调整目录中的所有图像的大小

Question

我必须调整目录图像的大小，

但我收到错误，拒绝访问， 在这一行

System.IO.File.Delete(_path);

我知道这是因为我阅读的图像已被使用，但不知道如何处理它

我在SO上找到了链接，但都在php中： - （

for (int i = 1; i < dt.Rows.Count; i++)
{
    try
    {
        string _ImageUrl = HttpContext.Current.Request.PhysicalApplicationPath + 
            "Data\\" + dt.Rows[i]["ProductImage"].ToString();

        string _extName = System.IO.Path.GetExtension(_ImageUrl);

        System.Drawing.Image _productImage = ImageReSize(_ImageUrl, 500);
        string _path = _ImageUrl;

        if (System.IO.File.Exists(_path))
        System.IO.File.Delete(_path);

        _productImage.Save(_path);

        _productImage = ImageReSize(_ImageUrl, 85);
        string _strImageName2 = dt.Rows[i]["ProductSmallImage"].ToString();

        _path = HttpContext.Current.Request.PhysicalApplicationPath + 
            "Data\\" + _strImageName2;

        if (System.IO.File.Exists(_path))
        System.IO.File.Delete(_path);
        _productImage.Save(_path);
    }
}

调整大小的代码

 public System.Drawing.Image ImageReSize(string _imageUrl, int Width)
    {
        try
        {
            //uploadImageFile.PostedFile.InputSteam
            System.Drawing.Image oImg = System.Drawing.Image.FromFile(_imageUrl);

            //((oh *nw) / ow)*100

            int Height = ((oImg.Height * Width) / oImg.Width);              // (oImg.Width * Width);
            Size PictureThumbSize = new Size();
            PictureThumbSize.Height = Height;
            PictureThumbSize.Width = Width;
            System.Drawing.Image oThumbNail = new Bitmap(PictureThumbSize.Width, PictureThumbSize.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

            Graphics oGraphic = Graphics.FromImage(oThumbNail);

            oGraphic.CompositingQuality = CompositingQuality.HighQuality;

            oGraphic.SmoothingMode = SmoothingMode.HighQuality;

            oGraphic.InterpolationMode = InterpolationMode.HighQualityBicubic;

            Rectangle oRectangle = new Rectangle(0, 0, PictureThumbSize.Width, PictureThumbSize.Height);

            oGraphic.DrawImage(oImg, oRectangle);
            oImg.Dispose();
            return oThumbNail;
            //oThumbNail.Save(sPhysicalPath + @"\" + newFileName, ImageFormat.Jpeg);
        }
        catch (Exception Ex)
        {
            return null;
        }
    }

Answer 1

首先，您不必在保存之前删除文件，Image.Save（）函数将替换现有图像，但您必须确保处置指向图像的所有句柄。 这是一个解释我的观点的例子：

      var image = new Bitmap("test.png");

      var image2 = resizeImage(image, new Size(48, 48));
      //image.Dispose();
      image2.Save("test.png");

如果没有dipose，你将有一个exeption，但如果你取消注释行image.Dispose（）它将像魅力一样工作。

对于函数resizeImage我将其复制为问题Resize an Image C#

这是代码：

public static Image resizeImage(Image imgToResize, Size size)
{
  return (Image)(new Bitmap(imgToResize, size));
}

修改

看来Graphics对象是原因，你必须调用oGraphic.Dispose（）;

保存后调用_productImage.Dispose（）。

实际上更合适的方式是：

  for (int i = 1; i < dt.Rows.Count; i++)
  {
    try
    {
      string _ImageUrl = HttpContext.Current.Request.PhysicalApplicationPath +
          "Data\\" + dt.Rows[i]["ProductImage"].ToString();

      string _extName = System.IO.Path.GetExtension(_ImageUrl);

      using (System.Drawing.Image _productImage = ImageReSize(_ImageUrl, 500))
      {
        string _path = _ImageUrl;

        if (System.IO.File.Exists(_path))
          System.IO.File.Delete(_path);

        _productImage.Save(_path);
      }
      using (System.Drawing.Image _productImage = ImageReSize(_ImageUrl, 85))
      {
        string _strImageName2 = dt.Rows[i]["ProductSmallImage"].ToString();

        _path = HttpContext.Current.Request.PhysicalApplicationPath +
            "Data\\" + _strImageName2;

        if (System.IO.File.Exists(_path))
          System.IO.File.Delete(_path);
        _productImage.Save(_path);
      }
    }
    catch
    {
      //Handle the exeption
    }
  }

public System.Drawing.Image ImageReSize(string _imageUrl, int Width)
{

  try
  {
    //uploadImageFile.PostedFile.InputSteam
    using (System.Drawing.Image oImg = System.Drawing.Image.FromFile(_imageUrl))
    //((oh *nw) / ow)*100
    {
      int Height = ((oImg.Height * Width) / oImg.Width);              // (oImg.Width * Width);
      Size PictureThumbSize = new Size();
      PictureThumbSize.Height = Height;
      PictureThumbSize.Width = Width;
      System.Drawing.Image oThumbNail = new Bitmap(PictureThumbSize.Width, PictureThumbSize.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

      using (Graphics oGraphic = Graphics.FromImage(oThumbNail))
      {
        oGraphic.CompositingQuality = CompositingQuality.HighQuality;

        oGraphic.SmoothingMode = SmoothingMode.HighQuality;

        oGraphic.InterpolationMode = InterpolationMode.HighQualityBicubic;

        Rectangle oRectangle = new Rectangle(0, 0, PictureThumbSize.Width, PictureThumbSize.Height);

        oGraphic.DrawImage(oImg, oRectangle);
      }
      return oThumbNail;
    }
    //oThumbNail.Save(sPhysicalPath + @"\" + newFileName, ImageFormat.Jpeg);
  }
  catch (Exception Ex)
  {
    return null;
  }

}

Answer 2

也可以在Graphics对象上调用Dispose。

Answer 3

在尝试删除原始图像之前调用Dispose。