Arvel Miller

Arvel Miller

1624956517

Resize Image in Browser with High Quality and High Speed - Pica

pica - high quality image resize in browser

Resize images in browser without pixelation and reasonably fast. Autoselect the best of available technologies: webworkers, webassembly, createImageBitmap, pure JS.

demo

With pica you can:

  • Reduce upload size for large images, saving upload time.
  • Saves server resources on image processing.
  • Generate thumbnails in browser.
  • …

Note. If you need File/Blob resize (from form’s file input), consider use image-blob-reduce. It has additional machinery to process orientation, keep EXIF metadata and so on.

Migration from pica v6 to pica v7

Multiply unsharpAmount by 2, divide unsharpThreshold by 2, example:

  • pica@6: pica.resize(a, b, { unsharpAmount: 80, unsharpThreshold: 2 })
  • pica@7: pica.resize(a, b, { unsharpAmount: 160, unsharpThreshold: 1 })

Prior to use

Here is a short list of problems you can face:

  • Loading image:
    • Due to JS security restrictions, you can process images from the same domain or local files only. If you load images from remote domain use proper Access-Control-Allow-Origin header.
    • iOS has a memory limits for canvas elements, that may cause problems in some cases, more details.
    • If your source data is jpeg image, it can be rotated. Consider use image-blob-reduce.
  • Saving image:
    • Some ancient browsers do not support canvas.toBlob() method. Use pica.toBlob(), it includes required shim.
    • For jpeg source, it’s a good idea to keep exif data. Consider use image-blob-reduce.
  • Quality
    • JS canvas does not support access to info about gamma correction. Bitmaps have 8 bits per channel. That causes some quality loss, because with gamma correction precision could be 12 bits per channel.
    • Precision loss will not be noticeable for ordinary images like kittens, selfies and so on. But we don’t recommend this library for resizing professional quality images.

Install

npm install pica

Use

const pica = require('pica')();

// Resize from Canvas/Image to another Canvas
pica.resize(from, to, {
  unsharpAmount: 160,
  unsharpRadius: 0.6,
  unsharpThreshold: 1
})
.then(result => console.log('resize done!'));

// Resize & convert to blob
pica.resize(from, to)
  .then(result => pica.toBlob(result, 'image/jpeg', 0.90))
  .then(blob => console.log('resized to canvas & created blob!'));

API

new Pica(config)

Create resizer instance with given config (optional):

  • tile - tile width/height. Images are processed by regions, to restrict peak memory use. Default 1024.
  • features - list of features to use. Default is [ 'js', 'wasm', 'ww' ]. Can be [ 'js', 'wasm', 'cib', 'ww' ] or [ 'all' ].
  • idle - cache timeout, ms. Webworkers create is not fast. This option allow reuse webworkers effectively. Default 2000.
  • concurrency - max webworkers pool size. Default is autodetected CPU count, but not more than 4.
  • createCanvas - function which returns a new canvas, used internally by pica. Default returns a canvas element, but this function could return an OffscreenCanvas instead (to run pica in a Service Worker). Function signature: createCanvas(width: number, height: number): Canvas

Important! Latest browsers may support resize via createImageBitmap. This feature is supported (cib) but disabled by default and not recommended for use. So:

  • createImageBitmap() is used for non-blocking image decode (when available, without downscale).
  • It’s resize feature is blocked by default pica config. Enable it only on your own risk. Result with enabled cib will depend on your browser. Result without cib will be predictable and good.

resize(from, to, options) -> Promise

Resize image from one canvas (or image) to another. Sizes are taken from source and destination objects.

  • from - source, can be Canvas, Image or ImageBitmap.
  • to - destination canvas, its size is supposed to be non-zero.
  • options - quality (number) or object:
    • quality - 0…3. Default = 3 (lanczos, win=3).
    • alpha - use alpha channel. Default = false.
    • unsharpAmount - >=0, in percents. Default = 0 (off). Usually between 100 to 200 is good.
    • unsharpRadius - 0.5…2.0. By default it’s not set. Radius of Gaussian blur. If it is less than 0.5, Unsharp Mask is off. Big values are clamped to 2.0.
    • unsharpThreshold - 0…255. Default = 0. Threshold for applying unsharp mask.
    • cancelToken - Promise instance. If defined, current operation will be terminated on rejection.

