swaybar: do not retry search for tray icons

In case a tray icon cannot be found or does not have a desirable size,
swaybar retries the search again and again, which increases load on disk
and CPU. This commit solves it by storing target_size for each icon, so
that swaybar does not search for an icon of some size if it already tried to.

Fixes #3789.

include/swaybar/tray/item.h

@@ -20,6 +20,7 @@ struct swaybar_sni {
 	cairo_surface_t *icon;
 	int min_size;
 	int max_size;
+	int target_size;
 
 	// dbus properties
 	char *watcher_id;

swaybar/tray/item.c

@@ -1,6 +1,7 @@
 #define _POSIX_C_SOURCE 200809L
 #include <arpa/inet.h>
 #include <cairo.h>
+#include <limits.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
@@ -27,7 +28,7 @@ static bool sni_ready(struct swaybar_sni *sni) {
 
 static void set_sni_dirty(struct swaybar_sni *sni) {
 	if (sni_ready(sni)) {
-		sni->min_size = sni->max_size = 0; // invalidate previous icon
+		sni->target_size = sni->min_size = sni->max_size = 0; // invalidate previous icon
 		set_bar_dirty(sni->tray->bar);
 	}
 }
@@ -401,13 +402,8 @@ static enum hotspot_event_handling icon_hotspot_callback(
 	return HOTSPOT_PROCESS;
 }
 
-uint32_t render_sni(cairo_t *cairo, struct swaybar_output *output, double *x,
-		struct swaybar_sni *sni) {
-	uint32_t height = output->height * output->scale;
-	int padding = output->bar->config->tray_padding;
-	int ideal_size = height - 2*padding;
-	if ((ideal_size < sni->min_size || ideal_size > sni->max_size) && sni_ready(sni)) {
-		bool icon_found = false;
+static void reload_sni(struct swaybar_sni *sni, char *icon_theme,
+		int target_size) {
 	char *icon_name = sni->status[0] == 'N' ?
 		sni->attention_icon_name : sni->icon_name;
 	if (icon_name) {
@@ -417,7 +413,7 @@ uint32_t render_sni(cairo_t *cairo, struct swaybar_output *output, double *x,
 			list_add(icon_search_paths, sni->icon_theme_path);
 		}
 		char *icon_path = find_icon(sni->tray->themes, icon_search_paths,
-					icon_name, ideal_size, output->bar->config->icon_theme,
+				icon_name, target_size, icon_theme,
 				&sni->min_size, &sni->max_size);
 		list_free(icon_search_paths);
 		if (!icon_path && sni->icon_theme_path) {
@@ -428,42 +424,53 @@ uint32_t render_sni(cairo_t *cairo, struct swaybar_output *output, double *x,
 			cairo_surface_destroy(sni->icon);
 			sni->icon = load_background_image(icon_path);
 			free(icon_path);
-				icon_found = true;
+			return;
 		}
 	}
-		if (!icon_found) {
+
 	list_t *pixmaps = sni->status[0] == 'N' ?
 		sni->attention_icon_pixmap : sni->icon_pixmap;
 	if (pixmaps) {
-				int idx = -1;
-				unsigned smallest_error = -1; // UINT_MAX
+		struct swaybar_pixmap *pixmap = NULL;
+		int min_error = INT_MAX;
 		for (int i = 0; i < pixmaps->length; ++i) {
-					struct swaybar_pixmap *pixmap = pixmaps->items[i];
-					unsigned error = (ideal_size - pixmap->size) *
-						(ideal_size < pixmap->size ? -1 : 1);
-					if (error < smallest_error) {
-						smallest_error = error;
-						idx = i;
+			struct swaybar_pixmap *p = pixmaps->items[i];
+			int e = abs(target_size - pixmap->size);
+			if (e < min_error) {
+				pixmap = p;
+				min_error = e;
 			}
 		}
-				struct swaybar_pixmap *pixmap = pixmaps->items[idx];
 		cairo_surface_destroy(sni->icon);
 		sni->icon = cairo_image_surface_create_for_data(pixmap->pixels,
 				CAIRO_FORMAT_ARGB32, pixmap->size, pixmap->size,
 				cairo_format_stride_for_width(CAIRO_FORMAT_ARGB32, pixmap->size));
 	}
 }
+
+uint32_t render_sni(cairo_t *cairo, struct swaybar_output *output, double *x,
+		struct swaybar_sni *sni) {
+	uint32_t height = output->height * output->scale;
+	int padding = output->bar->config->tray_padding;
+	int target_size = height - 2*padding;
+	if (target_size != sni->target_size && sni_ready(sni)) {
+		// check if another icon should be loaded
+		if (target_size < sni->min_size || target_size > sni->max_size) {
+			reload_sni(sni, output->bar->config->icon_theme, target_size);
+		}
+
+		sni->target_size = target_size;
 	}
 
 	int icon_size;
 	cairo_surface_t *icon;
 	if (sni->icon) {
 		int actual_size = cairo_image_surface_get_height(sni->icon);
-		icon_size = actual_size < ideal_size ?
-			actual_size*(ideal_size/actual_size) : ideal_size;
+		icon_size = actual_size < target_size ?
+			actual_size*(target_size/actual_size) : target_size;
 		icon = cairo_image_surface_scale(sni->icon, icon_size, icon_size);
 	} else { // draw a :(
-		icon_size = ideal_size*0.8;
+		icon_size = target_size*0.8;
 		icon = cairo_image_surface_create(CAIRO_FORMAT_ARGB32, icon_size, icon_size);
 		cairo_t *cairo_icon = cairo_create(icon);
 		cairo_set_source_u32(cairo_icon, 0xFF0000FF);

swaybar/tray/tray.c

@@ -124,7 +124,9 @@ uint32_t render_tray(cairo_t *cairo, struct swaybar_output *output, double *x) {
 	struct swaybar_tray *tray = output->bar->tray;
 	for (int i = 0; i < tray->items->length; ++i) {
 		uint32_t h = render_sni(cairo, output, x, tray->items->items[i]);
-		max_height = h > max_height ? h : max_height;
+		if (h > max_height) {
+			max_height = h;
+		}
 	}
 
 	return max_height;