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how to convert Gif to spritesheet using Javascript

i am getting frames from gif using Libgif.
and then i am appending those frames in the div with Id = frames.
then i am taking those frames and trying to add each frames one after the other in canvas to make a spritesheet.
in the end i am getting an image in canvas but instead of getting different frames i am getting same image in the spritesheet.
Please help me find the issue.
I had taken canvas width 10000 assuming a gif wont have frames more than 100.
c = document.getElementById("myCanvas");
ctx = c.getContext("2d");
ctx.clearRect(0, 0, ctx.width, ctx.height);
ctx.beginPath();
var imageGiF = "";
var total = 0;
let canvasWidth = 0;
let canvasHeight = 0;
$('div.gifimage img').each(function(idx, img_tag) {
var total = 0;
if (/^.+\.gif$/.test($(img_tag).prop("src"))) {
var rub = new SuperGif({
gif: img_tag,
progressbar_height: 0
});
rub.load(function() {
for (let i = 0; i < rub.get_length(); i++) {
total += 1;
rub.move_to(i);
// var canvas = cloneCanvas(rub.get_canvas());
var canvas = rub.get_canvas().toDataURL("image/png");
img = $('<img id = "gifframe' + i + '"src= "' + canvas + '" class= frameimages>');
$("#frames").append(img);
}
var frameimages = document.getElementById("frames").querySelectorAll(".frameimages");
var totalimages = frameimages.length;
x = 0;
y = 0;
for (let i = 0; i < frameimages.length; i++) {
img = document.getElementById("gifframe" + i + "");
img.onload = function() {
ctx.drawImage(img, i * 100, 0, 100, 100);
total++;
console.log(total);
}
}
totalwidth = (total) * 100;
c.width = totalwidth;
c.height = 100;
setTimeout(() => {
imageGiF = c.toDataURL("image/png");
console.log(imageGiF);
// addBgimg(imageGiF)
}, 10);
});
}
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script src="https://cdn.rawgit.com/buzzfeed/libgif-js/master/libgif.js"></script>
<div class="gifimage" id="placehere">
<img src="https://media1.giphy.com/media/bzUwzbxcvJ3XQlcnoi/giphy.gif" alt="">
</div>
<div id="frames" class="classGIF"></div>
<canvas id='myCanvas' width="10000" height="300"></canvas>

You were looping through the images, using img in your event handler.
However, this variable img in the outer scope was overridden by every loop, until it was finished looping through everything, then img was stuck on the last frame added.
Then when the event handler triggered, it added the last frame in every instance, because that was the value of img at that point. The loop was done before the images could load.
By adding it to it's own scope by wrapping it in a function, the variable is preserved.
I also modified your code to store the DOM img elements in an array, so you don't need expensive DOM lookups which makes your code a tad bit faster.
I added comments in the code to explain my changes.
c = document.getElementById("myCanvas");
ctx = c.getContext("2d");
ctx.clearRect(0, 0, ctx.width, ctx.height);
ctx.beginPath();
var imageGiF = "";
var total = 0;
let canvasWidth = 0;
let canvasHeight = 0;
$('div.gifimage img').each(function(idx, img_tag) {
var total = 0;
if (/^.+\.gif$/.test($(img_tag).prop("src"))) {
var rub = new SuperGif({
gif: img_tag,
progressbar_height: 0
});
rub.load(function() {
// An array for the image references
let images = [];
// Keep the reference to save on expensive DOM lookups every iteration.
let frames = $("#frames");
for (let i = 0; i < rub.get_length(); i++) {
total += 1;
rub.move_to(i);
// var canvas = cloneCanvas(rub.get_canvas());
var canvas = rub.get_canvas().toDataURL("image/png");
img = $('<img id = "gifframe' + i + '"src= "' + canvas + '" class="frameimages">');
// Use the reference to append the image.
frames.append(img);
// Add image to images array with the current index as the array index.
// Use the jQuery get method to get the actual DOM element.
images[i] = img.get(0);
}
var frameimages = document.getElementById("frames").querySelectorAll(".frameimages");
var totalimages = frameimages.length;
x = 0;
y = 0;
// Loop through all the images in the image array
// Using a scope so the reference to img won't be overridden.
images.forEach((img, index) => {
img.onload = () => {
ctx.drawImage(img, index * 100, 0, 100, 100);
total++;
console.log(total);
}
})
totalwidth = (total) * 100;
c.width = totalwidth;
c.height = 100;
setTimeout(() => {
imageGiF = c.toDataURL("image/png");
console.log(imageGiF);
// addBgimg(imageGiF)
}, 10);
});
}
});
#frames { display:none;}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.6.0/jquery.min.js"></script>
<script src="https://cdn.rawgit.com/buzzfeed/libgif-js/master/libgif.js"></script>
<div class="gifimage" id="placehere">
<img src="https://media1.giphy.com/media/bzUwzbxcvJ3XQlcnoi/giphy.gif" alt="">
</div>
<div id="frames" class="classGIF"></div>
<canvas id='myCanvas' width="10000" height="300"></canvas>

