easing.js 2.9 KB

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  1. var Easing = {
  2. linear: function linear(k) {
  3. return k;
  4. },
  5. quadraticIn: function quadraticIn(k) {
  6. return k * k;
  7. },
  8. quadraticOut: function quadraticOut(k) {
  9. return k * (2 - k);
  10. },
  11. quadraticInOut: function quadraticInOut(k) {
  12. if ((k *= 2) < 1) {
  13. return 0.5 * k * k;
  14. }
  15. return -0.5 * (--k * (k - 2) - 1);
  16. },
  17. cubicIn: function cubicIn(k) {
  18. return k * k * k;
  19. },
  20. cubicOut: function cubicOut(k) {
  21. return --k * k * k + 1;
  22. },
  23. cubicInOut: function cubicInOut(k) {
  24. if ((k *= 2) < 1) {
  25. return 0.5 * k * k * k;
  26. }
  27. return 0.5 * ((k -= 2) * k * k + 2);
  28. },
  29. elasticIn: function elasticIn(k) {
  30. var s;
  31. var a = 0.1;
  32. var p = 0.4;
  33. if (k === 0) return 0;
  34. if (k === 1) return 1;
  35. if (!p) {
  36. p = 0.3;
  37. }
  38. if (!a || a < 1) {
  39. a = 1;
  40. s = p / 4;
  41. } else {
  42. s = p / (2 * Math.PI) * Math.asin(1 / a);
  43. }
  44. return -(a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p));
  45. },
  46. elasticOut: function elasticOut(k) {
  47. var s;
  48. var a = 0.1;
  49. var p = 0.4;
  50. if (k === 0) return 0;
  51. if (k === 1) return 1;
  52. if (!p) {
  53. p = 0.3;
  54. }
  55. if (!a || a < 1) {
  56. a = 1;
  57. s = p / 4;
  58. } else {
  59. s = p / (2 * Math.PI) * Math.asin(1 / a);
  60. }
  61. return a * Math.pow(2, -10 * k) * Math.sin((k - s) * (2 * Math.PI) / p) + 1;
  62. },
  63. elasticInOut: function elasticInOut(k) {
  64. var s;
  65. var a = 0.1;
  66. var p = 0.4;
  67. if (k === 0) return 0;
  68. if (k === 1) return 1;
  69. if (!p) {
  70. p = 0.3;
  71. }
  72. if (!a || a < 1) {
  73. a = 1;
  74. s = p / 4;
  75. } else {
  76. s = p / (2 * Math.PI) * Math.asin(1 / a);
  77. }
  78. if ((k *= 2) < 1) {
  79. return -0.5 * (a * Math.pow(2, 10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p));
  80. }
  81. return a * Math.pow(2, -10 * (k -= 1)) * Math.sin((k - s) * (2 * Math.PI) / p) * 0.5 + 1;
  82. },
  83. backIn: function backIn(k) {
  84. var s = 1.70158;
  85. return k * k * ((s + 1) * k - s);
  86. },
  87. backOut: function backOut(k) {
  88. var s = 1.70158;
  89. return (k = k - 1) * k * ((s + 1) * k + s) + 1;
  90. },
  91. backInOut: function backInOut(k) {
  92. var s = 1.70158 * 1.525;
  93. if ((k *= 2) < 1) {
  94. return 0.5 * (k * k * ((s + 1) * k - s));
  95. }
  96. return 0.5 * ((k -= 2) * k * ((s + 1) * k + s) + 2);
  97. },
  98. bounceIn: function bounceIn(k) {
  99. return 1 - Easing.bounceOut(1 - k);
  100. },
  101. bounceOut: function bounceOut(k) {
  102. if ((k /= 1) < 1 / 2.75) {
  103. return 7.5625 * k * k;
  104. } else if (k < 2 / 2.75) {
  105. return 7.5625 * (k -= 1.5 / 2.75) * k + 0.75;
  106. } else if (k < 2.5 / 2.75) {
  107. return 7.5625 * (k -= 2.25 / 2.75) * k + 0.9375;
  108. }
  109. return 7.5625 * (k -= 2.625 / 2.75) * k + 0.984375;
  110. },
  111. bounceInOut: function bounceInOut(k) {
  112. if (k < 0.5) {
  113. return Easing.bounceIn(k * 2) * 0.5;
  114. }
  115. return Easing.bounceOut(k * 2 - 1) * 0.5 + 0.5;
  116. }
  117. };
  118. module.exports = Easing;