I wrote the following code:
var image_pinch_help = document.getElementById("image_pinch_help");
var pinch_img_el = document.getElementById("pinch_img_el");
function openImage(img_url) {
pinch_img_el.src = img_url;
if (pinch_img_el.complete) {
IMGloaded();
}
else {
pinch_img_el.addEventListener('load', IMGloaded())
pinch_img_el.addEventListener('error', function() {
alert('error')
});
}
image_pinch_help.style.display = "block";
document.getElementById("pinch_values").setAttribute("content", "");
}
function IMGloaded() {
var screen_height = window.screen.height;
console.log("HERE IS THE HEIGHT: " + screen_height);
var img_height = pinch_img_el.offsetHeight;
console.log("HERE IS THE IMAGE: " + img_height);
}
The code starts at the function openImage(). This function is called to open an Image at my webpage. So the image gets the full width of the screen. The screen where the image is shown on is image_pinch_help. You see that I make this screen visible. To allow the user to zoom into the image I am manipulation the HTML DOM, that the user can scroll at the whole page. I do this here: document.getElementById("pinch_values").setAttribute("content", "");.
When the Image loaded I need to get the height of the screen, which works perfectly. But I also need to get the height of the loaded image. The problem is that its always returning an empty string. I read a long time ago that this could be caused by HTML DOM Manipulations.
But how to fix this disaster?
~Marcus
Related
I'm implementing a chrome extension with javascript to take a screenshot of a full page, so far I've managed to take the screenshot and make it into a canvas in a new tab, it shows the content of a tweet perfectly, but as you can see, the sidebars repeat all the time (Ignore the red button, that's part of my extension and I know how to delete it from the screenshots) screenshot of a tweet
This is the code I'm using to take the screenshot:
async function capture(){
navigator.mediaDevices.getDisplayMedia({preferCurrentTab:true}).then(mediaStream=>{
scrollTo(0,0);
var defaultOverflow = document.body.style.overflow;
//document.body.style.overflow = 'hidden';
var totalHeight = document.body.scrollHeight;
var actualHeight = document.documentElement.clientHeight;
var leftHeight = totalHeight-actualHeight;
var scroll = 200;
var blob = new Blob([document.documentElement.innerHTML],{ type: "text/plain;charset=utf-8" });
console.log('total Height:'+totalHeight+'client height:'+actualHeight+'Left Height:'+leftHeight);
var numScreenshots = Math.ceil(leftHeight/scroll);
var arrayImg = new Array();
var i = 0;
function myLoop() {
setTimeout(function() {
var track = mediaStream.getVideoTracks()[0];
let imgCapture = new ImageCapture(track);
imgCapture.grabFrame().then(bitmap=>{
arrayImg[i] = bitmap;
window.scrollBy(0,scroll);
console.log(i);
i++;
});
if (i <= numScreenshots) {
myLoop();
}else{
document.body.style.overflow = defaultOverflow;
saveAs(blob, "static.txt");
printBitMaps(arrayImg, numScreenshots, totalHeight);
}
}, 250)
}
myLoop();
})
}
async function printBitMaps(arrayImg, numScreenshots, totalHeight){
var win = window.open('about:blank', '_blank');
win.document.write('<canvas id="myCanvas" width="'+arrayImg[0].width+'px" height="'+totalHeight+'px" style="border:5px solid #000000;"></canvas>');
var e = numScreenshots+1;
function printToCanvas(){
setTimeout(function(){
var canvas = win.document.getElementById("myCanvas");
var ctx = canvas.getContext("2d");
ctx.drawImage(arrayImg[e], 0, 200*e);
e--;
if(e>=0){
printToCanvas();
}
},10);
}
printToCanvas();
}
Do you know any way by CSS or javascript that I can use to make the sidebars stay at the top of the page so they don't keep coming down with the scroll?
It's not really a case of "the sidebars ... coming down with the scroll" - the code you're using is taking a first screenshot, scrolling the page, taking another screenshot and then stitching it onto the last one and iterating to the bottom of the page. Thus it's inevitable you're seeing what you see on the screen at the point you take the subsequent screenshots.