Programmatically change SVG classes during runtime

-I want to draw the same SVG onto a canvas multiple times, but each time I want to PROGRAMMATICALLY change the colors of specific classes within that SVG.
For example take this house image below:
The SVG for this House has the following classes:
<style>
.window-class {
fill: lime;
}
.door-class {
fill: blue;
}
.house-class {
fill: tan;
}
.roof-class {
fill: red;
}
</style>
How do I programmatically access these specific Style-Classes so I can change their color values for each new house that I draw?
I’m constructing the SVG by creating an Image object and then drawing that image onto a canvas using the following code:
// 1. Create the CANVAS and the CONTEXT:
var theCanvas = document.getElementById("theCanvas");
var theContext = theCanvas.getContext("2d");
theContext.fillStyle = "lightblue";
theContext.fillRect(0, 0, theCanvas.width, theCanvas.height);
// 2. Define the SVG data:
var imageData = '<svg id="HOUSE" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" width="240.26" height="311.24" viewBox="0 0 240.26 311.24"><defs><style>.house-class {fill: tan;}.roof-class {fill: red;}.roof-class, .window-class, .door-class {stroke: #000;stroke-miterlimit: 10;}.window-class {fill: lime;}.door-class {fill: blue;}</style></defs><g id="House"><rect class="house-class" x="30.08" y="131.74" width="173.07" height="179"/><path d="M270,242V420H98V242H270m1-1H97V421H271V241Z" transform="translate(-67.39 -109.76)"/></g><polygon id="Roof" class="roof-class" points="1.11 131.74 239.11 131.74 117.11 0.74 1.11 131.74"/><rect id="Window2" class="window-class" x="145.11" y="160.74" width="30" height="42"/><rect id="Window1" class="window-class" x="58.61" y="160.74" width="30" height="42"/><rect id="Door" class="door-class" x="92.11" y="228.74" width="52" height="82"/></svg>';
var DOMURL = window.URL || window.webkitURL || window;
var img = new Image();
var svg = new Blob([imageData], { type: 'image/svg+xml;charset=utf-8' });
var url = DOMURL.createObjectURL(svg);
img.onload = function () {
theContext.drawImage(img, 0, 0);
DOMURL.revokeObjectURL(url);
}
img.src = url;
Ordinarily I'd be able to get at the specific Classes who's colors I want to change by using this:
let nodeList = document.getElementsByClassName("window-class");
And then I would iterate through that nodeList and at each element I find that is styled with this window-class, I would do:
element.style.fill = -whatever-the-next-color-would-be-;
But since I'm creating my image in the manner I showed above, I'm not sure how I can get at specific classes of its SVG.
Any thoughts?
==============================
UPDATE:
It was pointed out that the code for drawing the image/SVG multiple times wasn't included, so here it is:
// GLOBAL VARIABLES:
const TOTAL_IMAGES = 3; // could be 30, or 300
const canvasWidth = 250;
const canvasHeight = 320;
var canvasX, canvasY = 0;
// COLOR VARIABLES:
var colorCounter = 0;
let houseColorsArray = ["fuchsia", "gold", "lighblue"]; // Will have lots more colors for all of these
let windowColorsArray = ["yellow", "pink", "lightgreen"];
let roofColorsArray = ["maroon", "crimson", "darkred"];
let doorColorsArray = ["darkBlue", "purple", "darkslategray"];
// CLASS-NAMES
let classNamesToPaintArray = [".house-class", ".door-class", ".window-class", ".roof-class"];
function designOneHouse(theCanvas) {
console.log("\n\n==========================\n=");
console.log("= =>>In 'designOneHouse()'!\n");
// 1. Create a Color-Scheme:
let houseColor = houseColorsArray[colorCounter];
let doorColor = doorColorsArray[colorCounter];
let windowColor = windowColorsArray[colorCounter];
let roofColor = roofColorsArray[colorCounter];
console.log(" ->Current 'houseColor' = ", houseColor);
console.log(" ->Current 'doorColor' = ", doorColor);
console.log(" ->Current 'windowColor' = ", windowColor);
console.log(" ->Current 'roofColor' = ", roofColor);
let context = theCanvas.getContext("2d");
// Iterate the ColorCounter - making sure we don't overflow the ColorsArrays:
colorCounter++;
if(colorCounter == houseColorsArray.length) {
colorCounter = 0;
}
// Now GET-AT and PAINT the Individual SVG Components.
// STRATEGY:
// 1. Iterate through the Array containing all the CLASS-NAMES who's color I want to change.
// 2. For each of these classes, I'll need to iterate through all the HTML elements that are OF that class type
// (there may be like 10 elements that are all styled by the same Style; I want all of them to be updated!)
//
for(classNameCounter = 0; classNameCounter < classNamesToPaintArray.length; classNameCounter++) {
let currentClassName = classNamesToPaintArray[classNameCounter];
console.log("currentClassName = " + currentClassName);
let nodeList = document.getElementsByClassName(currentClassName);
console.log("nodeList = " + nodeList);
console.log("nodeList LENGTH = " + nodeList.length);
for(var counter = 0; counter < nodeList.length; counter++) {
console.log("\n\n===>>IN FOR LOOP -- Node-COUNTER = " + counter);
let currentNode = nodeList[counter];
console.dir(" > 'childNodes[0]' of 'currentNode' = ");
console.dir(currentNode.childNodes[0]);
let elements = document.querySelectorAll(".door-class");
// Change the text of multiple elements with a loop
elements.forEach(element => {
element.style.fill = "pink";
});
}
}
}
function makeCanvasGrid() {
console.log("\n\n====>In 'makeCanvasGrid()'!\n");
for(var canvasCounter = 0; canvasCounter < TOTAL_IMAGES; canvasCounter++) {
console.log("\n >FOR LOOP - canvasCounter = " + canvasCounter);
// 1. Create a new Canvas Object:
let newCanvas = document.createElement("canvas");
newCanvas.setAttribute("width", canvasWidth);
newCanvas.setAttribute("height", canvasHeight);
newCanvas.setAttribute("id", "newCanvas" + canvasCounter);
// Log-out just to verify the "id" property was set correctly:
console.log(" >newCanvas.id = " + newCanvas.id);
// 2. Place the Canvas at (x,y) (top, left) coordinates:
newCanvas.style.position = "absolute";
newCanvas.style.left = canvasX; //"100px";
newCanvas.style.top = canvasY; //"100px";
designOneHouse(newCanvas);
// Check the current Canvas' (X, Y) coords, and if needed, reset X to 0 and SKIP to the next "ROW" of Canvasses:
if(canvasCounter > 0 && canvasCounter % 3 == 0) {
console.log(" >>NEXT ROW PLEASE!!!! canvasCount = ", canvasCounter);
canvasX = 0;
canvasY += canvasHeight + 20;
}
else {
canvasX += canvasWidth + 10;
}
}
}
makeCanvasGrid();
SO when I run this right now, the console shows me the nodeList is empty:
nodeList LENGTH = 0
So basically this statement isn't working:
let nodeList = document.getElementsByClassName(currentClassName);

