小编Kin*_*tic的帖子

我想在HTML5画布中绘制甜甜圈.如果画布的背景颜色是纯色,我就可以绘制它.但它是渐变色,我无法画出来.

当画布的背景颜色是渐变色时,我想知道如何绘制甜甜圈.

喜欢:

资源

这是我的代码:

function background(context, coordinate, properties) {
  var x = coordinate.x //???x
  , y = coordinate.y //??? y
  , w = coordinate.w //??(??-????????)
  , h = coordinate.h //??(??-????????)
  , gradientFactor, gradientColor; //????, ???

  context.save();
  switch( properties["background-fill-type"] ) {
     case "solid":
       context.fillStyle = properties["background-color"];
       break;
     case "gradient":
       gradientFactor = properties["background-gradient-factor"];
       gradientColor = context.createLinearGradient(x, y, x + w, y);
       gradientColor.addColorStop(gradientFactor, properties["background-first-color"]);
       gradientColor.addColorStop(1 - gradientFactor, properties["background-second-color"]);
       context.fillStyle = gradientColor;
       break;
     case "image":
       break;
   }
   context.fillRect(x, y, w, h);
   context.restore();
} …

我想用HTML5 <canvas>元素编写一个蛇游戏演示.我试图注册键盘(onkeydown)事件,但它不起作用.

码:

   canvas.onkeydown = divertDirection; //don't work
   //canvas.addEventListener("keydown", divertDirection, false);  //don't work

   //?????????????
   function divertDirection(ev) {
        console.log(ev);
    }

    //register this event for widnow
   window.addEventListener("keydown", divertDirection, false); //ok