zxing/csharp/qrcode/detector/FinderPattern.cs

using System;

/*
 * Copyright 2007 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.
 */

namespace com.google.zxing.qrcode.detector
{

	using ResultPoint = com.google.zxing.ResultPoint;

	/// <summary>
	/// <p>Encapsulates a finder pattern, which are the three square patterns found in
	/// the corners of QR Codes. It also encapsulates a count of similar finder patterns,
	/// as a convenience to the finder's bookkeeping.</p>
	/// 
	/// @author Sean Owen
	/// </summary>
	public sealed class FinderPattern : com.google.zxing.ResultPoint
	{

	  private readonly float estimatedModuleSize;
	  private int count;

	  internal FinderPattern(float posX, float posY, float estimatedModuleSize) : this(posX, posY, estimatedModuleSize, 1)
	  {
	  }

	  private FinderPattern(float posX, float posY, float estimatedModuleSize, int count) : base(posX, posY)
	  {
		this.estimatedModuleSize = estimatedModuleSize;
		this.count = count;
	  }

	  public float EstimatedModuleSize
	  {
		  get
		  {
			return estimatedModuleSize;
		  }
	  }

	  internal int Count
	  {
		  get
		  {
			return count;
		  }
	  }

	  internal void incrementCount()
	  {
		this.count++;
	  }

	  /// <summary>
	  /// <p>Determines if this finder pattern "about equals" a finder pattern at the stated
	  /// position and size -- meaning, it is at nearly the same center with nearly the same size.</p>
	  /// </summary>
	  internal bool aboutEquals(float moduleSize, float i, float j)
	  {
		if (Math.Abs(i - Y) <= moduleSize && Math.Abs(j - X) <= moduleSize)
		{
		  float moduleSizeDiff = Math.Abs(moduleSize - estimatedModuleSize);
		  return moduleSizeDiff <= 1.0f || moduleSizeDiff <= estimatedModuleSize;
		}
		return false;
	  }

	  /// <summary>
	  /// Combines this object's current estimate of a finder pattern position and module size
	  /// with a new estimate. It returns a new {@code FinderPattern} containing a weighted average
	  /// based on count.
	  /// </summary>
	  internal FinderPattern combineEstimate(float i, float j, float newModuleSize)
	  {
		int combinedCount = count + 1;
		float combinedX = (count * X + j) / combinedCount;
		float combinedY = (count * Y + i) / combinedCount;
		float combinedModuleSize = (count * estimatedModuleSize + newModuleSize) / combinedCount;
		return new FinderPattern(combinedX, combinedY, combinedModuleSize, combinedCount);
	  }

	}

}