src/core/common/GridSampler.ts
/*
* 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.
*/
/*namespace com.google.zxing.common {*/
import BitMatrix from './BitMatrix';
import PerspectiveTransform from './PerspectiveTransform';
import NotFoundException from '../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
*/
abstract class GridSampler {
/**
* 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 {@link BitMatrix} to sample from image
* @param dimensionY height of {@link BitMatrix} 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 {@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 sampleGrid(
image: BitMatrix,
dimensionX: number /*int*/,
dimensionY: number /*int*/,
p1ToX: number/*float*/, p1ToY: number/*float*/,
p2ToX: number/*float*/, p2ToY: number/*float*/,
p3ToX: number/*float*/, p3ToY: number/*float*/,
p4ToX: number/*float*/, p4ToY: number/*float*/,
p1FromX: number/*float*/, p1FromY: number/*float*/,
p2FromX: number/*float*/, p2FromY: number/*float*/,
p3FromX: number/*float*/, p3FromY: number/*float*/,
p4FromX: number/*float*/, p4FromY: number/*float*/
): BitMatrix; /*throws NotFoundException*/
public abstract sampleGridWithTransform(
image: BitMatrix,
dimensionX: number /*int*/,
dimensionY: number /*int*/,
transform: PerspectiveTransform
): BitMatrix; /*throws NotFoundException*/
/**
* <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 checkAndNudgePoints(
image: BitMatrix,
points: Float32Array
): void /*throws NotFoundException*/ {
const width: number /*int*/ = image.getWidth();
const height: number /*int*/ = image.getHeight();
// Check and nudge points from start until we see some that are OK:
let nudged: boolean = true;
for (let offset = 0; offset < points.length && nudged; offset += 2) {
const x = Math.floor(points[offset]);
const y = Math.floor(points[offset + 1]);
if (x < -1 || x > width || y < -1 || y > height) {
throw new NotFoundException();
}
nudged = false;
if (x === -1) {
points[offset] = 0.0;
nudged = true;
} else if (x === width) {
points[offset] = width - 1;
nudged = true;
}
if (y === -1) {
points[offset + 1] = 0.0;
nudged = true;
} else if (y === height) {
points[offset + 1] = height - 1;
nudged = true;
}
}
// Check and nudge points from end:
nudged = true;
for (let offset = points.length - 2; offset >= 0 && nudged; offset -= 2) {
const x = Math.floor(points[offset]);
const y = Math.floor(points[offset + 1]);
if (x < -1 || x > width || y < -1 || y > height) {
throw new NotFoundException();
}
nudged = false;
if (x === -1) {
points[offset] = 0.0;
nudged = true;
} else if (x === width) {
points[offset] = width - 1;
nudged = true;
}
if (y === -1) {
points[offset + 1] = 0.0;
nudged = true;
} else if (y === height) {
points[offset + 1] = height - 1;
nudged = true;
}
}
}
}
export default GridSampler;