使用wpaint绘图软件时：Uncaught DOMException: Failed to execute 'drawImage' on 'CanvasRenderin...

时间 2020-06-07

标签使用 wpaint 绘图软件 uncaught domexception failed execute drawimage canvasrenderin 繁體版

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使用wpaint绘图软件时：Uncaught DOMException: Failed to execute 'drawImage' on 'CanvasRenderingContext2D': The image argument is a canvas element with a width or height of 0.

1、总结

一句话总结：经过删除法和最简单模式找错，发现是style="display: none;"这个位置引起的错误

1 <div class="student_note_type_item" id="student_note_type_picture1" style="display: none;">
2  {include file="common/wpaint" /} 3 </div>

一、Uncaught DOMException表示什么？

Uncaught DOMException代表未获取dom元素javascript

二、排查错误的方法？

删除法：删除法删除代码以方便找到冲突代码css

（由于有些状况下是好的，多了代码就出错，哪确定是多的代码的问题）html

最简单模式：查看最简单模式下是否是好的，若是是，逐步增长代码查找冲突源java

三、使用wpaint绘图软件时：Uncaught DOMException出错的教训是什么？

给外部插件加的样式也颇有多是外部插件出错的缘由jquery

就是外部插件出错，不只多是js错误，css错误也很是常见canvas

2、Uncaught DOMException: Failed to execute 'drawImage' on 'CanvasRenderingContext2D'：

问题：

Uncaught DOMException: Failed to execute 'drawImage' on 'CanvasRenderingContext2D'：The HTMLImageElement provided is in the 'broken' state.dom

分析：

Uncaught DOMException代表未获取dom元素ide

The HTMLImageElement provided is in the 'broken' state.代表元素在获取过程当中被中断了，也即元素可能没有正确获取oop

图片路径不正确致使图片未正确获取也将致使该错误性能

代码：

HTML文件

<!DOCTYPE>
<html>
	<head>
		<mata name="viewport" content="width=device-width,initial-scale=1">
		<script type="text/javascript" src="js/jquery-1.11.0.min.js"></script>
		
	</head>
	<body>
		<div>
			<canvas id="start" width="800" height="600">
			</canvas>
		</div>
		 <img src="./img/girl.jpg" id="img" style="display:none"/>  <!--正确路径-->
		<script type="text/javascript" src="js/commonFunctions.js"></script>
		<script type="text/javascript" src="js/star.js"></script>
			
	</body>
</html>

start.js:

var can;
var ctx;
var width;
var height;
var imgGirl=new Image();
// $(document).ready(function(){
// 	init();
// })
document.body.onload=init;
function init(){
	can=document.getElementById("start");
	ctx=can.getContext("2d");

	width=can.width;
	height=can.height;
	imgGirl.src="../img/girl.jpg"//注意文件路径 正确路径为：./img/girl.jpg
	gameLoop();
}

function drawBg(){
	ctx.fillStyle="#393550";
	ctx.fillRect(0,0,width,height);
}
/** [gameLoop 刷新画布] */
function gameLoop(){
	window.requestAnimFrame(gameLoop);
	drawBg();
	drawImg();
}

//根据设备性能进行调用
function drawImg(){
	// star.js:39 Uncaught DOMException: Failed to execute 'drawImage' on 'CanvasRenderingContext2D': 
	// The HTMLImageElement provided is in the 'broken' state.
	// 分析：Uncaught DOMException代表未获取dom元素
	// 		  The HTMLImageElement provided is in the 'broken' state.代表元素在获取过程当中被中断了，也即元素可能还在加载中
	ctx.drawImage(imgGirl,100,100)
}

解决办法：

先判断图片路径在js中是否正确：

在html中添加img标签，经过js赋值看是否能够正常显示，若能够则路径正确

参考：Uncaught DOMException: Failed to execute 'drawImage' on 'CanvasRenderingContext2D'： - CSDN博客
https://blog.csdn.net/tjj3027/article/details/78914071

3、使用wpaint绘图软件时：Uncaught DOMException: Failed to execute 'drawImage' on 'CanvasRenderingContext2D': The image argument is a canvas element with a width or height of 0.

经过删除法和最简单模式逐步缩小错误代码范围找错，发现是style="display: none;"这个位置引起的错误

1 <div class="student_note_type_item" id="student_note_type_picture1" style="display: none;"> 2  {include file="common/wpaint" /} 3 </div>

{include file="common/wpaint" /}里面是wpaint