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Painterro - JavaScript painting plugin
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generate_font.js wordpress plugin Aug 3, 2017
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package.json 1.0.29 Nov 2, 2019 1.0.22 Oct 12, 2019
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Live Demo | npm | GitHub           npmvers npmDown totalNpm ghdownloads

JavaScript painting plugin which allows editing images in a browser. Can be easily integrated into any website or webapp by including only one JS file and calling simple initialization code.

Want to support? Just upvote us on StackOverflow


  • Paste image from clipboard with Ctrl+V (e.g. PtnScr screenshot), drag and drop it into widget, or load with file select dialog
  • Crop image by defined area
  • Paint primitives: line, rectangle, ellipse (alpha color can be used)
  • Add text (you can use Ctrl+B - bold, Ctrl+I - italic, Ctrl+U - underlined, or just pase formatted HTML)
  • Rotate / resize, scale image
  • Pixelize some area to hide sensitive data
  • Draw arrows

Painterro gif preview


  • It is lightweight and minimalistic - written with vanilla JS, you don't need dependencies to use it
  • Designed to process images with minimal clicks, most actions support hot-keys
  • Could be easily integrated into SPA application (React, Vue, Angular)
  • Could be used in Electron and Cordova apps
  • Flexibale image saving - you provide your save handler, and get base64 data with any jpeg/png compression
  • Could be translated to any language

Originally Painterro was designed for quick screenshots processing: You make screenshot by pressing PrtSc button, then open Painterro on your website, paste an image with Ctrl+V, crop it to interested area, highlight something with line/rectangle tool and/or add some text to the image and save on server with custom save handler (e.g. simple XHR request to your backend). In addition, you can use Painterro as image editor for any kind of raster images. Please try a demo. Also painterro has Wordpress Plugin.

If you want to see some feature in Painterro, please leave (or vote for) an issue here. There is no promise that it will be implemented soon or ever, but it is interesting to know what features users want to have.

Table of contents


With npm

If you have npm-based project (e.g. SPA like React/Vue) you can run:

npm install painterro --save

Then in your code

import Painterro from 'painterro'

By including script

You can download latest painterro-*.min.js here or build it by yourself.

Then insert <script> e.g to <head> section of your HTML file:

<script src="/xxx/painterro-x.x.x.min.js"></script>

Then in your code (body section, onclick handler, etc):


See example

Read after installation

To be able to save edited images on server or client see Saving image. For configurations see Configuration

Supported hotkeys

Ctrl + Z Cancel last operation
Ctrl + V Paste image from clipboard
Ctrl + C Copy selected aria to clipboard (*internal keyboard)
Shift when drawing rect/ellipse Draw square/circle
Shift when drawing line draw at angles of 0, 45, 90, 135 etc degrees
Alt when using pipette Hide zoom helper (colored grid)
Ctrl + Wheel mouse up/down Zoom image
Ctrl + S Save image

Also some tools have own one-button hotkeys e.g. C - crop, you could see this shortcuts if you will hold mouse on toolbutton.


You can pass parameters map to Painterro constructor:

