How to Manipulate Image After Uploaded To Canvas (FabricJS) - javascript

I've been racking my brain on this for a while now, but I can't seem to rotate the image on Canvas after uploading. Here's the code sample in question:
// INITIATE & DRAW CANVAS
var canvas = new fabric.Canvas('CanvasArtArtboard');
// CREATE OVERLAY GRIDS
canvas.setOverlayColor('rgba(205, 173, 64, 0.6)', canvas.renderAll.bind(canvas));
// UPLOAD USER IMAGE TO CANVAS
document.getElementById('imgLoader').onchange = function handleImage(e) {
var reader = new FileReader();
reader.onload = function (event) {
var imgObj = new Image();
imgObj.src = event.target.result;
imgObj.onload = function () {
// start fabricJS stuff
var image = new fabric.Image(imgObj);
image.set({
originX: 'left',
originY: 'top',
padding: 0,
cornersize: 10,
scaleX: 0.4,
scaleY: 0.4,
});
//image.scale(getRandomNum(0.1, 0.25)).setCoords();
canvas.add(image);
image.sendToBack();
canvas.renderAll();
//end fabricJS stuff
}
}
reader.readAsDataURL(e.target.files[0]);
}
// ROTATE UPLOADED IMAGE
$("#angle-control").click(function(){
var curAngle = canvas.item(0).getAngle();
canvas.item(0).setAngle(curAngle+15);
canvas.renderAll();
});
I've looked at the following example:
Add image from user computer to canvas (Stack OverFlow Question)
http://jsfiddle.net/PromInc/3efe2x9j/
Once the user uploads their image and clicks the "rotate 90*" button, I'm looking for the image to then rotate.
EDIT: Apologies, here is my JSFiddle in it's current state: http://jsfiddle.net/darnellcreates/oq6htzew/3/

I had a look at your fiddle and there is a lot wrong. The code for rotating is ok (sort of) but the page is full of problems.
First there is no JQuery and you are using the JQuery $ function as selector to access DOM elements. I do not see the point in using jQuery if all you are doing is using it as a selector, you use document.getElementById in some parts and $ in others. This totally negates any benefit Jquery would provide.
Second you are duplicating DOM element ID's (This is a strict no no) DOM ID's must be unique to the page.
To get you on your way here are a few changes,
Change the slider element in the HTML to
<input type="range" id="angleControl1" value="0" min="-90" max="90">
Note that the id is unique to the page. I have also avoided the naming convention (did not make it angle-control1) as this is a simple page and I will take some shortcuts and access the DOM elements directly in JavaScript.
Next remove the click handler for the range slider and replace it with a mouse move event listener.
// keep a copy of the last value so there is no needless rotates
var lastValue = angleControl1.value; // no need to search the node tree.
// you can access elements directly by
// their ID.
// Listen to the mousemoves of the range control. Click, change will
// only update at the end of the mouse down up process. This does not
// provide good user feedback
angleControl1.addEventListener("mousemove",function(){
if(this.value !== lastValue){ // only update the angle if it has changed
// set the angle to the absolute angle rather than relative as you had it
canvas.item(0).setAngle(Number(this.value)); // Number() is me being pedantic
canvas.renderAll(); // rerender
lastValue = this.value; // remember the last value
}
}); // all done for this function
Note. Direct DOM element access can be problematic in some situations (if you duplicate ID's, use that id as a variable before the DOM has loaded, your page is sharing the global namespace, or someone is using an old netscape browser) but for simple pages it is the easiest and safest way (If someone has netscape they can't run the page anyway because there is not canvas element).
Also remove the other Jquery calls $() as they cause the page to crash and stop everything from running.
You need to use the DevTools in these types of situations. It will show you all the errors and give you warnings (FireFox) for bad habits. To access the DevTool hit f12 on most browsers.The DevTools console will list errors and provide a link directly to the code where it is happening. You can also step through the code line by line so you can see what is going on.

i updated your jsfiddle ,to work both the rotate button 90o and the range bar,
just in case you need it.
link: http://jsfiddle.net/rqevmp3y/1/
$("#angle-control").on('click', function (event) {
console.log('rotate');
var curAngle = canvas._objects[0].getAngle();
canvas._objects[0].setAngle(curAngle+90);
canvas.renderAll();
});
$("#rangeControl").on('change', function (event) {
console.log('rotate from range',$(this).val());
var curAngle = canvas._objects[0].getAngle();
canvas._objects[0].setAngle(curAngle+parseInt($(this).val()));
canvas.renderAll();
});

Related

How to disable dataTransfer onDrag in a react component?

