ImageResizer - 将图像保存为更大尺寸

Question

我正在尝试使用 .net ImageResizer 将图像保存为指定大小。我无法使用我正在使用的当前代码将较小的图像保存到较大的尺寸。例如，我上传的图片是 200x200，_thumb 版本会保存为 100x100，但 _medium 和 _large 版本仍然是 200x200。

如何将上传的图片保存为指定的大图？如versions.Add("_extraLarge", "width=2000&height=2000&crop=auto&format=jpg");或versions.Add("_XXL", "width=auto&height=3000&crop=auto&format=jpg");

//GenerateVersions(FileUpload1.PostedFile.FileName);
Dictionary<string, string> versions = new Dictionary<string, string>();
//Define the versions to generate
versions.Add("_thumb", "width=100&height=100&crop=auto&format=jpg"); //Crop to square thumbnail
versions.Add("_medium", "maxwidth=400&maxheight=400&format=jpg"); //Fit inside 400x400 area, jpeg
versions.Add("_large", "maxwidth=1900&maxheight=1900&format=jpg"); //Fit inside 1900x1200 area

//Loop through each uploaded file
foreach (string fileKey in HttpContext.Current.Request.Files.Keys)
{
    HttpPostedFile file = HttpContext.Current.Request.Files[fileKey];
    if (file.ContentLength <= 0) continue; //Skip unused file controls.

    //Get the physical path for the uploads folder and make sure it exists
    string uploadFolder = MapPath("~/uploadsAIM");
    if (!Directory.Exists(uploadFolder)) Directory.CreateDirectory(uploadFolder);

    //Generate each version
    foreach (string suffix in versions.Keys)
    {
        ////Generate a filename (GUIDs are best).
        //string fileName = Path.Combine(uploadFolder, System.Guid.NewGuid().ToString() + suffix);
        string fileName = Path.Combine(uploadFolder, file.FileName + suffix);

        //Let the image builder add the correct extension based on the output file type
        //fileName = ImageBuilder.Current.Build(file, fileName, new ResizeSettings(versions[suffix]), false, true); //deprecated fileName
        fileName = ImageBuilder.Current.Build(new ImageJob(file, fileName, new Instructions(versions[suffix]), false, true)).FinalPath;
    }
}

Answer 1

默认情况下，缩放模式设置为DownscaleOnly。根据您的需要，将说明中的Scale 设置为up or both。

请注意，放大图像会产生模糊的图像。