I want to receive the width of a JPG after dragging it into the browser window. The strange thing is, sometimes it works perfectly and sometimes a width of zero is returned.
fiddle
document.body.addEventListener('drop', function ( e )
{
e.stopPropagation();
e.preventDefault();
file = e.dataTransfer.files[0];
reader.readAsDataURL( file );
reader.onloadend = function()
{
var source = this.result;
var currentImg = new Image();
currentImg.src = source;
var someDiv = document.createElement("div");
someDiv.innerHTML = '<li>'+currentImg.width+'</li>';
document.getElementById("logs").appendChild(someDiv);
}
});
This happens because you probably get width before the image is loaded.
Put some code like this and you works correctly.
...
var currentImg = new Image();
currentImg.onload = function() {
var someDiv = document.createElement("div");
someDiv.innerHTML = '<li>'+currentImg.width+'</li>';
document.getElementById("logs").appendChild(someDiv);
}
currentImg.src = source;
...
put the onload before setting the sorce because onload is a callback function.
Related
I have the following code to create an image with JavaScipt, the image appear on a button click. The problem is when the image is created and i click again the button another one appear, and i don't want that.
How i can solve that?
var img = new Image();
var div = document.getElementById('Table');
img.onload = function() {
div.appendChild(img);
};
img.src = 'Images/Email.png';
You could use a flag, which indicate when the image has been created, loaded and added to your DOM:
var div = document.getElementById('Table');
var hasImage = false; // flag
var button = document.getElementById('button');
button.addEventListener('click', function(event){
createImage();
});
var createImage = function(){
if(!hasImage) {
var img = new Image();
img.src = 'http://pipsum.com/435x310.jpg';
img.onload = function() {
div.appendChild(img);
hasImage = true;
};
}else{
console.log('image is already present');
}
};
<button id="button" type="button">Click Me!</button>
<div id="Table"></div >
Check if the image is already added to the DOM. If not, do so. If already added, only update the source.
It could be something like this:
var img = new Image();
var div = document.getElementById('Table');
var appended = false;
function appendImage() {
appended = true;
div.appendChild(img);
img.removeEventListener('load', appendImage);
}
function onClick() {
if (!appended) {
img.addEventListener('load', appendImage);
}
img.src = 'Images/Email.png';
}
I want to put next to each thumbnail a little cross to be able to remove them one by one. I am able to remove image by click on it but I would like to have seperate button "x" to remove it.
fileInput.addEventListener("change", function (e) {
var filesVAR = this.files;
showThumbnail(filesVAR);
}, false);
function showThumbnail(files) {
var file = files[0]
var image = document.createElement("img");
var thumbnail = document.getElementById("thumbnail");
image.file = file;
image.setAttribute('class', 'imgKLIK5');
thumbnail.appendChild(image)
var reader = new FileReader()
reader.onload = (function (aImg) {
return function (e) {
aImg.src = e.target.result;
};
}(image))
var ret = reader.readAsDataURL(file);
var canvas = document.createElement("canvas");
ctx = canvas.getContext("2d");
image.onload = function () {
ctx.drawImage(image, 100, 100);
}
}
});
Here is my code in JFIDDLE
Can You help me out, please?
see this example with close button:http://jsfiddle.net/kevalbhatt18/r0taz01L/1/
$('div').on('click', '.closeDiv', function () {
$(this).prev().remove();
$(this).remove();
$('#upload-file').val("");
});
And I made this changes in your showThumbnail function
function showThumbnail(files) {
var file = files[0]
var thumbnail = document.getElementById("thumbnail");
var pDiv = document.createElement("div");
var image = document.createElement("img");
var div = document.createElement("div");
pDiv.setAttribute('class', 'pDiv');
thumbnail.appendChild(pDiv);
image.setAttribute('class', 'imgKLIK5');
pDiv.appendChild(image)
div.innerHTML = "X";
div.setAttribute('class', 'closeDiv');
pDiv.appendChild(div).......
...................
Just add new button element on each preview with following style attributes,
float:right;
position:relative;
you can remove the img from div thumbnail on click the "x" button, check this fiddle
I have an image uploader in my drawing application that I've written in Javascript. I want to allow the user to place multiple of the same image on the canvas. However, when I try to upload an image that's already on the canvas, nothing happens and a breakpoint in my event handler for the uploader never gets hit. What's going on and how can I fix it? Thanks!
