Develop Reference

jsPDF autoTable not displaying images with original dimensions properly in PDF

My HTML table displays dynamic images properly on the webpage, however, an attempt to generate a PDF using jsPDF following this example created on codepen is failing me. I'm getting the below pdf without the image filling the entire width and the height appears to be reduced instead of getting the original image size- I'm using base64:
I have also looked at several questions and answers here on SO and elsewhere extensively with no avail like this one here How to get table row image in PDF using jsPDF? and followed this discussion here https://github.com/simonbengtsson/jsPDF-AutoTable/issues/173, but I don't seem to wrap my head around this.
function createPdf(){
var doc = new jsPDF();
doc.autoTable({
html: '#mytable',
bodyStyles: {minCellHeight : 30},
didDrawCell: function(data){
if(data.cell.section ==='body' && data.column.index ===1) {
var td = data.cell.raw;
var img = td.getElementsByTagName('img')[0];
var dim = data.cell.height - data.cell.padding('vertical');
var textPos = data.cell.textPos;
doc.addImage(img.src, textPos.x, textPos.y, dim, dim);
}
}
})
doc.save("table.pdf");
}
The issue appears to do with the width and height dimensions which is dynamic and also the images are further on the right. However, the priority issue is to set auto value for height to provide desirable outcome.
Anyone with expertise in this, kindly Check what I have used here https://jsfiddle.net/kibika2020/0rtoph6s/5/
function createPdf(){
var doc = new jsPDF();
doc.autoTable({
html: '#mytable',
bodyStyles: {minCellHeight : 50},
didDrawCell: function(data){
if(data.cell.section ==='body' && data.column.index ===1) {
var td = data.cell.raw;
var img = td.getElementsByTagName('img')[0];
var dim = data.cell.height - data.cell.padding('vertical');
var textPos = data.cell.textPos;
doc.addImage(img.src, textPos.x, textPos.y, dim, dim);
}
}
})
doc.save("autoble.pdf");
}
I'm a beginner and finding this jsPDF stuff really tough than I expected. Take a look and advise me accordingly.
Thank you.

Using `jsgif` to build layers over animated GIFs

I'm looking to get some help or guidance on the use of the excellent libgif.js library.
My objective is to take a page that has an animated gif and a png of text with transparent background, and then show the 2 images overlaid such that the resulting image can be copied to the clipboard.
I've succeeded in doing this with a static image as a template
However, if I try this with a gif, it merges the animated gif with the text image, but freezes the gif.
I've familiarized myself with the libgif.js library and have succeeded in using it to build a canvas from an animated gif and have it remain animated.
However, the text image is not being displayed in the final canvas, and I'm a little lost as to how I might go about fixing this.
Is it obvious to anyone why the textImage is being properly sized and (somewhat) apparently placed on the canvas, but not displayed in the final result?
As a side question, does anyone know why the progress bar completes quickly at first and then progresses more slowly a second time?
The HTML is rather long, but the JS from the JSFiddle is shown below (for those not willing to click through to the link).
function doit() {
var isGIF = true; // always true for now TODO: better way to test if-gif than regex for ".gif"
var previewContainer = document.getElementById("previewContainer");
var textImage = document.getElementById("textImage");
var templateImage = document.getElementById("templateImage");
var w = document.getElementById("templateImage").width;
var h = document.getElementById("templateImage").height;
previewContainer.removeChild(previewContainer.children[1]);
if (isGIF) {
var gif = new SuperGif({
gif: templateImage,
progressbar_height: 5,
auto_play: true,
loop_mode: true,
draw_while_loading: true
});
gif.load();
var canvas = gif.get_canvas();
var context = canvas.getContext('2d');
context.drawImage(textImage, 0, 0, w, h);
previewContainer.replaceChild(canvas, previewContainer.children[0]);
}
}
Note: this solution was originally based on Arend's solution in the comments of this question from this JSFiddle.

You would have to tweak the library in order to get access to their rendering loop (like a frame_rendered event).
This way, you would be able to add whatever you want over the image the library drawn at every frame.
But since I'm too lazy to dig in there, here is a workaround :
Instead of appending the canvas returned by the library in the document, you can keep it offscreen, and draw it on an other, visible, canvas.
It is on this new canvas that you will also draw your textImage, in an rAF loop.
function doit() {
var previewContainer = document.getElementById("previewContainer");
var textImage = document.getElementById("textImage");
var templateImage = document.getElementById("templateImage");
var w = templateImage.width;
var h = templateImage.height;
previewContainer.removeChild(previewContainer.children[1]);
var gif = new SuperGif({
gif: templateImage,
progressbar_height: 5,
auto_play: true,
loop_mode: true,
draw_while_loading: true
});
gif.load();
var gif_canvas = gif.get_canvas(); // the lib canvas
// a copy of this canvas which will be appended to the doc
var canvas = gif_canvas.cloneNode();
var context = canvas.getContext('2d');
function anim(t) { // our animation loop
context.clearRect(0,0,canvas.width,canvas.height); // in case of transparency ?
context.drawImage(gif_canvas, 0, 0); // draw the gif frame
context.drawImage(textImage, 0, 0, w, h); // then the text
requestAnimationFrame(anim);
};
anim();
previewContainer.replaceChild(canvas, previewContainer.children[0]);
}
<script src="https://cdn.rawgit.com/buzzfeed/libgif-js/master/libgif.js"></script>
<div>
<input type="submit" id="doit" value="Do it!" onclick="doit()" />
</div>
<div id="previewContainer">
<img id="templateImage" src="https://i.imgur.com/chWt4Yg.gif" />
<img id="textImage" src="https://i.stack.imgur.com/CmErq.png" />
</div>

