Fetch Prominent Colors From an Image


Fetch prominent colors from an image.

Example 1 Demo 1 Android Demo 1 iOS
Demo 2 Android Demo 2 iOS

This module is a wrapper around the Palette class on Android and UIImageColors on iOS.


$ npm install react-native-image-colors


$ yarn add react-native-image-colors


Rebuild the app.


Install the pod, then rebuild the app.

npx pod-install

RN < 0.62: if you face a compilation error while building, your Xcode project likely does not support Swift which this package requires. You can fix this by either a) Creating a blank dummy swift file using Xcode or b) Following steps 1,2,3 here.


Start by importing the module

import ImageColors from "react-native-image-colors"

🎨 Fetch colors

const colors = await ImageColors.getColors(URI, config)


Can be:

  • URL:


  • Local file:

    const catImg = require("./images/cat.jpg")
  • Base64:

    const catImgBase64 = "data:image/jpeg;base64,/9j/4Ri..."

    The mime type prefix for base64 is required (e.g. data:image/png;base64).


Property Description Type Required Default
fallback If a color property couldn’t be retrieved, it will default to this hex color string (note: do not use shorthand hex. e.g. #fff). string No "#000000"
pixelSpacing (Android only) How many pixels to skip when iterating over image pixels. Higher means better performance (note: value cannot be lower than 1). number No 5
quality (iOS only) Highest implies no downscaling and very good colors, but it is very slow. See UIImageColors 'lowest'
'highest' No "low"

Result (android)

On android, you will get an object with the following color properties, plus a platform key to help you figure out that this is the android result type.

Property Type
dominant string
average string
vibrant string
darkVibrant string
lightVibrant string
darkMuted string
lightMuted string
muted string
platform "android"

Result (iOS)

On iOS, you get the following color properties object, plus the respective platform key.

Property Type
background string
primary string
secondary string
detail string
platform "ios"


const coolImage = require("./cool.jpg")

const colors = await ImageColors.getColors(coolImage, {
  fallback: "#228B22",

if (colors.platform === "android") {
  // Access android properties
  // e.g.
  const averageColor = colors.average
} else {
  // Access iOS properties
  // e.g.
  const backgroundColor = colors.background


  • There is an example react-native project.

Download Details:

Author: osamaqarem

Source Code: https://github.com/osamaqarem/react-native-image-colors

#react-native #react #mobile-apps

What is GEEK

Buddha Community

Fetch Prominent Colors From an Image
Queenie  Davis

Queenie Davis


EasyMDE: Simple, Beautiful and Embeddable JavaScript Markdown Editor

EasyMDE - Markdown Editor 

This repository is a fork of SimpleMDE, made by Sparksuite. Go to the dedicated section for more information.

A drop-in JavaScript text area replacement for writing beautiful and understandable Markdown. EasyMDE allows users who may be less experienced with Markdown to use familiar toolbar buttons and shortcuts.

In addition, the syntax is rendered while editing to clearly show the expected result. Headings are larger, emphasized words are italicized, links are underlined, etc.

EasyMDE also features both built-in auto saving and spell checking. The editor is entirely customizable, from theming to toolbar buttons and javascript hooks.

Try the demo


Quick access

Install EasyMDE

Via npm:

npm install easymde

Via the UNPKG CDN:

<link rel="stylesheet" href="https://unpkg.com/easymde/dist/easymde.min.css">
<script src="https://unpkg.com/easymde/dist/easymde.min.js"></script>

Or jsDelivr:

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/easymde/dist/easymde.min.css">
<script src="https://cdn.jsdelivr.net/npm/easymde/dist/easymde.min.js"></script>

How to use

Loading the editor

After installing and/or importing the module, you can load EasyMDE onto the first textarea element on the web page:

const easyMDE = new EasyMDE();

Alternatively you can select a specific textarea, via JavaScript:

<textarea id="my-text-area"></textarea>
const easyMDE = new EasyMDE({element: document.getElementById('my-text-area')});

Editor functions

Use easyMDE.value() to get the content of the editor:


Use easyMDE.value(val) to set the content of the editor:

easyMDE.value('New input for **EasyMDE**');


