---
title: Convert SVG to PNG with JavaScript
slug: convert-svg-to-png-with-javascript
published_at: 2021-02-24 18:00:00 +0000
updated_at: 2026-03-04 20:14:27 +0000
summary: 
description: In this segment, we&#39;ll work on converting an SVG to a PNG using an HTML canvas.  We&#39;ll dynamically render content into the SVG image including custom fonts from Google fonts. In the next episode, we&#39;ll show how to take the PNG image and upload it to YouTube with the YouTube Data API to use as the thumbnail.  Code: https://github.com/cjavdev/video_automation Twitter: https://twitter.com/cjav_dev Feedback: https://forms.gle/Q31hhjJGsMrvY4mL6  It turns out there&#39;s a really excellent tool called TubeBuddy that already exists and does most of what I was planning to build. I&#39;ve started using TubeBuddy in the past few months and really like it. If you use this link to buy a license, I&#39;ll get a small cut for being an affiliate: https://www.tubebuddy.com/cjavdev. #rails #rubyonrails
tags: [svg to png, svg to png with javascript, svg to png with js, javascript, js, google fonts, convert svg to png, write code to convert from svg to png, svg to png with canvas, html canvas, png to svg, svg converter, how to, how to convert svg to png, svg converter software]
views: 9083
author: CJ Avilla
url: https://www.cjav.dev/videos/convert-svg-to-png-with-javascript
youtube_url: https://www.youtube.com/watch?v=-oXRpzLyz6Q
youtube_id: -oXRpzLyz6Q
embed_url: https://www.youtube.com/embed/-oXRpzLyz6Q
thumbnail_url: https://i.ytimg.com/vi/-oXRpzLyz6Q/hqdefault.jpg
type: video
---

# Convert SVG to PNG with JavaScript

*Published: February 24, 2021*
*Views: 9083*

## Watch

[Watch on YouTube](https://www.youtube.com/watch?v=-oXRpzLyz6Q)

[![Convert SVG to PNG with JavaScript](https://i.ytimg.com/vi/-oXRpzLyz6Q/hqdefault.jpg)](https://www.youtube.com/watch?v=-oXRpzLyz6Q)

## Description

In this segment, we&#39;ll work on converting an SVG to a PNG using an HTML canvas.  We&#39;ll dynamically render content into the SVG image including custom fonts from Google fonts. In the next episode, we&#39;ll show how to take the PNG image and upload it to YouTube with the YouTube Data API to use as the thumbnail.

Code: https://github.com/cjavdev/video_automation
Twitter: https://twitter.com/cjav_dev
Feedback: https://forms.gle/Q31hhjJGsMrvY4mL6

It turns out there&#39;s a really excellent tool called TubeBuddy that already exists and does most of what I was planning to build. I&#39;ve started using TubeBuddy in the past few months and really like it. If you use this link to buy a license, I&#39;ll get a small cut for being an affiliate: https://www.tubebuddy.com/cjavdev.
#rails #rubyonrails