I have an draggable div in a react app. When I enable dragging by using draggable={true}, I see a ghost image is created and it follows the mouse movement. I just wanted to get rid of it.
My actual component is the first one. The ghost image is the second one.
When I looked up for it, I found this stackoverflow solution. Implemented the following code snippet, and it cleared the old ghost.
let img = new Image();
img.src = empty; // this is just an empty png file
const onDragStartHandler = (event) => {
event.dataTransfer.setDragImage(img,0,0)
// ...
}
However, now I see a different animation for a fraction of a second at the very beginning of the drag operation. How can I remove that? Or is there a way to completely disable the dataTrasfer? Tried event.dataTransfer.clearData() but it did not worked out.

scroll zoom on two images

I have two images with same dimensions and same positions, but placed in divs with dynamic width depending on user interaction using the jquery beforeAfter plugin.
I would like to enable scroll zooming on these images using wheelzoom, such that zooming on one of these images will zoom the same amount in the same position as the other.
What I am unable to do is this linking of (I suppose) the event handlers along the lines of this:
function onwheel(e){
//adjust image to fit zoom level ...
other_img.onwheel(e);
}
If this is not possible, is it possible to copy the event and change the target image?
I am looking for a solution using either jquery or native Javascript.
Code here (ignore the handle).
EDIT: Any top-level pointers to what should work would also be appreciated
I made a worked example: http://plnkr.co/edit/kH0ec8TVMXUIYlMoBaMq?p=preview
here is the core code:
document.getElementsByClassName("before")[0].addEventListener("wheel", function(event){
if(flag){
flag= false;
return;
};
flag=true;
var newEvent = new WheelEvent("wheel",event);
var elementToTrigger = document.getElementsByClassName("after")[0];
elementToTrigger.dispatchEvent(newEvent);
});
I do something simple, when an event happening("wheel") a trigger the same event to another element and pass as argument the data from the first event to the new event. I use flag variable to deter the custom event trigger again the other event and start an eternal loop.
This is a solution without to edit the source code of plugin. You can do more good solutions if you change the code of wheelzoom.js.
Make the zooming a function that takes enough parameters to handle zooming, and get the values you need from the event handler.
function handleZoom(domNode, zoomDirection, zoomAmount) {
// Do stuff to change the size of `domNode`
}
var img1, img2;
img1 = /* select image node */;
img2 = /* select image node */;
function handleScroll(scrollEvent) {
var direction, amount;
// Use `scrollEvent` to figure out which direction and how far to zoom
handleZoom(img1, direction, amount);
handleZoom(img2, direction, amount);
}
img1.onscroll = handleScroll;
img2.onscroll = handleScroll;

How do I add a hyperlink to a shape in a KineticJS canvas?

I'm working on my homepage which consists of several shapes being drawn in the middle of the screen using an HTML5 canvas and KineticJS, but I've run into a roadblock trying to add hyperlinks to each of the shapes. My code thus far (which doesn't work) is:
midHexPoly.on('mouseover', function() {
document.body.style.cursor = 'pointer';
});
midHexPoly.on('mouseout', function() {
document.body.style.cursor = 'default';
}); //this works, the mouse changes to a pointer on
//mouseover, and back on mouseout
var linkTest = "http://www.google.com"
midHexPoly.on('click', function() {
window.open = linkTest;
});
After much googling, I can't seem to find any resolutions to this issue, and there doesn't seem to be a function in Kintetic for redirecting or adding hyperlinks.
Is there any way to fix this? Thanks!
window.open is a method, so you should call it like so: window.open(linkTest);. You'll find more info, such as its arguments on w3schools. I suggest using the second argument (name) to make sure all links will open in the same new window.
If however you want to open all links in the same window as your homepage, you could use this piece of code instead of window.open: location.assign(linkText);.
If those don't work, make sure the click event is fired by adding a console log inside your callback function, e.g.
midHexPoly.on('click', function() {
console.log('clicked on midHexPoly');
});
or
midHexPoly.on('click', function() {
alert('clicked on midHexPoly');
});

How to reset the Jcrop plugin? I.e. How to allow changing the source of the target image?

