Contxt.arc (x, y, R, 0, arc 1.5*math.pi PI to note case, clockwise =false counterclockwise true)
For example Context.arc (A, 0.5*math.pi, 1*math.pi, false);
<! DOCTYPE html>
<canvas id= "Diag" height= "$" width= "$" style= "border:1px solid" >update your</canvas>
<canvas id= "Diag2" height= "$" width= "$" style= "border:1px solid" >update your</canvas>
<script>
var canvas = document.getElementById (' diag '); Huo
var context = Canvas.getcontext (' 2d '); Get canvas up and down environment
Canvas.width = ' 800 ';
Canvas.height = ' 800 ';
context.linewidth=5;
Context.strokestyle= "#00f5f8"; The fill color of the line
Context.arc (+, 0.5*math.pi, 1*math.pi, false);
Context.fillstyle = "#aaa" Closed picture interior fill color
for (var i=0; i<10; i++) {
Context.beginpath ();
Context.arc (50*i, 0, 0.2*math.pi*i, false);
Context.fill ();
Context.stroke ();
}
</script>
HTML Canvas arc