canvas ----背景填充

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Document</title>
    <style>
      body {
        background: #000000;
      }
      canvas {
        background: #ffffff;
        transition: translate 0.5s;
      }
    </style>
  </head>
  <body>
    <canvas  id="canvas" width="400" height="400"></canvas>
  </body>
  <script>
    var oC = document.getElementById("canvas")
    var oGC =oC.getContext("2d")
    var yImg = new Image()

    yImg.onload = function(){
        draw(this)
    }
    yImg.src ="abc.png"

    function draw(that){
        var bg=oGC.createPattern(that,'repeat')
        oGC.fillStyle = bg;
          
        oGC.fillRect(0, 0, 300, 300);
          
    }

  </script>
</html>

canvas 渐变

http://www.w3school.com.cn/tags/canvas_createlineargradient.asp

例子

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Document</title>
    <style>
      body {
        background: #000000;
      }
      canvas {
        background: #ffffff;
        transition: translate 0.5s;
      }
    </style>
  </head>
  <body>
    <canvas  id="canvas" width="400" height="400"></canvas>
  </body>
  <script>
    var oC = document.getElementById("canvas")
    var oGC =oC.getContext("2d")
    
    var obj =oGC.createLinearGradient(0, 0, 170, 0);
    obj.addColorStop(1, "#ff0000");
    obj.addColorStop(0,"rgba(0,233,2333,0.1)")
    oGC.fillStyle = obj;
    oGC.fillRect(0,0,150,100);
      

  </script>
</html>

圆形渐变

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>Document</title>
    <style>
      body {
        background: #000000;
      }
      canvas {
        background: #ffffff;
        transition: translate 0.5s;
      }
    </style>
  </head>
  <body>
    <canvas  id="canvas" width="400" height="400"></canvas>
  </body>
  <script>
    var oC = document.getElementById("canvas")
    var oGC =oC.getContext("2d")
    
   var obj=oGC.createRadialGradient(
        50,50,4,50,50,70
    )
   
    obj.addColorStop(0,"red") 
    obj.addColorStop(1, "blue");
    oGC.fillStyle = obj;


    oGC.arc(50, 50, 50, 0, 2*Math.PI, false);
    oGC.fill();
    oGC.stroke()

  </script>
</html>

canvas ----背景填充

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