calculateBoxFitRatio static method

({double heightRatio, double widthRatio}) calculateBoxFitRatio({ required BoxFit boxFit, required Size cameraPreviewSize, required Size size, })

Calculate the scaling ratios for width and height to fit the provided cameraPreviewSize into the specified size, based on the specified boxFit.

Returns a record containing the width and height scaling ratios.

Implementation

static ({double widthRatio, double heightRatio}) calculateBoxFitRatio({
  required BoxFit boxFit,
  required Size cameraPreviewSize,
  required Size size,
}) {
  if (cameraPreviewSize.width <= 0 ||
      cameraPreviewSize.height <= 0 ||
      size.width <= 0 ||
      size.height <= 0) {
    return (widthRatio: 1.0, heightRatio: 1.0);
  }

  final widthRatio = size.width / cameraPreviewSize.width;
  final heightRatio = size.height / cameraPreviewSize.height;

  switch (boxFit) {
    case BoxFit.fill:
      // Stretch to fill the large box without maintaining aspect ratio.
      return (widthRatio: widthRatio, heightRatio: heightRatio);

    case BoxFit.contain:
      // Maintain aspect ratio,
      // ensure the content fits entirely within the large box.
      final double ratio = min(widthRatio, heightRatio);
      return (widthRatio: ratio, heightRatio: ratio);

    case BoxFit.cover:
      // Maintain aspect ratio, ensure the content fully covers the large box.
      final double ratio = max(widthRatio, heightRatio);
      return (widthRatio: ratio, heightRatio: ratio);

    case BoxFit.fitWidth:
      // Maintain aspect ratio, ensure the width matches the large box.
      return (widthRatio: widthRatio, heightRatio: widthRatio);

    case BoxFit.fitHeight:
      // Maintain aspect ratio, ensure the height matches the large box.
      return (widthRatio: heightRatio, heightRatio: heightRatio);

    case BoxFit.none:
      return (widthRatio: 1.0, heightRatio: 1.0);

    case BoxFit.scaleDown:
      // If the content is larger than the large box, scale down to fit.
      // Otherwise, no scaling is needed.
      final ratio = min(1, min(widthRatio, heightRatio)).toDouble();
      return (widthRatio: ratio, heightRatio: ratio);
  }
}