我正在使用Google 基于 HTML5 的网络应用程序的 Page Flip 演示（此处为教程，此处为演示），我从浏览器和网络中学到的 20 件事作为我正在创建的网站的基础。
简而言之，这本书的工作原理是将内容直接放入 DOM（搜索引擎友好）并使用 javascript 进行操作。翻页动画被绘制到覆盖的画布元素上。
当我开始在我的书中添加链接和联系表格时遇到了问题。由于某种原因，链接和输入元素不是“可点击的”。
我在这里创建了一个 jsFiddle来演示。
我认为这可能是一个 z-index 问题：覆盖画布 z-index 设置为 100。页面 z-indices 从 0 开始，一直到书的前面。如果我将链接/输入以更高的 z-index 放在前面怎么办？
但是改变有问题的元素的 z-index 并没有解决问题。无论如何，页面本身是使用 z 索引分层的，因此即使将链接/输入带到顶层确实有效，它也不是一个可行的解决方案，因为这样链接就不会与它们各自的页面正确分层。
我该如何解决这个问题： 使链接和输入元素在画布下/通过画布“可点击”？
HTML：
<body>
<div id="book">
<canvas id="pageflip-canvas"></canvas>
<div id="pages">
<section>
<div>
<h2>Test Page</h2>
<p>This demo is fantastic! ...apart from the fact that link and input elements aren't supported. The canvas element and JS on which the entire magic relies, renders both "unclickable" - a major drawback. See below:</p>
<a href="#">Click me!</a>
<input type="text"></input>
</div>
</section>
<section>
<div>
<h2>History</h2>
<p>Canvas was initially introduced by Apple for use inside their own Mac OS X WebKit component, powering applications like Dashboard widgets and the Safari browser. Later, it was adopted by Gecko browsers and Opera and standardized by the WHATWG on new proposed specifications for next generation web technologies.</p>
</div>
</section>
</div>
</div>
</body>
CSS：
body, h2, p {
margin: 0;
padding: 0;
}
body {
background-color: #444;
color: #333;
font-family: Helvetica, sans-serif;
}
#book {
background: url("https://dl.dropboxusercontent.com/u/3799114/page-flip-demo/book.png") no-repeat;
position: absolute;
width: 830px;
height: 260px;
left: 50%;
top: 50%;
margin-left: -400px;
margin-top: -125px;
}
#pages section {
background: url("https://dl.dropboxusercontent.com/u/3799114/page-flip-demo/paper.png") no-repeat;
display: block;
width: 400px;
height: 250px;
position: absolute;
left: 415px;
top: 5px;
overflow: hidden;
}
#pages section>div {
display: block;
width: 400px;
height: 250px;
font-size: 12px;
}
#pages section p,
#pages section h2 {
padding: 3px 35px;
line-height: 1.4em;
text-align: justify;
}
#pages section h2{
margin: 15px 0 10px;
}
#pageflip-canvas {
position: absolute;
z-index: 100;
}
jQuery：
(function() {
// Dimensions of the whole book
var BOOK_WIDTH = 830;
var BOOK_HEIGHT = 260;
// Dimensions of one page in the book
var PAGE_WIDTH = 400;
var PAGE_HEIGHT = 250;
// Vertical spacing between the top edge of the book and the papers
var PAGE_Y = ( BOOK_HEIGHT - PAGE_HEIGHT ) / 2;
// The canvas size equals to the book dimensions + this padding
var CANVAS_PADDING = 60;
var page = 0;
var canvas = document.getElementById( "pageflip-canvas" );
var context = canvas.getContext( "2d" );
var mouse = { x: 0, y: 0 };
var flips = [];
var book = document.getElementById( "book" );
// List of all the page elements in the DOM
var pages = book.getElementsByTagName( "section" );
// Organize the depth of our pages and create the flip definitions
for( var i = 0, len = pages.length; i < len; i++ ) {
pages[i].style.zIndex = len - i;
flips.push( {
// Current progress of the flip (left -1 to right +1)
progress: 1,
// The target value towards which progress is always moving
target: 1,
// The page DOM element related to this flip
page: pages[i],
// True while the page is being dragged
dragging: false
} );
}
// Resize the canvas to match the book size
canvas.width = BOOK_WIDTH + ( CANVAS_PADDING * 2 );
canvas.height = BOOK_HEIGHT + ( CANVAS_PADDING * 2 );
// Offset the canvas so that it's padding is evenly spread around the book
canvas.style.top = -CANVAS_PADDING + "px";
canvas.style.left = -CANVAS_PADDING + "px";
// Render the page flip 60 times a second
setInterval( render, 1000 / 60 );
document.addEventListener( "mousemove", mouseMoveHandler, false );
document.addEventListener( "mousedown", mouseDownHandler, false );
document.addEventListener( "mouseup", mouseUpHandler, false );
function mouseMoveHandler( event ) {
// Offset mouse position so that the top of the book spine is 0,0
mouse.x = event.clientX - book.offsetLeft - ( BOOK_WIDTH / 2 );
mouse.y = event.clientY - book.offsetTop;
}
function mouseDownHandler( event ) {
// Make sure the mouse pointer is inside of the book
if (Math.abs(mouse.x) < PAGE_WIDTH) {
if (mouse.x < 0 && page - 1 >= 0) {
// We are on the left side, drag the previous page
flips[page - 1].dragging = true;