The application I'm working on allows users to add an unlimited number of images onto a viewport. With those images, a series of operations are allowed: resize, drag, rotate, and crop. For the cropping feature, I'm using the Jcrop plugin.
When clicking on the control icon for cropping, a lightbox appears, that shows the selected image (the <img> element is one and the same, only the src attribute value changes each time) and allows the user to crop it. The event handler associated triggered when the crop icon is clicked is:
$(document).on("click", "div.cropper", function(){
var ctrl = $(this),
ref = ctrl.attr("reference"),
obj = returnObj(objects,ref),
target = $("#crop-target")
crop_params = {};
target.attr("src",obj.src);
target.Jcrop({
onSelect: function(c){
crop_params = c;
}
});
});
Given the code above, the cropping works perfectly, but ONLY with the first image I try it on. When I click on the "cropper" icon for any other images after that, the first image is shown.
How can I work around this problem?
PS: I've searched through the already existing questions about Jcrop and couldn't find an answer to my particular problem.
You just need to create a new img tag and start jCrop with that.
$('#parent_tag #img_to_crop').remove();
$('#parent_tag').html('<img id="img_to_crop"></img>');
$('#parent_tag #img_to_crop').Jcrop({ options ... });

jCrop (jQuery) sometimes fails to load image/cropper area

I've got a pretty simple problem, but I've become clueless on what is causing the problem. In one of my applications I'm using jCrop as a small add-on to crop images to fit in banners/headers etc. These steps will be taken:
1) Select an image (using CKFinder for this, CKFinder returns the image path to an input field)
2) Click a button to load the image
3) Crop the image
4) Save the image
in about 75% of the cases everything goes according to plan, however the in the other 25% of the cases jCrop fails to load the cropping area and leaves it blank. Here's the jQuery code I'm using:
jQuery('#selectimg').live('click', function(e) {
e.preventDefault();
var newsrc = jQuery('#img2').val();
jQuery('#cropbox').attr('src', newsrc);
var jcrop_api = jQuery.Jcrop('#cropbox', {
boxWidth: 700,
boxHeight: 700,
onSelect: updateCoords,
onChange: updateCoords
});
//Some other JS code come's here for buttons (they work all the time)
});
I noticed that when I left the part away where #cropbox is being transformd in a cropable area, that the image is loading just fine, so the mistake lies with the var = jcrop_api part, but I slowsly start to think that there is no solution for this...
This is what I've tried so far:
Making a div <div id="cropper-box"></div> and use jQuery('#cropper-box').append('<img src="" id="cropbox" />'); and afterwards set the value. I tried the same thing but setting the image src in 1 step instead of afterwards.
I tried to put a placeholder on the page <img src="placeholder.png" id="cropbox" /> and change the source upon clicking the button. This works, but the cropperarea stays the size of the image (300x180px or something) and doesn't get bigger as it should.
// Edit:
Trying some more showed me that the image source is being replaced properly(! using Firefox to show the source for the selected text), I double checked the URL but this was a correct URL and a working image.
At the place where the cropper should be, there's an about 10x10 pixel white spot where the cropper icon (a plus sign) is popping up.. but as said before: the image isn't shown.
// Edit 2:
So I've took the sources for both the 1st and the 2nd try for the same image. As told before the first try the image won't load properly and the 2nd try it does (only when the 2nd try is the same image(!!)).
The selected page source shows 1 difference which is, first try:
<img style="position: absolute; width: 0px; height: 0px;" src="http://95.142.175.17/uploads/files/Desert.jpg">
second try:
<img style="position: absolute; width: 700px; height: 525px;" src="http://95.142.175.17/uploads/files/Desert.jpg">
I guess this is the image that's being replace by jCrop, but it's a complete riddle why it puts 0 heigth/width in there the first and the proper sizes the second time.
Okay guys, in case anyone else runs into this problem:
jCrop kinda gets messed up if the actions of loading an image and applying jCrop to it are queued too fast after eachother. I still find it strange that a second attempt works perfect, but I think that has something to do with cached image dimensions which are recognized by the DOM of the page or something.
The solution I came up with was by creating a function that converts the #cropbox into a jCrop area and then setting a 2 second interval, just to give jCrop some time to recognize the image and it's dimensions and then convert the element.
This is the part of html I used (with a preloader):