  activeColor: '#00ff00', // default brush color is green
  // ... other params here
Param Description Default
id If provided, then Painterro will be placed to some holder on page with this id, in other case holder-element will be created (fullscreen with margins) undefined
activeColor Line/Text color that selected by default '#ff0000'
activeColorAlpha Transparancy of activeColor from 0.0 to 1.0, 0.0 = transparent 1
activeFillColor Fill color that selected by default '#000000'
activeFillColorAlpha Transparancy of activeColor from 0.0 to 1.0 0
defaultLineWidth Line width in px that selected by default 5
defaultEraserWidth Eraser width in px that selected by default 5
backgroundFillColor Default background color when image created/erased '#ffffff'
backgroundFillColorAlpha Transparancy of backgroundFillColor from 0.0 to 1.0 1.0
textStrokeColor Stroke color of text tool '#ffffff'
textStrokeColorAlpha Stroke color of text tool 1.0
defaultFontSize Default font size in pixels 24
defaultSize default image size, should be string in format <width>x<height> in pixel, e.g. '200x100'. If value is 'fill'(default) than all container size will be used 'fill'
fontStrokeSize default stroke width of text 0
defaultTool Tool selected by default 'select'
hiddenTools List of tools that you wish to exclude from toolbar e.g. something from this list ['crop', 'line', 'arrow', 'rect', 'ellipse', 'brush', 'text', 'rotate', 'resize', 'save', 'open', 'close'], You can't hide default tool ['redo']
initText Display some centered text before painting (supports HTML). If null, no text will be shown null
initTextColor Color of init text '#808080'
initTextStyle Style of init text "26px 'Open Sans', sans-serif"
pixelizePixelSize Default pixel size of pixelize tool. Can accept values - x - x pixels, x% - means percents of minimal area rectangle side 20%
availableLineWidths A list of the line width values that are available for selection in a drop down list e.g. [1,2,4,8,16,64]. Otherwise an input field is used. undefined
availableArrowLengths A list of the arrow sizes values that are available for selection in a drop down list e.g. [10,20,30,40,50,60]. Otherwise an input field is used. undefined
defaultArrowLength default arrow length 15
availableEraserWidths A list of the eraser width values that are available for selection in a drop down list e.g. [1,2,4,8,16,64]. Otherwise an input field is used. undefined
availableFontSizes A list of the font size values that are available for selection in a drop down list e.g. [1,2,4,8,16,64]. Otherwise an input field is used. undefined
toolbarPosition Whether to position the toolbar at the top or bottom. 'bottom'
fixMobilePageReloader By default painterro adds overflow-y: hidden to page body on mobile devices to prevent "super smart" feature lice Chrom's reload page. Unfortunately we can't prevent it by preventDefault. If your want to scroll page when painterro is open, set this to false true
language Language of the widget. 'en'
how_to_paste_actions List of paste options that will be suggested on paste using some paste dialog e.g. ['extend_right', 'extend_down'] . If there is only one option in list, then it will choosing automatically without dialog ['replace_all', 'paste_over', 'extend_right', 'extend_down']
hideByEsc If true then ESC press will hide widget false
saveByEnter If true then ENTER press will do same as Ctrl+S false


Param Description Accepted Arguments
onClose If passed will be triggered when painterro closed undefined
onChange Function that will be called if something will be changed (painted, erased, resized, etc) <exportable image>
onUndo Function that will be called if user will undo (Ctrl+Z) {<current history state>}
onRedo Function that will be called if user will redo (Ctrl+Z) {<current history state>}
onImageLoaded Function that will be called if you passed image to show and when it was loaded undefined
saveHandler Function that will be called when user presses Save (or Ctrl+S) {<exportable image>}, done callback

Events accepted arguments:

  • {<exportable image>} is object:
  image: {
   asBlob: ƒ asBlob(type, quality)
   asDataURL: ƒ asDataURL(type, quality)
   suggestedFileName: ƒ suggestedFileName(type)
   getWidth: ƒ getWidth()
   getHeight: ƒ getHeight()
  operationsDone: int
  • {<current history state>} is object:
  prev: {<current history state>} or undefined
  next: {<current history state>} or undefined
  prevCount: int
  sizeh: int
  sizew: int

UI color scheme

Next group of params used to configure painterro user interface. They should be placed under colorScheme group, for example:

  colorScheme: {
    main: '#fdf6b8', // make panels light-yellow
    control: '#FECF67' // change controls color
Param Description Default
main Color of panels, take most of UI space '#dbebff'
control Color of controls background (e.g. button background) '#abc6ff'
controlContent Content of controls (e.g. button text) '#000000'
activeControl Color for control when it active (e.g. button pressed) '#7485B1'
activeControlContent Color for activated control content main
inputBorderColor You can add border to inputs, by default color is same as main so borders will not be seen main
inputBackground Background of inputs '#ffffff'
inputText Color of text in input activeControl
backgroundColor Background color of component area which left outside of image due to it size/ratio '#999999'
dragOverBarColor Color of bar when dropping file to painterro '#899dff'
hoverControl Controls color when mouse hovered control
hoverControlContent Controls background color when mouse hovered '#1a3d67'
toolControlNameColor Color of toolbar labels that prepend controls rgba(255,255,255,0.7)


.show(openImage) - Shows painterro instance. openImage can have next values:

  • false - will open image that already was drawn before last close
  • some string value, e.g. '' - will try to load image from url
  • all another values - will clear content before open

.hide() - hide instance

.save() - call save (same save as on buttons bar). Can be used if save button is hidden (hiddenTools: ['save'])


var p = Painterro()


Want to translate Painterro into your language? If you need one of languages in table below, just pass pass language parameter, for example:

  language: 'es'  // Spanish

Translated languages:

language param Name
ca Catalan
de German
fa Iran-Farsi (Persian (Ir-Fa)
fr French
ja Japanese
en English
es Spanish
pt-PT European Portuguese
pt-BR Brazilian Portuguese

If you want to add another language, then fork. Create file in folder langs for your translation and copy [langs/en.lang.js] in it. Then translate all 'Strings' and add reference in [js/translation.js]. After that create pull-request, or just open issue if you don't know how to create a PR.