To manipulate the house's DOM, the SVG has to be in the DOM. So I've wrapped the SVG in a <div> and hidden the div. I've put it way offscreen, but I could have hidden the div in several other ways.
Once you do that, your next problem is that you are changing the fill of the elements, but that will be overridded by the CSS in your SVG. So you have to remove those CSS styles.
Thirdly, you are creating canvas objects, but you are not attaching them to the DOM.
Also you are getting an error because canvasX isn't initialised. Plus CSS lengths must have units. So you need newCanvas.style.left = canvasX + "px" etc.
You were also looking up your elements wrongly. getElementsByClassName(".hose-class") won't find anything. It needed to be getElementsByClassName(".hose-class").
Finally, I've rewritten the element lookup and colour assignment code. I've bundled each colour scheme up into an array of colour scheme objects. It makes mapping classes to colours much simpler.
// GLOBAL VARIABLES:
const TOTAL_IMAGES = 3; // could be 30, or 300
const canvasWidth = 250;
const canvasHeight = 320;
var canvasX = 0, canvasY = 0;
// COLOR VARIABLES:
var colorCounter = 0;
let houseColorSchemes = [ {".house-class": "fuchsia",
".door-class": "darkblue",
".window-class": "yellow",
".roof-class": "maroon"},
{".house-class": "gold",
".door-class": "purple",
".window-class": "pink",
".roof-class": "crimson"},
{".house-class": "lightblue",
".door-class": "darkslategray",
".window-class": "lightgreen",
".roof-class": "darkred"} ];
// CLASS-NAMES
let classNamesToPaintArray = [".house-class", ".door-class", ".window-class", ".roof-class"];
// SVG template
let houseSVG = document.getElementById("HOUSE");
function designOneHouse(theCanvas) {
console.log("\n\n==========================\n=");
console.log("= =>>In 'designOneHouse()'!\n");
let context = theCanvas.getContext("2d");
// Now GET-AT and PAINT the Individual SVG Components.
// STRATEGY:
// 1. Iterate through the Array containing all the CLASS-NAMES who's color I want to change.
// 2. For each of these classes, I'll need to iterate through all the HTML elements that are OF that class type
// (there may be like 10 elements that are all styled by the same Style; I want all of them to be updated!)
//
let colorScheme = houseColorSchemes[colorCounter];
classNamesToPaintArray.forEach(className => {
let elements = houseSVG.querySelectorAll(className);
elements.forEach(element => element.style.fill = colorScheme[className]);
});
var imageData = houseSVG.outerHTML;
var DOMURL = window.URL || window.webkitURL || window;
var img = new Image();
var svg = new Blob([imageData], { type: 'image/svg+xml;charset=utf-8' });
var url = DOMURL.createObjectURL(svg);
img.onload = function () {
context.drawImage(img, 0, 0);
DOMURL.revokeObjectURL(url);
}
img.src = url;
// Iterate the ColorCounter - making sure we don't overflow the ColorsArrays:
colorCounter++;
if(colorCounter == houseColorSchemes.length) {
colorCounter = 0;
}
}
function makeCanvasGrid() {
console.log("\n\n====>In 'makeCanvasGrid()'!\n");
for(var canvasCounter = 0; canvasCounter < TOTAL_IMAGES; canvasCounter++) {
console.log("\n >FOR LOOP - canvasCounter = " + canvasCounter);
// 1. Create a new Canvas Object:
let newCanvas = document.createElement("canvas");
newCanvas.setAttribute("width", canvasWidth);
newCanvas.setAttribute("height", canvasHeight);
newCanvas.setAttribute("id", "newCanvas" + canvasCounter);
// Log-out just to verify the "id" property was set correctly:
console.log(" >newCanvas.id = " + newCanvas.id);
// 2. Place the Canvas at (x,y) (top, left) coordinates:
newCanvas.style.position = "absolute";
newCanvas.style.left = canvasX + "px"; //"100px";
newCanvas.style.top = canvasY + "px"; //"100px";
document.body.appendChild(newCanvas);
designOneHouse(newCanvas);
// Check the current Canvas' (X, Y) coords, and if needed, reset X to 0 and SKIP to the next "ROW" of Canvasses:
if(canvasCounter > 0 && canvasCounter % 3 == 0) {
console.log(" >>NEXT ROW PLEASE!!!! canvasCount = ", canvasCounter);
canvasX = 0;
canvasY += canvasHeight + 20;
}
else {
canvasX += canvasWidth + 10;
}
}
}
makeCanvasGrid();
#house-template {
position: absolute;
left: -1000px;
}
<div id="house-template">
<svg id="HOUSE" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" width="240.26" height="311.24" viewBox="0 0 240.26 311.24">
<defs>
<style>
.roof-class, .window-class, .door-class {stroke: #000;stroke-miterlimit: 10;}
</style>
</defs>
<g id="House">
<rect class="house-class" x="30.08" y="131.74" width="173.07" height="179"/>
<path d="M270,242V420H98V242H270m1-1H97V421H271V241Z" transform="translate(-67.39 -109.76)"/>
</g>
<polygon id="Roof" class="roof-class" points="1.11 131.74 239.11 131.74 117.11 0.74 1.11 131.74"/>
<rect id="Window2" class="window-class" x="145.11" y="160.74" width="30" height="42"/>
<rect id="Window1" class="window-class" x="58.61" y="160.74" width="30" height="42"/>
<rect id="Door" class="door-class" x="92.11" y="228.74" width="52" height="82"/>
</svg>
</div>