## Transcript

all right what&#39;s up friends i wanted to go through the process today of converting an svg into a png uh using a couple of different tricks that i have developed and this is all to like create thumbnails automatically from a rails application and so i&#39;ve got here i&#39;m in figma and so this is where i generally work on designing the thumbnail and so i&#39;ve got a thumbnail design here it has like a the subheading and then it has the main heading a little logo and then maybe like a little floating window of myself hanging out over there so like maybe for this video i&#39;ll try to just grab some screenshot like this or something uh and so that would be like dropped right here um and so the way this works is like in in figma i can specify that i want to export this as svg and so then i can say export thumbnail and this will give me a thumbnail here and if i drop it and i can just say like this is a thumb demo okay so i&#39;ve created a new svg called thumb demo thumb demo and if we look at the actual svg right it&#39;s just a bunch of sort of uh html markup right like this this whole thing is just html and so we can mess around with this to try to get this into the web and the idea is that like once we&#39;re able to render it on the browser we can then um drop in our own code that will render in place of these this subheading in this main heading so i kind of want to just like render this as if it was like an html page to a png so that it can then so we can set up like one subheading and one main heading for a bunch of different videos and then have it just export several different thumbnails um for a bunch of different videos so if we take this thumbnail that we just created right and we just say uh let&#39;s open this in finder so if we grab it in finder thumb demo and we just drop it in the browser this will open like so and so if we you&#39;ll notice that you can&#39;t like highlight the text here that&#39;s because when figma exported it did not export it as text so if we inspect this we&#39;ll see that uh you can see each of these little elements but it used a path tag to write this javascript basics thing here and so what we want to do is we want to edit the svg and replace this path with a text object so uh in in svg we can use we can use the a text tag to create this text so let&#39;s replace javascript basics here with uh with just a text tag so i&#39;m going to open um open the demo here and i&#39;m going to delete the path actually let&#39;s leave the let&#39;s leave the path for now and just say text and we have to give it the x and y position and we also want to give it a class i&#39;m going to use a class and i&#39;m going to call this um gonna call this this content here the subheading and so i&#39;m just gonna give it a class of like sub head okay and then in here i can just write whatever this was javascript basics um okay so that&#39;s probably what this subheading actually is it&#39;s javascript basics just like that right and now in order to figure out where this thing belongs x and y um initially we can just maybe just give it like 200 and uh like one i don&#39;t know 120 or something just to like see if we can get it on the page the other thing we can do is inside of the svg itself we can create a style tag and this will give us the ability to use css to style our svg elements so now we can say like dot sub head and we can say the you know the color is um because we have a a pretty dark background i&#39;m going to make the color white and then we&#39;ll just refresh the page here and see if anything is showing up so we&#39;ve got our style i don&#39;t see that text anywhere so let&#39;s try to find the text okay so we can see the text object is in is in the is in the html but we don&#39;t actually see it showing up anywhere i can&#39;t remember if this needs to be fill fill instead of color okay there we go fill so the fill the fill populated it and now we can actually highlight it so that&#39;s kind of cool so this is pretty far from this though right like the the font is different the size is different the location is different so um directly from the browser here i&#39;m going to mess around with this number to try to get it to the right spot 200 maybe 100 and if if i look at the path i don&#39;t actually know if this path has x and y coordinates yeah it doesn&#39;t look like it does it does have a fill though so this is probably the color that we want to fill with so let&#39;s change this to use the the color that matches okay and then instead of just using x and y coordinates um i you know what probably in this d i bet you like there&#39;s something in this d thing that talks about where it actually lives um but i&#39;m just gonna keep moving this thing around so let&#39;s say the x is 400 okay so that&#39;s too far i think it&#39;s maybe we want to go back 120. uh and then maybe this 77 so like 77 is the the the x coordinate for the logo that&#39;s at the bottom so maybe that&#39;s like where this is aligned so let&#39;s try 77 okay that looks pretty good and then for y let&#39;s go 200 okay so we&#39;re almost in the right spot maybe like 210 um all right two let&#39;s go 300 that&#39;s too far 250 i don&#39;t know we&#39;re just kind of like moving it around right and then instead of so 77 and 250 let&#39;s make that update real quick uh here&#39;s we want 77 and 250. all right and then what the other thing that we want to do is we want to change the font family so that it matches this this font family so in figma for that font i was using roboto which is available on google fonts so if we go to google fonts we can find roboto i was using light roboto light and the font size was 60. so i think we can just change we can just set that here so like font size 60px font