vis.js is a dynamic, browser-based visualization library
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  1. /**
  2. * @constructor DataStep
  3. * The class DataStep is an iterator for data for the lineGraph. You provide a start data point and an
  4. * end data point. The class itself determines the best scale (step size) based on the
  5. * provided start Date, end Date, and minimumStep.
  6. *
  7. * If minimumStep is provided, the step size is chosen as close as possible
  8. * to the minimumStep but larger than minimumStep. If minimumStep is not
  9. * provided, the scale is set to 1 DAY.
  10. * The minimumStep should correspond with the onscreen size of about 6 characters
  11. *
  12. * Alternatively, you can set a scale by hand.
  13. * After creation, you can initialize the class by executing first(). Then you
  14. * can iterate from the start date to the end date via next(). You can check if
  15. * the end date is reached with the function hasNext(). After each step, you can
  16. * retrieve the current date via getCurrent().
  17. * The DataStep has scales ranging from milliseconds, seconds, minutes, hours,
  18. * days, to years.
  19. *
  20. * Version: 1.2
  21. *
  22. * @param {Date} [start] The start date, for example new Date(2010, 9, 21)
  23. * or new Date(2010, 9, 21, 23, 45, 00)
  24. * @param {Date} [end] The end date
  25. * @param {Number} [minimumStep] Optional. Minimum step size in milliseconds
  26. */
  27. function DataStep(start, end, minimumStep, containerHeight, customRange, formattingFunction, alignZeros) {
  28. // variables
  29. this.current = 0;
  30. this.autoScale = true;
  31. this.stepIndex = 0;
  32. this.step = 1;
  33. this.scale = 1;
  34. this.formattingFunction = formattingFunction;
  35. this.marginStart;
  36. this.marginEnd;
  37. this.deadSpace = 0;
  38. this.majorSteps = [1, 2, 5, 10];
  39. this.minorSteps = [0.25, 0.5, 1, 2];
  40. this.alignZeros = alignZeros;
  41. this.setRange(start, end, minimumStep, containerHeight, customRange);
  42. }
  43. /**
  44. * Set a new range
  45. * If minimumStep is provided, the step size is chosen as close as possible
  46. * to the minimumStep but larger than minimumStep. If minimumStep is not
  47. * provided, the scale is set to 1 DAY.
  48. * The minimumStep should correspond with the onscreen size of about 6 characters
  49. * @param {Number} [start] The start date and time.
  50. * @param {Number} [end] The end date and time.
  51. * @param {Number} [minimumStep] Optional. Minimum step size in milliseconds
  52. */
  53. DataStep.prototype.setRange = function(start, end, minimumStep, containerHeight, customRange) {
  54. this._start = customRange.min === undefined ? start : customRange.min;
  55. this._end = customRange.max === undefined ? end : customRange.max;
  56. if (this._start === this._end) {
  57. this._start = customRange.min === undefined ? this._start - 0.75 : this._start;
  58. this._end = customRange.max === undefined ? this._end + 1 : this._end;;
  59. }
  60. if (this.autoScale === true) {
  61. this.setMinimumStep(minimumStep, containerHeight);
  62. }
  63. this.setFirst(customRange);
  64. };
  65. /**
  66. * Automatically determine the scale that bests fits the provided minimum step
  67. * @param {Number} [minimumStep] The minimum step size in pixels
  68. */
  69. DataStep.prototype.setMinimumStep = function(minimumStep, containerHeight) {
  70. // round to floor
  71. var range = this._end - this._start;
  72. var safeRange = range * 1.2;
  73. var minimumStepValue = minimumStep * (safeRange / containerHeight);
  74. var orderOfMagnitude = Math.round(Math.log(safeRange)/Math.LN10);
  75. var minorStepIdx = -1;
  76. var magnitudefactor = Math.pow(10,orderOfMagnitude);
  77. var start = 0;
  78. if (orderOfMagnitude < 0) {
  79. start = orderOfMagnitude;
  80. }
  81. var solutionFound = false;
  82. for (var i = start; Math.abs(i) <= Math.abs(orderOfMagnitude); i++) {
  83. magnitudefactor = Math.pow(10,i);
  84. for (var j = 0; j < this.minorSteps.length; j++) {
  85. var stepSize = magnitudefactor * this.minorSteps[j];
  86. if (stepSize >= minimumStepValue) {
  87. solutionFound = true;
  88. minorStepIdx = j;
  89. break;
  90. }
  91. }
  92. if (solutionFound === true) {
  93. break;
  94. }
  95. }
  96. this.stepIndex = minorStepIdx;
  97. this.scale = magnitudefactor;
  98. this.step = magnitudefactor * this.minorSteps[minorStepIdx];
  99. };
  100. /**
  101. * Round the current date to the first minor date value
  102. * This must be executed once when the current date is set to start Date
  103. */
  104. DataStep.prototype.setFirst = function(customRange) {
  105. if (customRange === undefined) {
  106. customRange = {};
  107. }
  108. var niceStart = customRange.min === undefined ? this._start - (this.scale * 2 * this.minorSteps[this.stepIndex]) : customRange.min;
  109. var niceEnd = customRange.max === undefined ? this._end + (this.scale * this.minorSteps[this.stepIndex]) : customRange.max;
  110. this.marginEnd = customRange.max === undefined ? this.roundToMinor(niceEnd) : customRange.max;
  111. this.marginStart = customRange.min === undefined ? this.roundToMinor(niceStart) : customRange.min;
  112. // if we need to align the zero's we need to make sure that there is a zero to use.
