是否可以从canvas元素中呈现的文本中创建html链接？
答案 0 :(得分：26)
没有简单的方法。您必须将链接文本绘制到画布上，然后检查鼠标点击。这是一个演示html页面：
<html>
<head>
<script type="text/javascript">
var canvas = document.getElementById("myCanvas");
var ctx;
var linkText="http://stackoverflow.com";
var linkX=5;
var linkY=15;
var linkHeight=10;
var linkWidth;
var inLink = false;
// draw the balls on the canvas
function draw(){
canvas = document.getElementById("myCanvas");
// check if supported
if(canvas.getContext){
ctx=canvas.getContext("2d");
//clear canvas
ctx.clearRect(0, 0, canvas.width, canvas.height);
//draw the link
ctx.font='10px sans-serif';
ctx.fillStyle = "#0000ff";
ctx.fillText(linkText,linkX,linkY);
linkWidth=ctx.measureText(linkText).width;
//add mouse listeners
canvas.addEventListener("mousemove", on_mousemove, false);
canvas.addEventListener("click", on_click, false);
}
}
//check if the mouse is over the link and change cursor style
function on_mousemove (ev) {
var x, y;
// Get the mouse position relative to the canvas element.
if (ev.layerX || ev.layerX == 0) { //for firefox
x = ev.layerX;
y = ev.layerY;
}
x-=canvas.offsetLeft;
y-=canvas.offsetTop;
//is the mouse over the link?
if(x>=linkX && x <= (linkX + linkWidth) && y<=linkY && y>= (linkY-linkHeight)){
document.body.style.cursor = "pointer";
inLink=true;
}
else{
document.body.style.cursor = "";
inLink=false;
}
}
//if the link has been clicked, go to link
function on_click(e) {
if (inLink) {
window.location = linkText;
}
}
</script>
</head>
<body onload="draw()">
<center>
<canvas id="myCanvas" width="200" height="200" style="border-style:solid;border-width:1px">Canvas not supported.</canvas>
</center>
</body>
</html>
答案 1 :(得分：10)
此示例显示如何向HTML画布添加多个链接：
<!DOCTYPE html>
<!-- This page shows how to add multiple links to <canvas> (by Yakovenko Max) -->
<html>
<head>
<title>Canvas Links Example</title>
<script>
function OnLoad(){
// Get canvas
var canvas = document.getElementById("myCanvas");
// 2d context
var ctx = canvas.getContext("2d");
ctx.translate(0.5, 0.5); // * Move the canvas by 0.5px to fix blurring
// Block border
ctx.strokeStyle = "#5F7FA2";
ctx.strokeRect(50, 50, 185, 90);
// Photo
var img = new Image();
img.src = "http://www.cs.washington.edu/education/courses/csep576/05wi/projects/project4/web/artifact/liebling/average_face.gif";
img.onload = function(){
ctx.drawImage(img, 59.5, 59.5); // Use -0.5px on photos to prevent blurring caused by * fix
}
// Text
ctx.fillStyle = "#000000";
ctx.font = "15px Tahoma";
ctx.textBaseline = "top";
ctx.fillText("Username", 95, 65);
// ***** Magic starts here *****
// Links
var Links = new Array(); // Links information
var hoverLink = ""; // Href of the link which cursor points at
ctx.fillStyle = "#0000ff"; // Default blue link color
ctx.font = "15px Courier New"; // Monospace font for links
ctx.textBaseline = "top"; // Makes left top point a start point for rendering text
// Draw the link
function drawLink(x,y,href,title){
var linkTitle = title,
linkX = x,
linkY = y,
linkWidth = ctx.measureText(linkTitle).width,
linkHeight = parseInt(ctx.font); // Get lineheight out of fontsize
// Draw the link
ctx.fillText(linkTitle, linkX, linkY);
// Underline the link (you can delete this block)
ctx.beginPath();
ctx.moveTo(linkX, linkY + linkHeight);
ctx.lineTo(linkX + linkWidth, linkY + linkHeight);
ctx.lineWidth = 1;
ctx.strokeStyle = "#0000ff";
ctx.stroke();
// Add mouse listeners
canvas.addEventListener("mousemove", on_mousemove, false);
canvas.addEventListener("click", on_click, false);
// Add link params to array
Links.push(x + ";" + y + ";" + linkWidth + ";" + linkHeight + ";" + href);
}
// Link hover
function on_mousemove (ev) {
var x, y;
// Get the mouse position relative to the canvas element
if (ev.layerX || ev.layerX == 0) { // For Firefox
x = ev.layerX;
y = ev.layerY;
}
// Link hover
for (var i = Links.length - 1; i >= 0; i--) {
var params = new Array();
// Get link params back from array
params = Links[i].split(";");
var linkX = parseInt(params[0]),
linkY = parseInt(params[1]),
linkWidth = parseInt(params[2]),
linkHeight = parseInt(params[3]),
linkHref = params[4];
// Check if cursor is in the link area
if (x >= linkX && x <= (linkX + linkWidth) && y >= linkY && y <= (linkY + linkHeight)){
document.body.style.cursor = "pointer";
hoverLink = linkHref;
break;
}
else {
document.body.style.cursor = "";
hoverLink = "";
}
};
}
// Link click
function on_click(e) {
if (hoverLink){
window.open(hoverLink); // Use this to open in new tab
//window.location = hoverLink; // Use this to open in current window
}
}
// Ready for use ! You are welcome !
