feat: Make HELP text dependand on alpha support is enabled

Cargo.toml

@@ -4,6 +4,8 @@ version = "0.1.0"
 edition = "2021"
 
 [dependencies]
+chrono = "0.4"
+const_format = "0.2"
 clap = { version = "4.3", features = ["derive"] }
 rusttype = "0.9"
 number_prefix = "0.4"
@@ -17,7 +19,6 @@ simple_moving_average = "0.1"
 thread-priority = "0.13"
 tokio = { version = "1.28", features = ["fs", "rt-multi-thread", "net", "io-util", "macros", "process", "signal", "sync", "time"] }
 vncserver = { version ="0.2", optional = true}
-chrono = "0.4.26"
 
 [dev-dependencies]
 criterion = {version = "0.5", features = ["async_tokio"]}

src/parser.rs

@@ -1,21 +1,26 @@
+use crate::framebuffer::FrameBuffer;
+use const_format::formatcp;
 use std::sync::Arc;
-
 use tokio::io::AsyncWriteExt;
 
-use crate::framebuffer::FrameBuffer;
-
 pub const PARSER_LOOKAHEAD: usize = "PX 1234 1234 rrggbbaa\n".len(); // Longest possible command
-pub const HELP_TEXT: &[u8] = "\
+pub const HELP_TEXT: &[u8] = formatcp!("\
 Pixelflut server powered by breakwater https://github.com/sbernauer/breakwater
 Available commands:
 HELP: Show this help
 PX x y rrggbb: Color the pixel (x,y) with the given hexadecimal color rrggbb
-PX x y rrggbbaa: Color the pixel (x,y) with the given hexadecimal color rrggbb (alpha channel is ignored by default, unless breakwater is compiled with \"--feature alpha\". This is for performance reasons)
+{}
 PX x y gg: Color the pixel (x,y) with the hexadecimal color gggggg. Basically this is the same as the other commands, but is a more efficient way of filling white, black or gray areas
 PX x y: Get the color value of the pixel (x,y)
 SIZE: Get the size of the drawing surface, e.g. `SIZE 1920 1080`
 OFFSET x y: Apply offset (x,y) to all further pixel draws on this connection. This can e.g. be used to pre-calculate an image/animation and simply use the OFFSET command to move it around the screen without the need to re-calculate it
-".as_bytes();
+",
+if cfg!(feature = "alpha") {
+    "PX x y rrggbbaa: Color the pixel (x,y) with the given hexadecimal color rrggbb and a transparency of aa, where ff means draw normally on top of the existing pixel and 00 means fully transparent (no change at all)"
+} else {
+    "PX x y rrggbbaa: Color the pixel (x,y) with the given hexadecimal color rrggbb. The alpha part is discarded for performance reasons, as breakwater was compiled without the alpha feature"
+}
+).as_bytes();
 
 #[derive(Clone, Default, Debug)]
 pub struct ParserState {