How do i deal with data:img elements populating in my resources? - javascript

Notice the data:img images... I dont know how to remove them from memory and document.images does not contain them...
I am writing a Chrome Extension. Its somewhat of a hybrid screenshot app and basically when a user scrolls it takes the new part of the screen that the user has scrolled to and appends it on to a master screenshot of the entire site (yeah i have used googles screenshot app). My code works, but when I pass the img from the extension to the content script its storing the data:img sources into somewhere in memory where I cant access. I have tried document.images and tested to see if they may be populated within but with no luck.
Heres the code if you are interested.
page.js
var ovr = 0;
var run = (window==window.top)?1:0;
if(run&&ovr){
function obj(){
window.onload = function(){
obj.conversion = .5;
obj.screenShot();
obj.startRecordingScroll();
obj.showShot();
};
}
obj.showShot = function(){
obj.fullShot = document.createElement('canvas');
obj.fullShot.zIndex = -100;
obj.fullShot.style.position = 'fixed';
obj.fullShot.style.top = '70px';
obj.fullShot.style.right = '20px';
obj.fullShot.style.backgroundColor = '#999999';
obj.fullShot.width = window.innerWidth*obj.conversion;
obj.fullShot.height = document.height*obj.conversion;
document.body.appendChild(obj.fullShot);
obj.ctx = obj.fullShot.getContext('2d');
};
obj.startRecordingScroll = function(){
document.onscroll = function(){
obj.scroll();
};
};
obj.scroll = function(){
var pagxoff = window.pageXOffset;
var pagyoff = window.pageYOffset;
alert(document.images.length);
console.log("scroll");
obj.screenShot();
};
obj.displayScreenShot = function(img){
console.log('displayScreenShot');
var ycur = window.pageYOffset;
var yMaxCur = window.innerHeight+window.pageYOffset;
var distance = yMaxCur - obj.lastMaxYSeen;
distance = Math.abs(distance);
if(!obj.firstRunShot){
obj.lastMinYSeen = window.pageYOffset;
obj.lastMinXSeen = window.pageXOffset;
obj.lastMaxYSeen = (window.innerHeight+window.pageYOffset);
obj.lastMaxXSeen = (window.innerWidth+window.pageXOffset);
var shot = document.createElement('img');
shot.src = img;
console.log(img);
shot.onload = function(){
obj.ctx.drawImage(
shot,
0, // 0 right
0, // 0 down
window.innerWidth, // viewport width
window.innerHeight, // viewport height
0, // 0 right
0, // 0 down
window.innerWidth*obj.conversion,
window.innerHeight*obj.conversion
);
};
obj.firstRunShot = true;
return;
}
if(obj.firstRunShot){
if(ycur>obj.lastMinYSeen){
obj.lastMinYSeen = window.pageYOffset;
obj.lastMinXSeen = window.pageXOffset;
obj.lastMaxYSeen = (window.innerHeight+window.pageYOffset);
obj.lastMaxXSeen = (window.innerWidth+window.pageXOffset);
var xshot = document.createElement('img');
xshot.src = img;
xshot.onload = function(){
obj.ctx.drawImage(
xshot,
0,
window.innerHeight-distance,
window.innerWidth,
distance,
0,
(obj.lastMaxYSeen-distance)*obj.conversion,
window.innerWidth*obj.conversion,
(distance)*obj.conversion
);
};
return;
}
}
};
obj.screenShot = function(){
var port = chrome.extension.connect({
name: "screenshot"
});
port.postMessage({
request: "screenshot"
});
port.onMessage.addListener(function (msg) {
obj.displayScreenShot(msg);
});
console.log('screenShot');
};
var builder = new obj();
}

You can track resources being added and manipulate all contents of these resources using chrome.devtools.inspectedWindow API's, if you want to delete some resource modify DOM by deleting node(s).
document.images does contain the resources.