Result is Promise, resolved with to on success.

(!) If you need to process multiple images, do it sequentially to optimize CPU & memory use. Pica already knows how to use multiple cores (if browser allows).

toBlob(canvas, mimeType [, quality]) -> Promise

Convenience method, similar to canvas.toBlob(), but with promise interface & polyfill for old browsers.

resizeBuffer(options) -> Promise

Supplementary method, not recommended for direct use. Resize Uint8Array with raw RGBA bitmap (don’t confuse with jpeg / png / … binaries). It does not use tiles & webworkers. Left for special cases when you really need to process raw binary data (for example, if you decode jpeg files “manually”).

  • options:
    • src - Uint8Array with source data.
    • width - src image width.
    • height - src image height.
    • toWidth - output width, >=0, in pixels.
    • toHeight - output height, >=0, in pixels.
    • quality - 0…3. Default = 3 (lanczos, win=3).
    • alpha - use alpha channel. Default = false.
    • unsharpAmount - >=0, in percents. Default = 0 (off). Usually between 50 to 100 is good.
    • unsharpRadius - 0.5…2.0. Radius of Gaussian blur. If it is less than 0.5, Unsharp Mask is off. Big values are clamped to 2.0.
    • unsharpThreshold - 0…255. Default = 0. Threshold for applying unsharp mask.
    • dest - Optional. Output buffer to write data, if you don’t wish pica to create new one.

Result is Promise, resolved with resized rgba buffer.

What is “quality”

Pica has presets to adjust speed/quality ratio. Simply use quality option param:

  • 0 - Box filter, window 0.5px
  • 1 - Hamming filter, window 1.0px
  • 2 - Lanczos filter, window 2.0px
  • 3 - Lanczos filter, window 3.0px

In real world you will never need to change default (max) quality. All this variations were implemented to better understand resize math :)

Unsharp mask

After scale down image can look a bit blured. It’s good idea to sharpen it a bit. Pica has built-in “unsharp mask” filter (off by default). Set unsharpAmount to positive number to activate the filter.

Filter’s parameters are similar to ones from Photoshop. We recommend to start with unsharpAmount = 160, unsharpRadius = 0.6 and unsharpThreshold = 1. There is a correspondence between UnsharpMask parameters in popular graphics software.

Browser support

We didn’t have time to test all possible combinations, but in general:

Note. Though you can run this package on node.js, browsers are the main target platform. On server side we recommend to use sharp.

References

You can find these links useful:

pica for enterprise

Available as part of the Tidelift Subscription.

The maintainers of pica and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source packages you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact packages you use. Learn more.

Download Details:

Author: nodeca
The Demo/Documentation: View The Demo/Documentation
Download Link: Download The Source Code
Official Website: https://github.com/nodeca/pica
License: MIT

#image #pica #web-development #webdev

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Resize Image in Browser with High Quality and High Speed - Pica
Queenie Davis

Queenie Davis

1653123600

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

Preview

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:

<textarea></textarea>
<script>
const easyMDE = new EasyMDE();
</script>

Alternatively you can select a specific textarea, via JavaScript:

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

Editor functions

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

<script>
easyMDE.value();
</script>

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

<script>
easyMDE.value('New input for **EasyMDE**');
</script>

Configuration

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.

NameActionTooltip
Class
boldtoggleBoldBold
fa fa-bold
italictoggleItalicItalic
fa fa-italic
strikethroughtoggleStrikethroughStrikethrough
fa fa-strikethrough
headingtoggleHeadingSmallerHeading
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
codetoggleCodeBlockCode
fa fa-code
quotetoggleBlockquoteQuote
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
undoundoUndo
fa fa-undo
redoredoRedo
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
Ctrl-'Cmd-'"toggleBlockquote"
Ctrl-BCmd-B"toggleBold"
Ctrl-ECmd-E"cleanBlock"
Ctrl-HCmd-H"toggleHeadingSmaller"
Ctrl-ICmd-I"toggleItalic"
Ctrl-KCmd-K"drawLink"
Ctrl-LCmd-L"toggleUnorderedList"
Ctrl-PCmd-P"togglePreview"
Ctrl-Alt-CCmd-Alt-C"toggleCodeBlock"
Ctrl-Alt-ICmd-Alt-I"drawImage"
Ctrl-Alt-LCmd-Alt-L"toggleOrderedList"
Shift-Ctrl-HShift-Cmd-H"toggleHeadingBigger"
F9F9"toggleSideBySide"
F11F11"toggleFullScreen"

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", () => {
    console.log(easyMDE.value());
});

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.toTextArea();
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.

