1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.gallery3d.filtershow.imageshow; 18 19 import android.graphics.Rect; 20 import android.graphics.RectF; 21 22 public class GeometryMath { 23 24 // Math operations for 2d vectors 25 public static float clamp(float i, float low, float high) { 26 return Math.max(Math.min(i, high), low); 27 } 28 29 public static float[] lineIntersect(float[] line1, float[] line2) { 30 float a0 = line1[0]; 31 float a1 = line1[1]; 32 float b0 = line1[2]; 33 float b1 = line1[3]; 34 float c0 = line2[0]; 35 float c1 = line2[1]; 36 float d0 = line2[2]; 37 float d1 = line2[3]; 38 float t0 = a0 - b0; 39 float t1 = a1 - b1; 40 float t2 = b0 - d0; 41 float t3 = d1 - b1; 42 float t4 = c0 - d0; 43 float t5 = c1 - d1; 44 45 float denom = t1 * t4 - t0 * t5; 46 if (denom == 0) 47 return null; 48 float u = (t3 * t4 + t5 * t2) / denom; 49 float[] intersect = { 50 b0 + u * t0, b1 + u * t1 51 }; 52 return intersect; 53 } 54 55 public static float[] shortestVectorFromPointToLine(float[] point, float[] line) { 56 float x1 = line[0]; 57 float x2 = line[2]; 58 float y1 = line[1]; 59 float y2 = line[3]; 60 float xdelt = x2 - x1; 61 float ydelt = y2 - y1; 62 if (xdelt == 0 && ydelt == 0) 63 return null; 64 float u = ((point[0] - x1) * xdelt + (point[1] - y1) * ydelt) 65 / (xdelt * xdelt + ydelt * ydelt); 66 float[] ret = { 67 (x1 + u * (x2 - x1)), (y1 + u * (y2 - y1)) 68 }; 69 float[] vec = { 70 ret[0] - point[0], ret[1] - point[1] 71 }; 72 return vec; 73 } 74 75 // A . B 76 public static float dotProduct(float[] a, float[] b) { 77 return a[0] * b[0] + a[1] * b[1]; 78 } 79 80 public static float[] normalize(float[] a) { 81 float length = (float) Math.sqrt(a[0] * a[0] + a[1] * a[1]); 82 float[] b = { 83 a[0] / length, a[1] / length 84 }; 85 return b; 86 } 87 88 // A onto B 89 public static float scalarProjection(float[] a, float[] b) { 90 float length = (float) Math.sqrt(b[0] * b[0] + b[1] * b[1]); 91 return dotProduct(a, b) / length; 92 } 93 94 public static float[] getVectorFromPoints(float[] point1, float[] point2) { 95 float[] p = { 96 point2[0] - point1[0], point2[1] - point1[1] 97 }; 98 return p; 99 } 100 101 public static float[] getUnitVectorFromPoints(float[] point1, float[] point2) { 102 float[] p = { 103 point2[0] - point1[0], point2[1] - point1[1] 104 }; 105 float length = (float) Math.sqrt(p[0] * p[0] + p[1] * p[1]); 106 p[0] = p[0] / length; 107 p[1] = p[1] / length; 108 return p; 109 } 110 111 public static RectF scaleRect(RectF r, float scale) { 112 return new RectF(r.left * scale, r.top * scale, r.right * scale, r.bottom * scale); 113 } 114 115 // A - B 116 public static float[] vectorSubtract(float[] a, float[] b) { 117 int len = a.length; 118 if (len != b.length) 119 return null; 120 float[] ret = new float[len]; 121 for (int i = 0; i < len; i++) { 122 ret[i] = a[i] - b[i]; 123 } 124 return ret; 125 } 126 127 public static float vectorLength(float[] a) { 128 return (float) Math.sqrt(a[0] * a[0] + a[1] * a[1]); 129 } 130 131 public static float scale(float oldWidth, float oldHeight, float newWidth, float newHeight) { 132 if (oldHeight == 0 || oldWidth == 0) 133 return 1; 134 return Math.min(newWidth / oldWidth, newHeight / oldHeight); 135 } 136 137 public static Rect roundNearest(RectF r) { 138 Rect q = new Rect(Math.round(r.left), Math.round(r.top), Math.round(r.right), 139 Math.round(r.bottom)); 140 return q; 141 } 142 143 } 144