Below is one way to produce your desired result.
The approach below has the <svg> element in the HTML to be used as a template. That template is cloned, colors applied, converted into an Image and placed into the canvas for each house that has colors.
Note: the structure of the SVG changed. The class attributes are replaced by a custom data- attribute data-part that is used to apply the fill style through a normal CSS selector.
The coordinate positions of each house are in an array of space separated x y coordinates. The array also indicates how many houses are to be drawn
The colors for the house 'parts' are included in an Object that lists the house 'part' and its corresponding color (the count of colors should match the number of houses)
All <canvas> CSS is moved to the stylesheet.
I'll let you deal with sizing the image on the canvas.
const canvas = document.querySelector('canvas');
const context = canvas.getContext("2d");
const housePositions = ["0 10", "85 10", "170 10"];
const parts = {
House: ["fuchsia", "gold", "lightblue"],
Window: ["yellow", "pink", "lightgreen"],
Roof: ["maroon", "crimson", "darkred"],
Door: ["darkBlue", "purple", "darkslategray"]
};
function addHouse(colorIndex, x, y) {
let clonedSvgElement = document.querySelector('svg').cloneNode(true);
Object.keys(parts)
.forEach(part => {
clonedSvgElement.querySelectorAll(`[data-part=${part}]`)
.forEach(item => {
item.style.fill = parts[part][colorIndex];
});
const blob = new Blob([clonedSvgElement.outerHTML], { type: 'image/svg+xml;charset=utf-8' });
const blobURL = URL.createObjectURL(blob);
const image = new Image();
image.onload = () => {
context.drawImage(image, x, y, 130, 110);
URL.revokeObjectURL(this.src);
};
image.src = blobURL;
});
}
housePositions.forEach((coordString, index) => {
const [x, y] = coordString.split(' ');
addHouse(index, x, y);
});
canvas {
position: absolute;
left: 10px;
top: 10px;
width: 150px;
height: 80px;
border: 1px solid;
background-color: lightblue;
}
svg {
display: none;
}
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<link rel="stylesheet" href="index.css">
<title>Document</title>
<script defer src="index.js"></script>
</head>
<body>
<canvas></canvas>
<svg id="HOUSE" data-name="Layer 1" xmlns="http://www.w3.org/2000/svg" width="140" height="140" viewBox="0 0 240.26 311.24"><defs></defs><g id="House"><rect data-part="House" x="30.08" y="131.74" width="173.07" height="179"/><path d="M270,242V420H98V242H270m1-1H97V421H271V241Z" transform="translate(-67.39 -109.76)"/></g><polygon data-part="Roof" points="1.11 131.74 239.11 131.74 117.11 0.74 1.11 131.74"/><rect data-part="Window" x="145.11" y="160.74" width="30" height="42"/><rect data-part="Window" x="58.61" y="160.74" width="30" height="42"/><rect data-part="Door" x="92.11" y="228.74" width="52" height="82"/></svg>
</body>
</html>

How do I get the full canvas content (even the hidden ones) with Javascript?

