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image management in asp.net?

问题描述:

in my application i am uploading the image into database. before it is store in the database, i want to do image management like decreasing size and decreasing height and width of the image. can u help me. is there any source code or any reference please.

网友答案:

What codebehind language are you using?

I find 4guysfromrolla to be a good ASP.NET reference, try this article for starters:

http://www.4guysfromrolla.com/articles/012203-1.aspx

网友答案:

If you're talking about something like creating a thumbnail image. the Image() class will let you scale an existing image up or down. YMMV.

网友答案:

You want to be looking at the System.Drawing name space for manipulating images with ASP.NET. You can load any supported image file type (i.e. jpg, gif, png, etc) using Image.FromFile(), Image.FromStream(), etc. From there you use the Drawing Graphics context to manipulate the image. To give you a flavour here is my resize image function:

// Creates a re-sized image from the SourceFile provided that retails the same aspect ratio of the SourceImage. 
// -    If either the width or height dimensions is not provided then the resized image will use the 
//      proportion of the provided dimension to calculate the missing one.
// -    If both the width and height are provided then the resized image will have the dimensions provided 
//      with the sides of the excess portions clipped from the center of the image.
public static Image ResizeImage(Image sourceImage, int? newWidth, int? newHeight)
{
    bool doNotScale = newWidth == null || newHeight == null; ;

    if (newWidth == null)
    {
        newWidth = (int)(sourceImage.Width * ((float)newHeight / sourceImage.Height));
    }
    else if (newHeight == null)
    {
        newHeight = (int)(sourceImage.Height * ((float)newWidth) / sourceImage.Width);
    }

    var targetImage = new Bitmap(newWidth.Value, newHeight.Value);

    Rectangle srcRect;
    var desRect = new Rectangle(0, 0, newWidth.Value, newHeight.Value);

    if (doNotScale)
    {
        srcRect = new Rectangle(0, 0, sourceImage.Width, sourceImage.Height);
    }
    else
    {
        if (sourceImage.Height > sourceImage.Width)
        {
            // clip the height
            int delta = sourceImage.Height - sourceImage.Width;
            srcRect = new Rectangle(0, delta / 2, sourceImage.Width, sourceImage.Width);
        }
        else
        {
            // clip the width
            int delta = sourceImage.Width - sourceImage.Height;
            srcRect = new Rectangle(delta / 2, 0, sourceImage.Height, sourceImage.Height);
        }
    }

    using (var g = Graphics.FromImage(targetImage))
    {
        g.SmoothingMode = SmoothingMode.HighQuality;
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;

        g.DrawImage(sourceImage, desRect, srcRect, GraphicsUnit.Pixel);
    }

    return targetImage;
}
网友答案:

You can either use the image class or a 3rd party DLL such as ASPJPEG. A few ASPJPEG samples can be found here. I do a lot of image processing and my host reliablesite supports this dll on their servers.

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