implement slowdown for animation speed

sample files/pandora.kdl

@@ -21,4 +21,10 @@ output "DP-2" {
     mode "static"
 }
 
+animation {
+
+    // Slow down animation by this factor. Values below 1 speeds up instead.
+    // slowdown 0.5
+}
+
 // logging "default"

src/pithos/config.rs

@@ -44,6 +44,7 @@ impl LogLevel {
 pub enum ConfigNode {
     Output(OutputConfig),
     Logging(#[knuffel(argument)] LogLevel),
+    Animation(AnimationConfig),
 }
 
 #[derive(Clone, Debug, knuffel::DecodeScalar, serde::Serialize, serde::Deserialize)]
@@ -97,11 +98,18 @@ pub struct WorkspaceConfig {
     pub trigger: Vec<ConfigTriggers>,
 }
 
+#[derive(Clone, Debug, Default, knuffel::Decode, serde::Serialize, serde::Deserialize)]
+pub struct AnimationConfig {
+    #[knuffel(child, unwrap(argument), default=1.0)]
+    pub slowdown: f64,
+}
+
 #[derive(Clone, Default, Debug, serde::Serialize, serde::Deserialize)]
 pub struct DaemonConfig {
     pub outputs: Vec<OutputConfig>,
     // lockscreen: LockscreenConfig,
     pub log_level: LogLevel,
+    pub animation: AnimationConfig,
 }
 
 pub fn get_config_dir() -> PathBuf {
@@ -149,6 +157,7 @@ pub fn load_config() -> miette::Result<DaemonConfig> {
         }
     }
 
+
     let config_nodes = knuffel::parse::<Vec<ConfigNode>>(
         config_path.to_str().unwrap(),
         config_file_contents.clone().unwrap().as_str(),
@@ -157,6 +166,7 @@ pub fn load_config() -> miette::Result<DaemonConfig> {
     let mut config = DaemonConfig {
         outputs: Vec::new(),
         log_level: LogLevel::DEFAULT,
+        animation: AnimationConfig::default(),
     };
     for node in config_nodes {
         match node {
@@ -176,6 +186,7 @@ pub fn load_config() -> miette::Result<DaemonConfig> {
                 config.outputs.push(n)
             }
             ConfigNode::Logging(level) => config.log_level = level,
+            ConfigNode::Animation(animation) => config.animation = animation,
         }
     }
 

src/wayland/render_base.rs

@@ -172,6 +172,7 @@ pub struct WallpaperRenderState {
     pub position_x: i32,
     pub position_y: i32,
     pub scroll_state: Option<ScrollState>, // should be None'd once scroll is finished
+    pub slowdown: f64,
 }
 
 impl WallpaperRenderState {
@@ -184,6 +185,7 @@ impl WallpaperRenderState {
         wl_output: WlOutput,
         output_state: &OutputState,
         initial_pos: Option<(i32, i32)>,
+        slowdown: f64,
     ) -> Self {
         // create new buffer, load image into it, attach it to surface, apply role through daemon
         let pandora = weak.upgrade().unwrap();
@@ -271,6 +273,7 @@ impl WallpaperRenderState {
             position_y,
             scroll_state: None,
             mode: mode,
+            slowdown,
         };
     }
 
@@ -344,6 +347,7 @@ impl WallpaperRenderState {
             anim_start: Instant::now(),
             anim_duration: spring.duration(),
             anim: spring,
+            slowdown: self.slowdown,
         });
 
         if !is_already_scrolling {
@@ -359,7 +363,9 @@ impl WallpaperRenderState {
     fn calc_next_pos(&self) -> i32 {
         let scroll_state = self.scroll_state.as_ref().unwrap();
         let eclipsed_duration = Instant::now() - scroll_state.anim_start;
-        return scroll_state.anim.value_at(eclipsed_duration).round() as i32;
+        let seconds = eclipsed_duration.as_secs_f64() / scroll_state.slowdown;
+        let scaled_duration = Duration::from_secs_f64(seconds);
+        return scroll_state.anim.value_at(scaled_duration).round() as i32;
     }
 
     fn do_scroll_tick(&mut self, conn: &mut Connection<RenderThreadState>) {
@@ -429,6 +435,7 @@ pub struct ScrollState {
     pub anim_start: Instant,
     pub anim_duration: Duration, // only needed for LERP'd animations with fixed durations
     pub anim: Spring,
+    pub slowdown: f64,
 }
 
 impl ScrollState {
@@ -497,6 +504,7 @@ pub fn initialize_wallpaper_outputs(
             output.wl_output,
             output_state,
             None,
+            config.animation.slowdown.max(0.001),
         );
         output_state.render_state =
             Some(crate::wayland::render_base::OutputRenderStateVariety::Wallpaper(wallpaper_state));