Contributing

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 

Arvel Miller

Arvel Miller

1624956517

Resize Image in Browser with High Quality and High Speed - Pica

pica - high quality image resize in browser

Resize images in browser without pixelation and reasonably fast. Autoselect the best of available technologies: webworkers, webassembly, createImageBitmap, pure JS.

demo

With pica you can:

  • Reduce upload size for large images, saving upload time.
  • Saves server resources on image processing.
  • Generate thumbnails in browser.
  • …

Note. If you need File/Blob resize (from form’s file input), consider use image-blob-reduce. It has additional machinery to process orientation, keep EXIF metadata and so on.

Migration from pica v6 to pica v7

Multiply unsharpAmount by 2, divide unsharpThreshold by 2, example:

  • pica@6: pica.resize(a, b, { unsharpAmount: 80, unsharpThreshold: 2 })
  • pica@7: pica.resize(a, b, { unsharpAmount: 160, unsharpThreshold: 1 })

Prior to use

Here is a short list of problems you can face:

  • Loading image:
    • Due to JS security restrictions, you can process images from the same domain or local files only. If you load images from remote domain use proper Access-Control-Allow-Origin header.
    • iOS has a memory limits for canvas elements, that may cause problems in some cases, more details.
    • If your source data is jpeg image, it can be rotated. Consider use image-blob-reduce.
  • Saving image:
    • Some ancient browsers do not support canvas.toBlob() method. Use pica.toBlob(), it includes required shim.
    • For jpeg source, it’s a good idea to keep exif data. Consider use image-blob-reduce.
  • Quality
    • JS canvas does not support access to info about gamma correction. Bitmaps have 8 bits per channel. That causes some quality loss, because with gamma correction precision could be 12 bits per channel.
    • Precision loss will not be noticeable for ordinary images like kittens, selfies and so on. But we don’t recommend this library for resizing professional quality images.

Install

npm install pica

Use

const pica = require('pica')();

// Resize from Canvas/Image to another Canvas
pica.resize(from, to, {
  unsharpAmount: 160,
  unsharpRadius: 0.6,
  unsharpThreshold: 1
})
.then(result => console.log('resize done!'));

// Resize & convert to blob
pica.resize(from, to)
  .then(result => pica.toBlob(result, 'image/jpeg', 0.90))
  .then(blob => console.log('resized to canvas & created blob!'));

API

new Pica(config)

Create resizer instance with given config (optional):

  • tile - tile width/height. Images are processed by regions, to restrict peak memory use. Default 1024.
  • features - list of features to use. Default is [ 'js', 'wasm', 'ww' ]. Can be [ 'js', 'wasm', 'cib', 'ww' ] or [ 'all' ].
  • idle - cache timeout, ms. Webworkers create is not fast. This option allow reuse webworkers effectively. Default 2000.
  • concurrency - max webworkers pool size. Default is autodetected CPU count, but not more than 4.
  • createCanvas - function which returns a new canvas, used internally by pica. Default returns a canvas element, but this function could return an OffscreenCanvas instead (to run pica in a Service Worker). Function signature: createCanvas(width: number, height: number): Canvas

Important! Latest browsers may support resize via createImageBitmap. This feature is supported (cib) but disabled by default and not recommended for use. So:

  • createImageBitmap() is used for non-blocking image decode (when available, without downscale).
  • It’s resize feature is blocked by default pica config. Enable it only on your own risk. Result with enabled cib will depend on your browser. Result without cib will be predictable and good.

resize(from, to, options) -> Promise

Resize image from one canvas (or image) to another. Sizes are taken from source and destination objects.

