canvas绘图详解-08-样式填充

样式填充

fillStyle = color    颜色值

　　　　　gradient    渐变色

              image     图片

　　　　　canvas    画布

　　　　　video      视频

 strokeStyle也适用

 1、fillStyle = color可以填充任何css承认的颜色值

2、fillStyle = gradient    渐变色（线性渐变||镜像渐变）

var linearGrd = context.createLinearGradient( 50,50,300,300);
linearGrd.addColorStop(0.0,"#fff");
linearGrd.addColorStop(0.5,"#ff0");
linearGrd.addColorStop(1.0,"#f00");

context.fillStyle = linearGrd;
context.fillRect(0,0,800,800);

var radialGrd = context.createRadialGradient( 200,200,400,500,200,400);
radialGrd.addColorStop(0.0,"#fff");
radialGrd.addColorStop(0.25,"#0f0");
radialGrd.addColorStop(0.5,"#ff0");
radialGrd.addColorStop(0.75,"#00f");
radialGrd.addColorStop(1.0,"#f00");

context.fillStyle = radialGrd;
context.fillRect(0,0,800,800);

3、fillStyle = image||canvas||video 

图片填充

<script type="text/javascript">
        window.onload=function(){
            var canvas = document.getElementById('canvas');
            var context = canvas.getContext('2d');
            canvas.width = 1200;
            canvas.height = 800;

            var img = new Image();
            img.src = "QQ截图20170116150903.png";

            img.onload =function(){
                var grd = context.createPattern(img,"repeat-x");
                context.fillStyle = grd;
                context.fillRect(0,0,800,800);
            }
        }
    </script>

画布填充

<script type="text/javascript">
        window.onload=function(){
            var canvas = document.getElementById('canvas');
            var context = canvas.getContext('2d');

            //添加另一个Canvas画布
            var backCanvas = createBackgroundCanvas();
            var pattern = context.createPattern(backCanvas,"repeat");
            context.fillStyle = pattern;
            context.fillRect(0,0,800,800);
                          
            }
            function createBackgroundCanvas(){
                //document.createElement('canvas')这块是创造
                var backCanvas = document.createElement('canvas');
                backCanvas.width = 100;
                backCanvas.height = 100;
                var backCanvasContext = backCanvas.getContext('2d');
                drawStar(backCanvasContext,50,50,50,0);
                return backCanvas;
            }
            function drawStar(cxt,x,y,R,rot) {
                cxt.save();

                cxt.translate(x,y);
                cxt.rotate(rot/180*Math.PI);
                cxt.scale(R,R);

                starPath(cxt);

                cxt.fillStyle="#fb3";
                cxt.fill();

                cxt.restore();
            }

            function starPath(cxt){
                cxt.beginPath();
                for(var i=0; i<5; i++){
                    cxt.lineTo(Math.cos((18+i*72)/180*Math.PI),
                        -Math.sin((18+i*72)/180*Math.PI));
                    cxt.lineTo(Math.cos((54+i*72)/180*Math.PI)*0.5,
                        -Math.sin((54+i*72)/180*Math.PI)*0.5);
                }
                cxt.closePath();
            }
        </script>