calculateImageFitSize function

Size calculateImageFitSize(
  1. Image image,
  2. Size contentSize
)

Implementation

Size calculateImageFitSize(ui.Image image, Size contentSize) {
  // 获取图像的宽高
  final double imageWidth = image.width.toDouble();
  final double imageHeight = image.height.toDouble();

  // 获取内容区域的宽高
  final double contentWidth = contentSize.width;
  final double contentHeight = contentSize.height;

  // 计算宽高比
  final double imageAspectRatio = imageWidth / imageHeight;
  final double contentAspectRatio = contentWidth / contentHeight;

  double fitWidth;
  double fitHeight;

  if (imageAspectRatio > contentAspectRatio) {
    // 图像宽高比大于内容宽高比，按宽度适配
    fitWidth = contentWidth;
    fitHeight = contentWidth / imageAspectRatio;
  } else {
    // 图像宽高比小于或等于内容宽高比，按高度适配
    fitWidth = contentHeight * imageAspectRatio;
    fitHeight = contentHeight;
  }

  // 如果图像的宽高小于内容区域的宽高，则放大到内容区域的宽高
  if (fitWidth < contentWidth) {
    fitWidth = contentWidth;
    fitHeight = contentWidth / imageAspectRatio;
  }
  if (fitHeight < contentHeight) {
    fitWidth = contentHeight * imageAspectRatio;
    fitHeight = contentHeight;
  }

  return Size(fitWidth, fitHeight);
}