图像的GDI +调整 [英] Image resizing with GDI+

问题描述

我真的想钉出了这么一个小节目的码多一点的表现。这不是一个代码heavly使用一下，但使用每一个新的图像上载时间，4次为每个图像（100像素，200像素，500像素，700像素）。因此，当出现任何超过2或3的图像处理，它会在服务器上一点忙。我也正在试图弄清楚如何让它正确地用低分辨率处理图像。目前，它只是扒它关闭完成了一半，不plesent。
例子：原始，的大， XLARGE

I'm really trying to nail out a little more performance out of this tidbit of code. It's not a heavly used bit of code but is used every time a new image is uploaded, and 4 times for each image (100px, 200px, 500px, 700px). So when there are any more than 2 or 3 images processing, it gets a little busy on the server. Also I'm trying to figure out how to make it correctly process images with a low resolution. Currently it just chops it off half way through, not plesent. Examples: Original, large, xLarge

public static byte[] ResizeImageFile(byte[] imageFile, int targetSize)
{
    using (System.Drawing.Image oldImage = System.Drawing.Image.FromStream(new MemoryStream(imageFile)))
    {
        Size newSize = CalculateDimensions(oldImage.Size, targetSize);

        using (Bitmap newImage = new Bitmap(newSize.Width, newSize.Height, PixelFormat.Format32bppRgb))
        {
            newImage.SetResolution(oldImage.HorizontalResolution, oldImage.VerticalResolution);
            using (Graphics canvas = Graphics.FromImage(newImage))
            {
                canvas.SmoothingMode = SmoothingMode.AntiAlias;
                canvas.InterpolationMode = InterpolationMode.HighQualityBicubic;
                canvas.PixelOffsetMode = PixelOffsetMode.HighQuality;
                canvas.DrawImage(oldImage, new Rectangle(new Point(0, 0), newSize));
                MemoryStream m = new MemoryStream();
                newImage.Save(m, ImageFormat.Jpeg);
                return m.GetBuffer();
            }
        }

    }
}

private static Size CalculateDimensions(Size oldSize, int targetSize)
{
    Size newSize = new Size();
    if (oldSize.Width > oldSize.Height)
    {
        newSize.Width = targetSize;
        newSize.Height = (int)(oldSize.Height * (float)targetSize / (float)oldSize.Width);
    }
    else
    {
        newSize.Width = (int)(oldSize.Width * (float)targetSize / (float)oldSize.Height);
        newSize.Height = targetSize;
    }
    return newSize;
}

感谢和帮助！

Thanks for and help!

推荐答案

这想到的第一个念头就是，你有没有想过多线程呢？即，主叫在单独的线程为每个图像此方​​法（或一批图像）？这样，如果你的服务器有几个内核就可以把事情做得更快。只是一个想法......

The first thought that comes to mind is, have you thought about Multithreading it? i.e. calling this method for each image (or batch of images) in a separate thread? That way, if your server has a few cores you can get things done quicker. Just a thought...

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