C＃StorageFile图像大小调整为一定数量的字节

Question

I have already read a lot of posts on Stack about image resizing and quality reducing, but non of them has been about reducing quality to certain physical disk space

I have a code that takes a picture:

private async void TakeAPhoto_Click(object sender, RoutedEventArgs e)
{
    CameraCaptureUI captureUI = new CameraCaptureUI();
    captureUI.PhotoSettings.Format = CameraCaptureUIPhotoFormat.Jpeg;

    StorageFile photo = await captureUI.CaptureFileAsync(CameraCaptureUIMode.Photo);
    if (photo != null)
    {

    }
}

Now i need to send the data to the server, but before, i need to ensure that the photo is not more than 3 MB.

So i do this:

BasicProperties pro = await photo.GetBasicPropertiesAsync();
if (pro.Size < 3072)
{
    // SEND THE FILE TO SERVER
}
else
{
    // DECREASE QUALITY BEFORE SENDING
}

So the question is about ELSE block

Is there a better or maybe i have missed some built-in approach to fit image into the certain amount of megabytes by decreasing it's quality?

Because doing this:

while (pro.Size <= 3072)
{
    photo = // some logic to decrease quality on 10%
}

Doesn't really look good.

Answer 1

Just Create one function :

    /// <summary>
    /// function to reduce image size and returns local path of image
    /// </summary>
    /// <param name="scaleFactor"></param>
    /// <param name="sourcePath"></param>
    /// <param name="targetPath"></param>
    /// <returns></returns>
    private string ReduceImageSize(double scaleFactor, Stream sourcePath, string targetPath)
    {
        try
        {
            using (var image = System.Drawing.Image.FromStream(sourcePath))
            {
                //var newWidth = (int)(image.Width * scaleFactor);
                //var newHeight = (int)(image.Height * scaleFactor);


                var newWidth = (int)1280;
                var newHeight = (int)960;

                var thumbnailImg = new System.Drawing.Bitmap(newWidth, newHeight);
                var thumbGraph = System.Drawing.Graphics.FromImage(thumbnailImg);
                thumbGraph.CompositingQuality = CompositingQuality.HighQuality;
                thumbGraph.SmoothingMode = SmoothingMode.HighQuality;
                thumbGraph.InterpolationMode = InterpolationMode.HighQualityBicubic;
                var imageRectangle = new System.Drawing.Rectangle(0, 0, newWidth, newHeight);
                thumbGraph.DrawImage(image, imageRectangle);
                thumbnailImg.Save(targetPath, image.RawFormat);
                return targetPath;



            }
        }
        catch (Exception e)
        {
            Console.WriteLine("Exception in ReduceImageSize" + e);
            return "";
        }
    }

And then call this function in your else block as below you will get same image with reduced size :

        string ImageLink = "https://imagesus-ssl.homeaway.com/mda01/337b3cbe-80cf-400a-aece-c932852eb929.1.10";
        string FinalTargetPath=@"F:\ReducedImage.png";
        HttpWebRequest imageRequest = (HttpWebRequest)WebRequest.Create(ImageLink);
        WebResponse imageResponse = imageRequest.GetResponse();
        Stream responseStream = imageResponse.GetResponseStream();

       string ImagePath= ReduceImageSize(0.5, responseStream, FinalTargetPath);