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html5之Canvas画图

阅读更多

层叠加,效果图如下

 

 


 

 

 

<!DOCTYPE html>
<html>
<head>
    <title>html5之Canvas学习</title>
     <script>
         function init(){
            var canvas = document.getElementById("canvas");
            var ctx = canvas.getContext('2d');

            var rectWidth = 150;
            var rectHeight = 75;

            ctx.save();   // save state 1
            ctx.translate(canvas.width / 2, canvas.height / 2);

            ctx.save();  // save state 2
            ctx.rotate(Math.PI / 4);

            ctx.save();// save state 3
            ctx.scale(2, 2);

            ctx.fillStyle = "blue";
            ctx.fillRect(-rectWidth / 2, -rectHeight / 2, rectWidth, rectHeight);

            ctx.restore(); // restore state 3
            ctx.fillStyle = "red";
            ctx.fillRect(-rectWidth / 2, -rectHeight / 2,
                    rectWidth, rectHeight);

            ctx.restore(); // restore state 2
            ctx.fillStyle = "yellow";
            ctx.fillRect(-rectWidth / 2, -rectHeight / 2,
                    rectWidth, rectHeight);

            ctx.restore(); // restore state 1
            ctx.fillStyle = "green";
            ctx.fillRect(-rectWidth / 2, -rectHeight / 2,
                    rectWidth, rectHeight);
         }
    </script>
</head>
<body onload="init()">
<canvas width="150" height="200" id="canvas">
    element not supported.
</canvas>

</body>
</html>
 

来自于

http://www.html5canvastutorials.com/advanced/html5-canvas-transformation-state-stack-tutorial/

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