The Resources panel lets you inspect resources that are loaded in the inspected page, are you loading your image into inspected page to show up here?
If you are trying to store image to local disk using FILE API, remember they are sand-boxed and cannot be accessed by other means.
References
chrome.devtools.inspectedWindow
Resources Panel
File API
Content Scripts

Related

Javascript code executes correctly when debugging, but doesn't work without browser Dev Tools running

I am trying to build a simple image uploader/gallery viewer for a webpage using PhotoSwipe. The gallery viewer plugin works without issues and needs an array (items in the code below) with the image src and the width and height per image. The function readImageDimensions() gets the data and later saves it to items.
When I'm debugging the code it runs flawlessly and the gallery gets the data, but if I skip the debugger the item variable has indexed two objects, but the src, w, h all have null values. Is it something in the code that runs asynchronously or otherwise disrupt the flow when the code isn't running through the debug process?
Code for uploading and presenting the images:
var thumbsDiv = "";
var items = [];
document.addEventListener("DOMContentLoaded", init, false);
function init() {
document.querySelector('.file-uploader').addEventListener('change', onFilesSelected, false);
thumbsDiv = document.querySelector(".thumbs-div");
}
function onFilesSelected(e) {
if (!e.target.files || !window.FileReader) return;
thumbsDiv.innerHTML = "";
var width = 0;
var height = 0;
items = [];
function readImageDimensions(data) {
var image = new Image();
image.src = data;
width = image.width;
height = image.height;
}
var files = e.target.files;
var filesArr = Array.prototype.slice.call(files);
filesArr.forEach(function (f) {
if (!f.type.match("image.*")) {
return;
}
var reader = new FileReader();
reader.onloadend = function (e) {
var result = e.target.result;
var html = '<div class="img-wrap"><span class="close">×</span><img src="' + result + '"/>' + f.name + '</div>';
thumbsDiv.innerHTML += html;
readImageDimensions(result);
items.push({
src: result,
w: width,
h: height
});
}
reader.readAsDataURL(f);
});
}
Code for instantiating the gallery:
var openGallery = function () {
var pswpElement = document.querySelectorAll(".pswp")[0];
var options = {
index: 0
};
var gallery = new PhotoSwipe(pswpElement, PhotoSwipeUI_Default, items, options);
gallery.init();
}
The issue was in fact that the image data was loaded asynchronously, and the program tried to read the image dimensions before it was loaded. I used HMR's comment to further research the onload() handler and modified the readImageDimensions() like this:
function readImageDimensions(data) {
var image = new Image();
console.log(data);
image.onload = function () {
width = image.width;
height = image.height;
items.push({
src: data,
w: width,
h: height
});
}
image.src = data;
}
This way, the onload() gets "primed" with reading the width and height, and won't do that until the whole image data is loaded onto the browser cache. The code also pushes the data onto the items[] array and obviously I'll rename the method into something better, like setImageDataForGallery().

PDF.JS only updates every other time

I'm trying to implement a "drag-to-pan" function for the pfd.js viewer.
However, this only works every other time, so that after panning around, I have to click the viewer again to make it re-render.
Here's the code:
var pdfScale = 1;
var activePdf;
var rotate = 0;
var addX = 0;
var addY = 0;
function renderPage(page) {
activePdf = page;
var canvas = document.getElementById('the-canvas');
var wrapperStyle = window.getComputedStyle(document.getElementsByClassName("canvas-wrapper")[0]);
var context = canvas.getContext('2d');
var viewport = page.getViewport(pdfScale, rotate);
canvas.height = parseInt(wrapperStyle.height);
canvas.width = parseInt(wrapperStyle.width);
viewport.viewBox[0] -= addX;
viewport.viewBox[2] -= addX;
viewport.viewBox[1] += addY;
viewport.viewBox[3] += addY;
addX = addY = 0;
// Render PDF page into canvas context
var renderContext = {
canvasContext: context,
viewport: viewport
};
var renderTask = page.render(renderContext);
}
$(document).ready(function() {
var start = [0,0];
$('#the-canvas').mousedown(function(event) {
start[0] = event.screenX;
start[1] = event.screenY;
}).mouseup(function(event) {
console.log(event);
addX = event.screenX - start[0];
addY = event.screenY - start[1];
setTimeout(function() {
renderPage(activePdf);
}, 500);
});
var url = 'http://localhost/test.pdf';
// Disable workers to avoid yet another cross-origin issue (workers need
// the URL of the script to be loaded, and dynamically loading a cross-origin
// script does not work).
