tanatana/canvas_test.html

## canvas_test.html
<!DOCTYPE html>
<html lang="ja">
  <head>
    <meta charset="utf-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <title>canvas problem with iOS7.1 on HDPI device</title>

    <!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
    <!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
    <!--[if lt IE 9]>
      <script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
      <script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
    <![endif]-->
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
    <script>
     $(document).ready(function(){
       var $img    = $("#originalImage");
       $img.on("load", function(){
         var img = document.getElementById("originalImage");
         var canvas1 = document.getElementById("canvas1");
         var ctx     = canvas1.getContext("2d");
         ctx.drawImage(img,0,0,320,320,0,0,320,320);
         ctx.drawImage(canvas1,20,20,160,160,80,80,160,160);

         var canvas2 = document.getElementById("canvas2");
         var ctx2    = canvas2.getContext("2d");
         ctx2.drawImage(img,0,0,320,320,0,0,640,640);
         ctx2.drawImage(canvas2,40,40,320,320,160,160,320,320);
       });
     });
    </script>
  </head>
  <body>
    <h1>original image</h1>
    <img id="originalImage" src="images/test.png">
    <h1>normal</h1>
    <canvas id="canvas1" width="320" height="320"></canvas>
    <h1>retina support</h1>
    <canvas id="canvas2" width="640" height="640" style="width: 320px; height: 320px;"> </canvas>
  </body>
</html>
	<!DOCTYPE html>
	<html lang="ja">
	<head>
	<meta charset="utf-8">
	<meta http-equiv="X-UA-Compatible" content="IE=edge">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<title>canvas problem with iOS7.1 on HDPI device</title>

	<!-- HTML5 Shim and Respond.js IE8 support of HTML5 elements and media queries -->
	<!-- WARNING: Respond.js doesn't work if you view the page via file:// -->
	<!--[if lt IE 9]>
	<script src="https://oss.maxcdn.com/html5shiv/3.7.2/html5shiv.min.js"></script>
	<script src="https://oss.maxcdn.com/respond/1.4.2/respond.min.js"></script>
	<![endif]-->
	<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
	<script>
	$(document).ready(function(){
	var $img = $("#originalImage");
	$img.on("load", function(){
	var img = document.getElementById("originalImage");
	var canvas1 = document.getElementById("canvas1");
	var ctx = canvas1.getContext("2d");
	ctx.drawImage(img,0,0,320,320,0,0,320,320);
	ctx.drawImage(canvas1,20,20,160,160,80,80,160,160);

	var canvas2 = document.getElementById("canvas2");
	var ctx2 = canvas2.getContext("2d");
	ctx2.drawImage(img,0,0,320,320,0,0,640,640);
	ctx2.drawImage(canvas2,40,40,320,320,160,160,320,320);
	});
	});
	</script>
	</head>
	<body>
	<h1>original image</h1>
	<img id="originalImage" src="images/test.png">
	<h1>normal</h1>
	<canvas id="canvas1" width="320" height="320"></canvas>
	<h1>retina support</h1>
	<canvas id="canvas2" width="640" height="640" style="width: 320px; height: 320px;"> </canvas>
	</body>
	</html>