Options list

  • autoDownloadFontAwesome: If set to true, force downloads Font Awesome (used for icons). If set to false, prevents downloading. Defaults to undefined, which will intelligently check whether Font Awesome has already been included, then download accordingly.
  • autofocus: If set to true, focuses the editor automatically. Defaults to false.
  • autosave: Saves the text that's being written and will load it back in the future. It will forget the text when the form it's contained in is submitted.
    • enabled: If set to true, saves the text automatically. Defaults to false.
    • delay: Delay between saves, in milliseconds. Defaults to 10000 (10 seconds).
    • submit_delay: Delay before assuming that submit of the form failed and saving the text, in milliseconds. Defaults to autosave.delay or 10000 (10 seconds).
    • uniqueId: You must set a unique string identifier so that EasyMDE can autosave. Something that separates this from other instances of EasyMDE elsewhere on your website.
    • timeFormat: Set DateTimeFormat. More information see DateTimeFormat instances. Default locale: en-US, format: hour:minute.
    • text: Set text for autosave.
  • autoRefresh: Useful, when initializing the editor in a hidden DOM node. If set to { delay: 300 }, it will check every 300 ms if the editor is visible and if positive, call CodeMirror's refresh().
  • blockStyles: Customize how certain buttons that style blocks of text behave.
    • bold: Can be set to ** or __. Defaults to **.
    • code: Can be set to ``` or ~~~. Defaults to ```.
    • italic: Can be set to * or _. Defaults to *.
  • unorderedListStyle: can be *, - or +. Defaults to *.
  • scrollbarStyle: Chooses a scrollbar implementation. The default is "native", showing native scrollbars. The core library also provides the "null" style, which completely hides the scrollbars. Addons can implement additional scrollbar models.
  • element: The DOM element for the textarea element to use. Defaults to the first textarea element on the page.
  • forceSync: If set to true, force text changes made in EasyMDE to be immediately stored in original text area. Defaults to false.
  • hideIcons: An array of icon names to hide. Can be used to hide specific icons shown by default without completely customizing the toolbar.
  • indentWithTabs: If set to false, indent using spaces instead of tabs. Defaults to true.
  • initialValue: If set, will customize the initial value of the editor.
  • previewImagesInEditor: - EasyMDE will show preview of images, false by default, preview for images will appear only for images on separate lines.
  • imagesPreviewHandler: - A custom function for handling the preview of images. Takes the parsed string between the parantheses of the image markdown ![]( ) as argument and returns a string that serves as the src attribute of the <img> tag in the preview. Enables dynamic previewing of images in the frontend without having to upload them to a server, allows copy-pasting of images to the editor with preview.
  • insertTexts: Customize how certain buttons that insert text behave. Takes an array with two elements. The first element will be the text inserted before the cursor or highlight, and the second element will be inserted after. For example, this is the default link value: ["[", "](http://)"].
    • horizontalRule
    • image
    • link
    • table
  • lineNumbers: If set to true, enables line numbers in the editor.
  • lineWrapping: If set to false, disable line wrapping. Defaults to true.
  • minHeight: Sets the minimum height for the composition area, before it starts auto-growing. Should be a string containing a valid CSS value like "500px". Defaults to "300px".
  • maxHeight: Sets fixed height for the composition area. minHeight option will be ignored. Should be a string containing a valid CSS value like "500px". Defaults to undefined.
  • onToggleFullScreen: A function that gets called when the editor's full screen mode is toggled. The function will be passed a boolean as parameter, true when the editor is currently going into full screen mode, or false.
  • parsingConfig: Adjust settings for parsing the Markdown during editing (not previewing).
    • allowAtxHeaderWithoutSpace: If set to true, will render headers without a space after the #. Defaults to false.
    • strikethrough: If set to false, will not process GFM strikethrough syntax. Defaults to true.
    • underscoresBreakWords: If set to true, let underscores be a delimiter for separating words. Defaults to false.
  • overlayMode: Pass a custom codemirror overlay mode to parse and style the Markdown during editing.
    • mode: A codemirror mode object.
    • combine: If set to false, will replace CSS classes returned by the default Markdown mode. Otherwise the classes returned by the custom mode will be combined with the classes returned by the default mode. Defaults to true.
  • placeholder: If set, displays a custom placeholder message.
  • previewClass: A string or array of strings that will be applied to the preview screen when activated. Defaults to "editor-preview".
  • previewRender: Custom function for parsing the plaintext Markdown and returning HTML. Used when user previews.
  • promptURLs: If set to true, a JS alert window appears asking for the link or image URL. Defaults to false.
  • promptTexts: Customize the text used to prompt for URLs.
    • image: The text to use when prompting for an image's URL. Defaults to URL of the image:.
    • link: The text to use when prompting for a link's URL. Defaults to URL for the link:.
  • uploadImage: If set to true, enables the image upload functionality, which can be triggered by drag and drop, copy-paste and through the browse-file window (opened when the user click on the upload-image icon). Defaults to false.
  • imageMaxSize: Maximum image size in bytes, checked before upload (note: never trust client, always check the image size at server-side). Defaults to 1024 * 1024 * 2 (2 MB).
  • imageAccept: A comma-separated list of mime-types used to check image type before upload (note: never trust client, always check file types at server-side). Defaults to image/png, image/jpeg.
  • imageUploadFunction: A custom function for handling the image upload. Using this function will render the options imageMaxSize, imageAccept, imageUploadEndpoint and imageCSRFToken ineffective.
    • The function gets a file and onSuccess and onError callback functions as parameters. onSuccess(imageUrl: string) and onError(errorMessage: string)
  • imageUploadEndpoint: The endpoint where the images data will be sent, via an asynchronous POST request. The server is supposed to save this image, and return a JSON response.
    • if the request was successfully processed (HTTP 200 OK): {"data": {"filePath": "<filePath>"}} where filePath is the path of the image (absolute if imagePathAbsolute is set to true, relative if otherwise);
    • otherwise: {"error": "<errorCode>"}, where errorCode can be noFileGiven (HTTP 400 Bad Request), typeNotAllowed (HTTP 415 Unsupported Media Type), fileTooLarge (HTTP 413 Payload Too Large) or importError (see errorMessages below). If errorCode is not one of the errorMessages, it is alerted unchanged to the user. This allows for server-side error messages. No default value.
  • imagePathAbsolute: If set to true, will treat imageUrl from imageUploadFunction and filePath returned from imageUploadEndpoint as an absolute rather than relative path, i.e. not prepend window.location.origin to it.
  • imageCSRFToken: CSRF token to include with AJAX call to upload image. For various instances like Django, Spring and Laravel.
  • imageCSRFName: CSRF token filed name to include with AJAX call to upload image, applied when imageCSRFToken has value, defaults to csrfmiddlewaretoken.
  • imageCSRFHeader: If set to true, passing CSRF token via header. Defaults to false, which pass CSRF through request body.
  • imageTexts: Texts displayed to the user (mainly on the status bar) for the import image feature, where #image_name#, #image_size# and #image_max_size# will replaced by their respective values, that can be used for customization or internationalization:
    • sbInit: Status message displayed initially if uploadImage is set to true. Defaults to Attach files by drag and dropping or pasting from clipboard..
    • sbOnDragEnter: Status message displayed when the user drags a file to the text area. Defaults to Drop image to upload it..
    • sbOnDrop: Status message displayed when the user drops a file in the text area. Defaults to Uploading images #images_names#.
    • sbProgress: Status message displayed to show uploading progress. Defaults to Uploading #file_name#: #progress#%.
    • sbOnUploaded: Status message displayed when the image has been uploaded. Defaults to Uploaded #image_name#.
    • sizeUnits: A comma-separated list of units used to display messages with human-readable file sizes. Defaults to B, KB, MB (example: 218 KB). You can use B,KB,MB instead if you prefer without whitespaces (218KB).
  • errorMessages: Errors displayed to the user, using the errorCallback option, where #image_name#, #image_size# and #image_max_size# will replaced by their respective values, that can be used for customization or internationalization:
    • noFileGiven: The server did not receive any file from the user. Defaults to You must select a file..
    • typeNotAllowed: The user send a file type which doesn't match the imageAccept list, or the server returned this error code. Defaults to This image type is not allowed..
    • fileTooLarge: The size of the image being imported is bigger than the imageMaxSize, or if the server returned this error code. Defaults to Image #image_name# is too big (#image_size#).\nMaximum file size is #image_max_size#..
    • importError: An unexpected error occurred when uploading the image. Defaults to Something went wrong when uploading the image #image_name#..
  • errorCallback: A callback function used to define how to display an error message. Defaults to (errorMessage) => alert(errorMessage).
  • renderingConfig: Adjust settings for parsing the Markdown during previewing (not editing).
    • codeSyntaxHighlighting: If set to true, will highlight using highlight.js. Defaults to false. To use this feature you must include highlight.js on your page or pass in using the hljs option. For example, include the script and the CSS files like:
      <script src="https://cdn.jsdelivr.net/highlight.js/latest/highlight.min.js"></script>
      <link rel="stylesheet" href="https://cdn.jsdelivr.net/highlight.js/latest/styles/github.min.css">
    • hljs: An injectible instance of highlight.js. If you don't want to rely on the global namespace (window.hljs), you can provide an instance here. Defaults to undefined.
    • markedOptions: Set the internal Markdown renderer's options. Other renderingConfig options will take precedence.
    • singleLineBreaks: If set to false, disable parsing GitHub Flavored Markdown (GFM) single line breaks. Defaults to true.
    • sanitizerFunction: Custom function for sanitizing the HTML output of Markdown renderer.
  • shortcuts: Keyboard shortcuts associated with this instance. Defaults to the array of shortcuts.
  • showIcons: An array of icon names to show. Can be used to show specific icons hidden by default without completely customizing the toolbar.
  • spellChecker: If set to false, disable the spell checker. Defaults to true. Optionally pass a CodeMirrorSpellChecker-compliant function.
  • inputStyle: textarea or contenteditable. Defaults to textarea for desktop and contenteditable for mobile. contenteditable option is necessary to enable nativeSpellcheck.
  • nativeSpellcheck: If set to false, disable native spell checker. Defaults to true.
  • sideBySideFullscreen: If set to false, allows side-by-side editing without going into fullscreen. Defaults to true.
  • status: If set to false, hide the status bar. Defaults to the array of built-in status bar items.
    • Optionally, you can set an array of status bar items to include, and in what order. You can even define your own custom status bar items.
  • styleSelectedText: If set to false, remove the CodeMirror-selectedtext class from selected lines. Defaults to true.
  • syncSideBySidePreviewScroll: If set to false, disable syncing scroll in side by side mode. Defaults to true.
  • tabSize: If set, customize the tab size. Defaults to 2.
  • theme: Override the theme. Defaults to easymde.
  • toolbar: If set to false, hide the toolbar. Defaults to the array of icons.
  • toolbarTips: If set to false, disable toolbar button tips. Defaults to true.
  • direction: rtl or ltr. Changes text direction to support right-to-left languages. Defaults to ltr.