  • from - source, can be Canvas, Image or ImageBitmap.
  • to - destination canvas, its size is supposed to be non-zero.
  • options - quality (number) or object:
    • quality - 0…3. Default = 3 (lanczos, win=3).
    • alpha - use alpha channel. Default = false.
    • unsharpAmount - >=0, in percents. Default = 0 (off). Usually between 100 to 200 is good.
    • unsharpRadius - 0.5…2.0. By default it’s not set. Radius of Gaussian blur. If it is less than 0.5, Unsharp Mask is off. Big values are clamped to 2.0.
    • unsharpThreshold - 0…255. Default = 0. Threshold for applying unsharp mask.
    • cancelToken - Promise instance. If defined, current operation will be terminated on rejection.

Result is Promise, resolved with to on success.

(!) If you need to process multiple images, do it sequentially to optimize CPU & memory use. Pica already knows how to use multiple cores (if browser allows).

toBlob(canvas, mimeType [, quality]) -> Promise

Convenience method, similar to canvas.toBlob(), but with promise interface & polyfill for old browsers.

resizeBuffer(options) -> Promise

Supplementary method, not recommended for direct use. Resize Uint8Array with raw RGBA bitmap (don’t confuse with jpeg / png / … binaries). It does not use tiles & webworkers. Left for special cases when you really need to process raw binary data (for example, if you decode jpeg files “manually”).

  • options:
    • src - Uint8Array with source data.
    • width - src image width.
    • height - src image height.
    • toWidth - output width, >=0, in pixels.
    • toHeight - output height, >=0, in pixels.
    • quality - 0…3. Default = 3 (lanczos, win=3).
    • alpha - use alpha channel. Default = false.
    • unsharpAmount - >=0, in percents. Default = 0 (off). Usually between 50 to 100 is good.
    • unsharpRadius - 0.5…2.0. Radius of Gaussian blur. If it is less than 0.5, Unsharp Mask is off. Big values are clamped to 2.0.
    • unsharpThreshold - 0…255. Default = 0. Threshold for applying unsharp mask.
    • dest - Optional. Output buffer to write data, if you don’t wish pica to create new one.

Result is Promise, resolved with resized rgba buffer.

What is “quality”

Pica has presets to adjust speed/quality ratio. Simply use quality option param:

  • 0 - Box filter, window 0.5px
  • 1 - Hamming filter, window 1.0px
  • 2 - Lanczos filter, window 2.0px
  • 3 - Lanczos filter, window 3.0px

In real world you will never need to change default (max) quality. All this variations were implemented to better understand resize math :)

Unsharp mask

After scale down image can look a bit blured. It’s good idea to sharpen it a bit. Pica has built-in “unsharp mask” filter (off by default). Set unsharpAmount to positive number to activate the filter.

Filter’s parameters are similar to ones from Photoshop. We recommend to start with unsharpAmount = 160, unsharpRadius = 0.6 and unsharpThreshold = 1. There is a correspondence between UnsharpMask parameters in popular graphics software.

Browser support

We didn’t have time to test all possible combinations, but in general:

Note. Though you can run this package on node.js, browsers are the main target platform. On server side we recommend to use sharp.

References

You can find these links useful:

pica for enterprise

Available as part of the Tidelift Subscription.

The maintainers of pica and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source packages you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact packages you use. Learn more.

Download Details:

Author: nodeca
The Demo/Documentation: View The Demo/Documentation
Download Link: Download The Source Code
Official Website: https://github.com/nodeca/pica
License: MIT

#image #pica #web-development #webdev

Dexter Goodwin

Dexter Goodwin

1644628080

Pica: Resize Image in Browser with High Quality and High Speed

pica - high quality image resize in browser 

Resize images in browser without pixelation and reasonably fast. Autoselect the best of available technologies: webworkers, webassembly, createImageBitmap, pure JS.

demo

With pica you can:

  • Reduce upload size for large images, saving upload time.
  • Saves server resources on image processing.
  • Generate thumbnails in browser.
  • ...

Note. If you need File/Blob resize (from form's file input), consider use image-blob-reduce. It has additional machinery to process orientation, keep EXIF metadata and so on.

