Improve offset calculation for scale.offset option

chartjs · Aug 15, 2017 · bc4bc9e · bc4bc9e
1 parent b9afeaf
commit bc4bc9e
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Showing 2 changed files with 36 additions and 25 deletions.
diff --git a/src/scales/scale.time.js b/src/scales/scale.time.js
@@ -334,27 +334,39 @@ function generate(min, max, minor, major, capacity, options) {
  * Returns the right and left offsets from edges in the form of {left, right}.
  * Offsets are added when the `offset` option is true.
  */
-function computeOffsets(table, ticks, min, max, options) {
+function computeOffsets(table, ts, min, max, options) {
  var left = 0;
  var right = 0;
- var upper, lower;
-
- if (options.offset && ticks.length) {
- if (!options.time.min) {
- upper = ticks.length > 1 ? ticks[1] : max;
- lower = ticks[0];
- left = (
- interpolate(table, 'time', upper, 'pos') -
- interpolate(table, 'time', lower, 'pos')
- ) / 2;
- }
- if (!options.time.max) {
- upper = ticks[ticks.length - 1];
- lower = ticks.length > 1 ? ticks[ticks.length - 2] : min;
- right = (
- interpolate(table, 'time', upper, 'pos') -
- interpolate(table, 'time', lower, 'pos')
- ) / 2;
+ var timestamps = [];
+ var i, ilen, timestamp, length, upper, lower, divisor;
+
+ if (options.offset) {
+ [ts.labels, ts.data].forEach(function(data) {
+ // Remove labels outside the min/max range
+ for (i = 0, ilen = data.length; i < ilen; ++i) {
+ timestamp = data[i];
+ if (timestamp >= min && timestamp <= max) {
+ timestamps.push(timestamp);
+ }
+ }
+ if (timestamps.length) {
+ return;
+ }
+ });
+
+ length = timestamps.length;
+ if (length) {
+ divisor = length > 1 ? 2 : 1;
+ if (!options.time.min) {
+ upper = length > 1 ? interpolate(table, 'time', timestamps[1], 'pos') : 1;
+ lower = interpolate(table, 'time', timestamps[0], 'pos');
+ left = Math.max((upper - lower) / divisor - lower, 0);
+ }
+ if (!options.time.max) {
+ upper = interpolate(table, 'time', timestamps[length - 1], 'pos');
+ lower = length > 1 ? interpolate(table, 'time', timestamps[length - 2], 'pos') : 0;
+ right = Math.max((upper - lower) / divisor - (1 - upper), 0);
+ }
  }
  }
 
@@ -593,7 +605,7 @@ module.exports = function(Chart) {
  me._minorFormat = formats[unit];
  me._majorFormat = formats[majorUnit];
  me._table = buildLookupTable(me._timestamps.data, min, max, options.distribution);
- me._offsets = computeOffsets(me._table, ticks, min, max, options);
+ me._offsets = computeOffsets(me._table, me._timestamps, min, max, options);
 
  return ticksFromTimestamps(ticks, majorUnit);
  },

diff --git a/test/specs/scale.time.tests.js b/test/specs/scale.time.tests.js
@@ -1132,12 +1132,11 @@ describe('Time scale tests', function() {
  options.offset = true;
  chart.update();
 
- var numTicks = scale.ticks.length;
- var firstTickInterval = scale.getPixelForTick(1) - scale.getPixelForTick(0);
- var lastTickInterval = scale.getPixelForTick(numTicks - 1) - scale.getPixelForTick(numTicks - 2);
+ var firstInterval = scale.getPixelForValue('2019') - scale.getPixelForValue('2017');
+ var lastInterval = scale.getPixelForValue('2042') - scale.getPixelForValue('2025');
 
- expect(scale.getPixelForValue('2017')).toBeCloseToPixel(scale.left + firstTickInterval / 2);
- expect(scale.getPixelForValue('2042')).toBeCloseToPixel(scale.left + scale.width - lastTickInterval / 2);
+ expect(scale.getPixelForValue('2017')).toBeCloseToPixel(scale.left + firstInterval / 2);
+ expect(scale.getPixelForValue('2042')).toBeCloseToPixel(scale.left + scale.width - lastInterval / 2);
  });
 
  it ('should not add offset if min and max extend the labels range', function() {