  113. if (this.alignZeros === true && (this.marginEnd - this.marginStart) % this.step != 0) {
  114. this.marginEnd += this.marginEnd % this.step;
  115. }
  116. this.deadSpace = this.roundToMinor(niceEnd) - niceEnd + this.roundToMinor(niceStart) - niceStart;
  117. this.marginRange = this.marginEnd - this.marginStart;
  118. this.current = this.marginEnd;
  119. };
  120. DataStep.prototype.roundToMinor = function(value) {
  121. var rounded = value - (value % (this.scale * this.minorSteps[this.stepIndex]));
  122. if (value % (this.scale * this.minorSteps[this.stepIndex]) > 0.5 * (this.scale * this.minorSteps[this.stepIndex])) {
  123. return rounded + (this.scale * this.minorSteps[this.stepIndex]);
  124. }
  125. else {
  126. return rounded;
  127. }
  128. }
  129. /**
  130. * Check if the there is a next step
  131. * @return {boolean} true if the current date has not passed the end date
  132. */
  133. DataStep.prototype.hasNext = function () {
  134. return (this.current >= this.marginStart);
  135. };
  136. /**
  137. * Do the next step
  138. */
  139. DataStep.prototype.next = function() {
  140. var prev = this.current;
  141. this.current -= this.step;
  142. // safety mechanism: if current time is still unchanged, move to the end
  143. if (this.current === prev) {
  144. this.current = this._end;
  145. }
  146. };
  147. /**
  148. * Do the next step
  149. */
  150. DataStep.prototype.previous = function() {
  151. this.current += this.step;
  152. this.marginEnd += this.step;
  153. this.marginRange = this.marginEnd - this.marginStart;
  154. };
  155. /**
  156. * Get the current datetime
  157. * @return {String} current The current date
  158. */
  159. DataStep.prototype.getCurrent = function() {
  160. // prevent round-off errors when close to zero
  161. var current = (Math.abs(this.current) < this.step / 2) ? 0 : this.current;
  162. var returnValue = current.toPrecision(5);
  163. if (typeof this.formattingFunction === 'function') {
  164. returnValue = this.formattingFunction(current);
  165. }
  166. if (typeof returnValue === 'number') {
  167. return '' + returnValue;
  168. }
  169. else if (typeof returnValue === 'string') {
  170. return returnValue;
  171. }
  172. else {
  173. return current.toPrecision(5);
  174. }
  175. };
  176. /**
  177. * Check if the current value is a major value (for example when the step
  178. * is DAY, a major value is each first day of the MONTH)
  179. * @return {boolean} true if current date is major, else false.
  180. */
  181. DataStep.prototype.isMajor = function() {
  182. return (this.current % (this.scale * this.majorSteps[this.stepIndex]) === 0);
  183. };
  184. DataStep.prototype.shift = function(steps) {
  185. if (steps < 0) {
  186. for (let i = 0; i < -steps; i++) {
  187. this.previous();
  188. }
  189. }
  190. else if (steps > 0) {
  191. for (let i = 0; i < steps; i++) {
  192. this.next();
  193. }
  194. }
  195. }
  196. module.exports = DataStep;