将图像转换为流进行动态处理

Question

所以我使用SharpZipLib递归地浏览我的文档并打包它找到的任何JPEG图像，如下所示:

foreach (string filename in filenames)
{
    string[] file_split = filename.Split('.');
    if (file_split[file_split.Count() - 1].Equals("jpg"))
    {
        // You might replace these 3 lines with your own stream code
        ScaleImage scaleImage = new ScaleImage();
        FileStream file = new FileStream("path to file", FileMode.Open);
        using (Stream inputStream = File.OpenRead(filename))
        {
            string tarName = filename.Substring(3); // strip off "C:"
            Image tmpImg = scaleImage.scale(tmpImg);
            long fileSize = inputStream.Length;
            // Create a tar entry named as appropriate. You can set the name to anything,
            // but avoid names starting with drive or UNC
            TarEntry entry = TarEntry.CreateTarEntry(tarName);
            // Must set size, otherwise TarOutputStream will fail when output exceeds.
            entry.Size = fileSize;
            // Add the entry to the tar stream, before writing the data.
            tarOutputStream.PutNextEntry(entry);
            // this is copied from TarArchive.WriteEntryCore
            byte[] localBuffer = new byte[32 * 1024];
            while (true)
            {
                int numRead = inputStream.Read(localBuffer, 0, localBuffer.Length);
                if (numRead <= 0)
                {
                    break;
                }
                tarOutputStream.Write(localBuffer, 0, numRead);
            }
        }
        tarOutputStream.CloseEntry();
    }
}
// Recurse. Delete this if unwanted.
string[] directories = Directory.GetDirectories(sourceDirectory);
foreach (string directory in directories)
{
    CreateTarManually(tarOutputStream, directory);
}

尽量减少tar大小-我试图调整所有图像到指定的宽度x高度"在飞行中"从流中读取图像。我想我可以从流加载图像，一旦它进入使用(流inputStream)部分，并从那里使用一个函数发现，调整图像的大小。像这样:

public Bitmap scale(Image oldImage)
{
    double resizeFactor = 1;
    if (oldImage.Width > 150 || oldImage.Height > 150)
    {
        double widthFactor = Convert.ToDouble(oldImage.Width) / 150;
        double heightFactor = Convert.ToDouble(oldImage.Height) / 150;
        resizeFactor = Math.Max(widthFactor, heightFactor);
    }
    int width = Convert.ToInt32(oldImage.Width / resizeFactor);
    int height = Convert.ToInt32(oldImage.Height / resizeFactor);
    Bitmap newImage = new Bitmap(width, height);
    Graphics g = Graphics.FromImage(newImage);
    g.InterpolationMode =  System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    g.DrawImage(oldImage, 0, 0, newImage.Width, newImage.Height);
    return newImage;
}

我的问题是，我如何传递要调整大小的流对象，然后将流对象/调整大小的对象添加到tar文件，而不是原始文件本身?实际上，我希望所有这些都在内存中完成，以节省磁盘上每个文件在调整大小时的重复

Answer 1

用这里的答案

public Stream ImageToStream(Image image)
{
    //Save to stream
    MemoryStream stream = new MemoryStream();
    image.Save(stream, ImageFormat.Jpeg);
    stream.Seek(0, SeekOrigin.Begin); //Need to reset position to 0
    return stream;
}

不使用文件中的输入流，而是使用函数中的输入流:

Image oldImage = Image.FromFile(fileName);
Image newImage = scale(oldImage);
Stream inputStream = ImageToStream(newImage);

奖金建议:

如果你想检查文件扩展名，你可以像这样使用Path.GetExtension(fileName):

var fileExtension = Path.GetExtension(filename);
if (fileExtension.Equals(".jpg"))
{
     //ApplyLogic
}