text: /*
   * Copyright 2012 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.
   */
  
  @class ZXBitMatrix, ZXPerspectiveTransform;
  
  /**
   * Implementations of this class can, given locations of finder patterns for a QR code in an
   * image, sample the right points in the image to reconstruct the QR code, accounting for
   * perspective distortion. It is abstracted since it is relatively expensive and should be allowed
   * to take advantage of platform-specific optimized implementations, like Sun's Java Advanced
   * Imaging library, but which may not be available in other environments such as J2ME, and vice
   * versa.
   *
   * The implementation used can be controlled by calling `setGridSampler:`
   * with an instance of a class which implements this interface.
   */
  @interface ZXGridSampler : NSObject
  
  /**
   * Sets the implementation of GridSampler used by the library. One global
   * instance is stored, which may sound problematic. But, the implementation provided
   * ought to be appropriate for the entire platform, and all uses of this library
   * in the whole lifetime of the JVM. For instance, an Android activity can swap in
   * an implementation that takes advantage of native platform libraries.
   *
   * @param newGridSampler The platform-specific object to install.
   */
  + (void)setGridSampler:(ZXGridSampler *)newGridSampler;
  
  /**
   * @return the current implementation of GridSampler
   */
  + (ZXGridSampler *)instance;
  
  /**
   * Samples an image for a rectangular matrix of bits of the given dimension. The sampling
   * transformation is determined by the coordinates of 4 points, in the original and transformed
   * image space.
   *
   * @param image image to sample
   * @param dimensionX width of ZXBitMatrix to sample from image
   * @param dimensionY height of ZXBitMatrix to sample from image
   * @param p1ToX point 1 preimage X
   * @param p1ToY point 1 preimage Y
   * @param p2ToX point 2 preimage X
   * @param p2ToY point 2 preimage Y
   * @param p3ToX point 3 preimage X
   * @param p3ToY point 3 preimage Y
   * @param p4ToX point 4 preimage X
   * @param p4ToY point 4 preimage Y
   * @param p1FromX point 1 image X
   * @param p1FromY point 1 image Y
   * @param p2FromX point 2 image X
   * @param p2FromY point 2 image Y
   * @param p3FromX point 3 image X
   * @param p3FromY point 3 image Y
   * @param p4FromX point 4 image X
   * @param p4FromY point 4 image Y
   * @return ZXBitMatrix representing a grid of points sampled from the image within a region
   *   defined by the "from" parameters or nil if image can't be sampled, for example, if the transformation defined
   *   by the given points is invalid or results in sampling outside the image boundaries
   */
  - (ZXBitMatrix *)sampleGrid:(ZXBitMatrix *)image
                   dimensionX:(int)dimensionX
                   dimensionY:(int)dimensionY
                        p1ToX:(float)p1ToX p1ToY:(float)p1ToY
                        p2ToX:(float)p2ToX p2ToY:(float)p2ToY
                        p3ToX:(float)p3ToX p3ToY:(float)p3ToY
                        p4ToX:(float)p4ToX p4ToY:(float)p4ToY
                      p1FromX:(float)p1FromX p1FromY:(float)p1FromY
                      p2FromX:(float)p2FromX p2FromY:(float)p2FromY
                      p3FromX:(float)p3FromX p3FromY:(float)p3FromY
                      p4FromX:(float)p4FromX p4FromY:(float)p4FromY
                        error:(NSError **)error;
  
  - (ZXBitMatrix *)sampleGrid:(ZXBitMatrix *)image
                   dimensionX:(int)dimensionX
                   dimensionY:(int)dimensionY
                    transform:(ZXPerspectiveTransform *)transform
                        error:(NSError **)error;
  
  /**
   * <p>Checks a set of points that have been transformed to sample points on an image against
   * the image's dimensions to see if the point are even within the image.</p>
   *
   * <p>This method will actually "nudge" the endpoints back onto the image if they are found to be
   * barely (less than 1 pixel) off the image. This accounts for imperfect detection of finder
   * patterns in an image where the QR Code runs all the way to the image border.</p>
   *
   * <p>For efficiency, the method will check points from either end of the line until one is found
   * to be within the image. Because the set of points are assumed to be linear, this is valid.</p>
   *
   * @param image image into which the points should map
   * @param points actual points in x1,y1,...,xn,yn form
   * @returns NO if an endpoint is lies outside the image boundaries
   */
  + (BOOL)checkAndNudgePoints:(ZXBitMatrix *)image points:(float *)points pointsLen:(int)pointsLen error:(NSError **)error;
  
  @end
  