Question

I need to do two things to an image: resize it, then crop it.

I’m resizing like this:

nonResizedImage = new Bitmap(imagePath);
Bitmap scaled = new Bitmap(preCropWidth, preCropHeight);
using (Graphics scaledGraphics = Graphics.FromImage(scaled)) 
{ // scale image to the sizeo f the image the user cropped on
    scaledGraphics.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    scaledGraphics.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighSpeed;
    scaledGraphics.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceCopy;
    scaledGraphics.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
    scaledGraphics.Clear(ColorTranslator.FromHtml("#FFFFFF"));
    scaledGraphics.DrawImage(nonResizedImage, 0, 0, preCropWidth, preCropHeight);
}

Now I need to crop the image. I’ve found a function that does this:

static byte[] Crop(string Img, int Width, int Height, int X, int Y)
{
    try
    {
        using (SD.Image OriginalImage = SD.Image.FromFile(Img))
        {
            using (SD.Bitmap bmp = new SD.Bitmap(Width, Height))
            {
                bmp.SetResolution(OriginalImage.HorizontalResolution, OriginalImage.VerticalResolution);

                using (SD.Graphics Graphic = SD.Graphics.FromImage(bmp))
                {
                    Graphic.SmoothingMode = SmoothingMode.AntiAlias;
                    Graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
                    Graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
                    Graphic.DrawImage(OriginalImage, new SD.Rectangle(0, 0, Width, Height), X, Y, Width, Height, SD.GraphicsUnit.Pixel);
                    MemoryStream ms = new MemoryStream();
                    bmp.Save(ms, OriginalImage.RawFormat);
                    return ms.GetBuffer();
                }
            }
        }
    }

    catch (Exception Ex)
    {
        throw Ex;
    }
}

But this requires a image as input. So, I could save the output of my resize code to the disk, then read it back in again to do the crop, but this seems needlessly inefficient. I don’t really know much about image manipulation in c# though.

How do I crop the scaledGraphics I have, without first saving it to the disk?

Answer 1

One of the overloads for new Bitmap is Width, Height, Graphics Object. You should be able to just pass the graphics object in and then create the bitmap from that. Something like this

  static byte[] Crop(Graphics g, int Width, int Height, int X, int Y)
  {
      try
       {
          using (Bitmap bmp = new Bitmap(Width, Height, g))
          { 
           ...
          }
        }
        ......
    }