"use strict";
module.exports = function(Chart) {
var helpers = Chart.helpers;
var defaultConfig = {
position: "left",
// label settings
ticks: {
callback: function(value, index, arr) {
var remain = value / (Math.pow(10, Math.floor(helpers.log10(value))));
if (remain === 1 || remain === 2 || remain === 5 || index === 0 || index === arr.length - 1) {
return value.toExponential();
} else {
return '';
}
}
}
};
var LogarithmicScale = Chart.Scale.extend({
determineDataLimits: function() {
var _this = this;
var opts = _this.options;
var tickOpts = opts.ticks;
var chart = _this.chart;
var data = chart.data;
var datasets = data.datasets;
var getValueOrDefault = helpers.getValueOrDefault;
var isHorizontal = _this.isHorizontal();
function IDMatches(meta) {
return isHorizontal ? meta.xAxisID === _this.id : meta.yAxisID === _this.id;
}
// Calculate Range
_this.min = null;
_this.max = null;
if (opts.stacked) {
var valuesPerType = {};
helpers.each(datasets, function(dataset, datasetIndex) {
var meta = chart.getDatasetMeta(datasetIndex);
if (chart.isDatasetVisible(datasetIndex) && IDMatches(meta)) {
if (valuesPerType[meta.type] === undefined) {
valuesPerType[meta.type] = [];
}
helpers.each(dataset.data, function(rawValue, index) {
var values = valuesPerType[meta.type];
var value = +_this.getRightValue(rawValue);
if (isNaN(value) || meta.data[index].hidden) {
return;
}
values[index] = values[index] || 0;
if (opts.relativePoints) {
values[index] = 100;
} else {
// Don't need to split positive and negative since the log scale can't handle a 0 crossing
values[index] += value;
}
});
}
});
helpers.each(valuesPerType, function(valuesForType) {
var minVal = helpers.min(valuesForType);
var maxVal = helpers.max(valuesForType);
_this.min = _this.min === null ? minVal : Math.min(_this.min, minVal);
_this.max = _this.max === null ? maxVal : Math.max(_this.max, maxVal);
});
} else {
helpers.each(datasets, function(dataset, datasetIndex) {
var meta = chart.getDatasetMeta(datasetIndex);
if (chart.isDatasetVisible(datasetIndex) && IDMatches(meta)) {
helpers.each(dataset.data, function(rawValue, index) {
var value = +_this.getRightValue(rawValue);
if (isNaN(value) || meta.data[index].hidden) {
return;
}
if (_this.min === null) {
_this.min = value;
} else if (value < _this.min) {
_this.min = value;
}
if (_this.max === null) {
_this.max = value;
} else if (value > _this.max) {
_this.max = value;
}
});
}
});
}
_this.min = getValueOrDefault(tickOpts.min, _this.min);
_this.max = getValueOrDefault(tickOpts.max, _this.max);
if (_this.min === _this.max) {
if (_this.min !== 0 && _this.min !== null) {
_this.min = Math.pow(10, Math.floor(helpers.log10(_this.min)) - 1);
_this.max = Math.pow(10, Math.floor(helpers.log10(_this.max)) + 1);
} else {
_this.min = 1;
_this.max = 10;
}
}
},
buildTicks: function() {
var _this = this;
var opts = _this.options;
var tickOpts = opts.ticks;
var getValueOrDefault = helpers.getValueOrDefault;
// Reset the ticks array. Later on, we will draw a grid line at these positions
// The array simply contains the numerical value of the spots where ticks will be
var ticks = _this.ticks = [];
// Figure out what the max number of ticks we can support it is based on the size of
// the axis area. For now, we say that the minimum tick spacing in pixels must be 50
// We also limit the maximum number of ticks to 11 which gives a nice 10 squares on
// the graph
var tickVal = getValueOrDefault(tickOpts.min, Math.pow(10, Math.floor(helpers.log10(_this.min))));
while (tickVal < _this.max) {
ticks.push(tickVal);
var exp = Math.floor(helpers.log10(tickVal));
var significand = Math.floor(tickVal / Math.pow(10, exp)) + 1;
if (significand === 10) {
significand = 1;
++exp;
}
tickVal = significand * Math.pow(10, exp);
}
var lastTick = getValueOrDefault(tickOpts.max, tickVal);
ticks.push(lastTick);
if (!_this.isHorizontal()) {
// We are in a vertical orientation. The top value is the highest. So reverse the array
ticks.reverse();
}
// At this point, we need to update our max and min given the tick values since we have expanded the
// range of the scale
_this.max = helpers.max(ticks);
_this.min = helpers.min(ticks);
if (tickOpts.reverse) {
ticks.reverse();
_this.start = _this.max;
_this.end = _this.min;
} else {
_this.start = _this.min;
_this.end = _this.max;
}
},
convertTicksToLabels: function() {
this.tickValues = this.ticks.slice();
Chart.Scale.prototype.convertTicksToLabels.call(this);
},
// Get the correct tooltip label
getLabelForIndex: function(index, datasetIndex) {
return +this.getRightValue(this.chart.data.datasets[datasetIndex].data[index]);
},
getPixelForTick: function(index, includeOffset) {
return this.getPixelForValue(this.tickValues[index], null, null, includeOffset);
},
getPixelForValue: function(value, index, datasetIndex, includeOffset) {
var _this = this;
var innerDimension;
var pixel;
var start = _this.start;
var newVal = +_this.getRightValue(value);
var range = helpers.log10(_this.end) - helpers.log10(start);
var paddingTop = _this.paddingTop;
var paddingBottom = _this.paddingBottom;
var paddingLeft = _this.paddingLeft;
if (_this.isHorizontal()) {
if (newVal === 0) {
pixel = _this.left + paddingLeft;
} else {
innerDimension = _this.width - (paddingLeft + _this.paddingRight);
pixel = _this.left + (innerDimension / range * (helpers.log10(newVal) - helpers.log10(start)));
pixel += paddingLeft;
}
} else {
// Bottom - top since pixels increase downard on a screen
if (newVal === 0) {
pixel = _this.top + paddingTop;
} else {
innerDimension = _this.height - (paddingTop + paddingBottom);
pixel = (_this.bottom - paddingBottom) - (innerDimension / range * (helpers.log10(newVal) - helpers.log10(start)));
}
}
return pixel;
},
getValueForPixel: function(pixel) {
var _this = this;
var offset;
var range = helpers.log10(_this.end) - helpers.log10(_this.start);
var value;
var innerDimension;
if (_this.isHorizontal()) {
innerDimension = _this.width - (_this.paddingLeft + _this.paddingRight);
value = _this.start * Math.pow(10, (pixel - _this.left - _this.paddingLeft) * range / innerDimension);
} else {
innerDimension = _this.height - (_this.paddingTop + _this.paddingBottom);
value = Math.pow(10, (_this.bottom - _this.paddingBottom - pixel) * range / innerDimension) / _this.start;
}
return value;
}
});
Chart.scaleService.registerScaleType("logarithmic", LogarithmicScale, defaultConfig);
};
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