From 05cc2023daa57bfdb813e478ddb61c1b2f3156c4 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Dominik=20Sch=C3=BCrmann?= Date: Sat, 5 Oct 2013 20:43:42 +0200 Subject: Add parts of zxing library to generate qr codes --- .../google/zxing/common/PerspectiveTransform.java | 148 +++++++++++++++++++++ 1 file changed, 148 insertions(+) create mode 100644 OpenPGP-Keychain/src/com/google/zxing/common/PerspectiveTransform.java (limited to 'OpenPGP-Keychain/src/com/google/zxing/common/PerspectiveTransform.java') diff --git a/OpenPGP-Keychain/src/com/google/zxing/common/PerspectiveTransform.java b/OpenPGP-Keychain/src/com/google/zxing/common/PerspectiveTransform.java new file mode 100644 index 000000000..9e65baff1 --- /dev/null +++ b/OpenPGP-Keychain/src/com/google/zxing/common/PerspectiveTransform.java @@ -0,0 +1,148 @@ +/* + * 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; + +/** + *

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.

+ * + * @author Sean Owen + */ +public final class PerspectiveTransform { + + private final float a11, a12, a13, a21, a22, a23, a31, a32, a33; + + private PerspectiveTransform(float a11, float a21, float a31, + float a12, float a22, float a32, + float a13, float a23, float a33) { + this.a11 = a11; + this.a12 = a12; + this.a13 = a13; + this.a21 = a21; + this.a22 = a22; + this.a23 = a23; + this.a31 = a31; + this.a32 = a32; + this.a33 = a33; + } + + public static PerspectiveTransform quadrilateralToQuadrilateral(float x0, float y0, + float x1, float y1, + float x2, float y2, + float x3, float y3, + float x0p, float y0p, + float x1p, float y1p, + float x2p, float y2p, + float x3p, float y3p) { + + PerspectiveTransform qToS = quadrilateralToSquare(x0, y0, x1, y1, x2, y2, x3, y3); + PerspectiveTransform sToQ = squareToQuadrilateral(x0p, y0p, x1p, y1p, x2p, y2p, x3p, y3p); + return sToQ.times(qToS); + } + + public void transformPoints(float[] points) { + int max = points.length; + float a11 = this.a11; + float a12 = this.a12; + float a13 = this.a13; + float a21 = this.a21; + float a22 = this.a22; + float a23 = this.a23; + float a31 = this.a31; + float a32 = this.a32; + float a33 = this.a33; + for (int i = 0; i < max; i += 2) { + float x = points[i]; + float y = points[i + 1]; + float denominator = a13 * x + a23 * y + a33; + points[i] = (a11 * x + a21 * y + a31) / denominator; + points[i + 1] = (a12 * x + a22 * y + a32) / denominator; + } + } + + /** Convenience method, not optimized for performance. */ + public void transformPoints(float[] xValues, float[] yValues) { + int n = xValues.length; + for (int i = 0; i < n; i ++) { + float x = xValues[i]; + float y = yValues[i]; + float denominator = a13 * x + a23 * y + a33; + xValues[i] = (a11 * x + a21 * y + a31) / denominator; + yValues[i] = (a12 * x + a22 * y + a32) / denominator; + } + } + + public static PerspectiveTransform squareToQuadrilateral(float x0, float y0, + float x1, float y1, + float x2, float y2, + float x3, float y3) { + float dy2 = y3 - y2; + float dy3 = y0 - y1 + y2 - y3; + if (dy2 == 0.0f && dy3 == 0.0f) { + return new PerspectiveTransform(x1 - x0, x2 - x1, x0, + y1 - y0, y2 - y1, y0, + 0.0f, 0.0f, 1.0f); + } else { + float dx1 = x1 - x2; + float dx2 = x3 - x2; + float dx3 = x0 - x1 + x2 - x3; + float dy1 = y1 - y2; + float denominator = dx1 * dy2 - dx2 * dy1; + float a13 = (dx3 * dy2 - dx2 * dy3) / denominator; + float 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, 1.0f); + } + } + + public static PerspectiveTransform quadrilateralToSquare(float x0, float y0, + float x1, float y1, + float x2, float y2, + float x3, float y3) { + // Here, the adjoint serves as the inverse: + return squareToQuadrilateral(x0, y0, x1, y1, x2, y2, x3, y3).buildAdjoint(); + } + + PerspectiveTransform buildAdjoint() { + // Adjoint is the transpose of the cofactor matrix: + return new PerspectiveTransform(a22 * a33 - a23 * a32, + a23 * a31 - a21 * a33, + a21 * a32 - a22 * a31, + a13 * a32 - a12 * a33, + a11 * a33 - a13 * a31, + a12 * a31 - a11 * a32, + a12 * a23 - a13 * a22, + a13 * a21 - a11 * a23, + a11 * a22 - a12 * a21); + } + + PerspectiveTransform times(PerspectiveTransform other) { + return new PerspectiveTransform(a11 * other.a11 + a21 * other.a12 + a31 * other.a13, + a11 * other.a21 + a21 * other.a22 + a31 * other.a23, + a11 * other.a31 + a21 * other.a32 + a31 * other.a33, + a12 * other.a11 + a22 * other.a12 + a32 * other.a13, + a12 * other.a21 + a22 * other.a22 + a32 * other.a23, + a12 * other.a31 + a22 * other.a32 + a32 * other.a33, + a13 * other.a11 + a23 * other.a12 + a33 * other.a13, + a13 * other.a21 + a23 * other.a22 + a33 * other.a23, + a13 * other.a31 + a23 * other.a32 + a33 * other.a33); + + } + +} -- cgit v1.2.3