Here's the code for my image handler:
function handleImage(e) {
var reader = new FileReader();
reader.onload = function(event) {
var img = new Image();
img.onload = function() {
img.className = 'drag';
img.style.left = 0;
img.style.top = 0;
context.drawImage(img, parseInt(img.style.left, 10) , parseInt(img.style.top, 10));
images.push(img);
}
img.src = event.target.result;
}
reader.readAsDataURL(e.target.files[0]);
};
I do tend to agree with Rene Pot to use the same image again (duplicate button), but you still can't prevent the user from inserting/loading the same image again. I've encountered the problem a while ago and used this bit of code to check if the image is already cached (if cached, there is no load, hence the onload won't fire either).
var img = new Image();
img.src = event.target.result;
var insertImage = function() {
img.className = 'drag';
img.style.left = 0;
img.style.top = 0;
context.drawImage(img, parseInt(img.style.left, 10) , parseInt(img.style.top, 10));
images.push(img);
}
if(img.complete){
img.onload = insertImage;
} else {
insertImage();
}
Hope that helps.
The below handleFiles method is being passed files from both drag and drop and a file input. After it gets the data url for a given file it passes it to the processImage function. This function creates a new image and sets the src and file for that image. I then take different actions based on the width of the incoming image and insert the image into the dom. However, I noticed when dropping in a bunch of images imageWidth will get set to 0. I have confirmed the image.src is correctly set and that dropping the same image in by itself works fine. I also have confirmed that if I remove the width calculations the image does display correctly on the page. When I enter the debugger I can confirm that immediately after imageWidth is set to 0 i.width returns a correct value. At first I thought it might be a threading issue in Chrome, but then when I saw it happen in FireFox as well I became alarmed. I have not been able to pinpoint a certain threshold, but the more load you put on the browser the less likely it is to correctly get the width.
I am seeing the problem in both FireFox 16.0.2 and Chrome 23.0.1271.95.
function handleFiles(files) {
for (var i = 0; i < files.length; i++) {
var file = files[i];
if( !isImage(file) ) {
continue;
}
var reader = new FileReader();
reader.onloadend = function(e) {
var dataURL = e.target.result;
processImage(file, dataURL);
}
reader.readAsDataURL(file);
}
}
function processImage(file, dataURL) {
var i = new Image();
i.src = dataURL;
i.file = file;
//console.log(i);
var maxWidth = 600;
var imageWidth = i.width;
......
}
As with all images, they may need time to load before they will tell you their width:
var i = new Image();
i.onload = function() {
//console.log(i);
var maxWidth = 600;
var imageWidth = this.width;
}
i.src = dataURL;
i.file = file;
The width (and height) might be 0 because it's not loaded yet.
Try adding the load event like so:
function processImage(file, dataURL) {
var i = new Image();
i.addEventListener("load", function () {
var maxWidth = 600;
var imageWidth = i.width;
......
});
i.src = dataURL;
i.file = file;
}
I'm using html5 to create drag and drop image upload functionality. This works great for me in firefox but in chrome the image onload event only fires the first time. If I drag multiple images in only the first works and if I drag a second in it fails. I believe the problem is with the image onload.
here is the way my code works I have removed the irrelevant sections:
var img = document.createElement("img");
var reader = new FileReader();
var canvas = document.createElement("canvas");
var canvasData;
var ctx = canvas.getContext("2d");
var myFiles;
var i = 0;
reader.onload = (function (aImg)
{
return function (e)
{
aImg.src = e.target.result;
};
})(img);
img.onload = function (){
//resizes image
//draws it to the canvas
//posts to server
i++;
if(i < myFiles.length){
processNext(i);
}
}
function processNext(filei) {
var file = myFiles[filei];
img.file = file;
reader.readAsDataURL(file);
}
i = 0;
myFiles = files;
processNext(0);
Does anyone know why this works in firefox but not chrome?
Explanation from chromium tracker:
This is not a bug. WebKit is just more strict. You must instantiate a new Image() object before the replacement, like this:
var photo = document.getElementById('image_id');
var img = new Image();
img.addEventListener('load', myFunction, false);
img.src = 'http://newimgsource.jpg';
photo.src = img.src;
source: http://code.google.com/p/chromium/issues/detail?id=7731#c12
This is strange, none of the above worked for me. I was defining the image variable as local and change it to global and it started working. Does this make sense? Can somebody explain it?
This didnt worked for me:
function loadImage() {
var ImageToLoad = new Image();
ImageToLoad.onload = function() {
console.log("finish loading");
};
ImageToLoad.src = "myimage.png";
}
This did work:
var ImageToLoad = new Image();
function loadImage() {
ImageToLoad.onload = function() {
console.log("finish loading");
};
ImageToLoad.src = "myimage.png";
}