Question

I have ListView with the View type LargeIcon. The ListView has assigned LargeImageList. The assigned ImageList has ImageSize 200×200.
Images that will be added to the ImageList have size that doesn’t match to 200×200 ImageList size. They can have a lesser width or height. In both cases I want images to be aligned by center, i.e. MiddleCenter property for Winforms.Label class

Answer 1

ImageList will resize the image to fit the ImageSize. To get the image at its original size, and centered, you’ll need to create a new image with the desired properties. Sample code to do this (untested):

public static void AddCenteredImage(ImageList list, Image image) {
    using (var bmp = new Bitmap(list.ImageSize.Width, list.ImageSize.Height))
    using (var gr = Graphics.FromImage(bmp)) {
        gr.Clear(Color.Transparent);   // Change background if necessary
        var size = image.Size;
        if (size.Width > list.ImageSize.Width || size.Height > list.ImageSize.Height) {
            // Image too large, rescale to fit the image list
            double wratio = list.ImageSize.Width / size.Width;
            double hratio = list.ImageSize.Height / size.Height;
            double ratio = Math.Min(wratio, hratio);
            size = new Size((int)(ratio * size.Width), (int)(ratio * size.Height));
        }
        var rc = new Rectangle(
            (list.ImageSize.Width - size.Width) / 2,
            (list.ImageSize.Height - size.Height) / 2,
            size.Width, size.Height);
        gr.DrawImage(image, rc);
        list.Images.Add(bmp);
    }
}