LuminanceSource.cs

/*
* Copyright 2009 ZXing authors
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
using System;
namespace com.google.zxing
{
	
	/// <summary> The purpose of this class hierarchy is to abstract different bitmap implementations across
	/// platforms into a standard interface for requesting greyscale luminance values. The interface
	/// only provides immutable methods; therefore crop and rotation create copies. This is to ensure
	/// that one Reader does not modify the original luminance source and leave it in an unknown state
	/// for other Readers in the chain.
	/// 
	/// </summary>
	/// <author>  dswitkin@google.com (Daniel Switkin)
	/// </author>
	/// <author>www.Redivivus.in (suraj.supekar@redivivus.in) - Ported from ZXING Java Source 
	/// </author>

	public abstract class LuminanceSource
	{
		/// <summary> Fetches luminance data for the underlying bitmap. Values should be fetched using:
		/// int luminance = array[y * width + x] & 0xff;
		/// 
		/// </summary>
		/// <returns> A row-major 2D array of luminance values. Do not use result.length as it may be
		/// larger than width * height bytes on some platforms. Do not modify the contents
		/// of the result.
		/// </returns>
		public abstract sbyte[] Matrix{get;}
		/// <returns> The width of the bitmap.
		/// </returns>
		virtual public int Width
		{
			get
			{
				return width;
			}
			
		}
		/// <returns> The height of the bitmap.
		/// </returns>
		virtual public int Height
		{
			get
			{
				return height;
			}
			
		}
		/// <returns> Whether this subclass supports cropping.
		/// </returns>
		virtual public bool CropSupported
		{
			get
			{
				return false;
			}
			
		}
		/// <returns> Whether this subclass supports counter-clockwise rotation.
		/// </returns>
		virtual public bool RotateSupported
		{
			get
			{
				return false;
			}
			
		}
		
		//UPGRADE_NOTE: Final was removed from the declaration of 'width '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
		private int width;
		//UPGRADE_NOTE: Final was removed from the declaration of 'height '. "ms-help://MS.VSCC.v80/dv_commoner/local/redirect.htm?index='!DefaultContextWindowIndex'&keyword='jlca1003'"
		private int height;
		
		protected internal LuminanceSource(int width, int height)
		{
			this.width = width;
			this.height = height;
		}
		
		/// <summary> Fetches one row of luminance data from the underlying platform's bitmap. Values range from
		/// 0 (black) to 255 (white). Because Java does not have an unsigned byte type, callers will have
		/// to bitwise and with 0xff for each value. It is preferable for implementations of this method
		/// to only fetch this row rather than the whole image, since no 2D Readers may be installed and
		/// getMatrix() may never be called.
		/// 
		/// </summary>
		/// <param name="y">The row to fetch, 0 <= y < getHeight().
		/// </param>
		/// <param name="row">An optional preallocated array. If null or too small, it will be ignored.
		/// Always use the returned object, and ignore the .length of the array.
		/// </param>
		/// <returns> An array containing the luminance data.
		/// </returns>
		public abstract sbyte[] getRow(int y, sbyte[] row);
		
		/// <summary> Returns a new object with cropped image data. Implementations may keep a reference to the
		/// original data rather than a copy. Only callable if isCropSupported() is true.
		/// 
		/// </summary>
		/// <param name="left">The left coordinate, 0 <= left < getWidth().
		/// </param>
		/// <param name="top">The top coordinate, 0 <= top <= getHeight().
		/// </param>
		/// <param name="width">The width of the rectangle to crop.
		/// </param>
		/// <param name="height">The height of the rectangle to crop.
		/// </param>
		/// <returns> A cropped version of this object.
		/// </returns>
		public virtual LuminanceSource crop(int left, int top, int width, int height)
		{
			throw new System.SystemException("This luminance source does not support cropping.");
		}
		
		/// <summary> Returns a new object with rotated image data. Only callable if isRotateSupported() is true.
		/// 
		/// </summary>
		/// <returns> A rotated version of this object.
		/// </returns>
		public virtual LuminanceSource rotateCounterClockwise()
		{
			throw new System.SystemException("This luminance source does not support rotation.");
		}
	}
}