How to Copy and Resize Image in Windows 10 UWP

Question

I have used the code from http://www.codeproject.com/Tips/552141/Csharp-Image-resize-convert-and-save to resize images programmatically. However, that project uses the

Answer 1

I may want to return a copy of the original BitmapImage rather than modifying the original.

There is no good method to directly copy a BitmapImage, but we can reuse StorageFile for several times.

If you just want to select a picture, show it and in the meanwhile show the re-sized picture of original one, you can pass the StorageFile as parameter like this:

public static async Task<BitmapImage> ResizedImage(StorageFile ImageFile, int maxWidth, int maxHeight)
{
    IRandomAccessStream inputstream = await ImageFile.OpenReadAsync();
    BitmapImage sourceImage = new BitmapImage();
    sourceImage.SetSource(inputstream);
    var origHeight = sourceImage.PixelHeight;
    var origWidth = sourceImage.PixelWidth;
    var ratioX = maxWidth / (float)origWidth;
    var ratioY = maxHeight / (float)origHeight;
    var ratio = Math.Min(ratioX, ratioY);
    var newHeight = (int)(origHeight * ratio);
    var newWidth = (int)(origWidth * ratio);

    sourceImage.DecodePixelWidth = newWidth;
    sourceImage.DecodePixelHeight = newHeight;

    return sourceImage;
}

In this scenario you just need to call this task and show the re-sized image like this:

smallImage.Source = await ResizedImage(file, 250, 250);

If you want to keep the BitmapImage parameter due to some reasons (like the sourceImage might be a modified bitmap but not directly loaded from file), and you want to re-size this new picture to another one, you will need to save the re-sized picture as a file at first, then open this file and re-size it again.