Share your code. npm Orgs help your team discover, share, and reuse code. Create a free org »

    crop-rotate-resize-in-browserpublic

    Image Manipulation Methods

    This library exposes a simple API for retrieving, sending, and manipulating images in the browser.

    The demo allows the user to select a photo from his or her computer, crop and rotate the image, and upload directly to Google Cloud Storage using the gcs-signed-urls NPM module.

    See demo: http://floating-spire-3371.herokuapp.com/

    Features

    • Hermite sampling is used to resize images rather than canvas's drawImage. This results in a much better quality photo after resizing. See this stackoverflow.
    • The library parses EXIF meta data to always provide the correct orientation. Photos taken with older cameras rely on EXIF metadata and the browser does not take this metadata into account. See this article.

    Install

    The library is available on bower and npm.

    bower install image-manipulation
    

    OR

    npm install image-manipulation
    

    You can access via "window.ImageMethods"

    Examples

    Manipulators

    A canvas can be changed using the manipulator methods: rotate, resize and crop. One can use the static methods.

    var canvas = document.querySelector("canvas");
    
    var resizedCanvas = ImageMethods.resize(canvas, 100, 100);
    
    var rotatedCanvas = ImageMethods.rotate(resizedCanvas, 90);
    
    document.body.append(rotatedCanvas);
    

    or one can also make a manipulator instance and chain these methods.

    var canvas = document.querySelector("canvas");
    
    var manipulator = new ImageMethods(canvas);
    
    manipulator.resize(100, 100).rotate(90);
    
    document.body.append(manipulator.canvas);
    

    Retrieving images to manipulate

    Grab an image from the DOM and flip it upside down

    var img = document.querySelector("img"),
    	canvas = ImageMethods.getCanvasFromImage(img);
    
    img.src = ImageMethods.rotate(canvas, 180).toDataURL();
    

    Grab an image from an input element (<input type="file" accept="image/*">), create a thumbnail at 200px width and add it to the screen.

    document.querySelector("input[type=file]").onchange = function(e) {
    	ImageMethods.getCanvasFromFile(e.files[0], function(canvas) {
    		
    		var manipulator = new ImageMethods(canvas);
    		
    		manipulator.resize(200);
    		
    		// Add our resized canvas to the screen
    		document.body.appendChild(manipulator.canvas)
    		
    	});
    };
    

    Download an image from the server, cut it into 2 pieces, and upload the pieces back to the server via xhr2

    ImageMethods.getCanvasFromUrl("/path/to/image.jpg", function(canvas, file) {
    	
    	var manipulator = new ImageMethods(canvas);
    	
    	var piece1Canvas = ImageMethods.crop(0, 0, canvas.width/2, canvas.height),
    		piece2Canvas = ImageMethods.crop(canvas.width/2, 0, canvas.width/2, canvas.height),
    	
    	// Put together FormData for submission
    	var formData = new FormData();
    	formData.append("images[]", ImageMethods.toBlob(piece1Canvas), file.name);
    	formData.append("images[]", ImageMethods.toBlob(piece2Canvas), file.name);
    	
    	// Post to server
    	var xhr = new XMLHttpRequest();
    	xhr.open("POST", "/my/upload-handler", true);
    	
    });
    

    Reference

    Chainable instance methods

    // Create an manipulator instance likeso:
    var instance = new ImageMethods(canvas)
    
    // The canvas element can be exposed
    instance.canvas
    
    // You can convert your instance into a blob 
    var blob = instance.toBlob();
    
    rotate(degrees)
    crop(x, y, width, height)
    resize(width, height)

    Static methods

    These methods follow this form except getCanvasFromImage which simply returns a canvas element.

    ImageMethods.getOrientationFromFile(file, function(canvas) {
    	// Get access to the canvas element here
    });
    
    getCanvasFromImage(img)
    getOrientationFromFile(file, callback)
    getCanvasFromUrl(url, callback)
    getCanvasFromFile(file, callback)

    Keywords

    none

    install

    npm i crop-rotate-resize-in-browser

    Downloadslast 7 days

    1

    version

    0.0.1

    license

    MIT

    repository

    github.com

    last publish

    collaborators

    • avatar