• html5 canvas多个图像旋转


    <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
    <html xmlns="http://www.w3.org/1999/xhtml">
    <head>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <title>多个图像围绕中心点旋转</title>
    <script src="js/modernizr.js"></script>
    </head>
    
    <body>
    <script type="text/javascript">
    window.addEventListener('load',eventWindowLoaded,false);
    function eventWindowLoaded(){
        canvasApp();
    }
    function canvasSupport(){
        return Modernizr.canvas;
    }
    function canvasApp(){
        if(!canvasSupport()){
            return;
        }else{
            var theCanvas = document.getElementById('canvas')
            var context = theCanvas.getContext("2d")
    
        }
        drawScreen();
        function drawScreen(){
            
            
            context.setTransform(1,0,0,1,0,0);
            var angleInRadians = 45 * Math.PI / 180;
            var x = 50;
            var y = 100;
            var width = 40;
            var height = 40;
            context.translate(x+.5*width,y+.5*height);
            context.rotate(angleInRadians);
            context.fillStyle="red";
            context.fillRect(-.5*width,-.5*height,width,height);
            context.setTransform(1,0,0,1,0,0);
            var angleInRadians = 75 * Math.PI / 180;
            var x = 100;
            var y = 100;
            var width = 40;
            var height = 40;
            context.translate(x+.5*width,y+.5*height);
            context.rotate(angleInRadians);
            context.fillStyle="red";
            context.fillRect(-.5*width,-.5*height,width,height);
            context.setTransform(1,0,0,1,0,0);
            var angleInRadians = 90 * Math.PI / 180;
            var x = 150;
            var y = 100;
            var width = 40;
            var height = 40;
            context.translate(x+.5*width,y+.5*height);
            context.rotate(angleInRadians);
            context.fillStyle="red";
            context.fillRect(-.5*width,-.5*height,width,height);
            context.setTransform(1,0,0,1,0,0);
            var angleInRadians = 120 * Math.PI / 180;
            var x = 200;
            var y = 100;
            var width = 40;
            var height = 40;
            context.translate(x+.5*width,y+.5*height);
            context.rotate(angleInRadians);
            context.fillStyle="red";
            context.fillRect(-.5*width,-.5*height,width,height);
            
        }
        
    }
    
    
    </script>
    <canvas id="canvas" width="500" height="500">
    你的浏览器无法使用canvas
    小白童鞋;你的支持是我最大的快乐!!
    </canvas>
    </body>
    </html>

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  • 原文地址:https://www.cnblogs.com/LoveOrHate/p/4422555.html
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