family is roboto okay so then if we refresh the page um we can see like i guess if we just delete this path element now we can see that it&#39;s showing up but it&#39;s not actually using roboto because roboto is an external font that needs to be loaded and so in order to load this external font with light so this is font family 300 right we can just take this or we can use the at import statement to grab the font family so i don&#39;t know if you can see that but on the right you can select at import and grab this and then we can drop that into our style tag to import that font so now if we refresh the page here again okay so that&#39;s not working uh there&#39;s i think there&#39;s something weird where like it can&#39;t re yeah okay so like it can&#39;t for some reason it can&#39;t read the like ampersand in the url so it&#39;s really tough to see what this is looking like now so i think i am just going to delete i&#39;m just going to delete the path for that element just so that we can see this okay so javascript basics that looks pretty good but the other thing that i wanted to do was make it all uppercase right i don&#39;t want to necessarily force the all uppercase as part of the subheading but i do want to force it so that it looks pretty for for the svg so here we can say like text transform uh upper case i think let&#39;s see yeah okay cool so that is like almost exactly what it looks like in figma right so that&#39;s pretty cool and what&#39;s really neat about this is that if i change what the like subheading is so if we&#39;re talking about ruby meta programming which is another topic that i talk about sometimes we go back to the browser and refresh ruby meta programming so that loads up fine so that&#39;s that&#39;s super cool let&#39;s let&#39;s do the same thing for for the main heading and i&#39;m just going to speed this up so that you don&#39;t have to watch me do the same exact thing so let&#39;s do that so here okay so that&#39;s looking pretty good right that that matches pretty closely for what we had before uh in the original figma i actually used two different fonts for this main heading we had how does and then the this word is actually roboto mono but i&#39;m not going to support that in this initial this initial thing so um all right cool so we&#39;ve got the fonts working and we&#39;ve got our thumbnail or like the svg is like generally working and ideally we could go in here now if we wanted to and we could use erb to you to like print out like at video dot title or something right like if we wanted to or subtitle or whatever um uh or like yeah javascript basics right like so eventually we&#39;re gonna go through and replace these with with erb so that we can render out and make that part dynamic but before we get that far let&#39;s go to the next step which is taking the svg and converting it into a png so now what we want to do is let&#39;s say we have we have this thumb demo i&#39;m going to copy that into public and i&#39;m going to put it in public yeah just i&#39;m just going to put it in public directly and then i wanted to add a new route to videos i&#39;m going to call it get thumb here and then this will be a member route for videos so this this part is like rails specific but it doesn&#39;t really matter like i just i just need an html page where i can load up that svg and work with it so i&#39;m just going to add i&#39;m adding this but this again like isn&#39;t really um important for converting the svg thumb.html.edu uh okay so at the very top here okay so actually there&#39;s so there&#39;s a code snippet that i found um uh here in this blog post that i&#39;m gonna use and it&#39;s from what&#39;s it from this blocks what&#39;s it called yeah so someone posted this code snippet about how to convert svg to canvas png and so this is on blocks.org and i&#39;ll drop a link to this in the in the description but what it does is it has an svg container which has like the content for your svg and then separately it has an html canvas and a png container and then it uses a bit of javascript to read in and deserialize the svg then it it grabs the canvas element and its 2d context and then it finds the the url from the window so self is itself aka window url the webkit url or the window and then it&#39;s creating a new image with a blob from that svg string and um so it&#39;s it&#39;s creating like a the url for the svg string setting that as the source tag of the image and that means like as soon as the image loads this onload function will run and when it runs it draws the image into the canvas and then converts the canvas into a png and then takes the png content and drops that in as the image source for our png container tag and then i don&#39;t know why it needs this revoke url thing but i&#39;m sure it&#39;s something related to uh uh like memory leaks or something i don&#39;t know so let&#39;s let&#39;s grab that code snippet i&#39;m gonna drop it into this thumb here and so what this okay so we this is the code that we just went through that we just walked through so my canvas element i&#39;m making it 1920 by 1080 because that&#39;s the size of the thumbnail that i want and then i&#39;m reading in the thumbnail the svg file so this is using erb to just read in the raw content for that svg if i wanted to i could just like write the actual svg here but the svg file that we&#39;re working with this demo one is actually pretty big so uh like if we look at um if you look at some of the content here for these images like the image in the in the bottom right hand corner uh this is like a full big picture and in order to base64 encode this and have that in the svg it&#39;s like actually pretty massive so i don&#39;t want to like copy and paste these around very much so instead i&#39;m