#include "view.h"
+#include "window-rules.h"
+
+#if HAVE_LIBSFDO
+
+static struct lab_data_buffer *
+choose_best_icon_buffer(struct scaled_icon_buffer *self, int icon_size, double scale)
+{
+	int best_dist = -INT_MAX;
+	struct lab_data_buffer *best_buffer = NULL;
+
+	struct lab_data_buffer **buffer;
+	wl_array_for_each(buffer, &self->view_icon_buffers) {
+		int curr_dist = (*buffer)->base.width - (int)(icon_size * scale);
+		bool curr_is_better;
+		if ((curr_dist < 0 && best_dist > 0)
+				|| (curr_dist > 0 && best_dist < 0)) {
+			/* prefer too big icon over too small icon */
+			curr_is_better = curr_dist > 0;
+		} else {
+			curr_is_better = abs(curr_dist) < abs(best_dist);
+		}
+		if (curr_is_better) {
+			best_dist = curr_dist;
+			best_buffer = *buffer;
+		}
+	}
+	return best_buffer;
+}
+
+static struct lab_data_buffer *
+img_to_buffer(struct lab_img *img, int width, int height, double scale)
+{
+	struct lab_data_buffer *buffer = lab_img_render(img, width, height, scale);
+	lab_img_destroy(img);
+	return buffer;
+}
+
+/*
+ * Load an icon from application-supplied icon name or buffers.
+ * Wayland apps can provide icon names and buffers via xdg-toplevel-icon protocol.
+ * X11 apps can provide icon buffers via _NET_WM_ICON property.
+ */
+static struct lab_data_buffer *
+load_client_icon(struct scaled_icon_buffer *self, int icon_size, double scale)
+{
+	struct lab_img *img = desktop_entry_load_icon(self->server,
+		self->view_icon_name, icon_size, scale);
+	if (img) {
+		wlr_log(WLR_DEBUG, "loaded icon from client icon name");
+		return img_to_buffer(img, self->width, self->height, scale);
+	}
+
+	struct lab_data_buffer *buffer = choose_best_icon_buffer(self, icon_size, scale);
+	if (buffer) {
+		wlr_log(WLR_DEBUG, "loaded icon from client buffer");
+		return buffer_resize(buffer, self->width, self->height, scale);
+	}
+
+	return NULL;
+}
+
+/*
+ * Load an icon by a view's app_id. For example, if the app_id is 'firefox', then
+ * libsfdo will parse firefox.desktop to get the Icon name and then find that icon
+ * based on the icon theme specified in rc.xml.
+ */
+static struct lab_data_buffer *
+load_server_icon(struct scaled_icon_buffer *self, int icon_size, double scale)
+{
+	struct lab_img *img = desktop_entry_load_icon_from_app_id(self->server,
+		self->view_app_id, icon_size, scale);
+	if (img) {
+		wlr_log(WLR_DEBUG, "loaded icon by app_id");
+		return img_to_buffer(img, self->width, self->height, scale);
+	}
+
+	return NULL;
+}
+
+#endif /* HAVE_LIBSFDO */
+
+static struct lab_data_buffer *
+_create_buffer(struct scaled_buffer *scaled_buffer, double scale)
+{
+#if HAVE_LIBSFDO
+	struct scaled_icon_buffer *self = scaled_buffer->data;
+	int icon_size = MIN(self->width, self->height);
+	struct lab_img *img = NULL;
+	struct lab_data_buffer *buffer = NULL;
+
+	if (self->icon_name) {
+		/* generic icon (e.g. menu icons) */
+		img = desktop_entry_load_icon(self->server, self->icon_name,
+			icon_size, scale);
+		if (img) {
+			wlr_log(WLR_DEBUG, "loaded icon by icon name");
+			return img_to_buffer(img, self->width, self->height, scale);
+		}
+		return NULL;
+	}
+
+	/* window icon */
+	if (self->view_icon_prefer_client) {
+		buffer = load_client_icon(self, icon_size, scale);
+		if (buffer) {
+			return buffer;
+		}
+		buffer = load_server_icon(self, icon_size, scale);
+		if (buffer) {
+			return buffer;