PDFJS.disableWorker = true;
// The workerSrc property shall be specified.
PDFJS.workerSrc = 'build/pdf.worker.js';
// Asynchronous download of PDF
var loadingTask = PDFJS.getDocument(url);
loadingTask.promise.then(function(pdf) {
console.log('PDF loaded');
// Fetch the first page
var pageNumber = 1;
pdf.getPage(pageNumber).then(function(page) {
console.log('Page loaded');
renderPage(page);
});
}, function (reason) {
// PDF loading error
console.error(reason);
});
});
Even after adding the setTimeout, it still doesn't render correctly on the first time. How can I edit my logic to make it work?
Thanks!

Resizing a hidden-frame

I am trying to load a webpage into a hidden-frame (sdk/frame/hidden-frame) and then render a screenshot of it. I can get the screenshot just fine, but the frame is not properly sized. The screenshot is rendered by using the following code
var hiddenFrames = require("sdk/frame/hidden-frame");
let hiddenFrame = hiddenFrames.add(hiddenFrames.HiddenFrame({
onReady: function() {
this.element.contentWindow.location = "http://example.com";
let self = this;
this.element.addEventListener("DOMContentLoaded", function() {
var cnvs = self.element.contentDocument.createElement("canvas");
var width = self.element.contentDocument.body.clientHeight; //for some reason clientWidth is 0 for www.example.com
var height = self.element.contentDocument.body.clientHeight;
cnvs.width = width;
cnvs.height = height;
var ctx = cnvs.getContext("2d");
console.log(width+" "+height);
ctx.drawWindow(self.element.contentWindow, 0, 0, width, height, "rgb(255,255,255)");
console.log(cnvs.toDataURL());
}, true, true);
}
}));
I have tried changing the width and height of the iframe with
this.element.width = "1600";
this.element.height = "900";
changing the size of element.contentWindow with resizeTo(), and changing the size of the body. None of them seem to have an impact on the final screenshot, which looks like
Try adding this on the parent page after including the iframe (or script that includes the iframe).
$('iframe').load(function(){
$(this).css({
width: 1600,
height: 900
});
});

How to display whole PDF (not only one page) with PDF.JS?

I've created this demo:
http://polishwords.com.pl/dev/pdfjs/test.html
It displays one page. I would like to display all pages. One below another, or place some buttons to change page or even better load all standard controls of PDF.JS like in Firefox. How to acomplish this?
PDFJS has a member variable numPages, so you'd just iterate through them. BUT it's important to remember that getting a page in pdf.js is asynchronous, so the order wouldn't be guaranteed. So you'd need to chain them. You could do something along these lines:
var currPage = 1; //Pages are 1-based not 0-based
var numPages = 0;
var thePDF = null;
//This is where you start
PDFJS.getDocument(url).then(function(pdf) {
//Set PDFJS global object (so we can easily access in our page functions
thePDF = pdf;
//How many pages it has
numPages = pdf.numPages;
//Start with first page
pdf.getPage( 1 ).then( handlePages );
});
function handlePages(page)
{
//This gives us the page's dimensions at full scale
var viewport = page.getViewport( 1 );
//We'll create a canvas for each page to draw it on
var canvas = document.createElement( "canvas" );
canvas.style.display = "block";
var context = canvas.getContext('2d');
canvas.height = viewport.height;
canvas.width = viewport.width;
//Draw it on the canvas
page.render({canvasContext: context, viewport: viewport});
//Add it to the web page
document.body.appendChild( canvas );
//Move to next page
currPage++;
if ( thePDF !== null && currPage <= numPages )
{
thePDF.getPage( currPage ).then( handlePages );
}
}
Here's my take. Renders all pages in correct order and still works asynchronously.