Migration from pica v6 to pica v7

Multiply unsharpAmount by 2, divide unsharpThreshold by 2, example:

  • pica@6: pica.resize(a, b, { unsharpAmount: 80, unsharpThreshold: 2 })
  • pica@7: pica.resize(a, b, { unsharpAmount: 160, unsharpThreshold: 1 })

Prior to use

Here is a short list of problems you can face:

  • Loading image:
    • Due to JS security restrictions, you can process images from the same domain or local files only. If you load images from remote domain use proper Access-Control-Allow-Origin header.
    • iOS has a memory limits for canvas elements, that may cause problems in some cases, more details.
    • If your source data is jpeg image, it can be rotated. Consider use image-blob-reduce.
  • Saving image:
    • Some ancient browsers do not support canvas.toBlob() method. Use pica.toBlob(), it includes required shim.
    • For jpeg source, it's a good idea to keep exif data. Consider use image-blob-reduce.
  • Quality
    • JS canvas does not support access to info about gamma correction. Bitmaps have 8 bits per channel. That causes some quality loss, because with gamma correction precision could be 12 bits per channel.
    • Precision loss will not be noticeable for ordinary images like kittens, selfies and so on. But we don't recommend this library for resizing professional quality images.

Install

npm install pica

Use

const pica = require('pica')();

// Resize from Canvas/Image to another Canvas
pica.resize(from, to)
  .then(result => console.log('resize done!'));

// Resize & convert to blob
pica.resize(from, to)
  .then(result => pica.toBlob(result, 'image/jpeg', 0.90))
  .then(blob => console.log('resized to canvas & created blob!'));

API

new Pica(config)

Create resizer instance with given config (optional):

  • tile - tile width/height. Images are processed by regions, to restrict peak memory use. Default 1024.
  • features - list of features to use. Default is [ 'js', 'wasm', 'ww' ]. Can be [ 'js', 'wasm', 'cib', 'ww' ] or [ 'all' ]. Note, cib is buggy in Chrome and not supports default mks2013 filter.
  • idle - cache timeout, ms. Webworkers create is not fast. This option allow reuse webworkers effectively. Default 2000.
  • concurrency - max webworkers pool size. Default is autodetected CPU count, but not more than 4.
  • createCanvas - function which returns a new canvas, used internally by pica. Default returns a <canvas> element, but this function could return an OffscreenCanvas instead (to run pica in a Service Worker). Function signature: createCanvas(width: number, height: number): Canvas

Important! Latest browsers may support resize via createImageBitmap. This feature is supported (cib) but disabled by default and not recommended for use. So:

  • createImageBitmap() is used for non-blocking image decode (when available, without downscale).
  • It's resize feature is blocked by default pica config. Enable it only on your own risk. Result with enabled cib will depend on your browser. Result without cib will be predictable and good.

.resize(from, to, options) -> Promise

Resize image from one canvas (or image) to another. Sizes are taken from source and destination objects.

  • from - source, can be Canvas, Image or ImageBitmap.
  • to - destination canvas, its size is supposed to be non-zero.
  • options - quality (number) or object:
    • quality (deprecated, use .filter instead) - 0..3.
    • filter - filter name (Default - mks2013). See resize_filter_info.js for details. mks2013 does both resize and sharpening, it's optimal and not recommended to change.
    • unsharpAmount - >=0. Default = 0 (off). Usually value between 100 to 200 is good. Note, mks2013 filter already does optimal sharpening.
    • unsharpRadius - 0.5..2.0. By default it's not set. Radius of Gaussian blur. If it is less than 0.5, Unsharp Mask is off. Big values are clamped to 2.0.
    • unsharpThreshold - 0..255. Default = 0. Threshold for applying unsharp mask.
    • cancelToken - Promise instance. If defined, current operation will be terminated on rejection.

Result is Promise, resolved with to on success.

(!) If you need to process multiple images, do it sequentially to optimize CPU & memory use. Pica already knows how to use multiple cores (if browser allows).

.toBlob(canvas, mimeType [, quality]) -> Promise

Convenience method, similar to canvas.toBlob(), but with promise interface & polyfill for old browsers.

.resizeBuffer(options) -> Promise

Supplementary method, not recommended for direct use. Resize Uint8Array with raw RGBA bitmap (don't confuse with jpeg / png / ... binaries). It does not use tiles & webworkers. Left for special cases when you really need to process raw binary data (for example, if you decode jpeg files "manually").