How do I split image into pieces

I am looking at a way to divide the image into pieces.
The no of pieces that the image can be split into is configurable using tile_height and tile_width.Looking for help.
I would not want any solution with any frameworks. Only using vanilla JavaScript
I tried the below
var _clipX =0;
var _clipY = _clipX;
var _clipHeight = IMAGE_HEIGHT/TILE_HEIGHT;
var _clipWidth = IMAGE_WIDTH/TILE_WIDTH;
var _nRows = Math.floor(IMAGE_HEIGHT/TILE_HEIGHT);
var _nColumns = Math.floor(IMAGE_WIDTH/TILE_WIDTH);
for(var i=0;i<_nRows;i++){
for(var j=0;j<_nColumns;j++){
el.getContext('2d').drawImage(image, _clipX, _clipY, _clipWidth, _clipHeight, _clipX, _clipY,_clipWidth , _clipHeight);
_clipX = _clipX + _clipWidth;
}
_clipX = 0
_clipY = _clipY + _clipHeight;
}
Below is the JSFiddle for the work
JSFiddle

Yes!!!
Found it. Instead of iterating over the image tag dimensions when you call draw image it does iterate over the natural dimensions of the image hence the issue I faced.
Now I have tried with the image size same as my img tag dimensions and it works perfectly fine.
Thanks everyone for the help offered

HTML5 Canvas Tooltips

I am using the HTML5 Canvas. I have added images (BitmapImages) to the canvas and I now want to add simple tooltips to these bitmap images.
Is this possible ??? If so can someone tell / show me how I could achieve this ?
I am not sure if it makes a difference , but I am also using the Easel JS Framework ...
Here is an example of what I currently have:
var container = new Container(); // EaselJS Container
container.x = 100;
container.y = 100;
stage.addChild(container);
var image = new Image();
image.src = "image.png";
var bitmap = new Bitmap(image);
bitmap.x = 5;
bitmap.y = 5;
bitmap.mouseEnabled = true;
container.addChild(bitmap);
...
I have not tested this code, but basically a bitmap image is created and added to my stage. I now want to add a simple tool tip to my bitmap image, but cant seem to work out how :(
Any help would be greatly appreciated.
Cheers,
Jon.

Here's how I would do it:
stage.enableMouseOver();
bitmap.onMouseOver = function(e) {
stage.canvas.title = 'put your tooltip text here';
}
bitmap.onMouseOut = function(e) {
stage.canvas.title = '';
}
This works by using tooltips already provided by the browser.

converting Div to Canvas options [duplicate]

It would be incredibly useful to be able to temporarily convert a regular element into a canvas. For example, say I have a styled div that I want to flip. I want to dynamically create a canvas, "render" the HTMLElement into the canvas, hide the original element and animate the canvas.
Can it be done?

There is a library that try to do what you say.
See this examples and get the code
http://hertzen.com/experiments/jsfeedback/
http://html2canvas.hertzen.com/
Reads the DOM, from the html and render it to a canvas, fail on some, but in general works.

Take a look at this tutorial on MDN: https://developer.mozilla.org/en/HTML/Canvas/Drawing_DOM_objects_into_a_canvas (archived)
Its key trick was:
var canvas = document.getElementById('canvas');
var ctx = canvas.getContext('2d');
var data = '<svg xmlns="http://www.w3.org/2000/svg" width="200" height="200">' +
'<foreignObject width="100%" height="100%">' +
'<div xmlns="http://www.w3.org/1999/xhtml" style="font-size:40px">' +
'<em>I</em> like ' +
'<span style="color:white; text-shadow:0 0 2px blue;">' +
'cheese</span>' +
'</div>' +
'</foreignObject>' +
'</svg>';
var DOMURL = window.URL || window.webkitURL || window;
var img = new Image();
var svg = new Blob([data], {type: 'image/svg+xml;charset=utf-8'});
var url = DOMURL.createObjectURL(svg);
img.onload = function () {
ctx.drawImage(img, 0, 0);
DOMURL.revokeObjectURL(url);
}
img.src = url;
That is, it used a temporary SVG image to include the HTML content as a "foreign element", then renders said SVG image into a canvas element. There are significant restrictions on what you can include in an SVG image in this way, however. (See the "Security" section for details — basically it's a lot more limited than an iframe or AJAX due to privacy and cross-domain concerns.)