<style>
#pdf-viewer {
width: 100%;
height: 100%;
background: rgba(0, 0, 0, 0.1);
overflow: auto;
}
.pdf-page-canvas {
display: block;
margin: 5px auto;
border: 1px solid rgba(0, 0, 0, 0.2);
}
</style>
<script>
url = 'https://github.com/mozilla/pdf.js/blob/master/test/pdfs/tracemonkey.pdf';
var thePdf = null;
var scale = 1;
PDFJS.getDocument(url).promise.then(function(pdf) {
thePdf = pdf;
viewer = document.getElementById('pdf-viewer');
for(page = 1; page <= pdf.numPages; page++) {
canvas = document.createElement("canvas");
canvas.className = 'pdf-page-canvas';
viewer.appendChild(canvas);
renderPage(page, canvas);
}
});
function renderPage(pageNumber, canvas) {
thePdf.getPage(pageNumber).then(function(page) {
viewport = page.getViewport({ scale: scale });
canvas.height = viewport.height;
canvas.width = viewport.width;
page.render({canvasContext: canvas.getContext('2d'), viewport: viewport});
});
}
</script>
<div id='pdf-viewer'></div>
The pdfjs-dist library contains parts for building PDF viewer. You can use PDFPageView to render all pages. Based on https://github.com/mozilla/pdf.js/blob/master/examples/components/pageviewer.html :
var url = "https://cdn.mozilla.net/pdfjs/tracemonkey.pdf";
var container = document.getElementById('container');
// Load document
PDFJS.getDocument(url).then(function (doc) {
var promise = Promise.resolve();
for (var i = 0; i < doc.numPages; i++) {
// One-by-one load pages
promise = promise.then(function (id) {
return doc.getPage(id + 1).then(function (pdfPage) {
// Add div with page view.
var SCALE = 1.0;
var pdfPageView = new PDFJS.PDFPageView({
container: container,
id: id,
scale: SCALE,
defaultViewport: pdfPage.getViewport(SCALE),
// We can enable text/annotations layers, if needed
textLayerFactory: new PDFJS.DefaultTextLayerFactory(),
annotationLayerFactory: new PDFJS.DefaultAnnotationLayerFactory()
});
// Associates the actual page with the view, and drawing it
pdfPageView.setPdfPage(pdfPage);
return pdfPageView.draw();
});
}.bind(null, i));
}
return promise;
});
#container > *:not(:first-child) {
border-top: solid 1px black;
}
<link href="https://npmcdn.com/pdfjs-dist/web/pdf_viewer.css" rel="stylesheet"/>
<script src="https://npmcdn.com/pdfjs-dist/web/compatibility.js"></script>
<script src="https://npmcdn.com/pdfjs-dist/build/pdf.js"></script>
<script src="https://npmcdn.com/pdfjs-dist/web/pdf_viewer.js"></script>
<div id="container" class="pdfViewer singlePageView"></div>
The accepted answer is not working anymore (in 2021), due to the API change for var viewport = page.getViewport( 1 ); to var viewport = page.getViewport({scale: scale});, you can try the full working html as below, just copy the content below to a html file, and open it:
<html>
<head>
<script src="https://mozilla.github.io/pdf.js/build/pdf.js"></script>
<head>
<body>
</body>
<script>
var url = 'https://raw.githubusercontent.com/mozilla/pdf.js/ba2edeae/web/compressed.tracemonkey-pldi-09.pdf';
// Loaded via <script> tag, create shortcut to access PDF.js exports.