To resolve your issue, after your first screenshot you would need to set the div element for the side bar to be display=None by use of CSS. You can find details of the side bar by using the browser Dev Tools, right clicking an using "Inspect" in Chrome.
From what I can see, Twitter seems to use fairly cryptic class names, so it might be easiest and more robust to identify the div for the side bar with some other attribute. It appears they set data-testid="sidebarColumn" on it so give using that a go (but YMMV).
So I'm trying to do an onclick image change which worked, but I'd like the second image to be bigger than the first, is this possible?
Here is the JavaScript code (this is the first time I'm trying to use HTML aside from basic things)
function changeImage() {
if (document.getElementById("imgClickAndChange").src == "https://cdn.glitch.com/2191cc92-26e9-4b6e-9beb-428fb7eb3976%2FPicsArt_03-26-03.26.33.png?v=1616763476562")
{
document.getElementById("imgClickAndChange").src = "https://cdn.glitch.com/2191cc92-26e9-4b6e-9beb-428fb7eb3976%2FPicsArt_03-26-03.12.37.png?v=1616764012012";
}
else
{
document.getElementById("imgClickAndChange").src = "https://cdn.glitch.com/2191cc92-26e9-4b6e-9beb-428fb7eb3976%2FPicsArt_03-26-03.26.33.png?v=1616763476562";
}
}
I want to be able to change the size of that second image.
I'm not sure if you mean this but you can change the size of the Image using:
myelement.style.height = size + "px";
myelement.style.width = size + "px";
The size variable is basically the size of the image in pixels.
I am having a jQuery script that loads 15 images and their hover versions (the hover versions are used when... hovering, not when the page loads). In both Chrome and Firefox in the Network tab, i see this :
images/img1.png
images_hover/img1.png
This must mean the hover images are preloaded correctly, but... when i actually hover and those images are used, they are being loaded again. Here is the preload code :
var prel = new Image();
prel.src = "http://hdodov.byethost15.com/color-game/graphics/parts_hover/" + id + ".png";
I tried using the whole path - http://hdodov.byethost15.com/color-game/graphics/parts_hover/ and the short path too (where the root and the script is) - graphics/parts_hover/. It made no difference.
Could this be caused because my images have the same name? They are in different directories though.
For the next question, you really should paste more code, which makes it easier to help you. I checked your URL you provided, but for other people that might have the same problem, it will be hard to understand what went wrong...
OK, as I said, you are always requesting he images again on hover state...
This worked for me:
var context = new Array(15),
canvas = new Array(15),
canvasNum = -1,
hElem,
hElemPrev,
mousePos = {x:-1, y:-1},
images = [], //<-- Store preloaded images here
imagesHover = []; //<-- Store preloaded images here
... then save them on building like this:
function drawMenuItems(id, width, height){
var canNumHolder, createCanvas;
$('#canvas_holder').append($('<canvas></canvas>')
.attr({
width:width,
height:height,
id:id
})
);
canvasNum++;
canvas[canvasNum] = document.getElementById(id);
context[canvasNum] = canvas[canvasNum].getContext('2d');
canNumHolder = canvasNum;
images[id].crossOrigin = 'Anonymous';
images[id].onload = function(){
context[canNumHolder].drawImage(images[id],0,0);
};
images[id].src = 'graphics/parts/' + id + '.png';
//Hover states
imagesHover[id] = new Image();
imagesHover[id].src = "graphics/parts_hover/" + id + ".png";
}
... give just the id...
function hoverStateChange() {
//....rest of the code
if(hElem >= 0){
drawImageOnCanvas(
canvas[hElem],
context[hElem],
"hover", //pass somethink to checke what you want to do
$(canvas[hElem]).attr('id')
);
//....rest of the code
//change to normal texture
if(hElemPrev >= 0){
drawImageOnCanvas(
canvas[hElemPrev],
context[hElemPrev],
"", //pass empty for other state
$(canvas[hElemPrev]).attr('id')
);
$(canvas[hElemPrev]).removeClass('active');
$('#text_holder').removeClass('a' + hElemPrev);
}
.. and finally
function drawImageOnCanvas(canv, contxt, state, src){
contxt.clearRect(0,0,400,400);
if(state == "hover"){
contxt.drawImage(imagesHover[src],0,0);
}else {
contxt.drawImage(images[src],0,0);
}
}
Like this, you chache you images and not calling them again and again...
