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所以我的代码显示一个HTML页面,上面有一些文字,然后在下面,我有一个“明确的画布”按钮,我想有明确的画布上一次推,然后是能够在这张空白的画布上画画。我清晰的画布按钮不起作用,一旦推动就不会做任何事情。我正在使用回调函数来清除画布,并将html文件连接到一个JavaScript文件,然后在新的清除画布上绘制事物。这里的第一个代码是清除画布的.html文件,该文件也加入了.js文件。清除画布按钮/ HTML工作不
我试图context.Rect(X,Y,W,H); 和canvas.width.canvas.width; 并且都不起作用。我使用Chrome
<html><head></head>
<h3> </h3>
<body >
<canvas id="main" width="300" height="500"></canvas>
<script>
var canvas = document.getElementById("main");
var context = canvas.getContext('2d');
context.fillStyle = "#008000";
context.rect(0,0,300,300);
context.fill();
</script>
</body></html>
<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="user-scalble=no,initial-scale=1.0,maximum-scale=1.0" />
<style>
body { padding:10px; margin:0px; background-color: #FF9; }
#main { margin: 10px auto 0px auto; }
</style>
<script src=".js"></script>
</head>
<body >
<button id="clear">Clear Canvas</button><br>
<canvas id="main" width="300" height="500"></canvas>
</body>
</html>
//end of .html file
// JavaScript Document
// wait until window is fully loaded into browser
window.onload = function()
{
// so smart phone does not move/resize image when touched
document.ontouchmove = function(e)
{
e.preventDefault();
}
var canvas = document.getElementById('main');
// Number of pixels used by the Clear button above canvas
var canvasTop = canvas.offsetTop;
var context = canvas.getContext('2d');
var lastX, lastY;
context.strokeStyle = #FA8072;
context.lineCap = 'round';
context.lineJoin = 'round';
context.lineWidth = 8;
context.fill();
// Function to Clear the Canvas
function clear()
{
context.fillStyle = 'blue'
context.rect(0, 0, 300, 500);
context.fill();
}
// Function Dot (to start a new line or just a point)
function dot(x,y)
{
context.beginPath();
context.fillStyle = '#D2691E';
// draw tiny circle
context.arc(x,y,1,0, Math.PI*2, true);
context.fill();
context.closePath();
}
// Handle the Clear button
var clearButton = document.getElementById('clear');
// set callback funct. clear()for future touch events
clearButton.onclick = clear;
clear(); // do a clear canvas now
} // end window.onload
当我按下清除画布上什么也没有发生 – LewSim 2012-07-24 00:46:44
这是因为在演示中没有什么清楚,因为你有它调用'明确()'在的'onload'结束的功能。看看这个更新版本:http://jsfiddle.net/eMSXU/1/(不执行'明确()'onload事件,它会等待您点击) - 在FF作品反正... – nnnnnn 2012-07-24 00:56:05