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我想通过javascript拍摄某人摄像头的快照。代码工作除了生成的图像拉伸的方式太多,我可读。Javascript摄像头快照拉得太大
我搞砸与周围的:ctx.drawImage(视频,0,0);行
我试过ctx.drawImage(视频,0,0,1280,720);没有区别
我试过ctx.drawImage(video,0,0,100,100);主要区别在于。它使整个图像出现,但眼睛太小。
代码:
<html>
<head>
<video autoplay></video>
<img src="" width=1280, height=720>
<canvas style="display:none;"></canvas>
<script>
var errorCallback = function(e) {
console.log('Reeeejected!', e);
video.src = 'failure.mp4'; // fallback.
};
navigator.getUserMedia = navigator.getUserMedia || navigator.webkitGetUserMedia || navigator.mozGetUserMedia || navigator.msGetUserMedia;
var video = document.querySelector('video');
var canvas = document.querySelector('canvas');
var ctx = canvas.getContext('2d');
var localMediaStream = null;
var hdConstraints = {
video: {
mandatory: {
minWidth: 1280,
minHeight: 720
}
}
};
function snapshot() {
if (localMediaStream) {
ctx.drawImage(video, 0, 0);
// "image/webp" works in Chrome.
// Other browsers will fall back to image/png.
document.querySelector('img').src = canvas.toDataURL('image/webp');
}
}
function success(stream) {
video.src = window.URL.createObjectURL(stream);
localMediaStream = stream;
}
video.addEventListener('click', snapshot, false);
navigator.getUserMedia(hdConstraints, success,errorCallback);
</script>
</head>
</html>
结果:
视频:
图像输出:
你在正确的轨道上,将'ctx.drawImage(video,0,0,1280,720);'改成'ctx.drawImage(video,0,0,640,360)'的行;'for例。基本上你需要调整大小并保持相同的高宽比以使其看起来正确。 – Loktar 2014-10-29 18:40:27
噢好吧,这是有道理的,以及我没有得到整个图像适合使用以下内容:ctx.drawImage(video,0,0,320,180);.但是图像质量的损失非常激烈。有什么办法可以避免这种情况? – Kyle 2014-10-29 18:44:42