Options example

Most options demonstrate the non-default behavior:

const editor = new EasyMDE({
    autofocus: true,
    autosave: {
        enabled: true,
        uniqueId: "MyUniqueID",
        delay: 1000,
        submit_delay: 5000,
        timeFormat: {
            locale: 'en-US',
            format: {
                year: 'numeric',
                month: 'long',
                day: '2-digit',
                hour: '2-digit',
                minute: '2-digit',
        text: "Autosaved: "
    blockStyles: {
        bold: "__",
        italic: "_",
    unorderedListStyle: "-",
    element: document.getElementById("MyID"),
    forceSync: true,
    hideIcons: ["guide", "heading"],
    indentWithTabs: false,
    initialValue: "Hello world!",
    insertTexts: {
        horizontalRule: ["", "\n\n-----\n\n"],
        image: ["![](http://", ")"],
        link: ["[", "](https://)"],
        table: ["", "\n\n| Column 1 | Column 2 | Column 3 |\n| -------- | -------- | -------- |\n| Text     | Text      | Text     |\n\n"],
    lineWrapping: false,
    minHeight: "500px",
    parsingConfig: {
        allowAtxHeaderWithoutSpace: true,
        strikethrough: false,
        underscoresBreakWords: true,
    placeholder: "Type here...",

    previewClass: "my-custom-styling",
    previewClass: ["my-custom-styling", "more-custom-styling"],

    previewRender: (plainText) => customMarkdownParser(plainText), // Returns HTML from a custom parser
    previewRender: (plainText, preview) => { // Async method
        setTimeout(() => {
            preview.innerHTML = customMarkdownParser(plainText);
        }, 250);

