Ensure accessible target size for controls

[Robert Linder]

Motivation

The WCAG 2.1 SC 2.5.5 Target Size requires targets for pointer input to be at least 44 by 44 in CSS pixels. Meeting this requirement has multiple benefits, it'd be great to pass this criteria for Leaflet controls.

Edit: WCAG 2.2 (though it should be noted that the 2.2 version has not reached Recommendation status yet) has a more forgiving (from a designer's point of view!) Success Criterion: 2.5.8 Target Size (Minimum) which instead requires these targets to be at least 24 by 24 in CSS pixels.

Proposed solution

Increase the size of the following controls to 44x44 px (or 24x24 per WCAG 2.2 SC 2.5.8).

• General controls:
  

  Leaflet/dist/leaflet.css

  Lines 284 to 286 in 0f904a5

   width: 26px; 
   height: 26px; 
   line-height: 26px; 

  
  
• Markers:
  

  Leaflet/src/layer/marker/Icon.Default.js

  Line 26 in bc918d4

   iconSize:    [25, 41], 

  
  (Changing the marker's width and height to 44px would cause it to stretch. Either the image would need to be modified or padding (right and left) could be modified to achieve a 44 by 44 px target.)
  
  
• Popup's Close button:
  

  Leaflet/dist/leaflet.css

  Lines 517 to 518 in 0f904a5

   width: 18px; 
   height: 14px; 

Additional context

Increasing the default size of controls would also have the benefit of not needing extra CSS for conditional leaflet-touch sizing (presumably, since the controls would be large enough by default). For example, the following lines could be removed:

Leaflet/dist/leaflet.css

Lines 316 to 320 in 0f904a5

 .leaflet-touch .leaflet-bar a { 
 	width: 30px; 
 	height: 30px; 
 	line-height: 30px; 
 	} 

Leaflet/dist/leaflet.css

Lines 359 to 362 in 0f904a5

 .leaflet-touch .leaflet-control-layers-toggle { 
 	width: 44px; 
 	height: 44px; 
 	} 

[Robert Linder]

In any case 44 by 44 px cannot be achieved for these targets (for example, for markers it can get tricky if increasing the size of the image itself is not desired, but setting a padding is also not desired as it may cause markers to be unexpectedly interacted with since they're larger than percieved) it should be added as a known limitation in the accessibility statement.