Legend Marker Vertical Alignment

[bpostlethwaite]

A feature request has been made for legend marker alignment relative to legend trace names.

In the case where legend trace names are multi-line the request is to have options for marker vertical alignment. In this example the marker would align with the first legend text line when set to "top".

[etpinard]

Adding a legend-wide attribute should suffice. I'd vote for layout.legend.align or layout.legend.valign similar to what annotations/ uses:

plotly.js/src/components/annotations/attributes.js

Lines 87 to 111 in a070a8d

	align: {
	valType: 'enumerated',
	values: ['left', 'center', 'right'],
	dflt: 'center',
	role: 'style',
	editType: 'arraydraw',
	description: [
	'Sets the horizontal alignment of the `text` within the box.',
	'Has an effect only if `text` spans more two or more lines',
	'(i.e. `text` contains one or more <br> HTML tags) or if an',
	'explicit width is set to override the text width.'
	].join(' ')
	},
	valign: {
	valType: 'enumerated',
	values: ['top', 'middle', 'bottom'],
	dflt: 'middle',
	role: 'style',
	editType: 'arraydraw',
	description: [
	'Sets the vertical alignment of the `text` within the box.',
	'Has an effect only if an explicit height is set to override',
	'the text height.'
	].join(' ')
	},

[etpinard]

cc @antoinerg