Sorry, the browser won't render HTML into a canvas.
It would be a potential security risk if you could, as HTML can include content (in particular images and iframes) from third-party sites. If canvas could turn HTML content into an image and then you read the image data, you could potentially extract privileged content from other sites.
To get a canvas from HTML, you'd have to basically write your own HTML renderer from scratch using drawImage and fillText, which is a potentially huge task. There's one such attempt here but it's a bit dodgy and a long way from complete. (It even attempts to parse the HTML/CSS from scratch, which I think is crazy! It'd be easier to start from a real DOM node with styles applied, and read the styling using getComputedStyle and relative positions of parts of it using offsetTop et al.)

You can use dom-to-image library (I'm the maintainer).
Here's how you could approach your problem:
var parent = document.getElementById('my-node-parent');
var node = document.getElementById('my-node');
var canvas = document.createElement('canvas');
canvas.width = node.scrollWidth;
canvas.height = node.scrollHeight;
domtoimage.toPng(node).then(function (pngDataUrl) {
var img = new Image();
img.onload = function () {
var context = canvas.getContext('2d');
context.translate(canvas.width, 0);
context.scale(-1, 1);
context.drawImage(img, 0, 0);
parent.removeChild(node);
parent.appendChild(canvas);
};
img.src = pngDataUrl;
});
And here is jsfiddle

Building on top of the Mozdev post that natevw references I've started a small project to render HTML to canvas in Firefox, Chrome & Safari. So for example you can simply do:
rasterizeHTML.drawHTML('<span class="color: green">This is HTML</span>'
+ '<img src="local_img.png"/>', canvas);
Source code and a more extensive example is here.

No such thing, sorry.
Though the spec states:
A future version of the 2D context API may provide a way to render fragments of documents, rendered using CSS, straight to the canvas.
Which may be as close as you'll get.
A lot of people want a ctx.drawArbitraryHTML/Element kind of deal but there's nothing built in like that.
The only exception is Mozilla's exclusive drawWindow, which draws a snapshot of the contents of a DOM window into the canvas. This feature is only available for code running with Chrome ("local only") privileges. It is not allowed in normal HTML pages. So you can use it for writing FireFox extensions like this one does but that's it.

You could spare yourself the transformations, you could use CSS3 Transitions to flip <div>'s and <ol>'s and any HTML tag you want. Here are some demos with source code explain to see and learn: http://www.webdesignerwall.com/trends/47-amazing-css3-animation-demos/

the next code can be used in 2 modes, mode 1 save the html code to a image, mode 2 save the html code to a canvas.
this code work with the library: https://github.com/tsayen/dom-to-image
*the "id_div" is the id of the element html that you want to transform.
**the "canvas_out" is the id of the div that will contain the canvas
so try this code.
:
function Guardardiv(id_div){
var mode = 2 // default 1 (save to image), mode 2 = save to canvas
console.log("Process start");
var node = document.getElementById(id_div);
// get the div that will contain the canvas
var canvas_out = document.getElementById('canvas_out');
var canvas = document.createElement('canvas');
canvas.width = node.scrollWidth;
canvas.height = node.scrollHeight;
domtoimage.toPng(node).then(function (pngDataUrl) {
var img = new Image();
img.onload = function () {
var context = canvas.getContext('2d');
context.drawImage(img, 0, 0);
};
if (mode == 1){ // save to image
downloadURI(pngDataUrl, "salida.png");
}else if (mode == 2){ // save to canvas
img.src = pngDataUrl;
canvas_out.appendChild(img);
}
console.log("Process finish");
});
}
so, if you want to save to image just add this function:
function downloadURI(uri, name) {
var link = document.createElement("a");
link.download = name;
link.href = uri;
document.body.appendChild(link);
link.click();
}
Example of use:
<html>
<head>
</script src="/dom-to-image.js"></script>
</head>
<body>
<div id="container">
All content that want to transform
</div>
<button onclick="Guardardiv('container');">Convert<button>
<!-- if use mode 2 -->
<div id="canvas_out"></div>
</html>
Comment if that work.
Comenten si les sirvio :)

The easiest solution to animate the DOM elements is using CSS transitions/animations but I think you already know that and you try to use canvas to do stuff CSS doesn't let you to do. What about CSS custom filters? you can transform your elements in any imaginable way if you know how to write shaders. Some other link and don't forget to check the CSS filter lab.
Note: As you can probably imagine browser support is bad.

function convert() {
dom = document.getElementById('divname');
var script,
$this = this,
options = this.options,
runH2c = function(){
try {
var canvas = window.html2canvas([ document.getElementById('divname') ], {
onrendered: function( canvas ) {
window.open(canvas.toDataURL());
}
});
} catch( e ) {
$this.h2cDone = true;
log("Error in html2canvas: " + e.message);
}
};
if ( window.html2canvas === undefined && script === undefined ) {
} else {.
// html2canvas already loaded, just run it then
runH2c();
}
}