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Diffstat (limited to 'libraries/zxing/src/com/google/zxing/common/PerspectiveTransform.java')
| -rw-r--r-- | libraries/zxing/src/com/google/zxing/common/PerspectiveTransform.java | 148 |
1 files changed, 148 insertions, 0 deletions
diff --git a/libraries/zxing/src/com/google/zxing/common/PerspectiveTransform.java b/libraries/zxing/src/com/google/zxing/common/PerspectiveTransform.java new file mode 100644 index 000000000..9e65baff1 --- /dev/null +++ b/libraries/zxing/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;
+
+/**
+ * <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
+ */
+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);
+
+ }
+
+}
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