I have the following code that loads an image that I choose from files. It loads and draws it to a canvas, but if I make a change the the image file via an image editor, and then reload it- it doesn't refresh and show the changes(it uses the cached version)..
How can I get it to refresh??
var reader = new FileReader();
reader.onload = function(event){
img[num] = new Image();
img[num].onload = function () {
//handle image stuff
}
img[num].src = event.target.result;
}
reader.readAsDataURL(e.target.files[0]);
Sorry, was an issue with the input file change event. Since the filename wasn't different, it wasn't calling the change event
If I add the line to clear the value, it works.
$( "#imageReplacer" ).on("change", function( event ){
replaceImage(event);
$(this).val('');
}).hide();
Related
I've managed to upload images through drag & drop to a SP 2013 library by intercepting the paste and fileUploadrequest events (+ added mandatory headers and used /_api/web/getfolderbyserverrelativeurl(\'/sites/theSite/theLibrary\')/files/add(overwrite=true,%20url=\'aDynamicFilename.jpg\') as the request's URL).
The problem with this approach is that even if the image is uploaded, the image is not inserted in the editor (no error). I'm not setting config.uploadUrl for this approach.
Q#1: Is there any step which I should go through after the image is uploaded? Like telling the CKEDITOR instance to insert the image?
Later on, I've noticed that if I'm setting the config.uploadUrl to the same URL as I'm using above, the editor inserts successfully the image. The problem is that, from my trials, the config.uploadUrl is initialized together with the CKEDITOR instance (therefore, can't be assigned dynamically for each image, in case that multiple images are dragged and dropped on the editor).
Q#2: Is there another way to configure the uploadUrl or maybe some other config property that would allow the custom upload to work and insert the image in the editor?
Eventually made it work by following a similar approach as the on in this repo:
RyanSiu1995/ckeditor-ImageUploader
Use a FileReader and start loading the image when it's pasted to the
CKEditor
On the fileReader's onload event, create a img element in the
editor's document object with some opacity and with the fileReader's
Base64 string as the src
On the fileLoader's uploaded event, remove
the img and re-add it with the actual file's url (changing the src
attribute on the img was not triggering the editor's change event, which I was hooking into,so I chose to replace the whole element)
Here's the relevant section from the ckeditor-ImageUploader plugin:
fileDialog.on('change', function (e) {
var fileTools = CKEDITOR.fileTools,
uploadUrl = fileTools.getUploadUrl( editor.config, 'image' ),
file = e.target.files[0],
loader = editor.uploadRepository.create(file),
reader = new FileReader(),
notification,
img;
// verify
if (!/image/i.test(file.type)) {
notification = editor.showNotification( 'Please check the correct format.', 'warning' );
setTimeout(function() {
notification.hide()
}, 2000);
return false
}
loader.upload(uploadUrl);
// preview image
reader.readAsDataURL(e.target.files[0]);
reader.onload = function (e) {
img = editor.document.createElement('img');
img.setAttribute('src', e.target.result);
img.setStyle('opacity', 0.3);
editor.insertElement(img);
}
loader.on('uploaded', function(evt) {
editor.widgets.initOn(img, 'image', {
src: evt.sender.url
});
img.setAttribute('src', evt.sender.url);
img.setStyle('opacity', 1);
});
loader.on('error', function() {
img.$ && img.$.remove();
});
fileTools.bindNotifications(editor, loader);
// empty input
fileDialog[0].value = "";
I would like to validate by file dimensions (resolution).
on the documentation page there is only information regarding file name and size, nothing at all in the docs about dimensions, and I also had no luck on Google.
The purpose of this is that I don't want users to upload low-res photos to my server. Thanks.
As Ray Nicholus had suggested, using the getFile method to get the File object and then use that with the internal instance object qq.ImageValidation to run fineuploader's validation on the file. A promise must be return because this proccess is async.
function onSubmit(e, id, filename){
var promise = validateByDimensions(id, [1024, 600]);
return promise;
}
function validateByDimensions(id, dimensionsArr){
var deferred = new $.Deferred(),
file = uploaderElm.fineUploader('getFile', id),
imageValidator = new qq.ImageValidation(file, function(){}),
result = imageValidator.validate({
minWidth : dimensionsArr[0],
minHeight : dimensionsArr[1]
});
result.done(function(status){
if( status )
deferred.reject();
else
deferred.resolve();
});
return deferred.promise();
}
Remained question:
Now I wonder how to show the thumbnail of the image that was rejected, while not uploading it to the server, the UI could mark in a different color as an "invalid image", yet the user could see which images we valid and which weren't...
- Update - (regarding the question above)
While I do not see how I could have the default behavior of a thumbnail added to the uploader, but not being uploaded, but there is a way to generate thumbnail manually, like so:
var img = new Image();
uploaderElm.fineUploader("drawThumbnail", id, img, 200, false);
but then I'll to create an item to be inserted to qq-upload-list myself, and handle it all myself..but still it's not so hard.
