resize image c# / asp.net to specific format (widescreen 16:9)

开发者_如何学运维I am searching for a way to resize and crop images to a specific size in a fixed ratio like 16:9. So I have any image and any size and it should be resized and cropped in a ratio 16:9.

Just cropping is not very nice. I want that the image is resized more and if necessary maybe cropped. Or better: I want to reuse as much as possible from the original image but resize and crop it centered so I could use it in a fixed html div with a ration of 16:9.

Thanks!

Here is a solution that I have used several times. This should resize first, then crop on whichever dimension has excess. The image will not be stretched.

using System.Drawing;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
using System.IO;

protected Image imageCrop(Image image, int width, int height, AnchorPosition anchor)
{
    int sourceWidth = image.Width;
    int sourceHeight = image.Height;
    int sourceX = 0;
    int sourceY = 0;
    int destX = 0;
    int destY = 0;

    float nPercent = 0;
    float nPercentW = 0;
    float nPercentH = 0;

    nPercentW = (Convert.ToSingle(width) / Convert.ToSingle(sourceWidth));
    nPercentH = (Convert.ToSingle(height) / Convert.ToSingle(sourceHeight));

    if (nPercentH < nPercentW)
    {
        nPercent = nPercentW;
        switch (anchor) {
            case AnchorPosition.Top:
                destY = 0;
                break;
            case AnchorPosition.Bottom:
                destY = Convert.ToInt32(height - (sourceHeight * nPercent));
                break;
            default:
                destY = Convert.ToInt32((height - (sourceHeight * nPercent)) / 2);
                break;
        }
    }
    else
    {
        nPercent = nPercentH;
        switch (anchor) {
            case AnchorPosition.Left:
                destX = 0;
                break;
            case AnchorPosition.Right:
                destX = Convert.ToInt32((width - (sourceWidth * nPercent)));
                break;
            default:
                destX = Convert.ToInt32(((width - (sourceWidth * nPercent)) / 2));
                break;
        }
    }

    int destWidth = Convert.ToInt32((sourceWidth * nPercent));
    int destHeight = Convert.ToInt32((sourceHeight * nPercent));

    Bitmap bmPhoto = new Bitmap(width, height, PixelFormat.Format24bppRgb);
    bmPhoto.SetResolution(image.HorizontalResolution, image.VerticalResolution);

    Graphics grPhoto = Graphics.FromImage(bmPhoto);
    grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic;
    grPhoto.DrawImage(image, new Rectangle(destX, destY, destWidth, destHeight), new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight), GraphicsUnit.Pixel);
    grPhoto.Dispose();

    return bmPhoto;
}

public enum Dimensions
{
    Width,
    Height
}

public enum AnchorPosition
{
    Top,
    Center,
    Bottom,
    Left,
    Right
}

Here is an example of a call to the function:

Image image = image.FromFile(imagePath);
Image thumb = imageCrop(image, 100, 100, AnchorPosition.Top);

I did something similar to create a thumbnail of a standard size. Here is a link to the code (in a blog post).

http://blog.bobcravens.com/2009/07/mobileme-scrolling-image-viewer/

The concept is the same. I used some logic to automatically pick an area of the bitmap to crop based upon the dimensions.

Hope this helps.

Bob

You can use this code:

 Size NewSize = new Size();
                NewSize.Width = 70;
                NewSize.Height = 60;
                System.Drawing.Image small = resizeImage(Image.FromFile(source), NewSize);
                small.Save(your path);

// and this is function for resizing

    public System.Drawing.Image resizeImage(Image imgToResize, Size size)
        {
            int sourceWidth = imgToResize.Width;
            int sourceHeight = imgToResize.Height;
            float nPercent = 0;
            float nPercentW = 0;
            float nPercentH = 0;
            nPercentW = ((float)size.Width / (float)sourceWidth);
            nPercentH = ((float)size.Height / (float)sourceHeight);
            if (nPercentH < nPercentW) nPercent = nPercentH;
            else
                nPercent = nPercentW;
            int destWidth = (int)(sourceWidth * nPercent);
            int destHeight = (int)(sourceHeight * nPercent);
            Bitmap b = new Bitmap(destWidth, destHeight);
            Graphics g = Graphics.FromImage((Image)b);
            g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.DrawImage(imgToResize, 0, 0, destWidth, destHeight);
            g.Dispose();
            return (System.Drawing.Image)b;
        }