config: set a default value for blur_radius

Update the man page to include the default values of the blur config.

Fixes #347

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

man/picom.1.asciidoc

@@ -399,12 +399,13 @@ Available options of the 'blur' section are: ::
     A string. Controls the blur method. Corresponds to the *--blur-method* command line option. Available choices are:
       'none' to disable blurring; 'gaussian' for gaussian blur; 'box' for box blur; 'kernel' for convolution blur with a custom kernel.
     Note: 'gaussian' and 'box' blur methods are only supported by the experimental backends.
+    (default: none)
 
   *size*:::
-    An integer. The size of the blur kernel, required by 'gaussian' and 'box' blur methods. For the 'kernel' method, the size is included in the kernel. Corresponds to the *--blur-size* command line option.
+    An integer. The size of the blur kernel, required by 'gaussian' and 'box' blur methods. For the 'kernel' method, the size is included in the kernel. Corresponds to the *--blur-size* command line option (default: 3).
 
   *deviation*:::
-    A floating point number. The standard deviation for the 'gaussian' blur method. Corresponds to the *--blur-deviation* command line option.
+    A floating point number. The standard deviation for the 'gaussian' blur method. Corresponds to the *--blur-deviation* command line option (default: 0.84089642).
 
   *kernel*:::
     A string. The kernel to use for the 'kernel' blur method, specified in the same format as the *--blur-kerns* option. Corresponds to the *--blur-kerns* command line option.

src/config.c

@@ -540,7 +540,7 @@ char *parse_config(options_t *opt, const char *config_file, bool *shadow_enable,
 	    .detect_client_opacity = false,
 
 	    .blur_method = BLUR_METHOD_NONE,
-	    .blur_radius = -1,
+	    .blur_radius = 3,
 	    .blur_deviation = 0.84089642,
 	    .blur_background_frame = false,
 	    .blur_background_fixed = false,