I am currently working on a Javascript project and I am struggling with exporting the entire SVG image on the canvas. So far I've been only able to export the visible part of the canvas, with out the "hidden" parts.
How do I capture the full canvas content?
Is there a way to do it without messing around with the original canvas size?
I am using D3.js V3
Screenshot of my project
Here's my code:
var svgString;
window.onload = function(){
setTimeout(function() {
exportSVG = document.getElementById("canvas");
document.getElementById("canvas").style.fontFamily= "lato";
document.getElementById("canvas").style.width= exportSVG.getBBox().width * 1;
document.getElementById("canvas").style.height= exportSVG.getBBox().height * 1;
svgString = getSVGString(exportSVG);
console.log(exportSVG.getBBox().width + " / " + exportSVG.getBBox().height);
svgString2Image(svgString, exportSVG.getBBox().width, exportSVG.getBBox().height, 'png', save); // passes Blob and filesize String to the callback
console.log("svg export code loaded");
// console.log(svgString.getBBox().width); document.getElementById("canvas").getBBox().width
}, 5000);
};
function save(dataBlob, filesize) {
saveAs(dataBlob, 'D3 vis exported to PNG.png'); // FileSaver.js function
}
// Below are the functions that handle actual exporting:
// getSVGString ( svgNode ) and svgString2Image( svgString, width, height, format, callback )
function getSVGString(svgNode) {
svgNode.setAttribute('xlink', 'http://www.w3.org/1999/xlink');
var cssStyleText = getCSSStyles(svgNode);
appendCSS(cssStyleText, svgNode);
var serializer = new XMLSerializer();
var svgString = serializer.serializeToString(svgNode);
svgString = svgString.replace(/(\w+)?:?xlink=/g, 'xmlns:xlink='); // Fix root xlink without namespace
svgString = svgString.replace(/NS\d+:href/g, 'xlink:href'); // Safari NS namespace fix
return svgString;
function getCSSStyles(parentElement) {
var selectorTextArr = [];
// Add Parent element Id and Classes to the list
selectorTextArr.push('#' + parentElement.id);
for (var c = 0; c < parentElement.classList.length; c++)
if (!contains('.' + parentElement.classList[c], selectorTextArr))
selectorTextArr.push('.' + parentElement.classList[c]);
// Add Children element Ids and Classes to the list
var nodes = parentElement.getElementsByTagName("*");
for (var i = 0; i < nodes.length; i++) {
var id = nodes[i].id;
if (!contains('#' + id, selectorTextArr))
selectorTextArr.push('#' + id);
var classes = nodes[i].classList;
for (var c = 0; c < classes.length; c++)
if (!contains('.' + classes[c], selectorTextArr))
selectorTextArr.push('.' + classes[c]);
}
// Extract CSS Rules
var extractedCSSText = "";
for (var i = 0; i < document.styleSheets.length; i++) {
var s = document.styleSheets[i];
try {
if (!s.cssRules) continue;
} catch (e) {
if (e.name !== 'SecurityError') throw e; // for Firefox
continue;
}
var cssRules = s.cssRules;
for (var r = 0; r < cssRules.length; r++) {
if (contains(cssRules[r].selectorText, selectorTextArr))
extractedCSSText += cssRules[r].cssText;
}
}
return extractedCSSText;
function contains(str, arr) {
return arr.indexOf(str) === -1 ? false : true;
}
}
function appendCSS(cssText, element) {
var styleElement = document.createElement("style");
styleElement.setAttribute("type", "text/css");
styleElement.innerHTML = cssText;
var refNode = element.hasChildNodes() ? element.children[0] : null;
element.insertBefore(styleElement, refNode);
}
}
function svgString2Image(svgString, width, height, format, callback) {
var format = format ? format : 'png';
var imgsrc = 'data:image/svg+xml;base64,' + btoa(unescape(encodeURIComponent(svgString))); // Convert SVG string to data URL
var canvas = document.createElement("canvas");
var context = canvas.getContext("2d");
canvas.width = width;
canvas.height = height;
var image = new Image();
image.onload = function() {
context.clearRect(0, 0, width, height);
context.drawImage(image, 0, 0, width, height);
canvas.toBlob(function(blob) {
var filesize = Math.round(blob.length / 1024) + ' KB';
if (callback) callback(blob, filesize);
});
};
image.src = imgsrc;
}

Simply change your <svg> viewBox attribute before you serialize it to a string so that it displays everything:
var svg = document.querySelector('svg');
var toExport = svg.cloneNode(true); // avoids having to reset everything afterward
// grab its inner content BoundingBox
var bb = svg.getBBox();
// update its viewBox so it displays all its inner content
toExport.setAttribute('viewBox', bb.x + ' ' + bb.y + ' ' + bb.width + ' ' + bb.height);
toExport.setAttribute('width', bb.width);
toExport.setAttribute('height', bb.height);
var svgAsStr = new XMLSerializer().serializeToString(toExport);
var blob = new Blob([svgAsStr], {type: 'image/svg+xml'});
var img = new Image();
img.onload = drawToCanvas;
img.src = URL.createObjectURL(blob);
function drawToCanvas(evt) {
var canvas = document.createElement('canvas');
canvas.width = this.width;
canvas.height = this.height;
canvas.getContext('2d').drawImage(this, 0,0);
document.body.appendChild(canvas);
}
svg{border: 1px solid blue}
canvas{border: 1px solid green}
<svg width="50" height="50" viewBox="0 0 50 50">
<rect x="0" y="0" width="200" height="50" fill="#CCC"/>
</svg>

Convert SVG to PNG with applied images as background to svg elements

I have an external SVG file which contains some embedded image tags in pattern. Whenever I convert this SVG into PNG using toDataURL(), the generated PNG images does not contain the image I have applied as pattern to some SVG paths. Is there any way to solve this problem?

