<!doctype html>
<html>
	<head>
		<title>strong tag</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1.0, user-scalable=no">
		<script type="text/javascript" src="jquery-2.0.3.js"></script>
		<script type="text/javascript">
            var margin, s1, s2, s3, hook_separation, h1, h2, h3, h4, hook_overlap, hook_height, stroke_width, staple_rise, staple_offset, staple_width, hook_bite;
            var canvas, ctx;
            var w = this;
            $(document).ready(function() {
                              canvas = $('canvas')[0];
                              ctx = canvas.getContext("2d");
                              $('input').each(function() { w[$(this).attr('name')] = parseFloat($(this).val());});
                              $('input').on('change', function() { w[$(this).attr('name')] = parseFloat($(this).val()); redraw(); });
                              redraw();
            });
            
            function redraw() {
                h1 = margin;
                s1 = margin;
                staple_rise = staple_offset;
                staple_leg_height = staple_offset;
                interior_margin = margin;
                
                ctx.fillStyle = '#000'
                ctx.fillRect(0, 0, canvas.width, canvas.height);
                style();
                ctx.save();
                draw_on(ctx);
                ctx.translate(0, canvas.height);
                ctx.scale(1, -1);
                draw_on(ctx);
                ctx.translate(canvas.width, 0);
                ctx.scale(-1, 1);
                draw_on(ctx);
                ctx.translate(0, canvas.height);
                ctx.scale(1, -1);
                draw_on(ctx);
                ctx.restore();
            }
        
        function style() {
            var foreground = 'white';
            ctx.fillStyle = foreground;
            ctx.strokeStyle = foreground;
            ctx.lineJoin = "miter";
            ctx.lineCap = "square";
            ctx.lineWidth = stroke_width;
        }
        function draw_on(context) {
            // t
            var p1 = new Path2D();
            p1.moveTo(margin, margin);
            p1.lineTo(margin, canvas.height / 2);
            p1.lineTo(margin + s1, canvas.height / 2);
            ctx.stroke(p1)
            
            // arms
            var p2 = new Path2D();
            p2.moveTo(margin + s1, (canvas.height / 2) - h1);
            p2.lineTo(margin + s1, margin);
            p2.lineTo((canvas.width / 2) - hook_separation, margin);
            p2.lineTo((canvas.width / 2) - hook_separation, margin + hook_height);
            p2.lineTo((canvas.width / 2) - staple_width - hook_bite, margin + hook_height);
            ctx.stroke(p2);
            
            // staple
            var p3 = new Path2D();
            p3.moveTo((canvas.width / 2) - hook_separation + hook_bite, margin + staple_leg_height);
            p3.lineTo((canvas.width / 2) - staple_width, margin + staple_leg_height);
            p3.lineTo((canvas.width / 2) - staple_width, margin + hook_height + staple_offset);
            p3.lineTo((canvas.width / 2), margin + hook_height + staple_rise);
            ctx.stroke(p3);
            
            //interior
            var big_rect_x1 = margin + s1 + interior_margin;
            var big_rect_y1 = margin + interior_margin;
            var big_rect_x2 = (canvas.width / 2) - staple_width - interior_margin;
            var big_rect_y2 = (canvas.height / 2) + 1;
            ctx.fillRect(big_rect_x1, big_rect_y1, big_rect_x2 - big_rect_x1, big_rect_y2 - big_rect_y1);
            var small_rect_x1 = margin + s1 + interior_margin;
            var small_rect_y1 = margin + hook_height + staple_rise + interior_margin;
            var small_rect_x2 = (canvas.width / 2) + 1;
            var small_rect_y2 = (canvas.height / 2) + 1;
            ctx.fillRect(small_rect_x1, small_rect_y1, small_rect_x2 - small_rect_x1, small_rect_y2 - small_rect_y1);
        }
		</script>
        <style>
            canvas {
                width: 600px;
                height: 250px;
                border: 1px solid black;
                display: block;
            }
        </style>
	</head>
	<body>
		<canvas width="600" height="250"></canvas>
        <p><label for="stroke_width">channel width: </label><input type="range" name="stroke_width" min="0" max="20" step="2" value="8" /></p>
        <p><label for="margin">margin: </label><input type="range" name="margin" min="10" max="40" value="20"/></p>
        <p><label for="hook_separation">hook separation: </label><input type="range" name="hook_separation" min="5" max="40" value="16"/></p>
        <p><label for="hook_height">hooks height: </label><input type="range" name="hook_height" min="20" max="60" value="37"/></p>
        <p><label for="staple_width">staple width: </label><input type="range" name="staple_width" min="0" max="70" value="50"/></p>
        <p><label for="staple_offset">staple offset: </label><input type="range" name="staple_offset" min="5" max="60" value="17"/></p>
        <p><label for="hook_bite">hook bite: </label><input type="range" name="hook_bite" min="-40" max="-5" value="-15"/></p>
	</body>
</html>