compositor: Implement output configuration using windowed_output_api

This implements output configuration for outputs which use
previously added weston_windowed_output_api. The function
takes an output that's to be configured, default configuration
that's to be set in case no configuration is specified in
the config file or on command line and optional third argument,
parsed_options, which will override defaults and options for
configuration if they are present.

This also introduces new compositor specific functions for
setting output's scale and transform from either hardcoded
default, config file option or command line option.

Pending output handling helpers have also been introduced.

v2:

 - Adapt to changes in previous patch.
 - Fix potential double free().
 - Remove redundant variables for scale and transform setting.
 - Drop parsed_options helper and parameter and use it directly
   in wet_configure_windowed_output_from_config().

v3:

 - Remove unneeded checks for output->name == NULL as that
   has been disallowed.
 - Stop printing mode if it's invalid, as it can be NULL.

Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>
Reviewed-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
Signed-off-by: Armin Krezović <krezovic.armin@gmail.com>

compositor/main.c

@@ -63,11 +63,21 @@
 #include "compositor-fbdev.h"
 #include "compositor-x11.h"
 #include "compositor-wayland.h"
+#include "windowed-output-api.h"
 
 #define WINDOW_TITLE "Weston Compositor"
 
+struct wet_output_config {
+	int width;
+	int height;
+	int32_t scale;
+	uint32_t transform;
+};
+
 struct wet_compositor {
 	struct weston_config *config;
+	struct wet_output_config *parsed_options;
+	struct wl_listener pending_output_listener;
 };
 
 static FILE *weston_logfile = NULL;
@@ -425,6 +435,39 @@ to_wet_compositor(struct weston_compositor *compositor)
 	return weston_compositor_get_user_data(compositor);
 }
 
+static void
+wet_set_pending_output_handler(struct weston_compositor *ec,
+			       wl_notify_func_t handler)
+{
+	struct wet_compositor *compositor = to_wet_compositor(ec);
+
+	compositor->pending_output_listener.notify = handler;
+	wl_signal_add(&ec->output_pending_signal, &compositor->pending_output_listener);
+}
+
+static struct wet_output_config *
+wet_init_parsed_options(struct weston_compositor *ec)
+{
+	struct wet_compositor *compositor = to_wet_compositor(ec);
+	struct wet_output_config *config;
+
+	config = zalloc(sizeof *config);
+
+	if (!config) {
+		perror("out of memory");
+		return NULL;
+	}
+
+	config->width = 0;
+	config->height = 0;
+	config->scale = 0;
+	config->transform = UINT32_MAX;
+
+	compositor->parsed_options = config;
+
+	return config;
+}
+
 WL_EXPORT struct weston_config *
 wet_get_config(struct weston_compositor *ec)
 {
@@ -940,6 +983,110 @@ handle_exit(struct weston_compositor *c)
 	wl_display_terminate(c->wl_display);
 }
 
+static void
+wet_output_set_scale(struct weston_output *output,
+		     struct weston_config_section *section,
+		     int32_t default_scale,
+		     int32_t parsed_scale)
+{
+	int32_t scale = default_scale;
+
+	if (section)
+		weston_config_section_get_int(section, "scale", &scale, default_scale);
+
+	if (parsed_scale)
+		scale = parsed_scale;
+
+	weston_output_set_scale(output, scale);
+}
+
+/* UINT32_MAX is treated as invalid because 0 is a valid
+ * enumeration value and the parameter is unsigned
+ */
+static void
+wet_output_set_transform(struct weston_output *output,
+			 struct weston_config_section *section,
+			 uint32_t default_transform,
+			 uint32_t parsed_transform)
+{
+	char *t;
+	uint32_t transform = default_transform;
+
+	if (section) {
+		weston_config_section_get_string(section,
+						 "transform", &t, "normal");
+
+		if (weston_parse_transform(t, &transform) < 0) {
+			weston_log("Invalid transform \"%s\" for output %s\n",
+				   t, output->name);
+			transform = default_transform;
+		}
+		free(t);
+	}
+
+	if (parsed_transform != UINT32_MAX)
+		transform = parsed_transform;
+
+	weston_output_set_transform(output, transform);
+}
+
+static int
+wet_configure_windowed_output_from_config(struct weston_output *output,
+					  struct wet_output_config *defaults)
+{
+	const struct weston_windowed_output_api *api =
+		weston_windowed_output_get_api(output->compositor);
+
+	struct weston_config *wc = wet_get_config(output->compositor);
+	struct weston_config_section *section = NULL;
+	struct wet_compositor *compositor = to_wet_compositor(output->compositor);
+	struct wet_output_config *parsed_options = compositor->parsed_options;
+	int width = defaults->width;
+	int height = defaults->height;
+
+	assert(parsed_options);
+
+	if (!api) {
+		weston_log("Cannot use weston_windowed_output_api.\n");
+		return -1;
+	}
+
+	section = weston_config_get_section(wc, "output", "name", output->name);
+
+	if (section) {
+		char *mode;
+
+		weston_config_section_get_string(section, "mode", &mode, NULL);
+		if (!mode || sscanf(mode, "%dx%d", &width,
+				    &height) != 2) {
+			weston_log("Invalid mode for output %s. Using defaults.\n",
+				   output->name);
+			width = defaults->width;
+			height = defaults->height;
+		}
+		free(mode);
+	}
+
+	if (parsed_options->width)
+		width = parsed_options->width;
+
+	if (parsed_options->height)
+		height = parsed_options->height;
+
+	wet_output_set_scale(output, section, defaults->scale, parsed_options->scale);
+	wet_output_set_transform(output, section, defaults->transform, parsed_options->transform);
+
+	if (api->output_set_size(output, width, height) < 0) {
+		weston_log("Cannot configure output \"%s\" using weston_windowed_output_api.\n",
+			   output->name);
+		return -1;
+	}
+
+	weston_output_enable(output);
+
+	return 0;
+}
+
 static enum weston_drm_backend_output_mode
 drm_configure_output(struct weston_compositor *c,
 		     bool use_current_mode,
@@ -1659,6 +1806,7 @@ int main(int argc, char *argv[])
 	if (load_configuration(&config, noconfig, config_file) < 0)
 		goto out_signals;
 	user_data.config = config;
+	user_data.parsed_options = NULL;
 
 	section = weston_config_get_section(config, "core", NULL, NULL);
 
@@ -1683,6 +1831,8 @@ int main(int argc, char *argv[])
 		goto out;
 	}
 
+	weston_pending_output_coldplug(ec);
+
 	catch_signals();
 	segv_compositor = ec;
 
@@ -1766,6 +1916,9 @@ int main(int argc, char *argv[])
 	ret = ec->exit_code;
 
 out:
+	/* free(NULL) is valid, and it won't be NULL if it's used */
+	free(user_data.parsed_options);
+
 	weston_compositor_destroy(ec);
 
 out_signals: