canvas toDataURL from string - javascript

I'm new to canvas but have a good working code. The result is to generate a canvas and then convert it to base64.
The problem is that to make it work, I seems to need to have a canvas element in the HTML code and I don't need to show the canvas element on the page.
JS
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
...
console.log( canvas.toDataURL() );
HTML
<canvas id="canvas" width=64 height=64></canvas>
Question(s)
Can I to toDataUrl without adding a canvas element in the HTML?
Is my only option to hide it with CSS?

You can use document.createElement()
var canvas = document.createElement("canvas");
var context = canvas.getContext("2d");
canvas.width = 64;
canvas.height = 64;
//....
console.log(canvas.toDataURL());

Related

Resize and preview base64 image, javascript

i am a newbie to programming,
I have an HTML code for displaying base64 image the image is dynamic link, always come with different sizes
I need to resize that image and create preview mode with smaller image with an aspect ratio
ex:
my original image on html are 600x300 I need to preview it 300x150
my original image HTML are 1000x500 I need to preview 500x250
I have a javascript for resizing but can't figure out how to get image base64 from my HTML code
Please who can give me some help on these to archive my goal
I cant paste HTMl code here because is to long please check HTMl on codepin
https://codepen.io/Gilavani/pen/JjLXBOb
function resizedataURL(datas, wantedWidth, wantedHeight)
{
// We create an image to receive the Data URI
var img = document.createElement('img');
// When the event "onload" is triggered we can resize the image.
img.onload = function()
{
// We create a canvas and get its context.
var canvas = document.createElement('canvas');
var ctx = canvas.getContext('2d');
// We set the dimensions at the wanted size.
canvas.width = wantedWidth;
canvas.height = wantedHeight;
// We resize the image with the canvas method drawImage();
ctx.drawImage(this, 0, 0, wantedWidth, wantedHeight);
var dataURI = canvas.toDataURL();
/////////////////////////////////////////
// Use and treat your Data URI here !! //
/////////////////////////////////////////
};
// We put the Data URI in the image's src attribute
img.src = datas;
}
Thanks you in Advice
Best Regards
let srcImg = document.getElementById("orignal").src;
let prev = document.getElementById("preview");
function resizedataURL(datas, wantedWidth, wantedHeight)
{
prev.src = datas;
prev.onload = function()
{
var canvas = document.createElement('canvas');
var ctx = canvas.getContext('2d');
canvas.width = wantedWidth;
canvas.height = wantedHeight;
ctx.drawImage(this, 0, 0, wantedWidth, wantedHeight);
prev.src = canvas.toDataURL();
};
}
resizedataURL(srcImg, 150,150);
<html>
<body>
<img id="orignal" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAASwAAAEsCAYAAAB5fY51AAAAAXNSR0IArs4c6QAAFSpJREFUeF7tnTuLZcUWgGtAZJykYRR0EAykwcBAEDM18h+YGPiIBEFREMxE8fEDBPGBgpEPMHByYzWbxEyh6UhnDHTAZJysZZ+Z3XP69Dm9a+9aVbUe3yTXvl2Ptb611nf3PnPuveeuXLlydPHixXT+/PnEHwhAAAIaCdy8eTNdv349nTs8PDwa/mF/fz/t7e1pjJWYIACBwAT+/fffdHBwkIYHq3NXr149unDhwurfQFqBu4LUIaCQwCirwU03bty4JaxLly6l9V/wpKWwcoQEgWAENp107dq1O8IaWCCtYB1BuhBQSmCbi04JC2kprR5hQSAQgV0PTluFhbQCdQapQkAZgbPe8nYKC2kpqyLhQCAAgamPpM4UFtIK0CGkCAElBKZkNYQ5KSykpaSahAEBxwRyZJUtLKTluFNIDQKdCeTKapawkFbnqnI9BBwSmCOr2cJCWg47hpQg0InAXFktEhbS6lRdroWAIwJLZLVYWEjLUeeQCgQaE1gqqyJhIa3GVeY6CDggUCKrYmEhLQcdRAoQaESgVFYiwkJajarNNRAwTEBCVmLCQlqGO4nQIVCZgJSsRIWFtCpXneMhYJCApKzEhYW0DHYUIUOgEgFpWVURFtKqVH2OhYAhAjVkVU1YSMtQZxEqBIQJ1JJVVWEhLeEu4DgIGCBQU1bVhYW0DHQYIUJAiEBtWTURFtIS6gaOgYBiAi1k1UxYSEtxpxEaBAoJtJJVU2EhrcKuYDsEFBJoKavmwkJaCjuOkCCwkEBrWXURFtJa2B1sg4AiAj1k1U1YSEtR5xEKBGYS6CWrrsJCWjO7hOUQUECgp6y6CwtpKehAQoBAJoHeslIhLKSV2S0sg0BHAhpkpUZYSKtjJ3I1BCYIaJGVKmEhLeYGAvoIaJKVOmEhLX0NS0RxCWiTlUphIa24A0LmegholJVaYSEtPY1LJPEIaJWVamEhrXiDQsb9CWiWlXphIa3+DUwEcQhol5UJYSGtOANDpv0IWJCVGWEhrX6NzM3+CViRlSlhIS3/g0OG7QlYkpU5YSGt9g3NjX4JWJOVSWEhLb8DRGbtCFiUlVlhIa12jc1N/ghYlZVpYSEtf4NERvUJWJaVeWEhrfoNzg1+CFiXlQthIS0/A0Um9Qh4kJUbYSGteo3OyfYJeJGVK2EhLfuDRQbyBDzJyp2wkJZ8w3OiXQLeZOVSWEjL7oARuRwBj7JyKyykJdf4nGSPgFdZuRYW0rI3aERcTsCzrNwLC2mVDwAn2CHgXVYhhIW07AwckS4nEEFWYYSFtJYPAjv1E4giq1DCQlr6B48I5xOIJKtwwkJa8weCHXoJRJNVSGEhLb0DSGT5BCLKKqywkFb+YLBSH4GosgotLKSlbxCJaJpAZFmFFxbSmh4QVughEF1WCOt2L9IIeoaSSLYToEdvcbl27Vo6d/Xq1aNLly6F7hUaInT5VSdPb94pD8Jaa1UaQ/XchgyOnjxZdoS1MQY0SEgvqEyaXjxdFoS1pVVpFJXzGyooenB7uRHWjjGgYUL5QVWy9N7uciCsM1qVxlE1xyGCoefOLjPCmhgDGiiEJ1QkSa9NlwFhTTNKNFIGJJYUEaDH8vAhrDxOSCuTE8vmE0BW+cwQVj4rpDWDFUvzCCCrPE7jKoQ1jxfSmsmL5bsJIKv53YGw5jNDWguYseUkAWS1rCMQ1jJuSGshN7YleqegCRBWATz+U7IAXtCt9ExZ4RFWGT/+07KQX6TtyKq82girnCHSEmDo/QhkJVNhhCXDEWkJcfR4DLKSqyrCkmOJtARZejkKWclWEmHJ8kRawjwtH4es5KuHsOSZIq0KTK0diazqVAxh1eGKtCpxtXAssqpXJYRVjy3SqshW69HIqm5lEFZdvkirMl9NxyOr+tVAWPUZI60GjHtfgazaVABhteGMtBpx7nENsmpHHWG1Y420GrJudRWyakX61j0Iqy1vpNWYd83rkFVNutvPRljtmSOtDsylr0RW0kTzzkNYeZzEV9Hw4kibHUjtmqE+dRHC6seeJ62O7JdejayWkpPZh7BkOC4+hQFYjK75RmrVHDlPWP2Rn46AQdBYlZMxUSMdNeIJS0cdeD1UUodtYSArPcVBWHpqgbQU1WIMBVnpKgrC0lUPpKWoHshKUTFuh4Kw9NUEaSmoCbJSUIQtISAsnXVBWh3rgqw6wp+4GmHprQ3S6lAbZNUB+owrEdYMWD2WMkDtqMO6HeulNyGspeQa7mOQ6sOGcX3GEjcgLAmKDc5goOpBhm09ttInIyxpohXPY7Dk4cJUnmnNExFWTboVzmbA5KDCUo5lq5MQVivSgvcwaOUwYVjOsMcJCKsHdYE7GbjlEGG3nF3vnQirdwUK7mfw5sOD2XxmmnYgLE3VWBALA5gPDVb5rLSuRFhaKzMjLgZxGhaMphlZWIGwLFQpI0YGcjck2GQ0kJElCMtIoXLCZDBPU4JJTufYWYOw7NQqK1IG9A4mWGS1jKlFCMtUufKCZVAT/0sXea1ibhXCMleyvIAjSyty7nndYXcVwrJbu8nIIw5uxJwnG8HRAoTlqJjbUok0wJFydd62O9NDWAEqH2GQI+QYoFUnU0RYk4h8LPA80J5z89F9clkgLDmW6k/yONgec1LfSB0DRFgd4fe42tOAe8qlRy9YvBNhWaxaYcweBt1DDoVlDLkdYYUsu+0vViKroE2bUkJYcWtv8tvgyCpwwyKs2MUfsrckAEux0ll1CPCEVYerqVMtiMBCjKaKbjRYhGW0cNJhaxaC5tik68B5ZxNAWHTIMQGNYtAYEy3TjwDC6sde5c2aBKEpFpXFChgUwgpY9KmUNYhCQwxTnPh9ewIIqz1zEzf2FEbPu00UJ3CQCCtw8adS7yGOHndOceD3egggLD21UBlJS4G0vEslbIKaJICwJhGxoIVIWtxBJe0TQFj2a9gkg5pCqXl2Ezhc0owAwmqG2v5FNcRS40z7pMlgFwGERW/MIiApGMmzZiXBYrMEEJbZ0vULXEI0Emf0I8DNvQggrF7kjd9bIpySvcaxEX4hAYRVCDDy9iXiWbInMmNyP0kAYdERRQTmCGjO2qKg2OyWAMJyW9p2ieWIKGdNu4i5ySoBhGW1csriPktIyEpZsQyHg7AMF09b6NvEhKy0Vcl2PAjLdv3URb8uqCG4g4ODtL+/n/b29tTFSkD2CCAsezVTH/EorSFQZKW+XKYCRFimymUjWIRlo04Wo0RYFqumOGZeCRUXx0FoCMtBEbWkwIfuWirhNw6E5be2TTPjaw1NcYe9DGGFLb1c4jlfXchZIxcRJ3klgLC8VrZRXnNENGdto/C5xhgBhGWsYJrCXSKgJXs05UwsfQkgrL78zd5eIp6SvWaBEbgIAYQlgjHWIRLCkTgjFnWyHQggLPpgFgFJ0UieNSsJFpslgLDMlq594DUEU+PM9mS4sRUBhNWKtPF7aoql5tnGsRP+BgGERUtMEmghlBZ3TCbKAvUEEJb6EvUNsKVIWt7Vlyq3LyWAsJaSC7Cvh0B63BmglG5SRFhuSimbSE9x9LxbliKnSRNAWNJEHZynQRgaYnBQSncpICx3JS1LSJMoNMVSRpXdUgQQlhRJB+doFITGmByU2mwKCMts6WQD1ywGzbHJVoHTpgggrClCAX5vQQgWYgzQKt1TRFjdS9A3AEsisBRr36r6vR1h+a3tZGYWBWAx5slCsCCbAMLKRuVroeXBtxy7ry5qnw3Cas+8+40eBt5DDt0bwWAACMtg0UpC9jTonnIpqWmkvQgrULU9DrjHnAK15OxUEdZsZDY3eB5sz7nZ7LZ6USOsemzVnBxhoCPkqKahOgaCsDrCb3F1pEGOlGuL3tF4B8LSWBWhmCIOcMSchdrFxDEIy0SZ5gcZeXAj5z6/U2ztQFi26pUVLQObEgyyWsXcIoRlrmRnB8yg3uEDC2fNzf+Rqq+CMqCn6wkTXz3OE5aTejKYuwsJGydNzhOWj0IykNN1hNE0IwsreMKyUKUzYmQQ8wsIq3xWWlciLK2VyYiLAcyAtLEEZvOZadqBsDRVY0YsDN4MWEhrOSxlOxGWsoLkhIOsciidvQaG5Qx7nICwelAvuJNBK4DHk5YcvE4nIaxO4Jdci6yWUONJS55avxMRVj/2s25GVrNwzVoM21m4ui5GWF3x513OQOVxKlkF4xJ67fYirHasF93EIC3CtmgTrBdha7oJYTXFPe8yBmgeL4nVMJegWO8MhFWPbdHJDE4RvqLNsC/CV3UzwqqKd9nhDMwybpK7qIEkTbmzEJYcS5GTGBQRjCKHUAsRjKKHICxRnGWHMSBl/GrspiY1qC4/E2EtZye6k8EQxSl6GLURxVl0GMIqwiezmYGQ4VjzFGpUk27+2Qgrn1WVlQxCFaxVDqVWVbDOOhRhzcIlu5gBkOXZ4jRq1oLy7jsQVif+NH4n8ALXUjsBiAuPQFgLwZVso+FL6OnYSw371AFhNeZOozcGXvE6alkR7o6jEVZD5jR4Q9iNrqKmjUDfvgZhNeJNYzcC3eEaatsOOsJqwJqGbgC58xXUuE0BEFZlzjRyZcCKjqfW9YuBsCoypoErwlV6NDWvWxiEVYkvjVsJrIFjqX29IiGsCmxp2ApQjR1JD9QpGMIS5kqjCgM1fBy9IF88hCXIlAYVhOnkKHpCtpAIS4gnjSkE0uEx9IZcURGWAEsaUgCi8yPoEZkCI6xCjjRiIcBA2+mV8mIjrAKGNGABvKBb6ZmywiOshfxovIXg2JboneVNgLAWsKPhFkBjywkC9NCyhkBYM7nRaDOBsXwnAXppfnMgrBnMaLAZsFiaRYCeysJ0vAhhZfKisTJBsWw2AXorHxnCymBFQ2VAYkkRAXosDx/CmuBEI+U1EqvKCdBr0wwR1hmMaKDpBmKFLAF67myeCGsHHxpHdhA5LZ8AvbebFcLawoaGyR8uVtYhQA9u54qwNrjQKHUGkFPnE6AXTzNDWGtMaJD5Q8WOugToyZN8EdZtHjRG3cHj9OUE6M077BBWSvyXUZfPEjsbEUBat0CHFxaN0GjiuKaYAL0aXFg0QPEMcUBjAtF7NuwTVvTCN54zrhMkELl3QworcsEF54ajOhKI2sPhhBW10B1ni6srEYjYy6GEFbHAlWaFY5UQiNbTYYQVrbBK5okwGhCI1NshhBWpoA3mgysUEojS4+6FFaWQCmeIkBoTiNDrroUVoYCNZ4LrlBPw3vNuheW9cMrnhvA6EvDc+y6F5blgHeeAqw0R8DoD7oTltVCGZoVQlRDwOAuuhOWxQEp6nzCMEvA2E26E5a0wRueDsBUS8DQbLoTlqSAK+52QHBDwMiPmheWlEA5mghSUE/AwK6aF5aEAynuc8JwRsD4zZoVlHbyzOSAdQwQsz45JYVkGbqivCdUxAaszZE5YVkE77n1SM0rA4iyZEpZFwEZ7mbCDELA2U2aEZQ1skH4nTQcELM2WCWFZAuqgf0khIAErM6ZeWFZABuxxUnZGwMKsqRaWBYDOepZ0ghPQPnNqhaUdXPC+Jn3HBDTPnkphaQbmuE9JDQLHBLTOoDphaQVFL0MgGgGNs6hKWBoBRWtS8oXAOgFtM6lGWNrA0LYQgMAtAppmU4WwNAGhSSEAgdMEtMxod2FpAUGTQgACZxPQMKtdhaUBAE0KAQjkE+g9s92E1Tvx/BKxEgIQ0PJBfBdhISsGAAK2CfSa4ebC6pWo7fYgegjoI9BjlpsKq0eC+spMRBDwQ6D1TDcTVuvE/LQEmUBAN4GWs91EWC0T0l1aooOATwKtZry6sFol4rMNyAoCdgi0mPWqwmqRgJ1yEikE/BOoPfPVhFU7cP+lJ0MI2CRQc/arCKtmwDZLSNQQiEWglgPEhVUr0FjlJlsI2CdQwwWiwqoRoP2ykQEE4hKQdoKYsKQDi1tiMoeALwKSbhARlmRAvkpFNhCAwEBAyhHFwpIKhLJCAAK+CUi4okhYEgH4LhHZQQAC6wRKnbFYWKUXU0YIQCAmgRJ3LBJWyYUxS0TWEICAxJPWbGEhKxoPAhCQILDEJbOEteQCicQ4AwIQKCPwyy+/pKeeemp1yGOPPZa+//779Mgjjxwf+uGHH6Z333139fPPP/+cnnzyyePfffvtt+mFF15Y/fzNN9+k559/fjKYf/75Z7Xuxx9/3Lpv/czh7tdffz3t7e2t1v7+++/pueeeS7/++mt65ZVX0kcffZTuueee1e+yhYWsJmvEAgioJDAI4I033kgff/zxSlKDLL7++uvVv957771pkNkgjeHn33777fifh9+t7x2SWz9nV7L//fdfevPNN9PTTz+9ktYooE8//XQlws0zX3311fTaa6+lZ555Jt19993He5999tkT52QLC1mp7EOCgsAiApsCG2Q1/HnnnXfSKJsXX3xxJZdBYj/99NPxU86w9uGHH856yhqD2xTYtjMfeOCB9Pjjj6ejo6P09ttvH8t1kOkg1/Epa/IJC1kt6gk2QUAtgXVhDEGuPw1tymVdZsPa8ee33nprtW/4M8pk88ltBHCWINfPHJ7efvjhh/Tdd9+tXlk3n/6Gn88UFrJS23MEBoHZBNY/Gxo/p9p8ohoFMj5FbT5RDVI6PDw88TQ2vPo98cQTp14Xx7O/+OKL9MEHH6z2bJ4//Lx+5vCZ15dffpk+++yzdP/9969eH9977730ySefrAS2U1jIanY/sAECJgisf6Y0vIYNT0rjK+AcYQ1r1yW46wP5UVwPPvjgSlpnSXB4Bfzqq6/Syy+/nB599NH0119/TQsLWZnoO4KEwGICm6924wfkua+E49PSKLg///zzxN/mbQa2/sH+8PQ0/Fl/4hp/Htd9/vnn6fr16+nvv/9enTv+BcGpJyxktbgH2AgBEwS2SWl8Bdz2ofv4CrjtdW4QzPA3fMPr20svvbTzw/j1z80uX758/Fq5eeb6K+Bdd921+kxreH0d/oZx+GrDCWEhKxP9RpAQmEVg80PvUTLjd7GWfq1h/K7V8KR03333HX+G9dBDD534IH9cN7x2jl9zGL8eMSSy/lWJdZkOX2sYZDjIdPye1rGwLly4kA4ODtL+/v7xF7hmUWExBCCglsD6F0eHIDe/HDr3i6OjhIavPoyvdut/Szjcsf7F0fUP3YffnfVl1M0vjr7//vvpjz/+WLnpxo0b6dzh4eHR8L6IrNT2G4FBIDSB8e3v4sWL6dyVK1eOhn84f/58aCgkDwEI6CVw8+bN1Qfx/wPviqgmNjzArwAAAABJRU5ErkJggg==">
<h2>Preview</h2>
<img id="preview" src="#">
</body>
</html>

