fix: 🐛 set_frame to return an error for invalid frame number (#70)

* fix: 🐛 set_frame to return an error for invalid frame number

* fix: 🐛 validate frame no before updating the renderer

* fix: 🐛 only update the start_time when frame is updated

* chore: 🤖 update demo player

* chore: 🤖 always return a valid start_time

demo-player/src/main.rs

@@ -152,6 +152,13 @@ fn main() {
             lottie_player.play();
         }
 
+        if window.is_key_down(Key::J) {
+            let updated = lottie_player.set_frame(20.0);
+            if updated {
+                lottie_player.render();
+            }
+        }
+
         if window.is_key_down(Key::Left) {
             let mut config = lottie_player.config();
 

dotlottie-rs/src/dotlottie_player.rs

@@ -343,13 +343,21 @@ impl DotLottieRuntime {
         };
 
         // update start_time to account for the already elapsed time
-        self.start_time = Instant::now() - Duration::from_secs_f32(elapsed_time_for_frame);
+        self.start_time =
+            match Instant::now().checked_sub(Duration::from_secs_f32(elapsed_time_for_frame)) {
+                Some(start_time) => start_time,
+                None => Instant::now(),
+            };
     }
 
     pub fn set_frame(&mut self, no: f32) -> bool {
+        if no < self.start_frame() || no > self.end_frame() {
+            return false;
+        }
+
         let is_ok = self.renderer.set_frame(no).is_ok();
 
-        if self.is_playing() {
+        if self.is_playing() && is_ok {
             self.update_start_time_for_frame(no);
         }
 

dotlottie-rs/src/lottie_renderer/mod.rs

@@ -227,6 +227,17 @@ impl LottieRenderer {
             .as_mut()
             .ok_or(LottieRendererError::AnimationNotLoaded)?;
 
+        let total_frames = thorvg_animation
+            .get_total_frame()
+            .map_err(|e| LottieRendererError::ThorvgError(e))?;
+
+        if no < 0.0 || no >= total_frames {
+            return Err(LottieRendererError::InvalidArgument(format!(
+                "Frame number must be between 0 and {}",
+                total_frames - 1.0
+            )));
+        }
+
         thorvg_animation
             .set_frame(no)
             .map_err(|e| LottieRendererError::ThorvgError(e))