        return "Loading...";
    promptURLs: true,
    promptTexts: {
        image: "Custom prompt for URL:",
        link: "Custom prompt for URL:",
    renderingConfig: {
        singleLineBreaks: false,
        codeSyntaxHighlighting: true,
        sanitizerFunction: (renderedHTML) => {
            // Using DOMPurify and only allowing <b> tags
            return DOMPurify.sanitize(renderedHTML, {ALLOWED_TAGS: ['b']})
    shortcuts: {
        drawTable: "Cmd-Alt-T"
    showIcons: ["code", "table"],
    spellChecker: false,
    status: false,
    status: ["autosave", "lines", "words", "cursor"], // Optional usage
    status: ["autosave", "lines", "words", "cursor", {
        className: "keystrokes",
        defaultValue: (el) => {
            el.setAttribute('data-keystrokes', 0);
        onUpdate: (el) => {
            const keystrokes = Number(el.getAttribute('data-keystrokes')) + 1;
            el.innerHTML = `${keystrokes} Keystrokes`;
            el.setAttribute('data-keystrokes', keystrokes);
    }], // Another optional usage, with a custom status bar item that counts keystrokes
    styleSelectedText: false,
    sideBySideFullscreen: false,
    syncSideBySidePreviewScroll: false,
    tabSize: 4,
    toolbar: false,
    toolbarTips: false,

Toolbar icons

Below are the built-in toolbar icons (only some of which are enabled by default), which can be reorganized however you like. "Name" is the name of the icon, referenced in the JavaScript. "Action" is either a function or a URL to open. "Class" is the class given to the icon. "Tooltip" is the small tooltip that appears via the title="" attribute. Note that shortcut hints are added automatically and reflect the specified action if it has a key bind assigned to it (i.e. with the value of action set to bold and that of tooltip set to Bold, the final text the user will see would be "Bold (Ctrl-B)").

Additionally, you can add a separator between any icons by adding "|" to the toolbar array.

fa fa-bold
fa fa-italic
fa fa-strikethrough
fa fa-header
heading-smallertoggleHeadingSmallerSmaller Heading
fa fa-header
heading-biggertoggleHeadingBiggerBigger Heading
fa fa-lg fa-header
heading-1toggleHeading1Big Heading
fa fa-header header-1
heading-2toggleHeading2Medium Heading
fa fa-header header-2
heading-3toggleHeading3Small Heading
fa fa-header header-3
fa fa-code
fa fa-quote-left
unordered-listtoggleUnorderedListGeneric List
fa fa-list-ul
ordered-listtoggleOrderedListNumbered List
fa fa-list-ol
clean-blockcleanBlockClean block
fa fa-eraser
linkdrawLinkCreate Link
fa fa-link
imagedrawImageInsert Image
fa fa-picture-o
tabledrawTableInsert Table
fa fa-table
horizontal-ruledrawHorizontalRuleInsert Horizontal Line
fa fa-minus
previewtogglePreviewToggle Preview
fa fa-eye no-disable
side-by-sidetoggleSideBySideToggle Side by Side
fa fa-columns no-disable no-mobile
fullscreentoggleFullScreenToggle Fullscreen
fa fa-arrows-alt no-disable no-mobile
guideThis linkMarkdown Guide
fa fa-question-circle
fa fa-undo
fa fa-redo

Toolbar customization

Customize the toolbar using the toolbar option.

Only the order of existing buttons:

const easyMDE = new EasyMDE({
    toolbar: ["bold", "italic", "heading", "|", "quote"]

All information and/or add your own icons

const easyMDE = new EasyMDE({
    toolbar: [
            name: "bold",
            action: EasyMDE.toggleBold,
            className: "fa fa-bold",
            title: "Bold",
        "italics", // shortcut to pre-made button
            name: "custom",
            action: (editor) => {
                // Add your own code
            className: "fa fa-star",
            title: "Custom Button",
            attributes: { // for custom attributes
                id: "custom-id",
                "data-value": "custom value" // HTML5 data-* attributes need to be enclosed in quotation marks ("") because of the dash (-) in its name.
        "|" // Separator
        // [, ...]

Put some buttons on dropdown menu

const easyMDE = new EasyMDE({
    toolbar: [{
                name: "heading",
                action: EasyMDE.toggleHeadingSmaller,
                className: "fa fa-header",
                title: "Headers",
                name: "others",
                className: "fa fa-blind",
                title: "others buttons",
                children: [
                        name: "image",
                        action: EasyMDE.drawImage,
                        className: "fa fa-picture-o",
                        title: "Image",
                        name: "quote",
                        action: EasyMDE.toggleBlockquote,
                        className: "fa fa-percent",
                        title: "Quote",
                        name: "link",
                        action: EasyMDE.drawLink,
                        className: "fa fa-link",
                        title: "Link",
        // [, ...]

Keyboard shortcuts

EasyMDE comes with an array of predefined keyboard shortcuts, but they can be altered with a configuration option. The list of default ones is as follows:

Shortcut (Windows / Linux)Shortcut (macOS)Action

Here is how you can change a few, while leaving others untouched:

const editor = new EasyMDE({
    shortcuts: {
        "toggleOrderedList": "Ctrl-Alt-K", // alter the shortcut for toggleOrderedList
        "toggleCodeBlock": null, // unbind Ctrl-Alt-C
        "drawTable": "Cmd-Alt-T", // bind Cmd-Alt-T to drawTable action, which doesn't come with a default shortcut

Shortcuts are automatically converted between platforms. If you define a shortcut as "Cmd-B", on PC that shortcut will be changed to "Ctrl-B". Conversely, a shortcut defined as "Ctrl-B" will become "Cmd-B" for Mac users.

The list of actions that can be bound is the same as the list of built-in actions available for toolbar buttons.

Advanced use

Event handling

You can catch the following list of events: https://codemirror.net/doc/manual.html#events

const easyMDE = new EasyMDE();
easyMDE.codemirror.on("change", () => {

Removing EasyMDE from text area

You can revert to the initial text area by calling the toTextArea method. Note that this clears up the autosave (if enabled) associated with it. The text area will retain any text from the destroyed EasyMDE instance.

const easyMDE = new EasyMDE();
// ...
easyMDE = null;

If you need to remove registered event listeners (when the editor is not needed anymore), call easyMDE.cleanup().

