Add --no-cache option to swww-daemon

With the deprecation of swww init, swww-daemon was missing a key
featureof allowing users to start the deamon without caching wallpapers
fromprevious sessions. This is a step on fixing this issue, although
thisstill invalidates loading the cache even for new outputs (monitor
re-connections).

fix formatting

daemon/src/cli.rs

@@ -3,11 +3,13 @@ use utils::ipc::PixelFormat;
 pub struct Cli {
     pub format: Option<PixelFormat>,
     pub quiet: bool,
+    pub no_cache: bool,
 }
 
 impl Cli {
     pub fn new() -> Self {
         let mut quiet = false;
+        let mut no_cache = false;
         let mut format = None;
         let mut args = std::env::args();
         args.next(); // skip the first argument
@@ -25,6 +27,7 @@ impl Cli {
                     }
                 },
                 "-q" | "--quiet" => quiet = true,
+                "--no-cache" => no_cache = true,
                 "-h" | "--help" => {
                     println!("swww-daemon");
                     println!();
@@ -40,6 +43,12 @@ impl Cli {
                     println!("          Whatever you chose, make sure you compositor actually supports it!");
                     println!("          'xrgb' is the most compatible one.");
                     println!();
+                    println!("  --no-cache");
+                    println!(
+                        "          Don't search the cache for the last wallpaper for each output"
+                    );
+                    println!("          Useful if you always want to select which iamge `swww` loads manually using `swww img`");
+                    println!();
                     println!("  -q|--quiet    will only log errors");
                     println!("  -h|--help     print help");
                     println!("  -V|--version  print version");
@@ -57,6 +66,10 @@ impl Cli {
             }
         }
 
-        Self { format, quiet }
+        Self {
+            format,
+            quiet,
+            no_cache,
+        }
     }
 }

daemon/src/main.rs

@@ -137,7 +137,7 @@ fn main() -> Result<(), String> {
         registry_queue_init(&conn).expect("failed to initialize the event queue");
     let qh = event_queue.handle();
 
-    let mut daemon = Daemon::new(&globals, &qh);
+    let mut daemon = Daemon::new(&globals, &qh, cli.no_cache);
     // roundtrip to get the shm formats before setting up the outputs
     event_queue.roundtrip(&mut daemon).unwrap();
 
@@ -335,10 +335,11 @@ struct Daemon {
     // swww stuff
     wallpapers: Vec<Arc<Wallpaper>>,
     animator: Animator,
+    use_cache: bool,
 }
 
 impl Daemon {
-    fn new(globals: &GlobalList, qh: &QueueHandle<Self>) -> Self {
+    fn new(globals: &GlobalList, qh: &QueueHandle<Self>, no_cache: bool) -> Self {
         // The compositor (not to be confused with the server which is commonly called the compositor) allows
         // configuring surfaces to be presented.
         let compositor: WlCompositor = globals
@@ -372,6 +373,7 @@ impl Daemon {
 
             wallpapers: Vec::new(),
             animator: Animator::new(),
+            use_cache: !no_cache,
         }
     }
 
@@ -530,7 +532,7 @@ impl Dispatch<wl_output::WlOutput, ()> for Daemon {
                         height,
                         ..
                     } => wallpaper.set_dimensions(width, height),
-                    wl_output::Event::Done => wallpaper.commit_surface_changes(),
+                    wl_output::Event::Done => wallpaper.commit_surface_changes(state.use_cache),
                     wl_output::Event::Scale { factor } => match NonZeroI32::new(factor) {
                         Some(factor) => wallpaper.set_scale(Scale::Whole(factor)),
                         None => error!("received scale factor of 0 from compositor"),
@@ -579,7 +581,7 @@ impl Dispatch<WlSurface, ()> for Daemon {
                         match NonZeroI32::new(factor) {
                             Some(factor) => {
                                 wallpaper.set_scale(Scale::Whole(factor));
-                                wallpaper.commit_surface_changes();
+                                wallpaper.commit_surface_changes(state.use_cache);
                             }
                             None => error!("received scale factor of 0 from compositor"),
                         }
@@ -760,7 +762,7 @@ impl Dispatch<WpFractionalScaleV1, WlSurface> for Daemon {
                         match NonZeroI32::new(scale as i32) {
                             Some(factor) => {
                                 wallpaper.set_scale(Scale::Fractional(factor));
-                                wallpaper.commit_surface_changes();
+                                wallpaper.commit_surface_changes(state.use_cache);
                             }
                             None => error!("received scale factor of 0 from compositor"),
                         }

daemon/src/wallpaper.rs

@@ -234,11 +234,11 @@ impl Wallpaper {
     }
 
     #[inline]
-    pub fn commit_surface_changes(&self) {
+    pub fn commit_surface_changes(&self, use_cache: bool) {
         let mut inner = self.inner.write().unwrap();
         let staging = self.inner_staging.lock().unwrap();
 
-        if inner.name != staging.name {
+        if inner.name != staging.name && use_cache {
             let name = staging.name.clone().unwrap_or("".to_string());
             if let Err(e) = std::thread::Builder::new()
                 .name("cache loader".to_string())