Get a canvas object from an <IMG> element

The question on a single line:
Is there a toDataURL method working on a <IMG> element?
Most of the people seem to be interested in how to get an IMG from a CANVAS, but I need the opposite.
Why? I need to use the toDataURL() method on the IMG.
So, this is the pseudo code that I wish existed in reality:
var img = document.getElementById('myImage');
var canvas = img.getCanvasFromImage();
var dataURL = canvas.toDataURL();
Is there already a method, or a workaround (e.g. creating an empty canvas, copying the IMG on top, etc.) to do the getCanvasFromImage? I couldn't find one.
Some more details WHY, but there is no need to read further. I am using the VIDEO tag to get the camera stream, and when the user clicks a button, I copy the CANVAS to the IMG.
But since I do not want to show the whole picture while taking a photo (I want it to be consistent over different devices, regardless of the camera resolution, keeping a 16:9 aspect ratio), I only show a portion of the image using object-fit: cover; .
So, now I have a "partial" image, but if I do a toDataURL on the canvas I have, it gives me the WHOLE picture, regardless of the "object-fit" value.
If this is not clear, no problem :) I only need a "toDataURL" method working on a <IMG> element :)
HTMLImageElement.prototype.getCanvasFromImage = function(){
const canvas = document.createElement('canvas');
canvas.width = this.width;
canvas.height = this.height;
const ctx = canvas.getContext('2d');
ctx.drawImage(this, 0, 0);
return canvas;
};
const img = document.getElementById('myImage');
img.onload = () => {
const canvas = img.getCanvasFromImage();
const dataURL = canvas.toDataURL();
console.log(dataURL);
}
<img id="myImage" crossorigin="anonymous" src="https://dl.dropbox.com/s/zpoxft30lzrr5mg/20201012_102150.jpg" />
Its work, but please READ THIS. Better way is create pure function and pass image as argument:
function getCanvasFromImage(image) {
const canvas = document.createElement('canvas');
canvas.width = image.width;
canvas.height = image.height;
const ctx = canvas.getContext('2d');
ctx.drawImage(image, 0, 0);
return canvas;
}

HTML canvas image is far lower quality than original image. Why? [duplicate]

