| /* |
| * 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. |
| */ |
| |
| package com.google.zxing.common; |
| |
| import com.google.zxing.NotFoundException; |
| |
| /** |
| * 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 { |
| |
| private static GridSampler gridSampler = new DefaultGridSampler(); |
| |
| /** |
| * 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 The platform-specific object to install. |
| */ |
| 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() { |
| return gridSampler; |
| } |
| |
| /** |
| * <p>Samples an image for a square matrix of bits of the given dimension. This is used to extract |
| * the black/white modules of a 2D barcode like a QR Code found in an image. Because this barcode |
| * may be rotated or perspective-distorted, the caller supplies four points in the source image |
| * that define known points in the barcode, so that the image may be sampled appropriately.</p> |
| * |
| * <p>The last eight "from" parameters are four X/Y coordinate pairs of locations of points in |
| * the image that define some significant points in the image to be sample. For example, |
| * these may be the location of finder pattern in a QR Code.</p> |
| * |
| * <p>The first eight "to" parameters are four X/Y coordinate pairs measured in the destination |
| * {@link BitMatrix}, from the top left, where the known points in the image given by the "from" |
| * parameters map to.</p> |
| * |
| * <p>These 16 parameters define the transformation needed to sample the image.</p> |
| * |
| * @param image image to sample |
| * @param dimension width/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 |
| */ |
| public abstract BitMatrix sampleGrid(BitMatrix image, |
| int dimension, |
| float p1ToX, float p1ToY, |
| float p2ToX, float p2ToY, |
| float p3ToX, float p3ToY, |
| float p4ToX, float p4ToY, |
| float p1FromX, float p1FromY, |
| float p2FromX, float p2FromY, |
| float p3FromX, float p3FromY, |
| float p4FromX, float p4FromY) throws NotFoundException; |
| |
| public BitMatrix sampleGrid(BitMatrix image, |
| int dimension, |
| PerspectiveTransform transform) throws NotFoundException { |
| throw new IllegalStateException(); // Can't use UnsupportedOperationException |
| } |
| |
| |
| /** |
| * <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 |
| */ |
| protected static void checkAndNudgePoints(BitMatrix image, float[] points) |
| throws NotFoundException { |
| int width = image.getWidth(); |
| int height = image.getHeight(); |
| // Check and nudge points from start until we see some that are OK: |
| boolean nudged = true; |
| for (int offset = 0; offset < points.length && nudged; offset += 2) { |
| int x = (int) points[offset]; |
| int y = (int) points[offset + 1]; |
| if (x < -1 || x > width || y < -1 || y > height) { |
| throw NotFoundException.getNotFoundInstance(); |
| } |
| nudged = false; |
| if (x == -1) { |
| points[offset] = 0.0f; |
| nudged = true; |
| } else if (x == width) { |
| points[offset] = width - 1; |
| nudged = true; |
| } |
| if (y == -1) { |
| points[offset + 1] = 0.0f; |
| nudged = true; |
| } else if (y == height) { |
| points[offset + 1] = height - 1; |
| nudged = true; |
| } |
| } |
| // Check and nudge points from end: |
| nudged = true; |
| for (int offset = points.length - 2; offset >= 0 && nudged; offset -= 2) { |
| int x = (int) points[offset]; |
| int y = (int) points[offset + 1]; |
| if (x < -1 || x > width || y < -1 || y > height) { |
| throw NotFoundException.getNotFoundInstance(); |
| } |
| nudged = false; |
| if (x == -1) { |
| points[offset] = 0.0f; |
| nudged = true; |
| } else if (x == width) { |
| points[offset] = width - 1; |
| nudged = true; |
| } |
| if (y == -1) { |
| points[offset + 1] = 0.0f; |
| nudged = true; |
| } else if (y == height) { |
| points[offset + 1] = height - 1; |
| nudged = true; |
| } |
| } |
| } |
| |
| } |