Allow a fallback color to be specified for swaybg

This allows for a color to be set when the wallpaper does not fill the
entire output. If specified, the fallback color is also used when the
image path is inaccessible.

3 files changed, 44 insertions, 13 deletions

diff --git a/sway/commands/output/background.c b/sway/commands/output/background.c
index 4ed56c2a..e45b571e 100644
--- a/sway/commands/output/background.c
+++ b/sway/commands/output/background.c
@@ -6,6 +6,7 @@
 #include <errno.h>
 #include "sway/commands.h"
 #include "sway/config.h"
+#include "sway/swaynag.h"
 #include "log.h"
 #include "stringop.h"
 
@@ -36,6 +37,7 @@ struct cmd_results *output_cmd_background(int argc, char **argv) {
                 output->background = calloc(1, strlen(argv[0]) + 3);
                 snprintf(output->background, strlen(argv[0]) + 3, "\"%s\"", argv[0]);
                 output->background_option = strdup("solid_color");
+                output->background_fallback = NULL;
                 argc -= 2; argv += 2;
         } else {
                 bool valid = false;
@@ -104,16 +106,35 @@ struct cmd_results *output_cmd_background(int argc, char **argv) {
                         free(conf);
                 }
 
-                if (access(src, F_OK) == -1) {
-                        struct cmd_results *cmd_res = cmd_results_new(CMD_FAILURE, "output",
-                                "Unable to access background file '%s': %s", src, strerror(errno));
+                bool can_access = access(src, F_OK) != -1;
+                if (!can_access) {
+                        wlr_log(WLR_ERROR, "Unable to access background file '%s': %s",
+                                        src, strerror(errno));
+                        if (!config->validating) {
+                                swaynag_log(config->swaynag_command,
+                                                &config->swaynag_config_errors,
+                                                "Unable to access background file '%s'", src);
+                        }
                         free(src);
-                        return cmd_res;
+                } else {
+                        output->background = src;
+                        output->background_option = strdup(mode);
                 }
-
-                output->background = src;
-                output->background_option = strdup(mode);
                 argc -= j + 1; argv += j + 1;
+
+                output->background_fallback = NULL;
+                if (argc && *argv[0] == '#') {
+                        output->background_fallback = calloc(1, strlen(argv[0]) + 3);
+                        snprintf(output->background_fallback, strlen(argv[0]) + 3,
+                                        "\"%s\"", argv[0]);
+                        argc--; argv++;
+
+                        if (!can_access) {
+                                output->background = output->background_fallback;
+                                output->background_option = strdup("solid_color");
+                                output->background_fallback = NULL;
+                        }
+                }
         }
 
         config->handler_context.leftovers.argc = argc;
diff --git a/sway/config/output.c b/sway/config/output.c
index 504c48c6..1d8cb3ef 100644
--- a/sway/config/output.c
+++ b/sway/config/output.c
@@ -77,6 +77,10 @@ void merge_output_config(struct output_config *dst, struct output_config *src) {
                 free(dst->background_option);
                 dst->background_option = strdup(src->background_option);
         }
+        if (src->background_fallback) {
+                free(dst->background_fallback);
+                dst->background_fallback = strdup(src->background_fallback);
+        }
         if (src->dpms_state != 0) {
                 dst->dpms_state = src->dpms_state;
         }
@@ -226,17 +230,19 @@ void apply_output_config(struct output_config *oc, struct sway_container *output
                 wlr_log(WLR_DEBUG, "Setting background for output %d to %s",
                                 output_i, oc->background);
 
-                size_t len = snprintf(NULL, 0, "%s %d %s %s",
+                size_t len = snprintf(NULL, 0, "%s %d %s %s %s",
                                 config->swaybg_command ? config->swaybg_command : "swaybg",
-                                output_i, oc->background, oc->background_option);
+                                output_i, oc->background, oc->background_option,
+                                oc->background_fallback ? oc->background_fallback : "");
                 char *command = malloc(len + 1);
                 if (!command) {
                         wlr_log(WLR_DEBUG, "Unable to allocate swaybg command");
                         return;
                 }
-                snprintf(command, len + 1, "%s %d %s %s",
+                snprintf(command, len + 1, "%s %d %s %s %s",
                                 config->swaybg_command ? config->swaybg_command : "swaybg",
-                                output_i, oc->background, oc->background_option);
+                                output_i, oc->background, oc->background_option,
+                                oc->background_fallback ? oc->background_fallback : "");
                 wlr_log(WLR_DEBUG, "-> %s", command);
 
                 char *const cmd[] = { "sh", "-c", command, NULL };
diff --git a/sway/sway.5.scd b/sway/sway.5.scd
index 73a01152..31ab281b 100644
--- a/sway/sway.5.scd
+++ b/sway/sway.5.scd
@@ -489,9 +489,13 @@ The default colors are:
         setting an integral scale factor and adjusting the font size of your
         applications to taste.
 
-*output* <name> background|bg <file> <mode>
+*output* <name> background|bg <file> <mode> [<fallback\_color>]
         Sets the wallpaper for the given output to the specified file, using the
-        given scaling mode (one of "stretch", "fill", "fit", "center", "tile").
+        given scaling mode (one of "stretch", "fill", "fit", "center", "tile"). If
+        the specified file cannot be accessed or if the image does fill the entire
+        output, a fallback color may be provided to cover the rest of the output.
+        __fallback\_color__ should be specified as _#RRGGBB_. Alpha is not
+        supported.
 
 **output** <name> background|bg <color> solid\_color
         Sets the background of the given output to the specified color. _color_