just going to read the file directly from the rails roots public directory thumb demo that&#39;s where we just pasted in the svg that we were working with before and ideally it should load this up in the canvas and then print out in the svg container so we need to start our real server start rails server which is going to fire up on localhost 3000. again all you really need is an html page to load this in okay so if we pull up localhost 3000 we should get a list of videos okay so this is a list of all of our youtube videos make it a little bigger if we click on one of them and then just go to slash thumb this is the new route okay so here we see in the top we see the svg and then in the bottom we see the png or we see the canvas and then we see the png that was rendered and you&#39;ll notice that the text did not carry over like the font phase for the text did not carry over so this ended up being just whatever the basic browser text is this one down here is fine because this is a logo image and that&#39;s that&#39;s not impacted but um the font families did not carry over and so uh there&#39;s a there&#39;s there&#39;s an issue with our svg and that is that um this at import statement does not work when converting to svg so we need a different way to do this and so there&#39;s a there&#39;s a couple different approaches to this but the one that i have found to work is rather than using an import statement we need to use a font family right we&#39;re trying to use this at import statement which actually creates font faces and the url will be populated for us so if we were to just do like a um like a curl request for that url we see that two font faces come back right so this is the two font faces that we actually want in our thumb demo.svg so we can actually just paste those here and this will continue to work on the svg part but not the png so let&#39;s go look at this if we refresh the page you&#39;ll notice that the fonts continue working at the top but not at the bottom that&#39;s because the at import statement was basically just doing this exact same thing so in order to make this work we need to take the url here to the tff file and we need to base64 encode this so we&#39;re going to copy that url we&#39;re going to use base64 and pass in that actually i think we need to download the file first so let&#39;s let&#39;s do curl the url pipe to base64 so that should download it and then convert it into base64 and that&#39;s that&#39;s like the all of that binary that you see that should be the base64 encoded thing i think let&#39;s just make sure that this okay so binary output can mess up your terminal output use dash dash output all right so if i if i just do instead of curl i can just use w get and pipe it into or let&#39;s just do w get and then we know the name is like kf o whatever right so we&#39;ve got this file kf something something cat that into base64 and we get back the base64 for that tff file now if i use pipe pb copy that will put it on the on the clipboard for me and i can then replace this url instead of using that url directly i can just dump in that base64 encoded string that we got back so we don&#39;t have this will cause it to not download the font but will have the font at all times available locally to the svg so there&#39;s no request there&#39;s no network request that goes out and so i think this will allow the svg to render correctly there&#39;s one other thing that we need to do and that is when we paste in the data url like this we need to make sure that we&#39;re specifying all of the right properties and such for the data url so i&#39;m just going to let this complete uh okay so it&#39;s completed its thing all right and then at the beginning of the url we can&#39;t just start putting in the the base64 stuff so instead we need to also put at the front uh this data colon font true type char set tell it like all the different stuff about how to this is pretty common for data urls right like you have to do this with images also okay so at least our light for our light font should maybe work so let&#39;s refresh the page we&#39;ve got light font working on our svg and on our png cool so it&#39;s working the light font is working on our png also so let&#39;s do the same thing but we&#39;ll do it for um for the the the heavyweight or like the bold the bold one okay cool it looks like that finished um so we need the same sort of preamble thingy here and let&#39;s see okay so then if we refresh our page we&#39;ve got our font and the svg and our font on the png and if we right click and say save image as you&#39;ll notice that this downloads as a png file so if we go drop it in here and say like this is our thumb then we have saved a thumb that we can then upload to uh to youtube if we wanted right like this is this is kind of what we want to um what we want to do so we were able to successfully uh create an svg with figma export it and convert the we converted the paths that used text into text objects that we can then go and dynamically render different text here then we fought with google fonts for a bit to get our font fully embedded so that it could convert to a png when it&#39;s rendered i&#39;d love to hear how you&#39;re going to use this in your own application if you want to leave a comment in the in the comments below that would be awesome uh yeah just curious how other folks are trying to use svgs and convert them into pngs and why so uh yeah drop a comment and yeah in the x in the next episode for this series we&#39;re going to be taking this thumbnail creator and then populating it with the actual video content from rails so this is going to be specific to just like how do you convert svg to png so all right thanks friends

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