easing.js 2.9 KB

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