If you want to translate or change strings without contributing you can do this by passing translation parameter, for example:

  translation: {
    name: 'ua',
    strings: {
      apply: 'Застосувати'    
      // other strings

For all strings that can be translated, see [langs/en.lang.js]

Saving image

You should provide your save handler, which will post/update image on server or will pass image to another frontend components.

Binary saving

You can post data with binary multipart/form-data request which is the most efficient way to pass data to backend. Example uses raw XMLHttpRequest. Of course, you can use fetch, jQuery, etc insead.

var ptro = Painterro({
  saveHandler: function (image, done) {
    var formData = new FormData();
    formData.append('image', image.asBlob());
    // you can also pass suggested filename 
    // formData.append('image', image.asBlob(), image.suggestedFileName());
    var xhr = new XMLHttpRequest();'POST', '', true);
    xhr.onload = xhr.onerror = function () {

Here is python flask backend example (of course same can be implemented using any technology):

@app.route("/save-as-binary/", methods=['POST'])
def binary_saver():
    filename = '{:10d}.png'.format(int(time()))  # generate some filename
    filepath = os.path.join(get_tmp_dir(), filename)
    return jsonify({})

See full example in example directory. You can run it used python3 with installed Flask (pip install flask).

Base64 saving

You can also same image by posting base64 string via plain POST json call. Please note that base64 encoding is less efficient then binary data, for example some 1920 x 1080 image took 402398 bytes for base64 upload. The same image took 301949 bytes with multipart/form-data.

var ptro = Painterro({
    saveHandler: function (image, done) {
      // of course, instead of raw XHR you can use fetch, jQuery, etc
      var xhr = new XMLHttpRequest();"POST", "");
      xhr.setRequestHeader("Content-Type", "application/json");
        image: image.asDataURL()
      xhr.onload = function (e) {
        // after saving is done, call done callback
        done(true); //done(true) will hide painterro, done(false) will leave opened
    activeColor: '#00b400'  // change active color to green

Backend should convert base64 to binary and save file:

@app.route("/save-as-base64/", methods=['POST'])
def base64_saver():
    filename = '{:10d}.png'.format(int(time()))  # generate some filename
    filepath = os.path.join(get_tmp_dir(), filename)
    with open(filepath, "wb") as fh:
        base64_data = request.json['image'].replace('data:image/png;base64,', '')
    return jsonify({})

Saving to WYSIWYG

You can just insert image as data url to any WYSIWYG editor, e.g. TinyMCE:

    tinymce.init({ selector:'textarea', });
    var ptro = Painterro({
      saveHandler: function (image, done) {
        tinymce.activeEditor.execCommand('mceInsertContent', false, '<img src="' + image.asDataURL() + '" />');

Format and quality

When you call image.asDataURL() or image.asBlob(), you can also specify image mime type (format), e.g. image.asDataURL('image/jpeg'). Default type is 'image/png'. If type is image/jpeg or image/webp, you can also define image quality from 0.0 to 1.0, default is 0.92, example: image.asDataURL('image/jpeg', 0.5)

Example: Open Painterro by Ctrl+V

document.onpaste = (event) => {
  const { items } = event.clipboardData || event.originalEvent.clipboardData;
  Array.from(items).forEach((item) => {
    if (item.kind === 'file') {
      const blob = item.getAsFile();
      const reader = new FileReader();
      reader.onload = (readerEvent) => {
            saveHandler: (image, done) => {
              console.log('Save it here', image.asDataURL());  // you could provide your save handler


Code written on ES6 which transplited by Babel and packed (minified) to a single file using webpack. All configs are inside so all you have to do after pulling repo is installing node modules:

cd painterro
npm ci

Building painterro

npm run build

Result file for <script> import is build/painterro.min.js.

Actually, above command produces 4 versions of library:

  • build/painterro-x.y.z.min.js, build/painterro.min.js the same files but with different filenames (with and without versiontag) - this is var version which will be loaded as global variable (var painterro = <Library class>) when you will import it as <script src='painterro.min.js' /> tag. So this is for script tag only.
  • build/painterro.commonjs2.js - this version sutable for js require/import. That's why it is used as entry point in package.json file - if you are using webpack or other tool that can handle require/import of commonjs2 libraries then you can do npm install painterro, and do import painterro and it will use commonjs2 version.
  • build/painterro.amd.js and build/painterro.umd.js - these both are same as above but for AMD and UMD importers respectivly.


To start hot-reload dev server (for reloading code "on the fly"):

npm run dev

Then open http://localhost:8080 with demo page

Regenerating icons font

If you need add/edit icons in res folder, please after editing run

npm run buildfont


Pull-requests are welcome.

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