+		}
+	} else {
+		buffer = load_server_icon(self, icon_size, scale);
+		if (buffer) {
+			return buffer;
+		}
+		buffer = load_client_icon(self, icon_size, scale);
+		if (buffer) {
+			return buffer;
+		}
+	}
+	/* If both client and server icons are unavailable, use the fallback icon */
+	img = desktop_entry_load_icon(self->server, rc.fallback_app_icon_name,
+		icon_size, scale);
+	if (img) {
+		wlr_log(WLR_DEBUG, "loaded fallback icon");
+		return img_to_buffer(img, self->width, self->height, scale);
+	}
+#endif /* HAVE_LIBSFDO */
+	return NULL;
+}
+
+static void
+set_icon_buffers(struct scaled_icon_buffer *self, struct wl_array *buffers)
+{
+	struct lab_data_buffer **icon_buffer;
+	wl_array_for_each(icon_buffer, &self->view_icon_buffers) {
+		wlr_buffer_unlock(&(*icon_buffer)->base);
+	}
+	wl_array_release(&self->view_icon_buffers);
+	wl_array_init(&self->view_icon_buffers);
+
+	if (!buffers) {
+		return;
+	}
+
+	wl_array_for_each(icon_buffer, buffers) {
+		wlr_buffer_lock(&(*icon_buffer)->base);
+	}
+	wl_array_copy(&self->view_icon_buffers, buffers);
+}
+
+static void
+_destroy(struct scaled_buffer *scaled_buffer)
+{
+	struct scaled_icon_buffer *self = scaled_buffer->data;
+	if (self->view) {
+		wl_list_remove(&self->on_view.set_icon.link);
+		wl_list_remove(&self->on_view.new_title.link);
+		wl_list_remove(&self->on_view.new_app_id.link);
+		wl_list_remove(&self->on_view.destroy.link);
+	}
+	free(self->view_app_id);
+	free(self->view_icon_name);
+	set_icon_buffers(self, NULL);
+	free(self->icon_name);
+	free(self);
+}
+
+static bool
+icon_buffers_equal(struct wl_array *a, struct wl_array *b)
+{
+	if (a->size != b->size) {
+		return false;
+	}
+	return a->size == 0 || !memcmp(a->data, b->data, a->size);
+}
+
+static bool
+_equal(struct scaled_buffer *scaled_buffer_a,
+	struct scaled_buffer *scaled_buffer_b)
+{
+	struct scaled_icon_buffer *a = scaled_buffer_a->data;
+	struct scaled_icon_buffer *b = scaled_buffer_b->data;
+
+	return str_equal(a->view_app_id, b->view_app_id)
+		&& a->view_icon_prefer_client == b->view_icon_prefer_client
+		&& str_equal(a->view_icon_name, b->view_icon_name)
+		&& icon_buffers_equal(&a->view_icon_buffers, &b->view_icon_buffers)
+		&& str_equal(a->icon_name, b->icon_name)
+		&& a->width == b->width
+		&& a->height == b->height;
+}
+
+static struct scaled_buffer_impl impl = {
+	.create_buffer = _create_buffer,
+	.destroy = _destroy,
+	.equal = _equal,
+};
+
+struct scaled_icon_buffer *
+scaled_icon_buffer_create(struct wlr_scene_tree *parent, struct server *server,
+	int width, int height)
+{
+	assert(parent);
+	assert(width >= 0 && height >= 0);
+
+	struct scaled_buffer *scaled_buffer = scaled_buffer_create(
+		parent, &impl, /* drop_buffer */ true);
+	struct scaled_icon_buffer *self = znew(*self);
+	self->scaled_buffer = scaled_buffer;
+	self->scene_buffer = scaled_buffer->scene_buffer;
+	self->server = server;
+	self->width = width;
+	self->height = height;
+
+	scaled_buffer->data = self;
+
+	return self;
+}
+
+static void
+handle_view_set_icon(struct wl_listener *listener, void *data)
+{
+	struct scaled_icon_buffer *self =
+		wl_container_of(listener, self, on_view.set_icon);
+
+	bool icon_name_equal = str_equal(self->view_icon_name, self->view->icon.name);
+	if (icon_name_equal && icon_buffers_equal(&self->view_icon_buffers,
+			&self->view->icon.buffers)) {
+		return;
+	}
+
