Correctly handle decimal display size (#4009)

Fix the `readUsedSize` regular expression to correctly parse (truncate) pixel decimal values.

src/platforms/platform.dom.js

@@ -33,7 +33,7 @@ module.exports = function(Chart) {
  */
  function readUsedSize(element, property) {
  var value = helpers.getStyle(element, property);
- var matches = value && value.match(/(\d+)px/);
+ var matches = value && value.match(/^(\d+)(\.\d+)?px$/);
  return matches? Number(matches[1]) : undefined;
  }
 

test/specs/platform.dom.tests.js

@@ -226,6 +226,24 @@ describe('Platform.dom', function() {
  rw: 165, rh: 85,
  });
  });
+
+ // https://github.com/chartjs/Chart.js/issues/3860
+ it('should support decimal display width and/or height', function() {
+ var chart = acquireChart({
+ options: {
+ responsive: false
+ }
+ }, {
+ canvas: {
+ style: 'width: 345.42px; height: 125.42px;'
+ }
+ });
+
+ expect(chart).toBeChartOfSize({
+ dw: 345, dh: 125,
+ rw: 345, rh: 125,
+ });
+ });
  });
 
  describe('config.options.responsive: true (maintainAspectRatio: true)', function() {