}
else if (mouse.x > 0 && page + 1 < flips.length) {
// We are on the right side, drag the current page
flips[page].dragging = true;
}
}
// Prevents the text selection
event.preventDefault();
}
function mouseUpHandler( event ) {
for( var i = 0; i < flips.length; i++ ) {
// If this flip was being dragged, animate to its destination
if( flips[i].dragging ) {
// Figure out which page we should navigate to
if( mouse.x < 0 ) {
flips[i].target = -1;
page = Math.min( page + 1, flips.length );
}
else {
flips[i].target = 1;
page = Math.max( page - 1, 0 );
}
}
flips[i].dragging = false;
}
}
function render() {
// Reset all pixels in the canvas
context.clearRect( 0, 0, canvas.width, canvas.height );
for( var i = 0, len = flips.length; i < len; i++ ) {
var flip = flips[i];
if( flip.dragging ) {
flip.target = Math.max( Math.min( mouse.x / PAGE_WIDTH, 1 ), -1 );
}
// Ease progress towards the target value
flip.progress += ( flip.target - flip.progress ) * 0.2;
// If the flip is being dragged or is somewhere in the middle of the book, render it
if( flip.dragging || Math.abs( flip.progress ) < 0.997 ) {
drawFlip( flip );
}
}
}
function drawFlip( flip ) {
// Strength of the fold is strongest in the middle of the book
var strength = 1 - Math.abs( flip.progress );
// Width of the folded paper
var foldWidth = ( PAGE_WIDTH * 0.5 ) * ( 1 - flip.progress );
// X position of the folded paper
var foldX = PAGE_WIDTH * flip.progress + foldWidth;
// How far the page should outdent vertically due to perspective
var verticalOutdent = 20 * strength;
// The maximum width of the left and right side shadows
var paperShadowWidth = ( PAGE_WIDTH * 0.5 ) * Math.max( Math.min( 1 - flip.progress, 0.5 ), 0 );
var rightShadowWidth = ( PAGE_WIDTH * 0.5 ) * Math.max( Math.min( strength, 0.5 ), 0 );
var leftShadowWidth = ( PAGE_WIDTH * 0.5 ) * Math.max( Math.min( strength, 0.5 ), 0 );
// Change page element width to match the x position of the fold
flip.page.style.width = Math.max(foldX, 0) + "px";
context.save();
context.translate( CANVAS_PADDING + ( BOOK_WIDTH / 2 ), PAGE_Y + CANVAS_PADDING );
// Draw a sharp shadow on the left side of the page
context.strokeStyle = 'rgba(0,0,0,'+(0.05 * strength)+')';
context.lineWidth = 30 * strength;
context.beginPath();
context.moveTo(foldX - foldWidth, -verticalOutdent * 0.5);
context.lineTo(foldX - foldWidth, PAGE_HEIGHT + (verticalOutdent * 0.5));
context.stroke();
// Right side drop shadow
var rightShadowGradient = context.createLinearGradient(foldX, 0, foldX + rightShadowWidth, 0);
rightShadowGradient.addColorStop(0, 'rgba(0,0,0,'+(strength*0.2)+')');
rightShadowGradient.addColorStop(0.8, 'rgba(0,0,0,0.0)');
context.fillStyle = rightShadowGradient;
context.beginPath();
context.moveTo(foldX, 0);
context.lineTo(foldX + rightShadowWidth, 0);
context.lineTo(foldX + rightShadowWidth, PAGE_HEIGHT);
context.lineTo(foldX, PAGE_HEIGHT);
context.fill();
// Left side drop shadow
var leftShadowGradient = context.createLinearGradient(foldX - foldWidth - leftShadowWidth, 0, foldX - foldWidth, 0);
leftShadowGradient.addColorStop(0, 'rgba(0,0,0,0.0)');
leftShadowGradient.addColorStop(1, 'rgba(0,0,0,'+(strength*0.15)+')');
context.fillStyle = leftShadowGradient;
context.beginPath();
context.moveTo(foldX - foldWidth - leftShadowWidth, 0);
context.lineTo(foldX - foldWidth, 0);
context.lineTo(foldX - foldWidth, PAGE_HEIGHT);
context.lineTo(foldX - foldWidth - leftShadowWidth, PAGE_HEIGHT);
context.fill();
// Gradient applied to the folded paper (highlights & shadows)
var foldGradient = context.createLinearGradient(foldX - paperShadowWidth, 0, foldX, 0);
foldGradient.addColorStop(0.35, '#fafafa');
foldGradient.addColorStop(0.73, '#eeeeee');
foldGradient.addColorStop(0.9, '#fafafa');
foldGradient.addColorStop(1.0, '#e2e2e2');
context.fillStyle = foldGradient;
context.strokeStyle = 'rgba(0,0,0,0.06)';
context.lineWidth = 0.5;
// Draw the folded piece of paper
context.beginPath();
context.moveTo(foldX, 0);
context.lineTo(foldX, PAGE_HEIGHT);
context.quadraticCurveTo(foldX, PAGE_HEIGHT + (verticalOutdent * 2), foldX - foldWidth, PAGE_HEIGHT + verticalOutdent);
context.lineTo(foldX - foldWidth, -verticalOutdent);
context.quadraticCurveTo(foldX, -verticalOutdent * 2, foldX, 0);
context.fill();
context.stroke();
context.restore();
}
})();