Useful methods

The following self-explanatory methods may be of use while developing with EasyMDE.

const easyMDE = new EasyMDE();
easyMDE.isPreviewActive(); // returns boolean
easyMDE.isSideBySideActive(); // returns boolean
easyMDE.isFullscreenActive(); // returns boolean
easyMDE.clearAutosavedValue(); // no returned value

How it works

EasyMDE is a continuation of SimpleMDE.

SimpleMDE began as an improvement of lepture's Editor project, but has now taken on an identity of its own. It is bundled with CodeMirror and depends on Font Awesome.

CodeMirror is the backbone of the project and parses much of the Markdown syntax as it's being written. This allows us to add styles to the Markdown that's being written. Additionally, a toolbar and status bar have been added to the top and bottom, respectively. Previews are rendered by Marked using GitHub Flavored Markdown (GFM).

SimpleMDE fork

I originally made this fork to implement FontAwesome 5 compatibility into SimpleMDE. When that was done I submitted a pull request, which has not been accepted yet. This, and the project being inactive since May 2017, triggered me to make more changes and try to put new life into the project.

Changes include:

  • FontAwesome 5 compatibility
  • Guide button works when editor is in preview mode
  • Links are now https:// by default
  • Small styling changes
  • Support for Node 8 and beyond
  • Lots of refactored code
  • Links in preview will open in a new tab by default
  • TypeScript support

My intention is to continue development on this project, improving it and keeping it alive.

Hacking EasyMDE

You may want to edit this library to adapt its behavior to your needs. This can be done in some quick steps:

  1. Follow the prerequisites and installation instructions in the contribution guide;
  2. Do your changes;
  3. Run gulp command, which will generate files: dist/easymde.min.css and dist/easymde.min.js;
  4. Copy-paste those files to your code base, and you are done.


Want to contribute to EasyMDE? Thank you! We have a contribution guide just for you!

Author: Ionaru
Source Code: https://github.com/Ionaru/easy-markdown-editor
License: MIT license

#react-native #react 

I am Developer


Laravel 7/6 Image Validation

In this image validation in laravel 7/6, i will share with you how validate image and image file mime type like like jpeg, png, bmp, gif, svg, or webp before uploading image into database and server folder in laravel app.


#laravel image validation #image validation in laravel 7 #laravel image size validation #laravel image upload #laravel image validation max #laravel 6 image validation

Ahebwe  Oscar

Ahebwe Oscar


how to integrate CKEditor in Django

how to integrate CKEditor in Django

Welcome to my Blog, in this article we learn about how to integrate CKEditor in Django and inside this, we enable the image upload button to add an image in the blog from local. When I add a CKEditor first time in my project then it was very difficult for me but now I can easily implement it in my project so you can learn and implement CKEditor in your project easily.

how to integrate CKEditor in Django

#django #add image upload in ckeditor #add image upload option ckeditor #ckeditor image upload #ckeditor image upload from local #how to add ckeditor in django #how to add image upload plugin in ckeditor #how to install ckeditor in django #how to integrate ckeditor in django #image upload in ckeditor #image upload option in ckeditor

Guide To Image Color Analyzer In Python

In the modern age, we store all image data in digital memory. This can be your computer or your mobile device, or your cloud space. Whenever a device stores an image, it keeps it by breaking it into a very small mosaic or pixel form or simply saying that the computer breaks it into tiny box parts before storing any image. These small box parts can be considered as the pixel of the images. Therefore, as the size of tiles increases, the resolution of the image decreases, and the fineness of the tiles increases the resolution of the images.

The simplest way to explain the pixels is that they consist of Red, Green, and Blue. Pixels are the smallest unit of information about any image, which are arranged in the 2-dimensional grid.


If any of those three colours of any pixel is at full intensity, we can consider it is having a pixel value of 255. A pixel value can change between 0-255; if an image is fully red, then the RGB value is (255,0,0), where red is denoted by 255 and green and blue are 0. Below is the example where we can see the formation of a full-color image.

#developers corner #image color analyzer #opencv #opencv image processing #python #guide to image color analyzer in python

Beth  Cooper

Beth Cooper


Fast Read and Highly Scalable Optimized Social Activity Feed in Ruby


1. Scalable, Easy to Use Activity Feed Implementation.

Noteplease feel free to read this README in the formatted-for-print PDF Version.

1.1. Build & Gem Status

1.2. Test Coverage Map

Coverage Map

ImportantPlease read the (somewhat outdated) blog post Feeding Frenzy with SimpleFeed launching this library. Please leave comments or questions in the discussion thread at the bottom of that post. Thanks!

If you like to see this project grow, your donation of any amount is much appreciated.


This is a fast, pure-ruby implementation of an activity feed concept commonly used in social networking applications. The implementation is optimized for read-time performance and high concurrency (lots of users), and can be extended with custom backend providers. One data provider come bundled: the production-ready Redis provider.

Important Notes and Acknowledgements:

SimpleFeed does not depend on Ruby on Rails and is a pure-ruby implementation

SimpleFeed requires MRI Ruby 2.3 or later

SimpleFeed is currently live in production

SimpleFeed is open source thanks to the generosity of Simbi, Inc.

2. Features

SimpleFeed is a Ruby Library that can be plugged into any application to power a fast, Redis-based activity feed implementation so common on social networking sites. SimpleFeed offers the following features:

Modelled after graph-relationships similar to those on Twitter (bi-directional independent follow relationships):

Feed maintains a reverse-chronological order for heterogeneous events for each user.

It offers a constant time lookup for user’s feed, avoiding complex SQL joins to render it.

An API to read/paginate the feed for a given user

As well as to query the total unread items in the feed since it was last read by the user (typically shown on App icons).

