Enable custom legend box heights

docs/docs/configuration/legend.md

@@ -49,6 +49,7 @@ The legend label configuration is nested below the legend configuration using th
 | Name | Type | Default | Description
 | ---- | ---- | ------- | -----------
 | `boxWidth` | `number` | `40` | Width of coloured box.
+| `boxHeight` | `number` | fontSize | Height of the coloured box.
 | `font` | `Font` | `defaults.font` | See [Fonts](fonts.md)
 | `padding` | `number` | `10` | Padding between rows of colored boxes.
 | `generateLabels` | `function` | | Generates legend items for each thing in the legend. Default implementation returns the text + styling for the color box. See [Legend Item](#legend-item-interface) for details.

src/plugins/plugin.legend.js

@@ -2,7 +2,7 @@ import defaults from '../core/core.defaults';
 import Element from '../core/core.element';
 import layouts from '../core/core.layouts';
 import {drawPoint} from '../helpers/helpers.canvas';
-import {callback as call, mergeIf, valueOrDefault} from '../helpers/helpers.core';
+import {callback as call, mergeIf, valueOrDefault, isNullOrUndef} from '../helpers/helpers.core';
 import {toFont, toPadding} from '../helpers/helpers.options';
 import {getRtlAdapter, overrideTextDirection, restoreTextDirection} from '../helpers/helpers.rtl';
 
@@ -95,6 +95,19 @@ function getBoxWidth(labelOpts, fontSize) {
  labelOpts.boxWidth;
 }
 
+/**
+ * Helper function to get the box height
+ * @param {object} labelOpts - the label options on the legend
+ * @param {*} fontSize - the label font size
+ * @return {number} height of the color box area
+ */
+function getBoxHeight(labelOpts, fontSize) {
+ const {boxHeight} = labelOpts;
+ return (labelOpts.usePointStyle && boxHeight > fontSize) || isNullOrUndef(boxHeight) ?
+ fontSize :
+ labelOpts.boxHeight;
+}
+
 export class Legend extends Element {
 
  constructor(config) {
@@ -239,6 +252,9 @@ export class Legend extends Element {
  const ctx = me.ctx;
  const labelFont = toFont(labelOpts.font);
  const fontSize = labelFont.size;
+ const boxWidth = getBoxWidth(labelOpts, fontSize);
+ const boxHeight = getBoxHeight(labelOpts, fontSize);
+ const itemHeight = Math.max(boxHeight, fontSize);
 
  // Reset hit boxes
  const hitboxes = me.legendHitBoxes = [];
@@ -271,11 +287,10 @@ export class Legend extends Element {
  ctx.textBaseline = 'middle';
 
  me.legendItems.forEach((legendItem, i) => {
- const boxWidth = getBoxWidth(labelOpts, fontSize);
  const width = boxWidth + (fontSize / 2) + ctx.measureText(legendItem.text).width;
 
  if (i === 0 || lineWidths[lineWidths.length - 1] + width + 2 * labelOpts.padding > minSize.width) {
- totalHeight += fontSize + labelOpts.padding;
+ totalHeight += itemHeight + labelOpts.padding;
  lineWidths[lineWidths.length - (i > 0 ? 0 : 1)] = 0;
  }
 
@@ -284,7 +299,7 @@ export class Legend extends Element {
  left: 0,
  top: 0,
  width,
- height: fontSize
+ height: itemHeight
  };
 
  lineWidths[lineWidths.length - 1] += width + labelOpts.padding;
@@ -302,7 +317,6 @@ export class Legend extends Element {
 
  const heightLimit = minSize.height - titleHeight;
  me.legendItems.forEach((legendItem, i) => {
- const boxWidth = getBoxWidth(labelOpts, fontSize);
  const itemWidth = boxWidth + (fontSize / 2) + ctx.measureText(legendItem.text).width;
 
  // If too tall, go to new column
@@ -323,7 +337,7 @@ export class Legend extends Element {
  left: 0,
  top: 0,
  width: itemWidth,
- height: fontSize
+ height: itemHeight,
  };
  });
 
@@ -377,11 +391,13 @@ export class Legend extends Element {
  ctx.font = labelFont.string;
 
  const boxWidth = getBoxWidth(labelOpts, fontSize);
+ const boxHeight = getBoxHeight(labelOpts, fontSize);
+ const height = Math.max(fontSize, boxHeight);
  const hitboxes = me.legendHitBoxes;
 
  // current position
  const drawLegendBox = function(x, y, legendItem) {
- if (isNaN(boxWidth) || boxWidth <= 0) {
+ if (isNaN(boxWidth) || boxWidth <= 0 || isNaN(boxHeight) || boxHeight < 0) {
  return;
  }
 
@@ -417,9 +433,12 @@ export class Legend extends Element {
  drawPoint(ctx, drawOptions, centerX, centerY);
  } else {
  // Draw box as legend symbol
- ctx.fillRect(rtlHelper.leftForLtr(x, boxWidth), y, boxWidth, fontSize);
+ // Adjust position when boxHeight < fontSize (want it centered)
+ const yBoxTop = y + Math.max((fontSize - boxHeight) / 2, 0);
+
+ ctx.fillRect(rtlHelper.leftForLtr(x, boxWidth), yBoxTop, boxWidth, boxHeight);
  if (lineWidth !== 0) {
- ctx.strokeRect(rtlHelper.leftForLtr(x, boxWidth), y, boxWidth, fontSize);
+ ctx.strokeRect(rtlHelper.leftForLtr(x, boxWidth), yBoxTop, boxWidth, boxHeight);
  }
  }
 
@@ -429,8 +448,7 @@ export class Legend extends Element {
  const fillText = function(x, y, legendItem, textWidth) {
  const halfFontSize = fontSize / 2;
  const xLeft = rtlHelper.xPlus(x, boxWidth + halfFontSize);
- const yMiddle = y + halfFontSize;
-
+ const yMiddle = y + (height / 2);
  ctx.fillText(legendItem.text, xLeft, yMiddle);
 
  if (legendItem.hidden) {
@@ -473,7 +491,7 @@ export class Legend extends Element {
 
  overrideTextDirection(me.ctx, opts.textDirection);
 
- const itemHeight = fontSize + labelOpts.padding;
+ const itemHeight = height + labelOpts.padding;
  me.legendItems.forEach((legendItem, i) => {
  const textWidth = ctx.measureText(legendItem.text).width;
  const width = boxWidth + (fontSize / 2) + textWidth;

test/specs/plugin.legend.tests.js

@@ -373,6 +373,37 @@ describe('Legend block tests', function() {
  });
  });
 
+ it('should draw items with a custom boxHeight', function() {
+ var chart = window.acquireChart(
+ {
+ type: 'line',
+ data: {
+ datasets: [{
+ label: 'dataset1',
+ data: []
+ }],
+ labels: []
+ },
+ options: {
+ legend: {
+ position: 'right',
+ labels: {
+ boxHeight: 40
+ }
+ }
+ }
+ },
+ {
+ canvas: {
+ width: 512,
+ height: 105
+ }
+ }
+ );
+ const hitBox = chart.legend.legendHitBoxes[0];
+ expect(hitBox.height).toBe(40);
+ });
+
  it('should pick up the first item when the property is an array', function() {
  var chart = window.acquireChart({
  type: 'bar',