var ctx=document.getElementById('cv').getContext('2d');

​

​

​

function drawLine(x, y, thk, alpha) {

  ctx.save();

  ctx.translate(x,y);

  ctx.fillText('line drawn at ' + x  + ' ' + y + '   lineWidth ' + thk + '   alpha ' + alpha  , 0,0);

  ctx.moveTo(0,50);

  ctx.lineTo(50, 50);

  ctx.lineTo(50, 20);

  ctx.closePath();

  ctx.lineWidth=thk;

  ctx.globalAlpha  = alpha;

  ctx.stroke();

  ctx.restore();

}

​

drawLine(10,20,1.0, 1.0);

​

drawLine(10.5,80 + 20.5,1.0, 1.0 );

​

drawLine(10.5, 2*80 + 20.5, 0.5, 1.0 );

​

drawLine(10.5, 3*80 + 20.5, 1.0, 0.8  );

​

drawLine(10.5, 4*80 + 20.5, 0.25, 1.0 );

​

drawLine(10.5, 5*80 + 20.5, 1.0, 0.5 );

​