Scalable and well performing Redis-based activity feed —

Scales to millions of users (will need to use Twemproxy to shard across several Redis instances)

Stores a fixed number of events for each unique "user" — the default is 1000. When the feed reaches 1001 events, the oldest event is offloaded from the activity.

Implementation properties:

Fully thread-safe implementation, writing events can be done in eg. Sidekiq.

Zero assumptions about what you are storing: the "data" is just a string. Serialize it with JSON, Marshall, YAML, or whatever.

You can create as many different types of feeds per application as you like (no Ruby Singletons used).

Customize mapping from user_id to the activity id based on your business logic (more on this later).

2.1. Publishing Events

Pushing events to the feed requires the following:

An Event consisting of:

String data that, most commonly, is a foreign key to a database table, but can really be anything you like.

Float at (typically, the timestamp, but can be any float number)

One or more user IDs, or event consumers: basically — who should see the event being published in their feed.

You publish an event by choosing a set of users whose feed should be updated. For example, were you re-implementing Twitter, your array of user_ids when publishing an event would be all followers of the Tweet’s author. While the data would probably be the Tweet ID.

NotePublishing an event to the feeds of N users is roughly a O(N * log(N)) operation

2.2. Consuming Events (Reading / Rendering the Feed)

You can fetch the chronologically ordered events for a particular user, using:

Methods on the activity such as paginate, fetch.

Reading feed for one user (or one type of user) is a O(1) operation

For each activity (user) you can fetch the total_count and the unread_count — the number of total and new items in the feed, where unread_count is computed since the user last reset their read status.

Note: total_count can never exceed the maximum size of the feed that you configured. The default is 1000 items.

The last_read timestamp can be automatically reset when the user is shown the feed via paginate method (whether or not its reset is controlled via a method argument).

2.3. Modifying User’s Feed

For any given user, you can:

Wipe their feed with wipe

Selectively remove items from the feed with delete_if.

For instance, if a user un-follows someone they shouldn’t see their events anymore, so you’d have to call delete_if and remove any events published by the unfollowed user.

2.4. Aggregating Events

This is a feature planned for future versions.

Help us much appreciated, even if you are not a developer, but have a clear idea about how it should work.

3. Commercial & Enterprise Support

Commercial Support plans are available for SimpleFeed through author’s ReinventONE Inc consulting company. Please reach out to kig AT reinvent.one for more information.

4. Usage

4.1. Example

Please read the additional documentation, including the examples, on the project’s Github Wiki.

Below is a screen shot of an actual activity feed powered by this library.


4.2. Providers

A key concept to understanding SimpleFeed gem, is that of a provider, which is effectively a persistence implementation for the events belonging to each user.

One providers are supplied with this gem: the production-ready :redis provider, which uses the sorted set Redis data type to store and fetch the events, scored by time (but not necessarily).

You initialize a provider by using the SimpleFeed.provider([Symbol]) method.

4.3. Configuration

Below we configure a feed called :newsfeed, which in this example will be populated with the various events coming from the followers.

require 'simplefeed'

# Let's define a Redis-based feed, and wrap Redis in a in a ConnectionPool.

SimpleFeed.define(:newsfeed) do |f|
  f.provider   = SimpleFeed.provider(:redis,
                                      redis: -> { ::Redis.new },
                                      pool_size: 10)
  f.per_page   = 50     # default page size
  f.batch_size = 10     # default batch size
  f.namespace  = 'nf'   # only needed if you use the same redis for more than one feed

After the feed is defined, the gem creates a similarly named method under the SimpleFeed namespace to access the feed. For example, given a name such as :newsfeed the following are all valid ways of accessing the feed:



You can also get a full list of currently defined feeds with SimpleFeed.feed_names method.

4.4. Reading from and writing to the feed

For the impatient, here is a quick way to get started with the SimpleFeed.

# Let's use the feed we defined earlier and create activity for all followers of the current user
publish_activity = SimpleFeed.newsfeed.activity(@current_user.followers.map(&:id))

# Store directly the value and the optional time stamp
publish_activity.store(value: 'hello', at: Time.now)
# => true  # indicates that value 'hello' was not yet in the feed (all events must be unique)

# Or, using the event form:
publish_activity.store(event: SimpleFeed::Event.new('good bye', Time.now))
# => true

As we’ve added the two events for these users, we can now read them back, sorted by the time and paginated:

# Let's grab the first follower
user_activity = SimpleFeed.newsfeed.activity(@current_user.followers.first.id)

# Now we can paginate the events, while resetting this user's last-read timestamp:
user_activity.paginate(page: 1, reset_last_read: true)
# [
#     [0] #<SimpleFeed::Event: value=hello, at=1480475294.0579991>,
#     [1] #<SimpleFeed::Event: value=good bye, at=1480472342.8979871>,
# ]
ImportantNote that we stored the activity by passing an array of users, but read the activity for just one user. This is how you’d use SimpleFeed most of the time, with the exception of the alternative mapping described below.

4.5. User IDs

In the previous section you saw the examples of publishing events to many feeds, and then reading the activity for a given user.

SimpleFeed supports user IDs that are either numeric (integer) or string-based (eg, UUID). Numeric IDs are best for simplest cases, and are the most compact. String keys offer the most flexibility.

4.5.1. Activity Keys

In the next section we’ll talk about generating keys from user_ids. We mean — Redis Hash keys that uniquely map a user (or a set of users) to the activity feed they should see.

There are up to two keys that are computed depending on the situation:

data_key is used to store the actual feed events

meta_key is used to store user’s last_read status

4.5.2. Partitioning Schema

NoteThis feature is only available in SimpleFeed Version 3+.

You can take advantage of string user IDs for situations where your feed requires keys to be composite for instance. Just remember that SimpleFeed does not care about what’s in your user ID, and even what you call "a user". It’s convenient to think of the activities in terms of users, because typically each user has a unique feed that only they see.