var pdfjsLib = window['pdfjs-dist/build/pdf'];
// The workerSrc property shall be specified.
pdfjsLib.GlobalWorkerOptions.workerSrc = 'https://mozilla.github.io/pdf.js/build/pdf.worker.js';
var currPage = 1; //Pages are 1-based not 0-based
var numPages = 0;
var thePDF = null;
//This is where you start
pdfjsLib.getDocument(url).promise.then(function(pdf) {
//Set PDFJS global object (so we can easily access in our page functions
thePDF = pdf;
//How many pages it has
numPages = pdf.numPages;
//Start with first page
pdf.getPage( 1 ).then( handlePages );
});
function handlePages(page)
{
//This gives us the page's dimensions at full scale
var viewport = page.getViewport( {scale: 1.5} );
//We'll create a canvas for each page to draw it on
var canvas = document.createElement( "canvas" );
canvas.style.display = "block";
var context = canvas.getContext('2d');
canvas.height = viewport.height;
canvas.width = viewport.width;
//Draw it on the canvas
page.render({canvasContext: context, viewport: viewport});
//Add it to the web page
document.body.appendChild( canvas );
var line = document.createElement("hr");
document.body.appendChild( line );
//Move to next page
currPage++;
if ( thePDF !== null && currPage <= numPages )
{
thePDF.getPage( currPage ).then( handlePages );
}
}
</script>
</html>
The following answer is a partial answer targeting anyone trying to get a PDF.js to display a whole PDF in 2019, as the api has changed significantly. This was of course the OP's primary concern. inspiration sample code
Please take note of the following:
extra libs are being used -- Lodash (for range() function) and polyfills (for promises)....
Bootstrap is being used
<div class="row">
<div class="col-md-10 col-md-offset-1">
<div id="wrapper">
</div>
</div>
</div>
<style>
body {
background-color: #808080;
/* margin: 0; padding: 0; */
}
</style>
<link href="//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.1.266/pdf_viewer.css" rel="stylesheet"/>
<script src="//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.1.266/pdf.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.1.266/pdf_viewer.js"></script>
<script src="//cdn.polyfill.io/v2/polyfill.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.js"></script>
<script>
$(document).ready(function () {
// startup
});
'use strict';
if (!pdfjsLib.getDocument || !pdfjsViewer.PDFViewer) {
alert("Please build the pdfjs-dist library using\n" +
" `gulp dist-install`");
}
var url = '//www.pdf995.com/samples/pdf.pdf';
pdfjsLib.GlobalWorkerOptions.workerSrc =
'//cdnjs.cloudflare.com/ajax/libs/pdf.js/2.1.266/pdf.worker.js';
var loadingTask = pdfjsLib.getDocument(url);
loadingTask.promise.then(function(pdf) {
// please be aware this uses .range() function from lodash
var pagePromises = _.range(1, pdf.numPages).map(function(number) {
return pdf.getPage(number);
});
return Promise.all(pagePromises);
}).then(function(pages) {
var scale = 1.5;
var canvases = pages.forEach(function(page) {
var viewport = page.getViewport({ scale: scale, }); // Prepare canvas using PDF page dimensions
var canvas = document.createElement('canvas');
canvas.height = viewport.height;
canvas.width = viewport.width; // Render PDF page into canvas context
var canvasContext = canvas.getContext('2d');
var renderContext = {
canvasContext: canvasContext,
viewport: viewport
};
page.render(renderContext).promise.then(function() {
if (false)
return console.log('Page rendered');
});
document.getElementById('wrapper').appendChild(canvas);
});
},
function(error) {
return console.log('Error', error);
});
</script>
If you want to render all pages of pdf document in different canvases, all one by one synchronously this is kind of solution:
index.html
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>PDF Sample</title>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="pdf.js"></script>
<script type="text/javascript" src="main.js">
</script>
<link rel="stylesheet" type="text/css" href="main.css">
</head>
<body id="body">
</body>
</html>
main.css
canvas {
display: block;
}
main.js
$(function() {
var filePath = "document.pdf";
