Question

I have a list of same sized PNGs. I need to create a long image, with all images next to each other. I have no progressed. 🙂

I have loaded all the image paths into a List<>, and then created a BitMap, with the height of the images, and the length of the number of images , multiplied by their widths. (All images are equal dimensions).

I then need to go through each image, and basically paste it into it’s correct position in my BitMap. Can anyone possibly help me with a routine to do this? Iterate through all my items – and paste them onto my Bitmap.

I have tried this, but it’s failing with: Generic GDI Error.

using(Bitmap newFiles = new Bitmap(outputFileWidth, outputFileHeight))
{
     using(Graphics graphics = Graphics.FromImage(newFiles))
     {
         graphics.DrawImage(
            testImage,
            new Rectangle(0, 0, originalWidth, originalHeight),
            new Rectangle(new Point(), testImage.Size),
            GraphicsUnit.Pixel);
     }
     newFiles.Save(@"c:\test.png");
}

I have not yet done the loops. I am just trying to add the first image.

Answer 1

Answer located! Error was due to a locked file. Actually, permission on my folders. And this is a fantastic routine that I hope helps someone else.

public Bitmap Combine()
        {
            //read all images into memory
            List<Bitmap> images = new List<Bitmap>();
            Bitmap finalImage = null;

            try
            {
                int width = 0;
                int height = 0;

                foreach (var image in files)
                {
                    //create a Bitmap from the file and add it to the list
                    System.Drawing.Bitmap bitmap = new Bitmap(image.Filename);

                    //update the size of the final bitmap
                    width += bitmap.Width;
                    height = bitmap.Height > height ? bitmap.Height : height;

                    images.Add(bitmap);
                }

                //create a bitmap to hold the combined image
                finalImage = new System.Drawing.Bitmap(width, height);

                //get a graphics object from the image so we can draw on it
                using (Graphics g = Graphics.FromImage(finalImage))
                {
                    //set background color
                    g.Clear(Color.Black);

                    //go through each image and draw it on the final image
                    int offset = 0;
                    foreach (Bitmap image in images)
                    {
                        g.DrawImage(image,
                          new Rectangle(offset, 0, image.Width, image.Height));
                        offset += image.Width;
                    }
                }

                return finalImage;
            }
            catch (Exception ex)
            {
                if (finalImage != null)
                    finalImage.Dispose();

                throw ex;
            }
            finally
            {
                //clean up memory
                foreach (Bitmap image in images)
                {
                    image.Dispose();
                }
            }
        }