Render HTML as an Image

Render HTML to an image

There is a lot of options and they all have their pro and cons.

Option 1: Use an API

ApiFlash (based on chrome)
EvoPDF (has an option for html)
Grabzit
HTML/CSS to Image API
...

Pros

Execute Javascript
Near perfect rendering
Fast when caching options are correctly used
Scale is handled by the APIs
Precise timing, viewport, ...
Most of the time they offer a free plan

Cons

Not free if you plan to use them a lot

Option 2: Use one of the many available libraries

dom-to-image
wkhtmltoimage (included in the wkhtmltopdf tool)
IMGKit (for ruby and based on wkhtmltoimage)
imgkit (for python and based on wkhtmltoimage)
python-webkit2png
...

Pros

Conversion is quite fast most of the time

Cons

Bad rendering
Does not execute javascript
No support for recent web features (FlexBox, Advanced Selectors, Webfonts, Box Sizing, Media Queries, ...)
Sometimes not so easy to install
Complicated to scale

Option 3: Use PhantomJs and maybe a wrapper library

PhantomJs
node-webshot (javascript wrapper library for PhantomJs)
...

Pros

Execute Javascript
Quite fast

Cons

Bad rendering
No support for recent web features (FlexBox, Advanced Selectors, Webfonts, Box Sizing, Media Queries, ...)
Complicated to scale
Not so easy to make it work if there is images to be loaded ...

Option 4: Use Chrome Headless and maybe a wrapper library

Chrome Headless
chrome-devtools-protocol
Puppeteer (javascript wrapper library for Chrome headless)
...

Pros

Execute Javascript
Near perfect rendering

Cons

Not so easy to have exactly the wanted result regarding:
- page load timing
- viewport dimensions
Complicated to scale
Quite slow and even slower if the html contains external links

Disclosure: I'm the founder of ApiFlash. I did my best to provide an honest and useful answer.

HTML to IMAGE using Python

You can do this by using imgkit

import imgkit

imgkit.from_file('test.html', 'out.jpg')

Or you can also use htmlcsstoimage Api

# pip3 install requests
import requests

HCTI_API_ENDPOINT = "https://hcti.io/v1/image"
HCTI_API_USER_ID = 'your-user-id'
HCTI_API_KEY = 'your-api-key'

data = { 'html': "<div class='box'>Hello, world!</div>",
         'css': ".box { color: white; background-color: #0f79b9; padding: 10px; font-family: Roboto }",
         'google_fonts': "Roboto" }

image = requests.post(url = HCTI_API_ENDPOINT, data = data, auth=(HCTI_API_USER_ID, HCTI_API_KEY))

print("Your image URL is: %s"%image.json()['url'])
# https://hcti.io/v1/image/7ed741b8-f012-431e-8282-7eedb9910b32

How can I render Images with JavaScript into my HTML

The problem is that you use an equal sign (=) rather than a plus-equal sign (+=). The plus-equal sign will add the text to the variable, while the equal sign will overwrite the variable.

This line:

        getImgs = `<img scr="${imgs[i]}">`

getImgs is being set to the string, the string is not being added to it. You need to change it to something like this:

        getImgs += `<img scr="${imgs[i]}">`

(Notice the plus before the equal sign)

This way, the variable will not be completely changed, rather it will be appended to.

Full code:

const imgs = [
    "images/p1.jpg",
    "images/p2.jpg",
    "images/p3.jpg"
]

const container = document.getElementById("container")

function renderImages() {
    let getImgs = ""
    for (let i = 0; i < imgs.length; i++) {
        getImgs += `<img scr="${imgs[i]}">`
    }
    container.innerHTML = getImgs
}

renderImages()

/* I added css so you can see the images */
img {
  border: 1px solid black;
  width: 20px;
  height: 20px;
  background: linear-gradient(90deg, blue, green);
}

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <h1>Headline</h1>
    <div id="container">

