Jul*_*ian 5 javascript html5 canvas
我有JavaScript创建的多个canvas元素.我的问题是:"如何将多个canvas元素放到一个canvas元素中？".
小智 3
干得好;
只需提供#buffer画布元素display: none;，一切都会发生隐形（请查看此处；http://jsfiddle.net/Allendar/UqxCY/2/）。
超文本标记语言
<body onload="generatePNG()">
<canvas id="c1"></canvas>
<canvas id="c2"></canvas>
<canvas id="c3"></canvas>
<canvas id="buffer"></canvas>
<div id="output">Empty</div>
</body>
CSS
canvas[id^=c], div[id=output] {
border: 1px solid red;
}
canvas[id=buffer] {
border: 1px dotted green;
}
#output {
padding: 15px;
}
#output img {
border: 1px dotted blue;
}
JavaScript
function generatePNG() {
var b_canvas1 = document.getElementById("c1");
var b_context1 = b_canvas1.getContext("2d");
b_context1.fillRect(10, 50, 50, 50);
var b_canvas2 = document.getElementById("c2");
var b_context2 = b_canvas2.getContext("2d");
b_context2.fillRect(80, 50, 50, 50);
var b_canvas3 = document.getElementById("c3");
var b_context3 = b_canvas3.getContext("2d");
b_context3.fillRect(150, 50, 50, 50);
var img1 = new Image();
img1.src = b_canvas1.toDataURL("image/png");
var img2 = new Image();
img2.src = b_canvas2.toDataURL("image/png");
var img3 = new Image();
img3.src = b_canvas3.toDataURL("image/png");
var buffer = document.getElementById("buffer");
var buffer_context = buffer.getContext("2d");
buffer_context.drawImage(img1, 0, 0);
buffer_context.drawImage(img2, 0, 0);
buffer_context.drawImage(img3, 0, 0);
var buffer_img = new Image();
buffer_img.src = buffer.toDataURL("image/png");
var output = document.getElementById('output');
output.innerHTML = '<img src="' + buffer_img.src + '" alt="Canvas Image" />';
}