Yes there are : append the svg into your document and encode all the included images to dataURIs.
I am writing a script that does this and also some other stuff like including external style-sheets and some other fix of where toDataURL will fail (e.g external elements referenced through xlink:href attribute or <funciri>).
Here is the function I wrote for parsing the images content :
function parseImages(){
var xlinkNS = "http://www.w3.org/1999/xlink";
var total, encoded;
// convert an external bitmap image to a dataURL
var toDataURL = function (image) {
var img = new Image();
// CORS workaround, this won't work in IE<11
// If you are sure you don't need it, remove the next line and the double onerror handler
// First try with crossorigin set, it should fire an error if not needed
img.crossOrigin = 'Anonymous';
img.onload = function () {
// we should now be able to draw it without tainting the canvas
var canvas = document.createElement('canvas');
canvas.width = this.width;
canvas.height = this.height;
// draw the loaded image
canvas.getContext('2d').drawImage(this, 0, 0);
// set our <image>'s href attribute to the dataURL of our canvas
image.setAttributeNS(xlinkNS, 'href', canvas.toDataURL());
// that was the last one
if (++encoded === total) exportDoc();
};
// No CORS set in the response
img.onerror = function () {
// save the src
var oldSrc = this.src;
// there is an other problem
this.onerror = function () {
console.warn('failed to load an image at : ', this.src);
if (--total === encoded && encoded > 0) exportDoc();
};
// remove the crossorigin attribute
this.removeAttribute('crossorigin');
// retry
this.src = '';
this.src = oldSrc;
};
// load our external image into our img
img.src = image.getAttributeNS(xlinkNS, 'href');
};
// get an external svg doc to data String
var parseFromUrl = function(url, element){
var xhr = new XMLHttpRequest();
xhr.onload = function(){
if(this.status === 200){
var response = this.responseText || this.response;
var dataUrl = 'data:image/svg+xml; charset=utf8, ' + encodeURIComponent(response);
element.setAttributeNS(xlinkNS, 'href', dataUrl);
if(++encoded === total) exportDoc();
}
// request failed with xhr, try as an <img>
else{
toDataURL(element);
}
};
xhr.onerror = function(){toDataURL(element);};
xhr.open('GET', url);
xhr.send();
};
var images = svg.querySelectorAll('image');
total = images.length;
encoded = 0;
// loop through all our <images> elements
for (var i = 0; i < images.length; i++) {
var href = images[i].getAttributeNS(xlinkNS, 'href');
// check if the image is external
if (href.indexOf('data:image') < 0){
// if it points to another svg element
if(href.indexOf('.svg') > 0){
parseFromUrl(href, images[i]);
}
else // a pixel image
toDataURL(images[i]);
}
// else increment our counter
else if (++encoded === total) exportDoc();
}
// if there were no <image> element
if (total === 0) exportDoc();
}
Here the svgDoc is called svg,
and the exportDoc() function could just be written as :
var exportDoc = function() {
// check if our svgNode has width and height properties set to absolute values
// otherwise, canvas won't be able to draw it
var bbox = svg.getBoundingClientRect();
if (svg.width.baseVal.unitType !== 1) svg.setAttribute('width', bbox.width);
if (svg.height.baseVal.unitType !== 1) svg.setAttribute('height', bbox.height);
// serialize our node
var svgData = (new XMLSerializer()).serializeToString(svg);
// remember to encode special chars
var svgURL = 'data:image/svg+xml; charset=utf8, ' + encodeURIComponent(svgData);
var svgImg = new Image();
svgImg.onload = function () {
var canvas = document.createElement('canvas');
// IE11 doesn't set a width on svg images...
canvas.width = this.width || bbox.width;
canvas.height = this.height || bbox.height;
canvas.getContext('2d').drawImage(svgImg, 0, 0, canvas.width, canvas.height);
doSomethingWith(canvas)
};
svgImg.src = svgURL;
};
But once again, you will have to append your svg into the document first (either through xhr or into an <iframe> or an <object> element, and you will have to be sure all your resources are CORS compliant (or from same domain) in order to get these rendered.
var svg = document.querySelector('svg');
var doSomethingWith = function(canvas) {
document.body.appendChild(canvas)
};
function parseImages() {
var xlinkNS = "http://www.w3.org/1999/xlink";
var total, encoded;
// convert an external bitmap image to a dataURL
var toDataURL = function(image) {
var img = new Image();
// CORS workaround, this won't work in IE<11
// If you are sure you don't need it, remove the next line and the double onerror handler
// First try with crossorigin set, it should fire an error if not needed
img.crossOrigin = 'anonymous';
img.onload = function() {
// we should now be able to draw it without tainting the canvas
var canvas = document.createElement('canvas');
canvas.width = this.width;
canvas.height = this.height;
// draw the loaded image
canvas.getContext('2d').drawImage(this, 0, 0);
// set our <image>'s href attribute to the dataURL of our canvas
image.setAttributeNS(xlinkNS, 'href', canvas.toDataURL());
// that was the last one
if (++encoded === total) exportDoc();
};
// No CORS set in the response
img.onerror = function() {
// save the src
var oldSrc = this.src;
// there is an other problem
this.onerror = function() {
console.warn('failed to load an image at : ', this.src);
if (--total === encoded && encoded > 0) exportDoc();
};
// remove the crossorigin attribute
this.removeAttribute('crossorigin');
// retry
this.src = '';
this.src = oldSrc;
};
// load our external image into our img
var href = image.getAttributeNS(xlinkNS, 'href');
// really weird bug that appeared since this answer was first posted
// we need to force a no-cached request for the crossOrigin be applied
img.src = href + (href.indexOf('?') > -1 ? + '&1': '?1');
};
// get an external svg doc to data String
var parseFromUrl = function(url, element) {
var xhr = new XMLHttpRequest();
xhr.onload = function() {
if (this.status === 200) {
var response = this.responseText || this.response;
var dataUrl = 'data:image/svg+xml; charset=utf8, ' + encodeURIComponent(response);
element.setAttributeNS(xlinkNS, 'href', dataUrl);
if (++encoded === total) exportDoc();
}
// request failed with xhr, try as an <img>
else {
toDataURL(element);
}
};
xhr.onerror = function() {
toDataURL(element);
};
xhr.open('GET', url);
xhr.send();
};
var images = svg.querySelectorAll('image');
total = images.length;
encoded = 0;
// loop through all our <images> elements
for (var i = 0; i < images.length; i++) {
var href = images[i].getAttributeNS(xlinkNS, 'href');
// check if the image is external
if (href.indexOf('data:image') < 0) {
// if it points to another svg element
if (href.indexOf('.svg') > 0) {
parseFromUrl(href, images[i]);
} else // a pixel image
toDataURL(images[i]);
}
// else increment our counter
else if (++encoded === total) exportDoc();
}
// if there were no <image> element
if (total === 0) exportDoc();
}
var exportDoc = function() {
// check if our svgNode has width and height properties set to absolute values
// otherwise, canvas won't be able to draw it
var bbox = svg.getBoundingClientRect();
if (svg.width.baseVal.unitType !== 1) svg.setAttribute('width', bbox.width);
if (svg.height.baseVal.unitType !== 1) svg.setAttribute('height', bbox.height);
// serialize our node
var svgData = (new XMLSerializer()).serializeToString(svg);
// remember to encode special chars
var svgURL = 'data:image/svg+xml; charset=utf8, ' + encodeURIComponent(svgData);
var svgImg = new Image();
svgImg.onload = function() {
var canvas = document.createElement('canvas');
// IE11 doesn't set a width on svg images...
canvas.width = this.width || bbox.width;
canvas.height = this.height || bbox.height;
canvas.getContext('2d').drawImage(svgImg, 0, 0, canvas.width, canvas.height);
doSomethingWith(canvas)
};
svgImg.src = svgURL;
};
window.onload = parseImages;
canvas {
border: 1px solid green !important;
}
<svg width="200" height="200" xmlns="http://www.w3.org/2000/svg" version="1.1">
<defs>
<pattern id="Pattern" x="0" y="0" width=".25" height=".25">
<image xlink:href="https://dl.dropboxusercontent.com/s/1alt1303g9zpemd/UFBxY.png" width="100" height="100"/>
</pattern>
</defs>
<rect fill="url(#Pattern)" x="0" y="0" width="200" height="200"/>
</svg>

