我正在手机中制作一个简单的网络应用程序,它允许访问者使用 html5 input[type=file] 元素捕获照片。然后我将它显示在网络上进行预览,然后访问者可以选择将照片上传到我的服务器以用于其他目的(即:上传到FB)
当我使用 iPhone 拍照并垂直握住时,我发现照片的方向有问题。照片在标签中的方向正确。但是,当我尝试使用 drawImage() 方法将其绘制到画布中时,它被旋转 90 度绘制。
我尝试以 4 个方向拍照,其中只有一个可以在画布上绘制正确的图像,其他的可以旋转甚至倒置。
好吧,我很困惑获得正确的方向来解决这个问题......感谢您的帮助......
这是我的代码,主要是从 MDN 复制的
<div class="container">
<h1>Camera API</h1>
<section class="main-content">
<p>A demo of the Camera API, currently implemented in Firefox and Google Chrome on Android. Choose to take a picture with your device's camera and a preview will be shown through createObjectURL or a FileReader object (choosing local files supported too).</p>
<p>
<form method="post" enctype="multipart/form-data" action="index.php">
<input type="file" id="take-picture" name="image" accept="image/*">
<input type="hidden" name="action" value="submit">
<input type="submit" >
</form>
</p>
<h2>Preview:</h2>
<div style="width:100%;max-width:320px;">
<img src="about:blank" alt="" id="show-picture" width="100%">
</div>
<p id="error"></p>
<canvas id="c" width="640" height="480"></canvas>
</section>
</div>
<script>
(function () {
var takePicture = document.querySelector("#take-picture"),
showPicture = document.querySelector("#show-picture");
if (takePicture && showPicture) {
// Set events
takePicture.onchange = function (event) {
showPicture.onload = function(){
var canvas = document.querySelector("#c");
var ctx = canvas.getContext("2d");
ctx.drawImage(showPicture,0,0,showPicture.width,showPicture.height);
}
// Get a reference to the taken picture or chosen file
var files = event.target.files,
file;
if (files && files.length > 0) {
file = files[0];
try {
// Get window.URL object
var URL = window.URL || window.webkitURL;
// Create ObjectURL
var imgURL = URL.createObjectURL(file);
// Set img src to ObjectURL
showPicture.src = imgURL;
// Revoke ObjectURL
URL.revokeObjectURL(imgURL);
}
catch (e) {
try {
// Fallback if createObjectURL is not supported
var fileReader = new FileReader();
fileReader.onload = function (event) {
showPicture.src = event.target.result;
};
fileReader.readAsDataURL(file);
}
catch (e) {
// Display error message
var error = document.querySelector("#error");
if (error) {
error.innerHTML = "Neither createObjectURL or FileReader are supported";
}
}
}
}
};
}
})();
</script>