function Num(num) {
var num = num;
return function () {
return num;
}
};
function renderPDF(url, canvasContainer, options) {
var options = options || {
scale: 1.5
},
func,
pdfDoc,
def = $.Deferred(),
promise = $.Deferred().resolve().promise(),
width,
height,
makeRunner = function(func, args) {
return function() {
return func.call(null, args);
};
};
function renderPage(num) {
var def = $.Deferred(),
currPageNum = new Num(num);
pdfDoc.getPage(currPageNum()).then(function(page) {
var viewport = page.getViewport(options.scale);
var canvas = document.createElement('canvas');
var ctx = canvas.getContext('2d');
var renderContext = {
canvasContext: ctx,
viewport: viewport
};
if(currPageNum() === 1) {
height = viewport.height;
width = viewport.width;
}
canvas.height = height;
canvas.width = width;
canvasContainer.appendChild(canvas);
page.render(renderContext).then(function() {
def.resolve();
});
})
return def.promise();
}
function renderPages(data) {
pdfDoc = data;
var pagesCount = pdfDoc.numPages;
for (var i = 1; i <= pagesCount; i++) {
func = renderPage;
promise = promise.then(makeRunner(func, i));
}
}
PDFJS.disableWorker = true;
PDFJS.getDocument(url).then(renderPages);
};
var body = document.getElementById("body");
renderPDF(filePath, body);
});
First of all please be aware that doing this is really not a good idea; as explained in https://github.com/mozilla/pdf.js/wiki/Frequently-Asked-Questions#allthepages
How to do it;
Use the viewer provided by mozilla;
https://mozilla.github.io/pdf.js/web/viewer.html
modify BaseViewer class, _getVisiblePages() method in viewer.js to
/* load all pages */
_getVisiblePages() {
let visible = [];
let currentPage = this._pages[this._currentPageNumber - 1];
for (let i=0; i<this.pagesCount; i++){
let aPage = this._pages[i];
visible.push({ id: aPage.id, view: aPage, });
}
return { first: currentPage, last: currentPage, views: visible, };
}
If you want to render all pages of pdf document in different canvases
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="pdf.js"></script>
<script src="jquery.js"></script>
</head>
<body>
<h1>PDF.js 'Hello, world!' example</h1>
<div id="canvas_div"></div>
<body>
<script>
// If absolute URL from the remote server is provided, configure the CORS
// header on that server.
var url = 'pdff.pdf';
// Loaded via <script> tag, create shortcut to access PDF.js exports.
var pdfjsLib = window['pdfjs-dist/build/pdf'];
// The workerSrc property shall be specified.
pdfjsLib.GlobalWorkerOptions.workerSrc = 'worker.js';
var loadingTask = pdfjsLib.getDocument(url);
loadingTask.promise.then(function(pdf) {
var __TOTAL_PAGES = pdf.numPages;
// Fetch the first page
var pageNumber = 1;
for( let i=1; i<=__TOTAL_PAGES; i+=1){
var id ='the-canvas'+i;
$('#canvas_div').append("<div style='background-color:gray;text-align: center;padding:20px;' ><canvas calss='the-canvas' id='"+id+"'></canvas></div>");
var canvas = document.getElementById(id);
//var pageNumber = 1;
renderPage(canvas, pdf, pageNumber++, function pageRenderingComplete() {
if (pageNumber > pdf.numPages) {
return;
}
// Continue rendering of the next page
renderPage(canvas, pdf, pageNumber++, pageRenderingComplete);
});
}
});
function renderPage(canvas, pdf, pageNumber, callback) {
pdf.getPage(pageNumber).then(function(page) {
var scale = 1.5;
var viewport = page.getViewport({scale: scale});
var pageDisplayWidth = viewport.width;
var pageDisplayHeight = viewport.height;
//var pageDivHolder = document.createElement();
// Prepare canvas using PDF page dimensions
//var canvas = document.createElement(id);
var context = canvas.getContext('2d');
canvas.width = pageDisplayWidth;
canvas.height = pageDisplayHeight;
// pageDivHolder.appendChild(canvas);
// Render PDF page into canvas context
var renderContext = {
canvasContext: context,
viewport: viewport
};
page.render(renderContext).promise.then(callback);
});
}
</script>
<html>
The accepted answer works perfectly for a single PDF. In my case there were multiple PDFs that I wanted to render all pages for in the same sequence of the array.
