GridSampler.java revision 7e3fa36d69ffee874dd364b8e3d9aa3cab9a273b
/*
* 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
*
*
* 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.
*/
/**
* 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 {@link #setGridSampler(GridSampler)}
* with an instance of a class which implements this interface.
*
* @author Sean Owen
*/
public abstract class GridSampler {
/**
* 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.
*/
}
/**
* @return the current implementation of GridSampler
*/
public static GridSampler getInstance() {
return gridSampler;
}
/**
* Samples an image for a rectangular matrix of bits of the given dimension.
* @param image image to sample
* @param dimensionX width of {@link BitMatrix} to sample from image
* @param dimensionY height of {@link BitMatrix} to sample from image
* @return {@link BitMatrix} representing a grid of points sampled from the image within a region
* defined by the "from" parameters
* @throws NotFoundException 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
*/
int dimensionX,
int dimensionY,
int dimensionX,
int dimensionY,
/**
* <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
* @throws NotFoundException if an endpoint is lies outside the image boundaries
*/
float[] points) throws NotFoundException {
// Check and nudge points from start until we see some that are OK:
boolean nudged = true;
throw NotFoundException.getNotFoundInstance();
}
nudged = false;
if (x == -1) {
nudged = true;
} else if (x == width) {
nudged = true;
}
if (y == -1) {
nudged = true;
} else if (y == height) {
nudged = true;
}
}
// Check and nudge points from end:
nudged = true;
throw NotFoundException.getNotFoundInstance();
}
nudged = false;
if (x == -1) {
nudged = true;
} else if (x == width) {
nudged = true;
}
if (y == -1) {
nudged = true;
} else if (y == height) {
nudged = true;
}
}
}
}