This question already has answers here:
Html5 canvas drawImage: how to apply antialiasing
(6 answers)
Closed 5 years ago.
I have a simple HTML document with an image and a canvas element. The image src is just some high quality image found online, just to illustrate my point. When I try to draw the image onto the canvas, the resulting canvas image is very pixelated and low quality. I can't seem to figure out why.
Similar questions have been asked here, but I couldn't find an answer that seemed to solve the problem. If someone finds another post with a working answer, please let me know. Any help is greatly appreciated. Thanks in advance!
Here is the JSfiddle with the code:
https://jsfiddle.net/vey309b0/5/
HTML:
<p>the original image:</p>
<img id="img_cam" src="https://4.bp.blogspot.com/k8IX2Mkf0Jo/U4ze2gNn7CI/AAAAAAAA7xg/iKxa6bYITDs/s0/HOT+Balloon+Trip_Ultra+HD.jpg" width="400">
<p>the canvas with drawn image:</p>
<canvas id="imgcanvas" width="400"></canvas>
JavaScript:
var canvas = document.getElementById("imgcanvas");
var img_can = document.getElementById("img_cam");
var ctx = canvas.getContext("2d");
var imgWidth = img_can.width;
var imgHeight = img_can.height;
canvas.width = imgWidth;
canvas.height = imgHeight;
ctx.drawImage(img_can, 0, 0, imgWidth, imgHeight);
Set the width and the height of the canvas to the naturalWidth and naturalHeight of the image, and then use CSS to constrain the canvas size.
var canvas = document.getElementById("imgcanvas");
var ctx = canvas.getContext("2d");
var img_can = document.getElementById("img_cam");
img_can.onload = function() {
canvas.width = this.naturalWidth;
canvas.height = this.naturalHeight;
ctx.drawImage(this, 0, 0);
};
img_can.src = img_can.getAttribute('data-src');
<p>
the original image:
</p>
<img id="img_cam" data-src="https://4.bp.blogspot.com/-k8IX2Mkf0Jo/U4ze2gNn7CI/AAAAAAAA7xg/iKxa6bYITDs/s0/HOT+Balloon+Trip_Ultra+HD.jpg" width="400">
<p>
the canvas with drawn image:
</p>
<canvas id="imgcanvas" style="width:400px;"></canvas>
You should also really be doing this work in an onload listener on the img tag.

How to make html5 canvas display crisp image based off chrome screencap

I am making a chrome extension that uses the chrome.tabs.captureVisibleTab method to grab a screencap of the current tab and then displays that in a popup from the chrome extension. If I use the img tag and use the data coming from the chrome function, such as data:image/jpeg;base64,/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAMCAgMCAgMDAwMEAwME…UUUAFFFFABRRRQAUUUUAFFFFABRRRQAUUUUAFFFFABRRRQAUUUUAFFFFABRRRQAUUUUAf/2Q==, the <img> displays pixel perfect, it is crisp and that's what I want. Problem is that I need to make it into a canvas, and when I do that, it becomes blurry.
This is a screencap of the <img> that uses the link data provided by Google to be used as a comparison to the canvas which is below.
This is the blurry canvas.
This is the code that I am using to try to do this, but I can't figure out how to make the canvas crisp like the image.
chrome.runtime.sendMessage({msg: "capture"}, function(response) {
console.log(response.imgSrc);
var img = document.createElement('img');
var _canvas = document.createElement("canvas");
img.src = response.imgSrc;
img.height = 436;
img.width = 800;
document.getElementById('main-canvas').appendChild(img);
draw(response);
});
function draw(response) {
var canvas = document.getElementById('imageCanvas');
canvas.height = window.innerHeight;
canvas.width = window.innerWidth;
//Get a 2d context
var ctx = canvas.getContext('2d');
//use image to paint canvas
var _image = new Image();
_image.onload = function() {
ctx.drawImage(_image, 0, 0, 800, 436);
}
_image.src = response.imgSrc;
document.getElementById('main-canvas').appendChild(canvas);
}
This is what I used to fix my problem: High Resolution Canvas from HTML5Rocks

change image from path to embedded

I have an html image
<img src="/path/to/my/image.png" />
I want the same content, but as an embedded image
<img src="data:image/png:base64/xyzafasfasfafasfafasfasag">
can I do this transformation easily with Javascript?
html: <img src="/path/..." id="image">
js: document.getElementById('image').src = 'data:image/png:base64/qweqwe...';
Found the solution myself:
function getBase64Image(img) {
// Create an empty canvas element
var canvas = document.createElement("canvas");
canvas.width = img.width;
canvas.height = img.height;
// Copy the image contents to the canvas
var ctx = canvas.getContext("2d");
ctx.drawImage(img, 0, 0,img.width,img.height);
// Get the data-URL formatted image
// Firefox supports PNG and JPEG. You could check img.src to guess the
// original format, but be aware the using "image/jpg" will re-encode the image.
var dataURL = canvas.toDataURL("image/png");
return dataURL;//.replace(/^data:image\/(png|jpg);base64,/, "");
}

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