buildExposureDetector method

Widget buildExposureDetector(BuildContext context, BoxConstraints constraints)

The GestureDetector widget for setting exposure point manually. 用于手动设置曝光点的 GestureDetector

Implementation

Widget buildExposureDetector(
  BuildContext context,
  BoxConstraints constraints,
) {
  void focus(TapUpDetails d) {
    // Only call exposure point updates when the controller is initialized.
    if (innerController?.value.isInitialized ?? false) {
      Feedback.forTap(context);
      setExposureAndFocusPoint(d.localPosition, constraints);
    }
  }

  return Positioned.fill(
    child: Semantics(
      label: textDelegate.sCameraPreviewLabel(
        innerController?.description.lensDirection,
      ),
      image: true,
      onTap: () {
        // Focus on the center point when using semantics tap.
        final Size size = MediaQuery.of(context).size;
        final TapUpDetails details = TapUpDetails(
          kind: PointerDeviceKind.touch,
          globalPosition: Offset(size.width / 2, size.height / 2),
        );
        focus(details);
      },
      onTapHint: textDelegate.sActionManuallyFocusHint,
      sortKey: const OrdinalSortKey(1),
      hidden: innerController == null,
      excludeSemantics: true,
      child: GestureDetector(
        onTapUp: focus,
        behavior: HitTestBehavior.translucent,
        child: const SizedBox.expand(),
      ),
    ),
  );
}