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August 29, 2015 13:57
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Modified textOnPath to center text on path and rotate letter based on path direction
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// Based on http://stackoverflow.com/a/19122486/478725 | |
// Text is rotated to be read begin -> end | |
// Variable width fonts will still be a bit off center | |
var angle = function(v1, v2) { | |
ang = Math.atan2(v2.y - v1.y, v2.x - v1.x); | |
return { | |
radians: ang, | |
degrees: ang * 180 / Math.PI | |
}; | |
}; | |
function textOnPath( paper, message, path, fontSize, letterSpacing, kerning, geckoKerning) { | |
// if fontSize or letterSpacing are undefined, they are calculated to fill the path | |
// 10% of fontSize is usually good for manual letterspacing | |
// Gecko, i.e. Firefox etc, inflates and alters the letter spacing | |
var gecko = /rv:([^\)]+)\) Gecko\/\d{8}/.test(navigator.userAgent||'') ? true : false; | |
var letters = [], places = [], messageLength = 0; | |
for (var c=0; c < message.length; c++) { | |
var letter = paper.text(0, 0, message[c]).attr({"text-anchor" : "middle"}); | |
var character = letter.attr('text'), kern = 0; | |
letters.push(letter); | |
if (kerning) { | |
if(gecko && geckoKerning) { | |
kerning = geckoKerning; | |
} | |
var predecessor = letters[c-1] ? letters[c-1].attr('text') : ''; | |
if (kerning[c]) { | |
kern = kerning[c]; | |
} else if (kerning[character]) { | |
if( typeof kerning[character] === 'object' ) { | |
kern = kerning[character][predecessor] || kerning[character]['default'] || 0; | |
} else { | |
kern = kerning[character]; | |
} | |
} | |
if(kerning['default'] ) { | |
kern = kern + (kerning['default'][predecessor] || 0); | |
} | |
} | |
messageLength = messageLength ? messageLength : letter.getBBox().width; | |
messageLength += kern; | |
places.push(messageLength); | |
//spaces get a width of 0, so set min at 4px | |
messageLength += Math.max(4.5, letter.getBBox().width); | |
} | |
if( letterSpacing ){ | |
if (gecko) { | |
letterSpacing = letterSpacing * 0.83; | |
} | |
} else { | |
letterSpacing = letterSpacing || path.getTotalLength() / messageLength; | |
} | |
fontSize = fontSize || 10 * letterSpacing; | |
for (c = 0; c < letters.length; c++) { | |
letters[c].attr("font-size", fontSize + "px"); | |
p = path.getPointAtLength(places[c] * letterSpacing); | |
//var rotate = 'R' + (p.alpha <= 180 ? p.alpha + 180 : p.alpha > 360 ? p.alpha - 360 : p.alpha )+','+p.x+','+p.y; | |
var pp1 = path.getPointAtLength(places[c]*letterSpacing-0.1), | |
pp2 = path.getPointAtLength(places[c]*letterSpacing+0.1), | |
rotate = 'R' + angle(pp1, pp2).degrees +','+p.x+','+p.y; | |
letters[c].attr({ x: p.x, y: p.y, transform: rotate }); | |
} | |
} |
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