我已经编写了代码，它将使用相机拍摄照片并将其显示为快照。但在将其显示为快照之前，我正在调整图像大小并旋转（如果捕获的图像是水平的）。这个重新调整大小的图像是大小较小的二进制内容，因此将其上传到服务器变得很快。现在我想优化代码，使其在内存不足的情况下工作得更好。
面临的问题：在移动设备上，Chrome 浏览器有时会显示“由于内存不足，无法完成之前的操作”。
可能是可能的解决方案（我认为但有疑问）： 分块处理图像，会让思考工作得更好吗？
在此先感谢您的帮助。
您可能会在这里看到工作代码
或者
工作示例代码
<style>
#yourimage {
width:100%;
}
.imgWeightHght {
height: 290px !important;
width: 220px !important;
}
.captureInsuPanel img {
height: auto;
width: auto;
}
.newLoaderMask {
display: none;
background: #E5E5E5;
position: fixed;
left: 0;
top: 0;
z-index: 10;
width: 100%;
height: 100%;
opacity: 0.8;
z-index: 999;
}
</style>
<div id="mask" class="newLoaderMask">
<img src="http://jimpunk.net/Loading/wp-content/uploads/loading1.gif" width="200" id="loader" />
</div>
<input type="file" accept="image/*" capture="camera" id="takePictureField" />
<div class="captureInsuPanel">
<img id="yourimage" class="imgWeightHght" width="500" />
</div>
<script>
$(document).ready(function () {
$("#takePictureField").on("change", gotPic);
});
var max_width = 1000;
var max_height = 1000;
function gotPic(event) {
if (event.target.files.length == 1 && event.target.files[0].type.indexOf("image/") == 0) {
var image = event.target.files[0];
processCapturedImage(image, 90, max_width, max_height, $("#yourimage"));
}
}
function processCapturedImage(image, angle, max_width, max_height, thumbNailImage) {
$('#mask').show();
//create a hidden canvas object we can use to create new rotated image
var canvas = document.createElement('canvas');
canvas.id = "hidden_canvas_old";
canvas.style.display = "none";
document.body.appendChild(canvas);
//create a hidden canvas object we can use to create the new cropped &/or resized image data
var canvas_new = document.createElement('canvas');
canvas_new.id = "hidden_canvas_new";
canvas_new.style.display = "none";
document.body.appendChild(canvas_new);
var fileLoader = new FileReader(),
imageObj = new Image();
if (image.type.indexOf("image/") == 0) {
fileLoader.readAsDataURL(image);
} else {
alert('File is not an image');
}
fileLoader.onload = function () {
var data = this.result;
imageObj.src = data;
};
fileLoader.onabort = function () {
alert("The upload was aborted.");
};
fileLoader.onerror = function () {
alert("An error occured while reading the file.");
};
// set up the images onload function which clears the hidden canvas context,
// draws the new image then gets the blob data from it
imageObj.onload = function () {
var imgWidth = this.width;
var imgHeight = this.height;
if (imgWidth > imgHeight) {
//Rotate horizontal image to vertical and resizing is needed
rotateAndResize(this, imgWidth, imgHeight, angle, max_width, max_height, thumbNailImage);
} else {
//no need to rotate only resizing is needed
resize(this, imgWidth, imgHeight, max_width, max_height, thumbNailImage);
}
};
imageObj.onabort = function () {
alert("Image load was aborted.");
};
imageObj.onerror = function () {
alert("An error occured while loading image.");
};
}
function rotateAndResize(image, imgWidth, imgHeight, angle, max_width, max_height, thumbNailImage) {
var canvas = document.getElementById("hidden_canvas_old"),
ctx = canvas.getContext("2d");
var widthHalf = imgWidth / 2,
heightHalf = imgHeight / 2;
canvas.width = imgWidth;
canvas.height = imgWidth;
//clear canvas
ctx.clearRect(0, 0, canvas.width, canvas.height);
ctx.save();
//set coordinate to rotate canvas
ctx.translate(canvas.width / 2, canvas.height / 2);
//rotate canvas with given angle
ctx.rotate(angle * Math.PI / 180);
//draw image on rotated canvas with given coordinate
ctx.drawImage(image, -widthHalf, -widthHalf);
ctx.restore();
var tempCanvas = document.getElementById("hidden_canvas_new"),
tCtx = tempCanvas.getContext("2d");
tempCanvas.width = imgHeight;
tempCanvas.height = imgWidth;
/*
* Crop rotated image from old canvas to remove white space
* So that canvas will have only image content without extra padding
*/
tCtx.drawImage(canvas, canvas.width - imgHeight, 0, imgHeight, imgWidth, 0, 0, imgHeight, imgWidth);
tCtx.restore();
//Delete unwanted canvas to reduce page size
canvas.remove();
/**
* Resizing Rotated image
*/
// calculate the width and height, constraining the proportions
if (imgWidth > imgHeight) {
if (imgWidth > max_width) {
imgHeight = Math.round(imgHeight *= max_width / imgWidth);
imgWidth = max_width;
}
} else {
if (imgWidth > max_height) {
imgWidth = Math.round(imgWidth *= max_height / imgHeight);
imgHeight = max_height;
}
}
var tempCanvasTemp = tempCanvas;
tempCanvas.remove();
var tempCanvas1 = document.createElement("canvas"),
tCtx1 = tempCanvas1.getContext("2d");
tempCanvas1.id = 'hidden_canvas_new';
tempCanvas1.style.display = 'none';
tempCanvas1.width = imgHeight;
tempCanvas1.height = imgWidth;
tCtx1.drawImage(tempCanvasTemp, 0, 0, imgHeight, imgWidth);
tCtx1.restore();
document.body.appendChild(tempCanvas1);
thumbNailImage.attr("src", tempCanvas1.toDataURL('image/jpeg'));
$('#mask').hide();
}
function resize(image, imgWidth, imgHeight, max_width, max_height, thumbNailImage) {
/**
* Resizing image
*/
// calculate the width and height, constraining the proportions
if (imgWidth > imgHeight) {
if (imgWidth > max_width) {
//height *= max_width / width;
imgHeight = Math.round(imgHeight *= max_width / imgWidth);
imgWidth = max_width;
}
} else {
if (imgWidth > max_height) {
//width *= max_height / height;
imgWidth = Math.round(imgWidth *= max_height / imgHeight);
imgHeight = max_height;
}
}
var tempCanvas = document.getElementById("hidden_canvas_new"),
tCtx = tempCanvas.getContext("2d");
tempCanvas.width = imgWidth;
tempCanvas.height = imgHeight;
tCtx.drawImage(image, 0, 0, imgWidth, imgHeight);
thumbNailImage.attr("src", tempCanvas.toDataURL('image/jpeg'));
$('#mask').hide();
}
</script>