    </div>
</body>
</html>

Render HTML as an Image

What you can do is create an aspx page that changes the response type to be in the format you want and then put the image into the stream. I created a barcode generator that does a similar thing. Excluding all the formalities of generating the image, you'll Page_Load will look something like this:

Bitmap FinalBitmap = new Bitmap();
MemoryStream msStream = new MemoryStream();

strInputParameter == Request.Params("MagicParm").ToString()

// Magic code goes here to generate your bitmap image.
FinalBitmap.Save(msStream, ImageFormat.Png);

Response.Clear();
Response.ContentType = "image/png";

msStream.WriteTo(Response.OutputStream);

if ((FinalBitmap != null)) FinalBitmap.Dispose();

and that's it! Then all you have to do in your image is set the URL to be something like RenderImage.aspx?MagicParm=WooHoo or whatever you need. That way you can have it render whatever you want to specify.

Render HTML to an image

There is a lot of options and they all have their pro and cons.

Option 1: Use an API

ApiFlash (based on chrome)
EvoPDF (has an option for html)
Grabzit
HTML/CSS to Image API
...

Pros

Execute Javascript
Near perfect rendering
Fast when caching options are correctly used
Scale is handled by the APIs
Precise timing, viewport, ...
Most of the time they offer a free plan

Cons

Not free if you plan to use them a lot

Option 2: Use one of the many available libraries

dom-to-image
wkhtmltoimage (included in the wkhtmltopdf tool)
IMGKit (for ruby and based on wkhtmltoimage)
imgkit (for python and based on wkhtmltoimage)
python-webkit2png
...

Pros

Conversion is quite fast most of the time

Cons

Bad rendering
Does not execute javascript
No support for recent web features (FlexBox, Advanced Selectors, Webfonts, Box Sizing, Media Queries, ...)
Sometimes not so easy to install
Complicated to scale

Option 3: Use PhantomJs and maybe a wrapper library

PhantomJs
node-webshot (javascript wrapper library for PhantomJs)
...

Pros

Execute Javascript
Quite fast

Cons

Bad rendering
No support for recent web features (FlexBox, Advanced Selectors, Webfonts, Box Sizing, Media Queries, ...)
Complicated to scale
Not so easy to make it work if there is images to be loaded ...

Option 4: Use Chrome Headless and maybe a wrapper library

Chrome Headless
chrome-devtools-protocol
Puppeteer (javascript wrapper library for Chrome headless)
...

Pros

Execute Javascript
Near perfect rendering

Cons

Not so easy to have exactly the wanted result regarding:
- page load timing
- viewport dimensions
Complicated to scale
Quite slow and even slower if the html contains external links

Disclosure: I'm the founder of ApiFlash. I did my best to provide an honest and useful answer.

how can I render a whole image on the background?

You can't show a full image exactly on all devices/viewports because their aspect ratios differ from that of your image.

background-size: cover will cover the viewport but maintain aspect ratio, so if your image is for example very wide compared to the viewport height some of the image will get cropped at the sides.

If it is important that you actually show the full image as stated in the question then use background-size: contain but this will show space at top or sides if the aspect ratios of the viewport and your image are not the same.

To actually show the full image AND cover the entire viewport you can set background-size: 100% 100%; but this is often not satisfactory because it will stretch your image in one dimension or the other to fit which will make it look rather odd in most cases.

Render HTML as an Image

Render HTML to an image

Option 1: Use an API

Option 2: Use one of the many available libraries

Option 3: Use PhantomJs and maybe a wrapper library

Option 4: Use Chrome Headless and maybe a wrapper library

HTML to IMAGE using Python

How can I render Images with JavaScript into my HTML

Render HTML as an Image

Render HTML to an image

Option 1: Use an API

Option 2: Use one of the many available libraries

Option 3: Use PhantomJs and maybe a wrapper library

Option 4: Use Chrome Headless and maybe a wrapper library

how can I render a whole image on the background?

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