greenshot/Greenshot/Helpers/ScaleHelper.cs

/*
 * Greenshot - a free and open source screenshot tool
 * Copyright (C) 2007-2011  Thomas Braun, Jens Klingen, Robin Krom
 * 
 * For more information see: http://getgreenshot.org/
 * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/greenshot/
 * 
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 1 of the License, or
 * (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
using System;
using System.Drawing;

namespace Greenshot.Helpers {
	/// <summary>
	/// Offers a few helper functions for scaling/aligning an element with another element
	/// </summary>
	public class ScaleHelper {
		private ScaleHelper() {
		}
		
		/// <summary>
		/// calculates the Size an element must be resized to, in order to fit another element, keeping aspect ratio
		/// </summary>
		/// <param name="currentSize">the size of the element to be resized</param>
		/// <param name="targetSize">the target size of the element</param>
		/// <param name="crop">in case the aspect ratio of currentSize and targetSize differs: shall the scaled size fit into targetSize (i.e. that one of its dimensions is smaller - false) or vice versa (true)</param>
		/// <returns>a new SizeF object indicating the width and height the element should be scaled to</returns>
		public static SizeF GetScaledSize(SizeF currentSize, SizeF targetSize, bool crop) {
			float wFactor = targetSize.Width/currentSize.Width;
			float hFactor = targetSize.Height/currentSize.Height;
			
			float factor = crop ? Math.Max(wFactor, hFactor) : Math.Min(wFactor, hFactor);
			//System.Diagnostics.Debug.WriteLine(currentSize.Width+"..."+targetSize.Width);
			//System.Diagnostics.Debug.WriteLine(wFactor+"..."+hFactor+">>>"+factor);
			return new SizeF(currentSize.Width * factor, currentSize.Height * factor);
		}
		
		/// <summary>
		/// calculates the position of an element depending on the desired alignment within a RectangleF
		/// </summary>
		/// <param name="currentRect">the bounds of the element to be aligned</param>
		/// <param name="targetRect">the rectangle reference for aligment of the element</param>
		/// <param name="alignment">the System.Drawing.ContentAlignment value indicating how the element is to be aligned should the width or height differ from targetSize</param>
		/// <returns>a new RectangleF object with Location aligned aligned to targetRect</returns>
		public static RectangleF GetAlignedRectangle(RectangleF currentRect, RectangleF targetRect, ContentAlignment alignment) {
			RectangleF newRect = new RectangleF(targetRect.Location, currentRect.Size);
			switch(alignment) {
				case ContentAlignment.TopCenter:
					newRect.X = (targetRect.Width - currentRect.Width) / 2;
					break;
				case ContentAlignment.TopRight:
					newRect.X = (targetRect.Width - currentRect.Width);
					break;
				case ContentAlignment.MiddleLeft:
					newRect.Y = (targetRect.Height - currentRect.Height) / 2;
					break;
				case ContentAlignment.MiddleCenter:
					newRect.Y = (targetRect.Height - currentRect.Height) / 2;
					newRect.X = (targetRect.Width - currentRect.Width) / 2;
					break;
				case ContentAlignment.MiddleRight:
					newRect.Y = (targetRect.Height - currentRect.Height) / 2;
					newRect.X = (targetRect.Width - currentRect.Width);
					break;
				case ContentAlignment.BottomLeft:
					newRect.Y = (targetRect.Height - currentRect.Height);
					break;
				case ContentAlignment.BottomCenter:
					newRect.Y = (targetRect.Height - currentRect.Height);
					newRect.X = (targetRect.Width - currentRect.Width) / 2;
					break;
				case ContentAlignment.BottomRight:
					newRect.Y = (targetRect.Height - currentRect.Height);
					newRect.X = (targetRect.Width - currentRect.Width);
					break;
			}
			return newRect;
		}
		
		/// <summary>
		/// calculates the Rectangle an element must be resized an positioned to, in ordder to fit another element, keeping aspect ratio
		/// </summary>
		/// <param name="currentRect">the rectangle of the element to be resized/repositioned</param>
		/// <param name="targetRect">the target size/position of the element</param>
		/// <param name="crop">in case the aspect ratio of currentSize and targetSize differs: shall the scaled size fit into targetSize (i.e. that one of its dimensions is smaller - false) or vice versa (true)</param>
		/// <param name="alignment">the System.Drawing.ContentAlignment value indicating how the element is to be aligned should the width or height differ from targetSize</param>
		/// <returns>a new RectangleF object indicating the width and height the element should be scaled to and the position that should be applied to it for proper alignment</returns>
		public static RectangleF GetScaledRectangle(RectangleF currentRect, RectangleF targetRect, bool crop, ContentAlignment alignment) {
			SizeF newSize = GetScaledSize(currentRect.Size, targetRect.Size, crop);
			RectangleF newRect = new RectangleF(new Point(0,0), newSize);
			return GetAlignedRectangle(newRect, targetRect, alignment);
		}
	}
}