189 lines
7.0 KiB
PHP
189 lines
7.0 KiB
PHP
<?php
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/*
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* Copyright 2007 ZXing authors
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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namespace Zxing\Common;
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use Zxing\NotFoundException;
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/**
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* Implementations of this class can, given locations of finder patterns for a QR code in an
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* image, sample the right points in the image to reconstruct the QR code, accounting for
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* perspective distortion. It is abstracted since it is relatively expensive and should be allowed
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* to take advantage of platform-specific optimized implementations, like Sun's Java Advanced
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* Imaging library, but which may not be available in other environments such as J2ME, and vice
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* versa.
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*
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* The implementation used can be controlled by calling {@link #setGridSampler(GridSampler)}
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* with an instance of a class which implements this interface.
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*
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* @author Sean Owen
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*/
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abstract class GridSampler
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{
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private static $gridSampler;
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/**
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* Sets the implementation of GridSampler used by the library. One global
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* instance is stored, which may sound problematic. But, the implementation provided
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* ought to be appropriate for the entire platform, and all uses of this library
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* in the whole lifetime of the JVM. For instance, an Android activity can swap in
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* an implementation that takes advantage of native platform libraries.
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*
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* @param newGridSampler The platform-specific object to install.
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*/
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public static function setGridSampler($newGridSampler)
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{
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self::$gridSampler = $newGridSampler;
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}
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/**
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* @return the current implementation of GridSampler
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*/
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public static function getInstance()
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{
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if (!self::$gridSampler) {
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self::$gridSampler = new DefaultGridSampler();
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}
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return self::$gridSampler;
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}
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/**
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* <p>Checks a set of points that have been transformed to sample points on an image against
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* the image's dimensions to see if the point are even within the image.</p>
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*
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* <p>This method will actually "nudge" the endpoints back onto the image if they are found to be
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* barely (less than 1 pixel) off the image. This accounts for imperfect detection of finder
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* patterns in an image where the QR Code runs all the way to the image border.</p>
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*
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* <p>For efficiency, the method will check points from either end of the line until one is found
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* to be within the image. Because the set of points are assumed to be linear, this is valid.</p>
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*
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* @param image image into which the points should map
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* @param points actual points in x1,y1,...,xn,yn form
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*
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* @throws NotFoundException if an endpoint is lies outside the image boundaries
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*/
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protected static function checkAndNudgePoints(
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$image,
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$points
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) {
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$width = $image->getWidth();
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$height = $image->getHeight();
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// Check and nudge points from start until we see some that are OK:
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$nudged = true;
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for ($offset = 0; $offset < count($points) && $nudged; $offset += 2) {
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$x = (int)$points[$offset];
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$y = (int)$points[$offset + 1];
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if ($x < -1 || $x > $width || $y < -1 || $y > $height) {
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throw NotFoundException::getNotFoundInstance();
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}
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$nudged = false;
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if ($x == -1) {
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$points[$offset] = 0.0;
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$nudged = true;
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} else if ($x == $width) {
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$points[$offset] = $width - 1;
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$nudged = true;
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}
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if ($y == -1) {
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$points[$offset + 1] = 0.0;
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$nudged = true;
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} else if ($y == $height) {
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$points[$offset + 1] = $height - 1;
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$nudged = true;
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}
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}
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// Check and nudge points from end:
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$nudged = true;
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for ($offset = count($points) - 2; $offset >= 0 && $nudged; $offset -= 2) {
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$x = (int)$points[$offset];
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$y = (int)$points[$offset + 1];
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if ($x < -1 || $x > $width || $y < -1 || $y > $height) {
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throw NotFoundException::getNotFoundInstance();
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}
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$nudged = false;
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if ($x == -1) {
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$points[$offset] = 0.0;
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$nudged = true;
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} else if ($x == $width) {
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$points[$offset] = $width - 1;
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$nudged = true;
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}
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if ($y == -1) {
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$points[$offset + 1] = 0.0;
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$nudged = true;
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} else if ($y == $height) {
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$points[$offset + 1] = $height - 1;
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$nudged = true;
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}
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}
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}
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/**
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* Samples an image for a rectangular matrix of bits of the given dimension. The sampling
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* transformation is determined by the coordinates of 4 points, in the original and transformed
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* image space.
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*
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* @param image image to sample
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* @param dimensionX width of {@link BitMatrix} to sample from image
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* @param dimensionY height of {@link BitMatrix} to sample from image
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* @param p1ToX point 1 preimage X
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* @param p1ToY point 1 preimage Y
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* @param p2ToX point 2 preimage X
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* @param p2ToY point 2 preimage Y
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* @param p3ToX point 3 preimage X
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* @param p3ToY point 3 preimage Y
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* @param p4ToX point 4 preimage X
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* @param p4ToY point 4 preimage Y
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* @param p1FromX point 1 image X
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* @param p1FromY point 1 image Y
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* @param p2FromX point 2 image X
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* @param p2FromY point 2 image Y
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* @param p3FromX point 3 image X
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* @param p3FromY point 3 image Y
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* @param p4FromX point 4 image X
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* @param p4FromY point 4 image Y
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*
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* @return {@link BitMatrix} representing a grid of points sampled from the image within a region
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* defined by the "from" parameters
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* @throws NotFoundException if image can't be sampled, for example, if the transformation defined
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* by the given points is invalid or results in sampling outside the image boundaries
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*/
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public abstract function sampleGrid(
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$image,
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$dimensionX,
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$dimensionY,
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$p1ToX, $p1ToY,
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$p2ToX, $p2ToY,
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$p3ToX, $p3ToY,
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$p4ToX, $p4ToY,
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$p1FromX, $p1FromY,
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$p2FromX, $p2FromY,
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$p3FromX, $p3FromY,
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$p4FromX, $p4FromY
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);
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public abstract function sampleGrid_(
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$image,
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$dimensionX,
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$dimensionY,
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$transform
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);
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}
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