Adding more images to the canvas to drag and drop

I want to be able to spawn a new image to the canvas at the click of a button, rather than having to manually edit the code.
I have the following HTML5/JavaScript code that allows images to be dragged and dropped between multiple canvases and it works perfectly for what I require.
What I am doing:
<canvas style="float: left" height="125" width="400" id="cvs1">[No canvas support]</canvas>
<canvas style="float: left; margin-left: 100px" height="125" width="400" id="cvs2">[No canvas support]</canvas>
<script src="http://www.rgraph.net/libraries/RGraph.common.core.js" ></script>
<script>
window.onload = function ()
{
var canvas1 = document.getElementById("cvs1");
var canvas2 = document.getElementById("cvs2");
var context1 = canvas1.getContext('2d');
var context2 = canvas2.getContext('2d');
var imageXY = {x: 5, y: 5};
/**
* This draws the image to the canvas
*/
function Draw ()
{
//Clear both canvas first
canvas1.width = canvas1.width
canvas2.width = canvas2.width
//Draw a red rectangle around the image
if (state && state.dragging) {
state.canvas.getContext('2d').strokeStyle = 'red';
state.canvas.getContext('2d').strokeRect(imageXY.x - 2.5,
imageXY.y - 2.5,
state.image.width + 5,
state.image.height + 5);
}
// Now draw the image
state.canvas.getContext('2d').drawImage(state.image, imageXY.x, imageXY.y);
}
canvas2.onclick =
canvas1.onclick = function (e)
{
if (state && state.dragging) {
state.dragging = false;
Draw();
return;
}
var mouseXY = RGraph.getMouseXY(e);
state.canvas = e.target;
if ( mouseXY[0] > imageXY.x
&& mouseXY[0] < (imageXY.x + state.image.width)
&& mouseXY[1] > imageXY.y
&& mouseXY[1] < (imageXY.y + state.image.height)) {
state.dragging = true;
state.originalMouseX = mouseXY[0];
state.originalMouseY = mouseXY[1];
state.offsetX = mouseXY[0] - imageXY.x;
state.offsetY = mouseXY[1] - imageXY.y;
}
}
canvas1.onmousemove =
canvas2.onmousemove = function (e)
{
if (state.dragging) {
state.canvas = e.target;
var mouseXY = RGraph.getMouseXY(e);
// Work how far the mouse has moved since the mousedon event was triggered
var diffX = mouseXY[0] - state.originalMouseX;
var diffY = mouseXY[1] - state.originalMouseY;
imageXY.x = state.originalMouseX + diffX - state.offsetX;
imageXY.y = state.originalMouseY + diffY - state.offsetY;
Draw();
e.stopPropagation();
}
}
/**
* Load the image on canvas1 initially and set the state up with some defaults
*/
state = {}
state.dragging = false;
state.canvas = document.getElementById("cvs1");
state.image = new Image();
state.image.src = 'http://www.rgraph.net/images/logo.png';
state.offsetX = 0;
state.offsetY = 0;
state.image.onload = function ()
{
Draw();
}
}
</script>
This can also be seen on this JS Fiddle (Note: you have to click the image before you can drag it)
The problem I am having:
I would like to add more images to the canvases so that any of the images can then be dragged and dropped between however many canvases I choose to create.
I can quite easily add more canvases to the page to drag and drop between, however when it comes to adding/spawning more images to the canvases I cannot get it to work.
The only way I can think of being able to do this is by repeating the Draw() function for every single image that gets added. That would mean if I wanted 30 images to be able to drag and drop between 10 different canvases for example, I would need to repeat the Draw() function 30 times. Surely that cannot be the best way to do this?
Unless I am missing something very obvious I cannot see another way of doing this?

