How to justify align text in html5 canvas?
How can I align text within a html5 canvas to justif开发者_如何学JAVAy"? In the code below, text can be left/right/center aligned. I need to set align="justify". Please suggest how can this be done?
HTML:
<body onload="callMe()">
<canvas id="MyCanvas"></canvas>
</body>
JS:
function callMe() {
var canvas = document.getElementById("MyCanvas");
var ctx = canvas.getContext("2d");
var txt = "Welcome to the new hello world example";
cxt.font = "10pt Arial";
cxt.textAlign = "left";
/* code to text wrap*/
cxt.fillText(txt, 10, 20);
}
HTML5's canvas doesn't support multiline text drawing so there is no real effect to the alignment type.
If you want to support line-feeds, you have to support it yourself, you can see a previous discussion about it here: HTML5 Canvas - can I somehow use linefeeds in fillText()?
This is my implementation for word-wrap / line feeds:
function printAtWordWrap(context, text, x, y, lineHeight, fitWidth) {
fitWidth = fitWidth || 0;
lineHeight = lineHeight || 20;
var currentLine = 0;
var lines = text.split(/\r\n|\r|\n/);
for (var line = 0; line < lines.length; line++) {
if (fitWidth <= 0) {
context.fillText(lines[line], x, y + (lineHeight * currentLine));
} else {
var words = lines[line].split(' ');
var idx = 1;
while (words.length > 0 && idx <= words.length) {
var str = words.slice(0, idx).join(' ');
var w = context.measureText(str).width;
if (w > fitWidth) {
if (idx == 1) {
idx = 2;
}
context.fillText(words.slice(0, idx - 1).join(' '), x, y + (lineHeight * currentLine));
currentLine++;
words = words.splice(idx - 1);
idx = 1;
}
else
{ idx++; }
}
if (idx > 0)
context.fillText(words.join(' '), x, y + (lineHeight * currentLine));
}
currentLine++;
}
}
there is no support for alignment or justification there, you'll have to add it in
加载中,请稍侯......
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