But you can just as easily use zip code as the unique activity ID, and create one feed of events per geographical location, that all folks living in that zip code share. But what about other countries?

Now you use partitioning scheme: make the "user_id" argument a combination iso_country_code.postal_code, eg for San Francisco, you’d use us.94107, but for Australia you could use, eg au.3148.

4.5.3. Relationship between an Activity and a User

One to One

In the most common case, you will have one activity per user.

For instance, in the Twitter example, each Twitter user has a unique tweeter feed that only they see.

The events are published when someone posts a tweet, to the array of all users that follow the Tweet author.

One to Many

However, SimpleFeed supports one additional use-case, where you might have one activity shared among many users.

Imagine a service that notifies residents of important announcements based on user’s zip code of residence.

We want this feed to work as follows:

All users that share a zip-code should see the same exact feed.

However, all users should never share the individual’s last_read status: so if two people read the same activity from the same zip code, their unread_count should change independently.

In terms of the activity keys, this means:

data_key should be based on the zip-code of each user, and be one to many with users.

meta_key should be based on the user ID as we want it to be 1-1 with users.

To support this use-case, SimpleFeed supports two optional transformer lambdas that can be applied to each user object when computing their activity feed hash key:

SimpleFeed.define(:zipcode_alerts) do |f|
  f.provider   = SimpleFeed.provider(:redis, redis: -> { ::Redis.new }, pool_size: 10)
  f.namespace  = 'zc'
  f.data_key_transformer = ->(user) { user.zip_code }  # actual feed data is stored once per zip code
  f.meta_key_transformer = ->(user) { user.id }        # last_read status is stored once per user

When you publish events into this feed, you would need to provide User objects that all respond to .zip_code method (based on the above configuration). Since the data is only defined by Zip Code, you probably don’t want to be publishing it via a giant array of users. Most likely, you’ll want to publish event based on the zip code, and consume them based on the user ID.

To support this user-case, let’s modify our transformer lambda (only the data one) as follows — so that it can support both the consuming read by a user case, and the publishing a feed by zip code case:

Alternatively, you could do something like this:

  f.data_key_transformer = ->(entity) do
    case entity
      when User
      when String # UUIDs
      when ZipCode, Numeric
        raise ArgumentError, "Invalid type #{entity.class.name}"

Just make sure that your users always have .zip_code defined, and that ZipCode.new(94107).to_i returns exactly the same thing as @user.zip_code.to_i or your users won’t see the feeds they are supposed to see.

4.6. The Two Forms of the Feed API

The feed API is offered in two forms:

single-user form, and

a batch (multi-user) form.

The method names and signatures are the same. The only difference is in what the methods return:

In the single user case, the return of, say, #total_count is an Integer value representing the total count for this user.

In the multi-user case, the return is a SimpleFeed::Response instance, that can be thought of as a Hash, that has the user IDs as the keys, and return results for each user as a value.

Please see further below the details about the Batch API.

Single-User API

In the examples below we show responses based on a single-user usage. As previously mentioned, the multi-user usage is the same, except what the response values are, and is discussed further down below.

Let’s take a look at a ruby session, which demonstrates return values of the feed operations for a single user:

require 'simplefeed'

# Define the feed using Redis provider, which uses
# SortedSet to keep user's events sorted.
SimpleFeed.define(:followers) do |f|
  f.provider = SimpleFeed.provider(:redis)
  f.per_page = 50
  f.per_page = 2

# Let's get the Activity instance that wraps this
activity = SimpleFeed.followers.activity(user_id)         # => [... complex object removed for brevity ]

# let's clear out this feed to ensure it's empty
activity.wipe                                             # => true

# Let's verify that the counts for this feed are at zero
activity.total_count                                      # => 0
activity.unread_count                                     # => 0

# Store some events
activity.store(value: 'hello')                            # => true
activity.store(value: 'goodbye', at: Time.now - 20)       # => true
activity.unread_count                                     # => 2

# Now we can paginate the events, while resetting this user's last-read timestamp:
activity.paginate(page: 1, reset_last_read: true)
# [
#     [0] #<SimpleFeed::Event: value=good bye, at=1480475294.0579991>,
#     [1] #<SimpleFeed::Event: value=hello, at=1480475294.057138>
# ]
# Now the unread_count should return 0 since the user just "viewed" the feed.
activity.unread_count                                     # => 0
activity.delete(value: 'hello')                           # => true
# the next method yields to a passed in block for each event in the user's feed, and deletes
# all events for which the block returns true. The return of this call is the
# array of all events that have been deleted for this user.
activity.delete_if do |event, user_id|
  event.value =~ /good/
# => [
#     [0] #<SimpleFeed::Event: value=good bye, at=1480475294.0579991>
# ]
activity.total_count                                      # => 0

You can fetch all items (optionally filtered by time) in the feed using #fetch, #paginate and reset the last_read timestamp by passing the reset_last_read: true as a parameter.


Batch (Multi-User) API

This API should be used when dealing with an array of users (or, in the future, a Proc or an ActiveRecord relation).

There are several reasons why this API should be preferred for operations that perform a similar action across a range of users: various provider implementations can be heavily optimized for concurrency, and performance.

The Redis Provider, for example, uses a notion of pipelining to send updates for different users asynchronously and concurrently.

Multi-user operations return a SimpleFeed::Response object, which can be used as a hash (keyed on user_id) to fetch the result of a given user.

# Using the Feed API with, eg #find_in_batches
@event_producer.followers.find_in_batches do |group|

  # Convert a group to the array of IDs and get ready to store
  activity = SimpleFeed.get(:followers).activity(group.map(&:id))
  activity.store(value: "#{@event_producer.name} liked an article")

  # => [Response] { user_id1 => [Boolean], user_id2 => [Boolean]... }
  # true if the value was stored, false if it wasn't.