Here’s how to configure your code to create multiple objects and click-drag between canvases.
Demo: http://jsfiddle.net/m1erickson/Bnb6A/
Code an object factory function that creates new draggable objects and put all new objects in an array.
Keep this information about each draggable object:
dragging (true/false) indicating if this object is currently being dragged
image: the image for this object
x,y: the current top,left position of this object
width,height: the size of this object
offsetX,offsetY: indicates where the mouse clicked relative to top,left of this object
draw: (a function) that allows this object to draw itself (surrounded by a red rect if it’s being dragged)
On click:
Get the mouse position
Clear both canvases
Iterate through the object array
If an object is being dragged, unset the dragging flag
If an object is now selected, set the dragging flag and set the offsetX,offsetY for the starting mouse position relative to this object.
Redraw all objects
On mousemove:
Get the mouse position
Clear both canvases
Iterate through the object array
If an object is being dragged, move it to the mouse position (setting x,y adjusted for the offset)
Redraw all objects
Code:
<!doctype html>
<html>
<head>
<link rel="stylesheet" type="text/css" media="all" href="css/reset.css" /> <!-- reset css -->
<script src="http://code.jquery.com/jquery.min.js"></script>
<style>
body{ background-color: ivory; padding:20px; }
canvas{ border: 1px solid #808080; }
</style>
<script>
$(function(){
var canvas1 = document.getElementById("cvs1");
var canvas2 = document.getElementById("cvs2");
var contexts=[];
contexts.push(canvas1.getContext('2d'));
contexts.push(canvas2.getContext('2d'));
function clearAll(){
//Clear both canvas first
canvas1.width = canvas1.width
canvas2.width = canvas2.width
}
canvas1.onclick=function(e){ handleClick(e,1); };
canvas2.onclick=function(e){ handleClick(e,2); };
//
function handleClick(e,contextIndex){
e.stopPropagation();
var mouseX=parseInt(e.clientX-e.target.offsetLeft);
var mouseY=parseInt(e.clientY-e.target.offsetTop);
clearAll();
for(var i=0;i<states.length;i++){
var state=states[i];
if(state.dragging){
state.dragging=false;
state.draw();
continue;
}
if ( state.contextIndex==contextIndex
&& mouseX>state.x && mouseX<state.x+state.width
&& mouseY>state.y && mouseY<state.y+state.height)
{
state.dragging=true;
state.offsetX=mouseX-state.x;
state.offsetY=mouseY-state.y;
state.contextIndex=contextIndex;
}
state.draw();
}
}
canvas1.onmousemove = function(e){ handleMousemove(e,1); }
canvas2.onmousemove = function(e){ handleMousemove(e,2); }
//
function handleMousemove(e,contextIndex){
e.stopPropagation();
var mouseX=parseInt(e.clientX-e.target.offsetLeft);
var mouseY=parseInt(e.clientY-e.target.offsetTop);
clearAll();
for(var i=0;i<states.length;i++){
var state=states[i];
if (state.dragging) {
state.x = mouseX-state.offsetX;
state.y = mouseY-state.offsetY;
state.contextIndex=contextIndex;
}
state.draw();
}
}
var states=[];
var img=new Image();
img.onload=function(){
states.push(addState(0,0,img));
}
img.src="http://www.rgraph.net/images/logo.png";
function addState(x,y,image){
state = {}
state.dragging=false;
state.contextIndex=1;
state.image=image;
state.x=x;
state.y=y;
state.width=image.width;
state.height=image.height;
state.offsetX=0;
state.offsetY=0;
state.draw=function(){
var context=contexts[this.contextIndex-1];
if (this.dragging) {
context.strokeStyle = 'red';
context.strokeRect(this.x,this.y,this.width+5,this.height+5)
}
context.drawImage(this.image,this.x,this.y);
}
state.draw();
return(state);
}
$("#more").click(function(){
states.push(addState(states.length*100,0,img));
});
}); // end $(function(){});
</script>
</head>
<body>
<button id="more">Add Image</button><br>
<canvas height="125" width="300" id="cvs1">[No canvas support]</canvas><br>
<canvas height="125" width="300" id="cvs2">[No canvas support]</canvas>
</body>
</html>