Fix crash when wallpaper_image_path is missing

This makes the WM run fine even if wallpaper_image fails to load for any
other reason. Right now, it's still just a black background. At some
point, I plan to add the ability to also just set a color as a
background but that's a fairly low priority.

src/Config.zig

@@ -20,6 +20,10 @@ focus_follows_pointer: bool = true,
 /// Should the pointer warp to the center of newly-focused windows
 pointer_warp_on_focus_change: bool = true,
 
+// TODO: Implement a color when this is null
+/// Path to the wallpaper image
+wallpaper_image_path: []const u8 = "",
+
 /// Tag bind entries parsed from config (tag_bind nodes in keybinds block)
 tag_binds: std.ArrayList(Keybind) = .{},
 keybinds: std.ArrayList(Keybind) = .{},

src/Context.zig

@@ -27,7 +27,7 @@ buffer_pool: BufferPool = .{},
 
 /// Holds a pixman.Image (and its raw pixels) for the wallpaper
 /// (same image on all outputs, but scaled separately)
-wallpaper_image: *WallpaperImage,
+wallpaper_image: ?*WallpaperImage,
 
 // WM Configuration
 config: *Config,
@@ -60,6 +60,12 @@ pub fn create(options: Options) !*Context {
     const context = try utils.allocator.create(Context);
     errdefer context.destroy();
 
+    // FIXME: TODO: Get this from Config
+    const wallpaper_image = WallpaperImage.create("FIXME") catch |e| blk: {
+        log.err("Failed to load wallpaper image from path \"{s}\": {s}", .{ "FIXME", @errorName(e) });
+        break :blk null;
+    };
+
     context.* = .{
         .initialized = false,
         .wl_compositor = options.wl_compositor,
@@ -68,7 +74,7 @@ pub fn create(options: Options) !*Context {
         .wl_shm = options.wl_shm,
         .wl_outputs = options.wl_outputs,
         .zwlr_layer_shell_v1 = options.zwlr_layer_shell_v1,
-        .wallpaper_image = try WallpaperImage.create("FIXME"), // FIXME: TODO: Get this from Config
+        .wallpaper_image = wallpaper_image,
         .wm = try WindowManager.create(context, options.river_window_manager_v1),
         .xkb_bindings = try XkbBindings.create(context, options.river_xkb_bindings_v1),
         .config = options.config,
@@ -81,7 +87,9 @@ pub fn destroy(context: *Context) void {
     context.xkb_bindings.destroy();
     context.wm.destroy();
 
-    context.wallpaper_image.destroy();
+    if (context.wallpaper_image) |wallpaper_image| {
+        wallpaper_image.destroy();
+    }
     context.buffer_pool.deinit();
 
     utils.allocator.destroy(context);

src/Output.zig

@@ -208,6 +208,11 @@ fn wlOutputListener(_: *wl.Output, event: wl.Output.Event, output: *Output) void
 }
 
 fn initWallpaperLayerSurface(output: *Output) !void {
+    if (output.context.wallpaper_image == null) {
+        // No wallpaper image, so we don't need any surfaces
+        return;
+    }
+
     if (output.wl_surface) |_| {
         log.warn("Skipping adding a second wallpaper surface to {s}", .{output.name orelse "some output"});
         return;
@@ -319,16 +324,17 @@ fn renderWallpaper(output: *Output) !void {
     if (width == 0 or height == 0 or scale == 0) {
         return;
     }
-    const buffer: *Buffer = try context.buffer_pool.nextBuffer(context.wl_shm, width * scale, height * scale);
-
     // Scale our loaded image and then copy it into the Buffer's pixman.Image
-    const image = context.wallpaper_image.image;
+    const wallpaper_image = context.wallpaper_image orelse return;
+    const image = wallpaper_image.image;
     const image_data = image.getData();
     const image_width = image.getWidth();
     const image_height = image.getHeight();
     const image_stride = image.getStride();
     const image_format = image.getFormat();
 
+    const buffer: *Buffer = try context.buffer_pool.nextBuffer(context.wl_shm, width * scale, height * scale);
+
     const pix = pixman.Image.createBitsNoClear(image_format, image_width, image_height, image_data, image_stride);
     if (pix == null) {
         log.err("failed to copy the background image for rendering", .{});

src/main.zig

@@ -105,6 +105,10 @@ fn registryListener(registry: *wl.Registry, event: wl.Registry.Event, globals: *
                 globals.wl_shm = registry.bind(ev.name, wl.Shm, 1) catch |e| {
                     fatal("Failed to bind to wl_shm: {any}", .{@errorName(e)});
                 };
+            } else if (mem.orderZ(u8, ev.interface, river.LayerShellV1.interface.name) == .eq) {
+                globals.river_layer_shell_v1 = registry.bind(ev.name, river.LayerShellV1, 1) catch |e| {
+                    fatal("Failed to bind to river_layer_shell_v1: {any}", .{@errorName(e)});
+                };
             } else if (mem.orderZ(u8, ev.interface, river.WindowManagerV1.interface.name) == .eq) {
                 globals.river_window_manager_v1 = registry.bind(ev.name, river.WindowManagerV1, 3) catch |e| {
                     fatal("Failed to bind to river_window_manager_v1: {any}", .{@errorName(e)});