selectIndicator method

@override Widget selectIndicator(BuildContext context, AssetEntity asset)

Indicator for assets selected status. 资源是否已选的指示器

Implementation

@override
Widget selectIndicator(BuildContext context, AssetEntity asset) {
  final Duration duration = switchingPathDuration * 0.75;
  return Selector<DefaultAssetPickerProvider, String>(
    selector: (_, DefaultAssetPickerProvider p) => p.selectedDescriptions,
    builder: (BuildContext context, _, __) {
      final List<AssetEntity> selectedAssets =
          context.select<DefaultAssetPickerProvider, List<AssetEntity>>(
        (DefaultAssetPickerProvider p) => p.selectedAssets,
      );
      final bool selected = selectedAssets.contains(asset);
      final double indicatorSize =
          context.mediaQuery.size.width / gridCount / 3;
      final Widget innerSelector = AnimatedContainer(
        duration: duration,
        width: indicatorSize / (isAppleOS ? 1.25 : 1.5),
        height: indicatorSize / (isAppleOS ? 1.25 : 1.5),
        decoration: BoxDecoration(
          border:
              !selected ? Border.all(color: Colors.white, width: 2) : null,
          color: selected ? themeColor : null,
          shape: BoxShape.circle,
        ),
        child: AnimatedSwitcher(
          duration: duration,
          reverseDuration: duration,
          child: selected
              ? const Icon(Icons.check, size: 18)
              : const SizedBox.shrink(),
        ),
      );
      final GestureDetector selectorWidget = GestureDetector(
        behavior: HitTestBehavior.opaque,
        onTap: () async {
          final bool? selectPredicateResult = await selectPredicate?.call(
            context,
            asset,
            selected,
          );
          if (selectPredicateResult == false) {
            return;
          }
          if (selected) {
            provider.unSelectAsset(asset);
            return;
          }
          if (isSingleAssetMode) {
            provider.selectedAssets.clear();
          }
          provider.selectAsset(asset);
          if (isSingleAssetMode && !isPreviewEnabled) {
            Navigator.of(context).maybePop(provider.selectedAssets);
          }
        },
        child: Container(
          margin: EdgeInsets.all(
            context.mediaQuery.size.width / gridCount / 12,
          ),
          width: isPreviewEnabled ? indicatorSize : null,
          height: isPreviewEnabled ? indicatorSize : null,
          alignment: AlignmentDirectional.topEnd,
          child: (!isPreviewEnabled && isSingleAssetMode && !selected)
              ? const SizedBox.shrink()
              : innerSelector,
        ),
      );
      if (isPreviewEnabled) {
        return PositionedDirectional(
          top: 0,
          end: 0,
          child: selectorWidget,
        );
      }
      return selectorWidget;
    },
  );
}