<div id="cropper-loading" style="display: none;"><img src="images/analytics/ajax-loader.gif" /></div>
<img id="cropbox" src="images/placeholder.png" style="display: none;" />
As you can see both the cropbox image and cropper-loading div are hidden as they are not needed instantly. You could display the placeholder if you wanted though.. Then this HTML form is used:
<input name="image2" id="img2" type="text" readonly="readonly" onclick="openKCFinder(this)" value="click here to select an image" style="width: 285px;" /> <button class="button button-blue" type="submit" name="load" id="selectimg">Load Image in cropper</button>
In my case I've been using KCFinder to load the images (it's part of CKEditor, really worth watching into!), KCFinder handles uploads, renaming etc and after choosing it returns the chosen image path (relative/absolute is configurable) to the input field.
Then when clicking #selectimg this code is called:
jQuery('#selectimg').click(function(e) {
e.preventDefault();
jQuery('#cropper-loading').css('display', 'block');
var newsrc = jQuery('#img2').val();
jQuery('#cropbox').attr('src', newsrc);
jQuery('#img').val(newsrc);
function createJcropArea() {
jQuery('#cropper-loading').css('display', 'none');
jQuery('#cropbox').css('display', 'block');
var jcrop_api = jQuery.Jcrop('#cropbox', {
boxWidth: 700,
boxHeight: 700,
onSelect: updateCoords,
onChange: updateCoords
});
clearInterval(interval);
}
var interval = setInterval(createJcropArea, 2000);
});
At first I prevent the link too be followed as it normally would (or button action) and after that the loading div is displayed (that's my reason for hiding the placeholder image, otherwise it would look messed up).
Then the image location is being loaded from the input field and copied into another (#img), this field is used to process the image afterwards (PHP uses the value of #img to load this image). Also simultaneously the #cropbox src is being set to the new image.
And here comes the part which solved my problem:
Instead of directly activating jCrop, I've made a function that:
1) hides the loading icon
2) displays the image
3) converts #cropbox into a jCrop area
4) clean the interval (otherwise it would loop un-ending)
And after this function you can see that, just to be save, I took 2 seconds delay before the jCrop area is being converted.
Hope it helps anyone in the future!
Cheers and thanks for thinking #vector and whoever else did ;-)
Creating an 'Image' object and setting up the 'src' attribute does not apply that you can treat the image like it had already been loaded.
Also, giving any fixed timeout interval does not guaranty the image has already been loaded.
Instead, you should set up an 'onload' callback for the Image Object - which will then initialize the Jcrop Object:
var src = 'https://example.com/imgs/someimgtocrop.jpg';
var tmpImg = new Image();
tmpImg.onload = function() {
//This is where you can safely create an image and a Jcrop Object
};
tmpImg.src = src; //Note that the 'src' attribute is only added to the Image Object after the 'onload' listener was defined
Try the edge library on the repo here: https://github.com/tapmodo/Jcrop
This should solve your problem. The lines that are changed to solve your problem:
// Fix size of crop image.
// Necessary when crop image is within a hidden element when page is loaded.
if ($origimg[0].width != 0 && $origimg[0].height != 0) {
// Obtain dimensions from contained img element.
$origimg.width($origimg[0].width);
$origimg.height($origimg[0].height);
} else {
// Obtain dimensions from temporary image in case the original is not loaded yet (e.g. IE 7.0).
var tempImage = new Image();
tempImage.src = $origimg[0].src;
$origimg.width(tempImage.width);
$origimg.height(tempImage.height);
}
Don't call this function onChange : updateCoords
Try it without and it will run smooth on mobiles.
You can create base64 directly and show them as an image wherever you want.
Here my weird but fantastic solution:
if (obj.tagName == 'IMG') {
var tempImage = new Image();
tempImage.src = $origimg[0].src;
$origimg.width(tempImage.width);
$origimg.height(tempImage.height);
if ($origimg[0].width > 1 && $origimg[0].height > 1) {
$origimg.width($origimg[0].width);
$origimg.height($origimg[0].height);
} else {
var tempImage = new Image();
tempImage.src = $origimg[0].src;
$origimg.width(tempImage.width);
$origimg.height(tempImage.height);
//console.log('error'+$origimg[0].width + $origimg[0].height);
}
I know this is old, but it was happening randomly to my install recently. Found that it was due to images not being full loaded before before jCrop intialized.
All it took to fix it was wrapping the jCrop initialization stuff inside of a
$(window).on("load", function () { //jcrop stuff here });
And it has been working well since.

Categories