src/core/common/PerspectiveTransform.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 {*/
/**
* <p>This class implements a perspective transform in two dimensions. Given four source and four
* destination points, it will compute the transformation implied between them. The code is based
* directly upon section 3.4.2 of George Wolberg's "Digital Image Warping"; see pages 54-56.</p>
*
* @author Sean Owen
*/
export default class PerspectiveTransform {
private constructor(private a11: number/*float*/, private a21: number/*float*/, private a31: number/*float*/,
private a12: number/*float*/, private a22: number/*float*/, private a32: number/*float*/,
private a13: number/*float*/, private a23: number/*float*/, private a33: number/*float*/) { }
public static quadrilateralToQuadrilateral(
x0: number/*float*/, y0: number/*float*/,
x1: number/*float*/, y1: number/*float*/,
x2: number/*float*/, y2: number/*float*/,
x3: number/*float*/, y3: number/*float*/,
x0p: number/*float*/, y0p: number/*float*/,
x1p: number/*float*/, y1p: number/*float*/,
x2p: number/*float*/, y2p: number/*float*/,
x3p: number/*float*/, y3p: number/*float*/
): PerspectiveTransform {
const qToS = PerspectiveTransform.quadrilateralToSquare(x0, y0, x1, y1, x2, y2, x3, y3);
const sToQ = PerspectiveTransform.squareToQuadrilateral(x0p, y0p, x1p, y1p, x2p, y2p, x3p, y3p);
return sToQ.times(qToS);
}
public transformPoints(points: Float32Array): void {
const max = points.length;
const a11 = this.a11;
const a12 = this.a12;
const a13 = this.a13;
const a21 = this.a21;
const a22 = this.a22;
const a23 = this.a23;
const a31 = this.a31;
const a32 = this.a32;
const a33 = this.a33;
for (let i = 0; i < max; i += 2) {
const x = points[i];
const y = points[i + 1];
const denominator = a13 * x + a23 * y + a33;
points[i] = (a11 * x + a21 * y + a31) / denominator;
points[i + 1] = (a12 * x + a22 * y + a32) / denominator;
}
}
public transformPointsWithValues(xValues: Float32Array, yValues: Float32Array): void {
const a11 = this.a11;
const a12 = this.a12;
const a13 = this.a13;
const a21 = this.a21;
const a22 = this.a22;
const a23 = this.a23;
const a31 = this.a31;
const a32 = this.a32;
const a33 = this.a33;
const n = xValues.length;
for (let i = 0; i < n; i++) {
const x = xValues[i];
const y = yValues[i];
const denominator = a13 * x + a23 * y + a33;
xValues[i] = (a11 * x + a21 * y + a31) / denominator;
yValues[i] = (a12 * x + a22 * y + a32) / denominator;
}
}
public static squareToQuadrilateral(
x0: number/*float*/, y0: number/*float*/,
x1: number/*float*/, y1: number/*float*/,
x2: number/*float*/, y2: number/*float*/,
x3: number/*float*/, y3: number/*float*/
): PerspectiveTransform {
const dx3 = x0 - x1 + x2 - x3;
const dy3 = y0 - y1 + y2 - y3;
if (dx3 === 0.0 && dy3 === 0.0) {
// Affine
return new PerspectiveTransform(x1 - x0, x2 - x1, x0,
y1 - y0, y2 - y1, y0,
0.0, 0.0, 1.0);
} else {
const dx1 = x1 - x2;
const dx2 = x3 - x2;
const dy1 = y1 - y2;
const dy2 = y3 - y2;
const denominator = dx1 * dy2 - dx2 * dy1;
const a13 = (dx3 * dy2 - dx2 * dy3) / denominator;
const a23 = (dx1 * dy3 - dx3 * dy1) / denominator;
return new PerspectiveTransform(
x1 - x0 + a13 * x1, x3 - x0 + a23 * x3, x0,
y1 - y0 + a13 * y1, y3 - y0 + a23 * y3, y0,
a13, a23, 1.0
);
}
}
public static quadrilateralToSquare(
x0: number/*float*/, y0: number/*float*/,
x1: number/*float*/, y1: number/*float*/,
x2: number/*float*/, y2: number/*float*/,
x3: number/*float*/, y3: number/*float*/
): PerspectiveTransform {
// Here, the adjoint serves as the inverse:
return PerspectiveTransform.squareToQuadrilateral(x0, y0, x1, y1, x2, y2, x3, y3).buildAdjoint();
}
protected buildAdjoint(): PerspectiveTransform {
// Adjoint is the transpose of the cofactor matrix:
return new PerspectiveTransform(
this.a22 * this.a33 - this.a23 * this.a32,
this.a23 * this.a31 - this.a21 * this.a33,
this.a21 * this.a32 - this.a22 * this.a31,
this.a13 * this.a32 - this.a12 * this.a33,
this.a11 * this.a33 - this.a13 * this.a31,
this.a12 * this.a31 - this.a11 * this.a32,
this.a12 * this.a23 - this.a13 * this.a22,
this.a13 * this.a21 - this.a11 * this.a23,
this.a11 * this.a22 - this.a12 * this.a21
);
}
protected times(other: PerspectiveTransform): PerspectiveTransform {
return new PerspectiveTransform(
this.a11 * other.a11 + this.a21 * other.a12 + this.a31 * other.a13,
this.a11 * other.a21 + this.a21 * other.a22 + this.a31 * other.a23,
this.a11 * other.a31 + this.a21 * other.a32 + this.a31 * other.a33,
this.a12 * other.a11 + this.a22 * other.a12 + this.a32 * other.a13,
this.a12 * other.a21 + this.a22 * other.a22 + this.a32 * other.a23,
this.a12 * other.a31 + this.a22 * other.a32 + this.a32 * other.a33,
this.a13 * other.a11 + this.a23 * other.a12 + this.a33 * other.a13,
this.a13 * other.a21 + this.a23 * other.a22 + this.a33 * other.a23,
this.a13 * other.a31 + this.a23 * other.a32 + this.a33 * other.a33
);
}
}