+++ /dev/null
-/*
- * Copyright 2007 Google Inc.
- *
- * 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.
- */
-
-package com.google.zxing.qrcode.detector;
-
-import com.google.zxing.MonochromeBitmapSource;
-import com.google.zxing.ReaderException;
-import com.google.zxing.common.BitMatrix;
-
-/**
- * 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 srowen@google.com (Sean Owen)
- */
-public abstract class GridSampler {
-
- private static GridSampler gridSampler;
-
- /**
- * Sets the implementation of {@link 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
- */
- public static void setGridSampler(GridSampler newGridSampler) {
- if (newGridSampler == null) {
- throw new IllegalArgumentException();
- }
- gridSampler = newGridSampler;
- }
-
- /**
- * @return the current implementation of {@link GridSampler}
- */
- public static GridSampler getInstance() {
- if (gridSampler == null) {
- gridSampler = new DefaultGridSampler();
- }
- return gridSampler;
- }
-
- /**
- * <p>Given an image, locations of a QR Code's finder patterns and bottom-right alignment pattern,
- * and the presumed dimension in modules of the QR Code, implemntations of this method extract
- * the QR Code from the image by sampling the points in the image which should correspond to the
- * modules of the QR Code.</p>
- *
- * @param image image to sample
- * @param topLeft top-left finder pattern location
- * @param topRight top-right finder pattern location
- * @param bottomLeft bottom-left finder pattern location
- * @param alignmentPattern bottom-right alignment pattern location
- * @param dimension dimension of QR Code
- * @return {@link BitMatrix} representing QR Code's modules
- * @throws ReaderException if QR Code cannot be reasonably sampled -- for example if the location
- * of the finder patterns imply a transformation that would require sampling off the image
- */
- protected abstract BitMatrix sampleGrid(MonochromeBitmapSource image,
- FinderPattern topLeft,
- FinderPattern topRight,
- FinderPattern bottomLeft,
- AlignmentPattern alignmentPattern,
- int dimension) throws ReaderException;
-
- /**
- * <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 endpoints are even within the image.
- * This method actually only checks the endpoints since the points are assumed to lie
- * on a line.</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>
- *
- * @param image image into which the points should map
- * @param points actual points in x1,y1,...,xn,yn form
- * @throws ReaderException if an endpoint is lies outside the image boundaries
- */
- protected static void checkEndpoint(MonochromeBitmapSource image, float[] points) throws ReaderException {
- int width = image.getWidth();
- int height = image.getHeight();
- checkOneEndpoint(points, (int) points[0], (int) points[1], width, height);
- checkOneEndpoint(points, (int) points[points.length - 2], (int) points[points.length - 1], width, height);
- }
-
- private static void checkOneEndpoint(float[] points, int x, int y, int width, int height) throws ReaderException {
- if (x < -1 || x > width || y < -1 || y > height) {
- throw new ReaderException("Transformed point out of bounds at " + x + ',' + y);
- }
- if (x == -1) {
- points[0] = 0.0f;
- }
- if (y == -1) {
- points[1] = 0.0f;
- }
- if (x == width) {
- points[0] = width - 1;
- }
- if (y == height) {
- points[1] = height - 1;
- }
- }
-
-}