I adjusted the code so that the global variables are encapsulated in an object array as follows:
var docs = []; // Add this object array
var urls = []; // You would need an array of the URLs to start.
// Loop through each url. You will also need the index for later.
urls.forEach((url, ix) => {
//Get the document from the url.
PDFJS.getDocument(url).then(function(pdf) {
// Make new doc object and set the properties of the new document
var doc = {};
//Set PDFJS global object (so we can easily access in our page functions
doc.thePDF = pdf;
//How many pages it has
doc.numPages = pdf.numPages;
//Push the new document to the global object array
docs.push(doc);
//Start with first page -- pass through the index for the handlePages method
pdf.getPage( 1 ).then(page => handlePages(page, ix) );
});
});
function handlePages(page, ix)
{
//This gives us the page's dimensions at full scale
var viewport = page.getViewport( {scale: 1} );
//We'll create a canvas for each page to draw it on
var canvas = document.createElement( "canvas" );
canvas.style.display = "block";
var context = canvas.getContext('2d');
canvas.height = viewport.viewBox[3];
canvas.width = viewport.viewBox[2];
//Draw it on the canvas
page.render({canvasContext: context, viewport: viewport});
//Add it to an element based on the index so each document is added to its own element
document.getElementById('doc-' + ix).appendChild( canvas );
//Move to next page using the correct doc object from the docs object array
docs[ix].currPage++;
if ( docs[ix].thePDF !== null && docs[ix].currPage <= docs[ix].numPages )
{
console.log("Rendering page " + docs[ix].currPage + " of document #" + ix);
docs[ix].thePDF.getPage( docs[ix].currPage ).then(newPage => handlePages(newPage, ix) );
}
}
Because the entire operation is asynchronous, without a unique object for each document, global variables of thePDF, currPage and numPages will be overwritten when subsequent PDFs are rendered, resulting in random pages being skipped, documents entirely skipped or pages from one document being appended to the wrong document.
One last point is that if this is being done offline or without using ES6 modules, the PDFJS.getDocument(url).then() method should change to pdfjsLib.getDocument(url).promise.then().
Make it to be iterate every page how much you want.
const url = '/storage/documents/reports/AR-2020-CCBI IND.pdf';
pdfjsLib.GlobalWorkerOptions.workerSrc = '/vendor/pdfjs-dist-2.12.313/package/build/pdf.worker.js';
const loadingTask = pdfjsLib.getDocument({
url: url,
verbosity: 0
});
(async () => {
const pdf = await loadingTask.promise;
let numPages = await pdf.numPages;
if (numPages > 10) {
numPages = 10;
}
for (let i = 1; i <= numPages; i++) {
let page = await pdf.getPage(i);
let scale = 1.5;
let viewport = page.getViewport({ scale });
let outputScale = window.devicePixelRatio || 1;
let canvas = document.createElement('canvas');
let context = canvas.getContext("2d");
canvas.width = Math.floor(viewport.width * outputScale);
canvas.height = Math.floor(viewport.height * outputScale);
canvas.style.width = Math.floor(viewport.width) + "px";
canvas.style.height = Math.floor(viewport.height) + "px";
document.getElementById('canvas-column').appendChild(canvas);
let transform = outputScale !== 1
? [outputScale, 0, 0, outputScale, 0, 0]
: null;
let renderContext = {
canvasContext: context,
transform,
viewport
};
page.render(renderContext);
}
})();

Delay function until an asset has loaded?

