CropAround.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using ImageResizer.Resizing;
using System.Drawing;
using ImageResizer.ExtensionMethods;
using ImageResizer.Util;

namespace ImageResizer.Plugins.CropAround {
    public class CropAroundPlugin:BuilderExtension, IPlugin,IQuerystringPlugin  {
     
        public IPlugin Install(Configuration.Config c) {
            c.Plugins.add_plugin(this);
            return this;
        }

        public bool Uninstall(Configuration.Config c) {
            c.Plugins.remove_plugin(this);
            return true;
        }

        public IEnumerable<string> GetSupportedQuerystringKeys() {
            return new string[] { "c.focus", "c.zoom" };
        }

        protected override RequestedAction LayoutImage(ImageState s) {
            //Only activated if both width and height are specified, and mode=crop.
            if (s.settings.Mode != FitMode.Crop || s.settings.Width < 0 || s.settings.Height < 0) return RequestedAction.None;

            //Calculate bounding box for all coordinates specified.
            double[] focus = NameValueCollectionExtensions.GetList<double>(s.settings, "c.focus", null, 2, 4, 8, 12, 16, 20, 24, 28, 32, 36, 40, 44, 48, 52, 56, 60, 64, 68, 72);
            if (focus == null) return RequestedAction.None;
            RectangleF box = PolygonMath.GetBoundingBox(focus);

            var bounds = new RectangleF(new PointF(0,0),s.originalSize);
            //Clip box to original image bounds
            box = PolygonMath.ClipRectangle(box, bounds);

            var targetSize = new SizeF(s.settings.Width,s.settings.Height);

            SizeF copySize;

            //Now, we can either crop as closely as possible or as loosely as possible. 
            if (NameValueCollectionExtensions.Get<bool>(s.settings, "c.zoom", false) && box.Width > 0 && box.Height > 0) {
                //Crop close
                copySize = PolygonMath.ScaleOutside(box.Size, targetSize);
            } else {
                //Crop minimally
                copySize = PolygonMath.ScaleInside(targetSize, bounds.Size);
                //Ensure it's outside the box
                if (!PolygonMath.FitsInside(box.Size,copySize)) copySize = PolygonMath.ScaleOutside(box.Size, copySize);

            }
            //Clip to bounds.
            box = PolygonMath.ClipRectangle(PolygonMath.ExpandTo(box, copySize), bounds);

            s.copyRect = box;
            
            ///What is the vertical and horizontal aspect ratio different in result pixels?
            var padding = PolygonMath.ScaleInside(box.Size, targetSize);
            padding = new SizeF(targetSize.Width - padding.Width, targetSize.Height - padding.Height);

            //Crop off 1 or 2 pixels without worrying too much
            if (padding.Width + padding.Height < 3) s.settings.Mode = FitMode.Crop;
                //Otherwise pad the result
            else s.settings.Mode = FitMode.Pad;

            return RequestedAction.None;
        }
        
    }
}