+	if (!icon_name_equal) {
+		zfree(self->view_icon_name);
+		if (self->view->icon.name) {
+			xstrdup_replace(self->view_icon_name, self->view->icon.name);
+		}
+	}
+
+	set_icon_buffers(self, &self->view->icon.buffers);
+	scaled_buffer_request_update(self->scaled_buffer,
+		self->width, self->height);
+}
+
+static void
+handle_view_new_title(struct wl_listener *listener, void *data)
+{
+	struct scaled_icon_buffer *self =
+		wl_container_of(listener, self, on_view.new_title);
+
+	bool prefer_client = window_rules_get_property(
+		self->view, "iconPreferClient") == LAB_PROP_TRUE;
+	if (prefer_client == self->view_icon_prefer_client) {
+		return;
+	}
+	self->view_icon_prefer_client = prefer_client;
+	scaled_buffer_request_update(self->scaled_buffer,
+		self->width, self->height);
+}
+
+static void
+handle_view_new_app_id(struct wl_listener *listener, void *data)
+{
+	struct scaled_icon_buffer *self =
+		wl_container_of(listener, self, on_view.new_app_id);
+
+	const char *app_id = view_get_string_prop(self->view, "app_id");
+	if (str_equal(app_id, self->view_app_id)) {
+		return;
+	}
+
+	xstrdup_replace(self->view_app_id, app_id);
+	self->view_icon_prefer_client = window_rules_get_property(
+		self->view, "iconPreferClient") == LAB_PROP_TRUE;
+	scaled_buffer_request_update(self->scaled_buffer,
+		self->width, self->height);
+}
+
+static void
+handle_view_destroy(struct wl_listener *listener, void *data)
+{
+	struct scaled_icon_buffer *self =
+		wl_container_of(listener, self, on_view.destroy);
+	wl_list_remove(&self->on_view.destroy.link);
+	wl_list_remove(&self->on_view.set_icon.link);
+	wl_list_remove(&self->on_view.new_title.link);
+	wl_list_remove(&self->on_view.new_app_id.link);
+	self->view = NULL;
+}
+
+void
+scaled_icon_buffer_set_view(struct scaled_icon_buffer *self, struct view *view)
+{
+	assert(view);
+	if (self->view == view) {
+		return;
+	}
+
+	if (self->view) {
+		wl_list_remove(&self->on_view.set_icon.link);
+		wl_list_remove(&self->on_view.new_title.link);
+		wl_list_remove(&self->on_view.new_app_id.link);
+		wl_list_remove(&self->on_view.destroy.link);
+	}
+	self->view = view;
+
+	self->on_view.set_icon.notify = handle_view_set_icon;
+	wl_signal_add(&view->events.set_icon, &self->on_view.set_icon);
+
+	self->on_view.new_title.notify = handle_view_new_title;
+	wl_signal_add(&view->events.new_title, &self->on_view.new_title);
+
+	self->on_view.new_app_id.notify = handle_view_new_app_id;
+	wl_signal_add(&view->events.new_app_id, &self->on_view.new_app_id);
+
+	self->on_view.destroy.notify = handle_view_destroy;
+	wl_signal_add(&view->events.destroy, &self->on_view.destroy);
+
+	handle_view_set_icon(&self->on_view.set_icon, NULL);
+	handle_view_new_app_id(&self->on_view.new_app_id, NULL);
+	handle_view_new_title(&self->on_view.new_title, NULL);
+}
+
+void
+scaled_icon_buffer_set_icon_name(struct scaled_icon_buffer *self,
+	const char *icon_name)
+{
+	assert(icon_name);
+	if (str_equal(self->icon_name, icon_name)) {
+		return;
+	}
+	xstrdup_replace(self->icon_name, icon_name);
+	scaled_buffer_request_update(self->scaled_buffer, self->width, self->height);
+}
+
+struct scaled_icon_buffer *
+scaled_icon_buffer_from_node(struct wlr_scene_node *node)
+{
+	struct scaled_buffer *scaled_buffer =
+		node_scaled_buffer_from_node(node);
+	assert(scaled_buffer->impl == &impl);
+	return scaled_buffer->data;
+}