[英]Added svg image into canvas using fabric.js not visible in firefox
[英]Extract exif data/rotate image added to fabric.js canvas
在我的网络应用程序中,用户可以从输入类型文件在手机上拍照。
之前我使用js加载图片库自动检测EXIF数据并在必要时旋转它。
现在我已切换到fabric.js库,因为我希望允许用户在上传之前在画布图像上进行绘制。
问题是我不知道如何获取图像exif数据,或者在使用fabric.js时旋转图像。
我的代码:
从索引数据库获取图像
var image;
localforage.getItem('photo').then(function(value) {
image = value;
// THIS IS OLD CODE, BEFORE I USER js-load-image to automatically detect exif data
// and rotate if neccessary, then I just appended the result to wrapper
// $("#preview-wrapper").empty();
// if (image) {
// loadImage(
// image,
// function(img) {
// $("#preview-wrapper").append(img);
// },
// {orientation: true} // Options
// );
// }
})
loadFabricOnImageLoad(); // append image to fabric canvas
Fabric.js 函数
function loadFabricOnImageLoad(){
if(typeof image !== "undefined" && image){
let loaded = false;
if (loaded) {return;}
var c = document.getElementById('myCanvas');
canvas = new fabric.Canvas(c);
canvas.setWidth(width);
canvas.setHeight(500);
canvas.selection = false;
var url = URL.createObjectURL(image);
fabric.Image.fromURL(url, function(img) {
img.set({
left: 0,
right: 0,
top: 0,
});
img.scaleToWidth(width);
canvas.add(img);
canvas.setHeight(img.getScaledHeight());
$("#canvas-loader").hide();
});
fabric.Object.prototype.set({
evented: false
});
canvas.freeDrawingBrush = new fabric['PencilBrush'](canvas);
canvas.freeDrawingBrush.color = 'Red';
canvas.freeDrawingBrush.width = 6;
loaded = true;
} else {
setTimeout(loadFabricOnImageLoad, 250);
}
}
毕竟,通过从图像文件中获取 exif 数据,我自己设法做到了:
localforage.getItem('photo').then(function(value) {
image = value;
// extract the exif data from image file using exif.js
EXIF.getData(image, function() {
let obj = EXIF.getAllTags(this);
imageOrientation = obj.Orientation;
console.log( imageOrientation );
});
})
我必须进行大量缩放和调整大小才能正确获得旋转图像和画布的大小:
function loadFabricOnImageLoad(){
if(typeof image !== "undefined" && image){
let loaded = false;
if (loaded) {return;}
var c = document.getElementById('myCanvas');
canvas = new fabric.Canvas(c);
canvas.setWidth(width);
canvas.setHeight(500);
canvas.selection = false;
var url = URL.createObjectURL(image);
fabric.Image.fromURL(url, function(img) {
img.scaleToWidth(canvas.width);
if(imageOrientation == 3 || imageOrientation == 6 || imageOrientation == 8) {
img.scaleToHeight(canvas.height);
canvas.setHeight(img.getScaledHeight());
canvas.add(img);
img.scaleToWidth(canvas.height);
img.scaleToHeight(canvas.width);
img.rotate(getDegreesForOrientation(imageOrientation));
img.center();
} else {
canvas.setHeight(img.getScaledHeight());
canvas.add(img);
}
$("#canvas-loader").hide();
});
// console.log('slika '+JSON.stringify(fabric.Image));
fabric.Object.prototype.set({
evented: false
});
canvas.freeDrawingBrush = new fabric['PencilBrush'](canvas);
canvas.freeDrawingBrush.color = 'Red';
canvas.freeDrawingBrush.width = 6;
loaded = true;
} else {
setTimeout(loadFabricOnImageLoad, 250);
}
}
我知道这已经得到了回答,但我想建议不同的图书馆。 exif-js 已经死了 - 有问题并且不再维护,有数百个未解决的问题。
我希望你尝试exifr ,我开始开发它是出于对 exif-js 的挫败感。
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