js部分代码 var canvas = document.getElementById('mycanvas'); var cvs = canvas.getContext('2d'); canvas.onmousedown = function(e){ /*找到鼠标按下时的坐标*/ var start_x = e.pageX - canvas.offsetLeft + document.body.scrollLeft; var start_y = e.pageY - canvas.offsetTop + document....
The following code shows how to get mouse position. Example <html> <head> <title>A Simple Page</title> <script language="JavaScript"> function clicked()<!--from ww w . j a v a 2 s . co m--> { document.writeln("You clicked at the coordinates: X = " + event.x + " Y = ...
varcanvas = document.querySelector('.myCanvas');varwidth = canvas.width =window.innerWidth;varheight = canvas.height = window.innerHeight; 这里我们用canvas变量来存储画布的引用。第二行中我们将Window.innerWidth(可视区域宽度)赋值给一个新变量width和画布的canvas.width变量,(第三行同理)。然后我们就得...
}// Mouse event handlersfunctiononMouseMove(e) {}functiononMouseDown(e) {}functiononMouseUp(e) {}functiononMouseOut(e) {}// Get the mouse positionfunctiongetMousePos(canvas, e) {varrect = canvas.getBoundingClientRect();return{x:Math.round((e.clientX- rect.left)/(rect.right- rect.le...
1. canvas实现时钟转动 实现以下效果,分为几步: 1、找到canvas的中心,画出表心,以及表框 2、获取当前时间,并根据时间画出时针,分针,秒针,还有刻度 3、使用定时器,每过一秒获取新的时间,并重新绘图,达到时钟转动的效果 1.1 表心,表框 画表心,表框有两个知识点: ...
Use the coordinates to select the data on the canvas. Use the RGBA data of the pixel. Let's get started ! Retrieving mouse location on event As there are many possible errors and things that the user could do, we need to be exact as possible, therefore to guarantee ...
<script>canvas.onclick=(e)=>{console.log(e)}</script>  打开开发者工具,查看console,然后随便点击页面的白色位置,就会出现MouseEvent这个就是鼠标点击事件。  我们可以看见有好几个X 和 Y,到底使用哪个呢? 我们先尝试一下clientX和clientY
canvas.onmousemove = (e) => { console.log(e.clientX) console.log(e.clientY) //console.log 调试大法 获取目标位置 let div = document.createElement('div') div.style.position = 'absolute' div.style.left = e.clientX + 'px' div.style.top = e.clientY + 'px' ...
canvas.onmousemove = function(e) { var mouseX, mouseY; if(e.offsetX) { mouseX = e.offsetX; mouseY = e.offsetY; } else if(e.layerX) { mouseX = e.layerX; mouseY = e.layerY; } var c = ctx.getImageData(mouseX, mouseY, 1, 1).data; ...
41 41 div.style.position="absolute"; 42 42 div.style.left=(left)+"px"; 43 43 div.style.top=top+"px"; 44 44 div.innerText=comLength(x1,x2,y1,y2)+"mm"; 45 45 document.body.appendChild(div); 46 46 } 47 47 canvas.onmousemove = function(e){ ...