add method

Implementation

void add(KeyFrameBlock block) {
  // Support per-keyframe easing via `animation-timing-function` declared
  // inside the keyframe block. This easing applies to the segment starting
  // at this keyframe and ending at the next keyframe for the same property.
  // Default to linear if not specified.
  String easingForThisKeyframe = LINEAR;

  // First pass: detect block-level animation-timing-function if present.
  for (MapEntry<String, CSSPropertyValue> entry in block.declarations) {
    final propName = camelize(entry.key);
    if (propName == 'animationTimingFunction') {
      easingForThisKeyframe = entry.value.value;
      break;
    }
  }

  // For combined selectors like "0%, 100%", create keyframes for each.
  for (final String rawSel in block.blockSelectors) {
    final String keyText = rawSel.trim();
    double? offset;
    if (keyText == 'from') {
      offset = 0;
    } else if (keyText == 'to') {
      offset = 1;
    } else {
      offset = CSSPercentage.parsePercentage(keyText);
    }

    // Add keyframes for animatable properties, skipping the block-level timing function.
    for (MapEntry<String, CSSPropertyValue> entry in block.declarations) {
      final property = camelize(entry.key);
      if (property == 'animationTimingFunction') {
        continue; // already captured as easing
      }
      keyframes.add(Keyframe(property, entry.value.value, offset ?? 0, easingForThisKeyframe));
    }

    // (removed) verbose keyframe parse diagnostics
  }
}