I am playing with the canvas, and it seems to be working great in FF6, but in Chrome 13, the sprite that I am drawing does not appear reliably. I have done some research and found that the problem stems from the function firing before the asset has loaded completely.
Fiddle here:
http://jsfiddle.net/LqHY9/
Relevant Javascript:
function sprite(ipath, sh, sw, ih, iw){
/* BASIC INFO FOR SPRITE */
this.frameWidth = sw;
this.frameHeight= sh;
frame_rows = ih/sh;
frame_columns = iw/sw;
num_frames = frame_columns*frame_rows ;
this.frame = new Array();
frameNumber = 0;
for(row = 0; row<frame_rows; row++){
for(i=0;i<frame_columns;i++){
this.frame[frameNumber] = {};
this.frame[frameNumber].offsetX = this.frameWidth*i;
this.frame[frameNumber].offsetY = this.frameHeight*row;
frameNumber++
}
}
this.sheight = sh;
this.swidth = sw;
this.raw = new Image();
this.raw.src = ipath;
}
animation=new sprite("http://www.melonjs.org/tutorial/tutorial_final/data/sprite/gripe_run_right.png",64,64,64,512);
context.drawImage(animation.raw, animation.frame[0].offsetX, animation.frame[0].offsetY, animation.frameWidth, animation.frameHeight, 0, 0, animation.frameWidth,animation.frameHeight)
(Don't worry, my context variable is defined, I just cut that bit out, you can see the whole thing in the JSFiddle.)
The Image object has an onload event which you should hook into.
Assuming you have more than one image, you could implement a sort of a "loader". This would basically just take an array of image URLs, load each of them, and listen to their onload events. Once each image has loaded, it would in turn call some other function, which would signal that every resource has finished loading.
the Image() object has an onload(and onerror) event. If you need to execute something after it loads you can attach a function.
e.g.
var img = new Image();
img.onload = function() {
//do something
};
Just make sure you attach the onload before setting the src.
You need to use the onload handler for the image. You must set the handler before you set the .src for the object because in some browsers, the load event may fire immediately upon setting .src if the image is in the browser cache. Here's a piece of pseudo code:
var img = new Image();
img.onload = function () {
// image is now loaded and ready for handling
// you can safely start your sprite animation
}
img.src = "xxx";
You can see related sample code from another answer I wrote here: jQuery: How to check when all images in an array are loaded?.
function Sprite(urls, speed, box)
{
var that = this, running = false, interval = 0, loaded = false;
that.urls = urls;
that.speed = speed;
that.images = new Array();
that.box = box || { x: 0.0, y: 0.0, w: 64, h: 64 };
for(var i = 0; i < that.urls.length; ++i)
{
that.images[i] = new Image();
that.images[i].src = that.urls[i];
that.images[i].id = i;
var len = that.urls.length;
that.images[i].onload = function(){ if(parseInt(this.id) === len) { loaded = true; } };
}
that.current = 0;
var Draw = function(ctx)
{
if(loaded)
{
var curr = that.images[that.current];
ctx.drawImage(curr, 0.0, 0.0, curr.width, curr.height, that.box.x, that.box.y, that.box.w, that.box.h);
}
};
that.Run = function(ctx)
{
if(!running)
{
running = true;
interval = setInterval(function(){
Draw(ctx);
if(that.current < that.urls.length)
{
that.current++;
}
else
{
that.current = 0;
}
}, that.speed);
}
};
that.Clear = function()
{
if(running)
{
running = false;
clearInterval(interval);
}
};
}
// Exemple
var test = new Sprite(["image1.png", "image2.png", "image3.png"], 250);
test.Run(myContext);

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