  • options:
    • src - Uint8Array with source data.
    • width - src image width.
    • height - src image height.
    • toWidth - output width, >=0, in pixels.
    • toHeight - output height, >=0, in pixels.
    • quality (deprecated, use .filter instead) - 0..3.
    • filter - filter name (Default - mks2013). See resize_filter_info.js for details. mks2013 does both resize and sharpening, it's optimal and not recommended to change.
    • unsharpAmount - >=0. Default = 0 (off). Usually value between 100 to 200 is good. Note, mks2013 filter already does optimal sharpening.
    • unsharpRadius - 0.5..2.0. Radius of Gaussian blur. If it is less than 0.5, Unsharp Mask is off. Big values are clamped to 2.0.
    • unsharpThreshold - 0..255. Default = 0. Threshold for applying unsharp mask.
    • dest - Optional. Output buffer to write data, if you don't wish pica to create new one.

Result is Promise, resolved with resized rgba buffer.

What is "quality"

Pica has presets to adjust speed/quality ratio. Simply use quality option param:

  • 0 - Box filter, window 0.5px
  • 1 - Hamming filter, window 1.0px
  • 2 - Lanczos filter, window 2.0px
  • 3 - Lanczos filter, window 3.0px

In real world you will never need to change default (max) quality. All this variations were implemented to better understand resize math :)

Unsharp mask

After scale down image can look a bit blured. It's good idea to sharpen it a bit. Pica has built-in "unsharp mask" filter (off by default). Set unsharpAmount to positive number to activate the filter.

Filter's parameters are similar to ones from Photoshop. We recommend to start with unsharpAmount = 160, unsharpRadius = 0.6 and unsharpThreshold = 1. There is a correspondence between UnsharpMask parameters in popular graphics software.

Browser support

We didn't have time to test all possible combinations, but in general:

Note. Though you can run this package on node.js, browsers are the main target platform. On server side we recommend to use sharp.

References

You can find these links useful:

pica for enterprise

Available as part of the Tidelift Subscription.

The maintainers of pica and thousands of other packages are working with Tidelift to deliver commercial support and maintenance for the open source packages you use to build your applications. Save time, reduce risk, and improve code health, while paying the maintainers of the exact packages you use. Learn more.

Author: Nodeca
Source Code: https://github.com/nodeca/pica 
License: MIT License

#javascript #image

I am Developer

1597469369

Crop and Resize Image Before Upload In Laravel Using with jQuery Copper JS

Crop and resize image size before upload in laravel using jquery copper js. In this post, i will show you how to crop and resize image size in laravel using jQuery copper js in laravel.

This laravel crop image before upload using cropper js looks like:

laravel crop image before upload

Laravel Crop Image Before Uploading using Cropper js Tutorial

Laravel crop image before upload tutorial, follow the following steps and learn how to use cropper js to crop image before uploading in laravel app:

  • Step 1: Install New Laravel App
  • Step 2: Add Database Details
  • Step 3: Create Migration & Model
  • Step 4: Add Route
  • Step 5: Create Controller By Artisan
  • Step 6: Create Blade View
  • Step 7: Make Upload Directory
  • Step 8: Start Development Server

Read More => https://www.tutsmake.com/laravel-crop-image-before-upload-using-jquery-copper-js/

Live Demo Laravel Crop image Before Upload.

#laravel crop image before upload, #laravel crop and resize image using cropper.js #ajax image upload and crop with jquery and laravel #crop and upload image ajax jquery laravel #crop image while uploading with jquery laravel #image crop and upload using jquery with laravel ajax

I am Developer

1616903936

Node JS Resize Image Before Upload Example

Resize image before upload using multer, sharp with node js and express js. In this node js tutorial, you will learn how to resize image before upload using multer, sharp with node js and express js.

Image upload is the basic requirement of any application. So this example will guide you step by step on how to resize image before upload using multer in node js. And you can understand a concept of node js compress image before upload.

Node Express Resize Image Before Upload Tutorial Example

Step 1 - Create Node JS App

Step 2 - Install Express and Multer Dependencies

Step 3 - Import Dependencies in Server.js File

Step 4 - Create Server.js File

Step 5 - Create Form

Step 6 - Run Development Server

https://www.tutsmake.com/node-js-resize-image-before-upload-using-multer-sharp-example/

#how to upload multiple image in node js #resize image in nodejs #image processing in node js #node js image upload resize