Resize image in bytes[] to a different sized image also in bytes[] - Windows 8

Question

I have this piece of code that retrieves a image from a webservice and saves it to a StorageFile

StorageFolder folder = await ApplicationData.Current.LocalFolder.CreateFolderAsync(Constants.DataDirectory, CreationCollisionOption.OpenIfExists);
StorageFile imgFile;

using (var httpClient = new HttpClient { BaseAddress = Constants.baseAddress })
{
    string token = App.Current.Resources["token"] as string;
    httpClient.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", token);

    using (var response2 = await httpClient.GetAsync("user/image?userId=" + id))
    {
        Stream imageStream = await response2.Content.ReadAsStreamAsync();
        if (imageStream.Length != 0)
        {
            byte[] bytes = new byte[imageStream.Length];
            imageStream.Read(bytes, 0, (int)imageStream.Length);
            imgFile = await folder.CreateFileAsync(fname, CreationCollisionOption.ReplaceExisting);
            await FileIO.WriteBytesAsync(imgFile, bytes);  //i want the image bytes to be of a smaller version of the image at this point
        }
        return await response2.Content.ReadAsStringAsync();
    }
}

I would like to know if there is a way to convert the image bytes[] to a thumbnail version (50x50 for example) before writing them into the StorageFile.

Check out the solution I offered here: http://stackoverflow.com/questions/32792626/reduce-image-size-physical-and-dimensions-coming-from-httppostedfilebase-then — Lorek, Oct 01 '15 at 14:06

score 1 · Accepted Answer · answered Oct 10 '15 at 03:47

Here is the code to resize the image stream:

                var decoder = await BitmapDecoder.CreateAsync(stream);

                var pixels = await decoder.GetPixelDataAsync();

                var file = await folder.CreateFileAsync($"{_oriFile.DisplayName}_{size}.png",CreationCollisionOption.GenerateUniqueName);
                using (var fileStream = await file.OpenAsync(FileAccessMode.ReadWrite))
                {

                    var encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.PngEncoderId, fileStream);

                    encoder.BitmapTransform.ScaledWidth = size;
                    encoder.BitmapTransform.ScaledHeight = size;

                    encoder.SetPixelData(
                        decoder.BitmapPixelFormat,
                        decoder.BitmapAlphaMode,
                        decoder.PixelWidth, decoder.PixelHeight,
                        decoder.DpiX, decoder.DpiY,
                        pixels.DetachPixelData());

                    encoder.BitmapTransform.InterpolationMode = BitmapInterpolationMode.Fant;

                    await encoder.FlushAsync();
                }

When you get the image stream, you should do the resize thing before saving it as StorageFile. Of course you can do this later after saving it to StorageFile.

Resize image in bytes[] to a different sized image also in bytes[] - Windows 8

1 Answers1