Update (get even more control over dimensions validation)
You will have to edit (currently) the qq.ImageValidation function to expose outside the private function getWidthHeight. just change that function deceleration to:
this.getWidthHeight = function(){
Also, it would be even better to change the this.validate function to:
this.validate = function(limits) {
var validationEffort = new qq.Promise();
log("Attempting to validate image.");
if (hasNonZeroLimits(limits)) {
this.getWidthHeight().done(function(dimensions){
var failingLimit = getFailingLimit(limits, dimensions);
if (failingLimit) {
validationEffort.failure({ fail:failingLimit, dimensions:dimensions });
}
else {
validationEffort.success({ dimensions:dimensions });
}
}, validationEffort.success);
}
else {
validationEffort.success();
}
return validationEffort;
};
So you would get the fail reason, as well as the dimensions. always nice to have more control.
Now, we could write the custom validation like this:
function validateFileDimensions(dimensionsLimits){
var deferred = new $.Deferred(),
file = this.holderElm.fineUploader('getFile', id),
imageValidator = new qq.ImageValidation(file, function(){});
imageValidator.getWidthHeight().done(function(dimensions){
var minWidth = dimensions.width > dimensionsLimits.width,
minHeight = dimensions.height > dimensionsLimits.height;
// if min-width or min-height satisfied the limits, then approve the image
if( minWidth || minHeight )
deferred.resolve();
else
deferred.reject();
});
return deferred.promise();
}
This approach gives much more flexibility. For example, you would want to have different validation for portrait images than landscape ones, you could easily identify the image orientation and run your own custom code to do whatever.
Using AngularJS:
I'm displaying a list of images with ng-repeat. When I reset and rebuild the model (get new data from backend), I'm displaying the same images as before.
I understand these are new elements created by ng-repeat, but the image srcs are the same. Unlike IE or firefox, Chrome tries and gets a 403 for those same images and then renders them.
That causes a flicker. On IE and Firefox the images come from cache. No hit on the server to check for image changes. No flicker.
How can I prevent that? Should the images be served with some cache header? I tried loading the images to a dataurl, but then I hit the CORS problem, and would have to proxy those images on the backend to get them.
Possibly related: Chrome sometimes reloads image after jQuery .appendTo, recieves 304
Thanks
Some fix would be related to preload the images in javascript and after that display them
function loadImages(arrayOfImgs) {
var imageNumber=0;
$(arrayOfImgs).each(function(){
(new Image()).src = this;
if(arrayOfImgs.length == imageNumber) $scope.showImages = true;
else imageNumber++;
});
}
// Usage:
loadImages([
'img1.jpg',
'img2.jpg'
]);
if you are retriving images from backend use it at success promise
i hope it helps you
Check that example retrinving images from backend:
$scope.loading = true;
getImages().then(function (response) {
var objects= response.results;
var listImages = [];
angular.forEach(objects, function (item) {
listImages.push(item.UrlImage);
});
function preload(arrayOfImages) {
var numImages = 0;
$(arrayOfImages).each(function () {
var img = (new Image());
img.src = this;
$(img).load(function () {
numImages++;
if (numImages == arrayOfImages.length){
$scope.loading = false;
}
});
});
}
preload(listImages);
});
function pushImage () {
var img = new Image();
img.src = '/waroot/chart/chart.png';
document.getElementById("test1").innerHTML = "<img src='/waroot/chart/chart.png'>";
document.getElementById("test2").innerHTML = img;
}
Test 1 works and shows the image, but test 2 doesn't. I am not sure how to solve it but i will need the way test 2 works further along my project since i'm going to have to circle through a large amount of images.
The images are created by JFreeCharts, saved to png and then have to be posted to a site. As a side question: is it possible to push the freecharts objects straight to the jscript instead of having to save them prior (i could throw them into the dictionary and then look them up later but i'm not sure if this works)
Use .appendChild(img) instead of .innerHTML:
function pushImage () {
var img = new Image();
img.src = '/waroot/chart/chart.png';
document.getElementById("test1").innerHTML = "<img src='/waroot/chart/chart.png'>";
document.getElementById("test2").appendChild(img);
}
Demo
This is because img is an image object, not an html string, so you have to append it to the DOM.
P.S., don't forget that the alt attribute is required in the img tag!
var img = new Image();
img.src = '/images/backdrop.jpg';
ctx.drawImage(img,0,0);
I wanted to load an image from local disk on to canvas using dialog box mechanism rather than the path directly specified as in above example. I tried different sorts using JavaScript but in vain, even tried using the input type as file. What else can I try?
Take a look here:
https://developer.mozilla.org/en-US/docs/Web/API/Canvas_API/Tutorial/Using_images
It's important to have drawImage call after the image has loaded:
var img = new Image();
img.onload = function() {
var ctx = document.getElementById('ctx').getContext('2d');
ctx.drawImage(img, 0, 0);
}
img.src = 'images/backdrop.jpg';
Also, note that you probably want to use images/backdrop.jpg instead of /images/backdrop.jpg (note there's no slash in front), as using the latter would get the image from root directory, I would assume that's probably not where your images are.
As far as loading from a dialog box, you can replace the last line from the above with something like this:
var name = prompt("Enter the name of the file", "backdrop.jpg");
img.src = 'images/' + name;
This way, the user would be able to enter the name of the image file to load it. Of course, you need to have that file in your images folder.
Hope this helps.