1 files changed, 89 insertions, 0 deletions
diff --git a/rust/crates/animation/src/values.rs b/rust/crates/animation/src/values.rs
new file mode 100644
index 00000000..d16bf16a
--- /dev/null
+++ b/rust/crates/animation/src/values.rs
@@ -0,0 +1,89 @@
+use scene::ElementAnimations;
+use time::MediaTime;
+
+use crate::resolve::resolve_animation_path_value_at_time;
+use scene::ParamValue;
+
+pub fn resolve_opacity_at_time(
+    base_opacity: f64,
+    animations: Option<&ElementAnimations>,
+    local_time: MediaTime,
+) -> f64 {
+    match resolve_animation_path_value_at_time(
+        animations,
+        "opacity",
+        local_time.max(MediaTime::ZERO),
+        &ParamValue::Number(base_opacity),
+    ) {
+        ParamValue::Number(value) => value,
+        _ => base_opacity,
+    }
+}
+
+pub fn resolve_number_at_time(
+    base_value: f64,
+    animations: Option<&ElementAnimations>,
+    property_path: &str,
+    local_time: MediaTime,
+) -> f64 {
+    match resolve_animation_path_value_at_time(
+        animations,
+        property_path,
+        local_time.max(MediaTime::ZERO),
+        &ParamValue::Number(base_value),
+    ) {
+        ParamValue::Number(value) => value,
+        _ => base_value,
+    }
+}
+
+pub fn resolve_color_at_time(
+    base_color: &str,
+    animations: Option<&ElementAnimations>,
+    property_path: &str,
+    local_time: MediaTime,
+) -> String {
+    match resolve_animation_path_value_at_time(
+        animations,
+        property_path,
+        local_time.max(MediaTime::ZERO),
+        &ParamValue::String(base_color.to_string()),
+    ) {
+        ParamValue::String(value) => value,
+        _ => base_color.to_string(),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use scene::{AnimationChannel, ChannelData, ScalarAnimationKey, ScalarChannel, ScalarSegmentType, TangentMode};
+    use std::collections::BTreeMap;
+
+    #[test]
+    fn resolves_opacity_with_animation_and_fallback() {
+        let channel = AnimationChannel::Scalar(ScalarChannel {
+            keys: vec![ScalarAnimationKey {
+                id: "a".to_string(),
+                time: MediaTime::from_ticks(0),
+                value: 0.25,
+                left_handle: None,
+                right_handle: None,
+                segment_to_next: ScalarSegmentType::Linear,
+                tangent_mode: TangentMode::Flat,
+            }],
+            extrapolation: None,
+        });
+        let mut animations: ElementAnimations = BTreeMap::new();
+        animations.insert("opacity".to_string(), ChannelData::Single(channel));
+        assert_eq!(
+            resolve_opacity_at_time(1.0, Some(&animations), MediaTime::from_ticks(0)),
+            0.25
+        );
+        assert_eq!(
+            resolve_opacity_at_time(1.0, Some(&animations), MediaTime::from_ticks(-5)),
+            0.25
+        );
+        assert_eq!(resolve_opacity_at_time(1.0, None, MediaTime::from_ticks(0)), 1.0);
+    }
+}