Resizes a bitmap's width and height independently

Description

Demo Code


using System.Net;
using System.IO;//from w  w w  .j  av a2 s.  c  om
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Drawing;
using System;

public class Main{
        /// <summary>
      /// Resizes a bitmap's width and height independently
      /// </summary>
      /// <param name="inputBmp">Bitmap to resize</param>
      /// <param name="imgWidth">New width</param>
      /// <param name="imgHeight">New height</param>
      /// <returns>Resized bitmap</returns>
      public static Bitmap ResizeBitmap(Bitmap inputBmp, int imgWidth, int imgHeight) {
         //Simply compute scale factors that result in the desired size, then call ScaleBitmap
         return ScaleBitmap(inputBmp,
                        (float)imgWidth/(float)inputBmp.Size.Width, 
                        (float)imgHeight/(float)inputBmp.Size.Height);
      }
     /// <summary>
      /// Scales a bitmap by a scale factor, growing or shrinking both axes independently, 
      /// possibly changing the aspect ration
      /// </summary>
      /// <param name="inputBmp">Bitmap to scale</param>
      /// <param name="scaleFactor">Factor by which to scale</param>
      /// <returns>New bitmap containing image from inputBmp, scaled by the scale factor</returns>
      public static Bitmap ScaleBitmap(Bitmap inputBmp, double xScaleFactor, double yScaleFactor) {
         //Create a new bitmap object based on the input
         Bitmap newBmp = new Bitmap(
                             (int)(inputBmp.Size.Width*xScaleFactor), 
                             (int)(inputBmp.Size.Height*yScaleFactor), 
                             PixelFormat.Format24bppRgb);//Graphics.FromImage doesn't like Indexed pixel format

         //Create a graphics object attached to the new bitmap
         Graphics newBmpGraphics = Graphics.FromImage(newBmp);

         //Set the interpolation mode to high quality bicubic 
         //interpolation, to maximize the quality of the scaled image
         newBmpGraphics.InterpolationMode = InterpolationMode.HighQualityBicubic;

         newBmpGraphics.ScaleTransform((float)xScaleFactor, (float)yScaleFactor);

         //Draw the bitmap in the graphics object, which will apply
         //the scale transform
         //Note that pixel units must be specified to ensure the framework doesn't attempt
         //to compensate for varying horizontal resolutions in images by resizing; in this case,
         //that's the opposite of what we want.
         Rectangle drawRect = new Rectangle(0, 0, inputBmp.Size.Width, inputBmp.Size.Height);
         newBmpGraphics.DrawImage(inputBmp, drawRect, drawRect, GraphicsUnit.Pixel);

         //Return the bitmap, as the operations on the graphics object
         //are applied to 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>
      /// Scales a bitmap by a scale factor, growing or shrinking both axes while
      /// maintaining the original aspect ratio
      /// </summary>
      /// <param name="inputBmp">Bitmap to scale</param>
      /// <param name="scaleFactor">Factor by which to scale</param>
      /// <returns>New bitmap containing image from inputBmp, scaled by the scale factor</returns>
      public static Bitmap ScaleBitmap(Bitmap inputBmp, double scaleFactor) {
         return ScaleBitmap(inputBmp, scaleFactor, scaleFactor);
      }
                /// <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));
      }
}
Resizes a bitmap's width and height independently - CSharp System.Drawing

Description

Demo Code

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