我开发了一个laravel Web应用程序,该应用程序具有接受用户上传的图像然后显示它的功能。测试时我遇到了一个问题,用手机上传的照片沿逆时针方向旋转了90度。但是当我使用javascript向用户显示上传图像的预览时,图像旋转了90度,但是当我保存图像时,它就变得正确了。我的JavaScript代码是
function imagePreview(input,elm) {
if (input.files && input.files[0]) {
var reader = new FileReader();
reader.onload = function (e) {
$(elm).css("background-image","url('"+e.target.result+"')");
}
reader.readAsDataURL(input.files[0]);
}
}
$("#settings_img").on("change",function(){
imagePreview(this,"#settings_img_elm");
});
任何人都可以通过编辑上面的代码来帮助我正确调整预览图像的方向,以便在需要时改变图像的方向。
仅使用CSS旋转图像呢?
reader.onload = function (e) {
$(elm).css({
"background-image":"url('"+e.target.result+"')",
"transform": "rotate(90deg)"
});
}
编辑:好吧,在简要了解EXIF数据领域之后,我想我可能会为您提供解决方案。我借用了@Nick建议的Ali的getOrientation()函数,然后按如下所示用CSS纠正了方向:
function correctOrientation(element, orientation){
switch (orientation) {
case 2: $(element).css("transform", "scaleX(-1)");
break;
case 3: $(element).css("transform", "rotate(180deg)");
break;
case 4: $(element).css("transform", "rotate(180deg) scaleX(-1)");
break;
case 5: $(element).css("transform", "rotate(-90deg) scaleX(-1)");
break;
case 6: $(element).css("transform", "rotate(90deg)");
break;
case 7: $(element).css("transform", "rotate(90deg) scaleX(-1)");
break;
case 8: $(element).css("transform", "rotate(-90deg)");
break;
default: break;
}
}
如果需要测试示例文件,请get them here。
编辑:将上载的图像放置在<img>
中,而不是div的背景图像中:https://jsfiddle.net/ynzvtLe2/2/
这应该有效。在这里,我获得了图像文件的原始方向,然后使用适当的旋转校正构建了画布。然后,我们将正确旋转的图像设置为预览。
function imagePreview(input,elm) {
// image file
var file = input.files[0];
if (!file.type.match('image/jpeg.*')) {
// image is not a jpeg, do something?
}
var reader = new FileReader();
reader.onload = function(e) {
var exif = piexif.load(e.target.result);
var image = new Image();
image.onload = function () {
//get original orientation of the uploaded image
var orientation = exif["0th"][piexif.ImageIFD.Orientation];
// Build a temperory canvas to manipulate image to required orientation
var canvas = document.createElement("canvas");
canvas.width = image.width;
canvas.height = image.height;
var ctx = canvas.getContext("2d");
var x = 0;
var y = 0;
ctx.save();
if (orientation == 2) {
x = -canvas.width;
ctx.scale(-1, 1);
} else if (orientation == 3) {
x = -canvas.width;
y = -canvas.height;
ctx.scale(-1, -1);
} else if (orientation == 4) {
y = -canvas.height;
ctx.scale(1, -1);
} else if (orientation == 5) {
canvas.width = image.height;
canvas.height = image.width;
ctx.translate(canvas.width, canvas.height / canvas.width);
ctx.rotate(Math.PI / 2);
y = -canvas.width;
ctx.scale(1, -1);
} else if (orientation == 6) {
canvas.width = image.height;
canvas.height = image.width;
ctx.translate(canvas.width, canvas.height / canvas.width);
ctx.rotate(Math.PI / 2);
} else if (orientation == 7) {
canvas.width = image.height;
canvas.height = image.width;
ctx.translate(canvas.width, canvas.height / canvas.width);
ctx.rotate(Math.PI / 2);
x = -canvas.height;
ctx.scale(-1, 1);
} else if (orientation == 8) {
canvas.width = image.height;
canvas.height = image.width;
ctx.translate(canvas.width, canvas.height / canvas.width);
ctx.rotate(Math.PI / 2);
x = -canvas.height;
y = -canvas.width;
ctx.scale(-1, -1);
}
ctx.drawImage(image, x, y);
ctx.restore();
var dataURL = canvas.toDataURL("image/jpeg", 1.0);
// set the preview image to your element
$(elm).css("background-image","url('"+dataURL+"')");
};
image.src = e.target.result;
};
reader.readAsDataURL(file);
}
$("#settings_img").on("change",function(){
imagePreview(this,"#settings_img_elm");
});
请确保首先包含此库: https://github.com/hMatoba/piexifjs
我从文档中获得了帮助: https://readthedocs.org/projects/piexif/downloads/pdf/latest/