I hope it helps.
Yuo can preload images with css like this:-
#preload-01 { background: url(http://domain.tld/image-01.png) no-repeat -9999px -9999px; }
My user can upload really big images, and for cropping and display purposes i'm adding width attribute so it will fit well in the browser window. Real image size can be - say 1920 x 1080 px.
<!-- width added for display purpose -->
<img class="croppable" src="images/fhd.jpg" width="640" />
In order to calculate real selection box dimension (if the x coordinate is 20px then would be 60px in the original full hd picture) i need to get the full image size before apply the width attribute.
The problem is that this will return 640 as value, taking into account the width attribute:
// Important: Use load event to avoid problems with webkit browser like safari
// when using cached images
$(window).load(function(){
$('img.croppable').each(function(){
alert(this.width);
});
});
Please don't flag this as duplicate since what i'm asking is completly different from simple image width/height retrival (which works, actually).
EDIT: Chris G. solution seems not working:
$(window).load(function(){
$('img.croppable').each(function(){
console.log(this.src);
var original = new Image(this.src);
console.log(original);
$("#original_w").text(original.width); // Temp, more images to be added
$("#original_h").text(original.height); // Temp, more images to be added
});
});
Console output:
http://localhost/DigitLifeAdminExtension/images/pillars-of-creation.jpg
<img width="0">
Get the width/height of the image itself, not the div it is contained within.
$(window).load(function(){
$('img.croppable').each(function(){
var img = new Image();
img.src = $(this).src;
alert(img.width);
});
});
You can remove the attributes, get the width and put the attributes in place again:
var $img = $(img);
var oldWidth = $img.attr("width");
var imgWidth = $img.removeAttr("width").width();
$img.width(oldWidth);
But I think Chris G.'s answer works well too, just making sure it will be loaded when you try to get the width:
img.onload = function() {
if (!img.complete) return; // IMG not loaded
width = img.width;
imgManipulationGoesHere();
}
Works in most up-to-date browsers and IE9.
$(window).load(function(){
$('img.croppable').each(function(){
alert(this.naturalHeight);
});
});
The working solution would be:
$(function(){
$('img.croppable').each(function () {
var original = new Image(this.src);
original.onload = function () {
alert(original.src + ': ' + original.width + 'x' +original.height);
};
});
});
I've read about various kinds of ways getting image dimensions once an image has fully loaded, but would it be possible to get the dimensions of any image once it just started to load?
I haven't found much about this by searching (which makes me believe it's not possible), but the fact that a browser (in my case Firefox) shows the dimensions of any image I open up in a new tab right in the title after it just started loading the image gives me hope that there actually is a way and I just missed the right keywords to find it.
You are right that one can get image dimensions before it's fully loaded.
Here's a solution (demo):
var img = document.createElement('img');
img.src = 'some-image.jpg';
var poll = setInterval(function () {
if (img.naturalWidth) {
clearInterval(poll);
console.log(img.naturalWidth, img.naturalHeight);
}
}, 10);
img.onload = function () { console.log('Fully loaded'); }
The following code returns width/height as soon as it's available. For testing change abc123 in image source to any random string to prevent caching.
There is a JSFiddle Demo as well.
<div id="info"></div>
<img id="image" src="https://upload.wikimedia.org/wikipedia/commons/d/da/Island_Archway,_Great_Ocean_Rd,_Victoria,_Australia_-_Nov_08.jpg?abc123">
<script>
getImageSize($('#image'), function(width, height) {
$('#info').text(width + ',' + height);
});
function getImageSize(img, callback) {
var $img = $(img);
var wait = setInterval(function() {
var w = $img[0].naturalWidth,
h = $img[0].naturalHeight;
if (w && h) {
clearInterval(wait);
callback.apply(this, [w, h]);
}
}, 30);
}
</script>
One way is to use the HEAD request, which asks for HTTP Header of the response only. I know in HEAD responses, the size of the body is included. But I don't know if there anything available for size of images.