Crops an image, resulting in a new image consisting of the portion of the original image contained in a provided bounding rectangle - CSharp System.Drawing

CSharp examples for System.Drawing:Image Size

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Description

Crops an image, resulting in a new image consisting of the portion of the original image contained in a provided bounding rectangle

Demo Code


using System.Net;
using System.IO;/*from  w w w  . ja v a 2  s .  c o  m*/
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing;
using System;

public class Main{
    /// <summary>
      /// Crops an image, resulting in a new image consisting of the portion of the
      /// original image contained in a provided bounding rectangle
      /// </summary>
      /// <param name="inputBmp">Bitmap to crop</param>
      /// <param name="cropRectangle">Rectangle specifying the range of pixels
      /// within the image which is to be retained</param>
      /// <returns>New bitmap consisting of the contents of the crop rectangle</returns>
      public static Bitmap CropBitmap(Bitmap inputBmp, Rectangle cropRectangle) {
         //Create a new bitmap object based on the input
         Bitmap newBmp = new Bitmap(cropRectangle.Width, 
                              cropRectangle.Height, 
                              PixelFormat.Format24bppRgb);//Graphics.FromImage doesn't like Indexed pixel format

         //Create a graphics object and attach it to the bitmap
         Graphics newBmpGraphics = Graphics.FromImage(newBmp);

         //Draw the portion of the input image in the crop rectangle
         //in the graphics object
         newBmpGraphics.DrawImage(inputBmp,
                            new Rectangle(0, 0, cropRectangle.Width, cropRectangle.Height),
                            cropRectangle,
                            GraphicsUnit.Pixel);

         //Return the bitmap
         newBmpGraphics.Dispose();

         //newBmp will have a RawFormat of MemoryBmp because it was created
         //from scratch instead of being based on inputBmp.  Since it it inconvenient
         //for the returned version of a bitmap to be of a different format, now convert
         //the scaled bitmap to the format of the source bitmap
         return ConvertBitmap(newBmp, inputBmp.RawFormat);
      }
    /// <summary>Converts a bitmap to another bitmap format, returning the new converted
      ///     bitmap
      /// </summary>
      /// 
      /// <param name="inputBmp">Bitmap to convert</param>
      /// <param name="destFormat">Bitmap format to convert to</param>
      /// 
      /// <returns>A new bitmap object containing the input bitmap converted.
      ///     If the destination format and the target format are the same, returns
      ///     a clone of the destination bitmap.</returns>
      public static Bitmap ConvertBitmap(Bitmap inputBmp, System.Drawing.Imaging.ImageFormat destFormat) {
         //If the dest format matches the source format and quality/bpp not changing, just clone
         if (inputBmp.RawFormat.Equals(destFormat)) {
            return(Bitmap)inputBmp.Clone();
         }

         //Create an in-memory stream which will be used to save
         //the converted image
         System.IO.Stream imgStream = new System.IO.MemoryStream();

         //Save the bitmap out to the memory stream, using the format indicated by the caller
         inputBmp.Save(imgStream, destFormat);

         //At this point, imgStream contains the binary form of the
         //bitmap in the target format.  All that remains is to load it
         //into a new bitmap object
         Bitmap destBitmap = new Bitmap(imgStream);

         //Free the stream
         //imgStream.Close();
         //For some reason, the above causes unhandled GDI+ exceptions
         //when destBitmap.Save is called.  Perhaps the bitmap object reads
         //from the stream asynchronously?

         return destBitmap;
      }
        /// <summary>Converts a bitmap to another bitmap format, returning the new converted
      ///     bitmap
      /// </summary>
      /// 
      /// <param name="inputBmp">Bitmap to convert</param>
      /// <param name="destMimeType">MIME type of format to convert to</param>
      /// 
      /// <returns>A new bitmap object containing the input bitmap converted.
      ///     If the destination format and the target format are the same, returns
      ///     a clone of the destination bitmap.</returns>
      public static Bitmap ConvertBitmap(Bitmap inputBmp, String destMimeType) {
         return ConvertBitmap(inputBmp, ImageFormatFromMimeType(destMimeType));
      }
}

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