drawLink(95,93,"http://www.facebook.com/","Me at facebook");
drawLink(95,110,"http://plus.google.com/","Me at G+");
}
</script>
</head>
<body onload="OnLoad();">
<canvas id="myCanvas" width="450" height="250" style="border:1px solid #eee;">
Canvas is not supported in your browser ! :(
</canvas>
</body>
</html>
答案 2 :(得分：2)
中没有内置，但如果您愿意，可以模拟链接功能。您可以记住文本的位置，对其进行不同的着色，当用户将鼠标悬停在该区域时为其指定不同的光标，并在用户点击该页面时将其重定向到另一个页面。
答案 3 :(得分：2)
我认为另一个简单的想法是将div放在您希望链接显示在画布上的位置，并将链接放在div上。您所需要做的就是正确定位和设置div。
答案 4 :(得分：1)
＆＃34;我认为另一个简单的想法是将div放在您希望链接显示在画布上的位置，并将链接放在div处。您所要做的就是正确定位和设置div。＆＃34; -Shamaila Tahir
我个人喜欢在画布上使用链接的想法，这是一个整页大小的画布示例。您可以将此示例用于许多事情，而不仅仅是画布，所以为什么不熟悉它。 `
<!DOCTYPE html>
<HEAD>
<style type="text/css">
html { height: 100%; width: 100%; overflow: hidden; }
body {
position: absolute;
height: 100%;
width: 100%;
overflow:hidden;
}
#contactBackground{
position: absolute;
height:100%;
width: 100%;
border: 2px solid green;
}
#contactBackground:hover{
border: 2px solid red;}
#contact{
position: absolute;
height:15%;
top: 52%;
left:70%;
width: 10%;
background-size:20%,20%;
}
#onOff{
position: absolute;
height:15%;
top: 52%;
left:20%;
width: 10%;
background-size:20%,20%;
}
#onOff:hover{border: 2px solid red;}
</style><TITLE>Kewl!! Buttons and Links with Canvas</TITLE></HEAD>
<script type="text/javascript">
window.addEventListener('load', canvas, false);
function canvas(){
var link="contact";
var canvas = document.getElementById("canvas");
var context = canvas.getContext('2d');
canvas.width = document.body.clientWidth;
canvas.height = document.body.clientHeight;
contact = document.getElementById("contact");
onOff = document.getElementById("onOff");
document.getElementById("onOff").style.visibility="visible";
switchLinks(link);
function switchLinks(isLink){
if(isLink!="contact"){
document.getElementById("contact").style.visibility="hidden";
}
if(isLink=="contact"){
document.getElementById("contact").style.visibility="visible";
}
}
onOff.addEventListener("mousedown",contactFunction, false);
function contactFunction(){
if(link=="contact"){link="";}else{link="contact";}
switchLinks(link);
}
}
</script><body>
<canvas id="canvas" width="0" height="0">Your browser does not support the HTML 5 Canvas.
</canvas>
<span id="contact" style="display:hidden">
<a href="mailto:Dude your Awesome!"><img id="contactBackground" src="https://encrypted-tbn3.gstatic.com/images?q=tbn:ANd9GcQP5qi1TPhjAPOfbogNgppFdc4r1LoNmr5D1n-NBfr7ll3x9VlY9w" alt="Send a message" title="Email" /></a>
</span>
<img id="onOff" src="https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRXvh9Fej5ZhBQstjlSpQbRLx46h47KS2IO_WIfoyyrHk_essLU" style="display:hidden" />
</body></HTML>``