Activity Feed DSL (Domain-Specific Language)

The library offers a convenient DSL for adding feed functionality into your current scope.

To use the module, just include SimpleFeed::DSL where needed, which exports just one primary method #with_activity. You call this method and pass an activity object created for a set of users (or a single user), like so:

require 'simplefeed/dsl'
include SimpleFeed::DSL

feed = SimpleFeed.newsfeed
activity = feed.activity(current_user.id)
data_to_store = %w(France Germany England)

def report(value)
  puts value

with_activity(activity, countries: data_to_store) do
  # we can use countries as a variable because it was passed above in **opts
  countries.each do |country|
    # we can call #store without a receiver because the block is passed to
    # instance_eval
    store(value: country) { |result| report(result ? 'success' : 'failure') }
    # we can call #report inside the proc because it is evaluated in the
    # outside context of the #with_activity

    # now let's print a color ASCII dump of the entire feed for this user:
  printf "Activity counts are: %d unread of %d total\n", unread_count, total_count

The DSL context has access to two additional methods:

#event(value, at) returns a fully constructed SimpleFeed::Event instance

#color_dump prints to STDOUT the ASCII text dump of the current user’s activities (events), as well as the counts and the last_read shown visually on the time line.


Below is an example output of color_dump method, which is intended for the debugging purposes.

sf color dump

Figure 1. #color_dump method output


5. Complete API

For completeness sake we’ll show the multi-user API responses only. For a single-user use-case the response is typically a scalar, and the input is a singular user_id, not an array of ids.

Multi-User (Batch) API

Each API call at this level expects an array of user IDs, therefore the return value is an object, SimpleFeed::Response, containing individual responses for each user, accessible via response[user_id] method.

@multi = SimpleFeed.get(:feed_name).activity(User.active.map(&:id))

@multi.store(value:, at:)
# => [Response] { user_id => [Boolean], ... } true if the value was stored, false if it wasn't.

@multi.delete(value:, at:)
# => [Response] { user_id => [Boolean], ... } true if the value was removed, false if it didn't exist

@multi.delete_if do |event, user_id|
  # if the block returns true, the event is deleted and returned
# => [Response] { user_id => [deleted_event1, deleted_event2, ...], ... }

# Wipe the feed for a given user(s)
# => [Response] { user_id => [Boolean], ... } true if user activity was found and deleted, false otherwise

# Return a paginated list of all items, optionally with the total count of items
@multi.paginate(page: 1,
                per_page: @multi.feed.per_page,
                with_total: false,
                reset_last_read: false)
# => [Response] { user_id => [Array]<Event>, ... }
# Options:
#   reset_last_read: false — reset last read to Time.now (true), or the provided timestamp
#   with_total: true — returns a hash for each user_id:
#        => [Response] { user_id => { events: Array<Event>, total_count: 3 }, ... }

# Return un-paginated list of all items, optionally filtered
@multi.fetch(since: nil, reset_last_read: false)
# => [Response] { user_id => [Array]<Event>, ... }
# Options:
#   reset_last_read: false — reset last read to Time.now (true), or the provided timestamp
#   since: <timestamp> — if provided, returns all items posted since then
#   since: :last_read — if provided, returns all unread items and resets +last_read+

# => [Response] { user_id => [Time] last_read, ... }

# => [Response] { user_id => [Integer, String] total_count, ... }

# => [Response] { user_id => [Integer, String] unread_count, ... }

# => [Response] { user_id => [Time] last_read, ... }

6. Providers

As we’ve discussed above, a provider is an underlying persistence mechanism implementation.

It is the intention of this gem that:

it should be easy to write new providers

it should be easy to swap out providers

One provider is included with this gem:

6.1. SimpleFeed::Providers::Redis::Provider

Redis Provider is a production-ready persistence adapter that uses the sorted set Redis data type.

This provider is optimized for large writes and can use either a single Redis instance for all users of your application, or any number of Redis shards by using a Twemproxy in front of the Redis shards.

If you set environment variable REDIS_DEBUG to true and run the example (see below) you will see every operation redis performs. This could be useful in debugging an issue or submitting a bug report.

7. Running the Examples and Specs

Source code for the gem contains the examples folder with an example file that can be used to test out the providers, and see what they do under the hood.

Both the specs and the example requires a local redis instance to be available.

To run it, checkout the source of the library, and then:

git clone https://github.com/kigster/simple-feed.git
cd simple-feed

# on OSX with HomeBrew:
brew install redis
brew services start redis

# check that your redis is up:
redis-cli info

# install bundler and other dependencies
gem install bundler --version 2.1.4
bundle install
bundle exec rspec  # make sure tests are passing

# run the example:
ruby examples/redis_provider_example.rb

The above command will help you download, setup all dependencies, and run the examples for a single user:

running example

Figure 2. Running Redis Example in a Terminal

If you set REDIS_DEBUG variable prior to running the example, you will be able to see every single Redis command executed as the example works its way through. Below is a sample output:

running example redis debug

Figure 3. Running Redis Example with REDIS_DEBUG set

7.1. Generating Ruby API Documentation

rake doc

This should use Yard to generate the documentation, and open your browser once it’s finished.

7.2. Installation

Add this line to your application’s Gemfile:

gem 'simple-feed'

And then execute:

$ bundle

Or install it yourself as:

$ gem install simple-feed

7.3. Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

7.4. Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/kigster/simple-feed

7.5. License

The gem is available as open source under the terms of the MIT License.

FOSSA Scan Status

7.6. Acknowledgements

This project is conceived and sponsored by Simbi, Inc..

Author’s personal experience at Wanelo, Inc. has served as an inspiration.

Author: kigster
Source code: https://github.com/kigster/simple-feed
License: MIT license

#ruby   #ruby-on-rails