How To Upload A Picture To A Discussion Forum In Canvas

JavaScript Canvass Image Conversion

At final calendar week'south Mozilla WebDev Offsite, we all spent half of the final 24-hour interval hacking on our hereafter Mozilla Market app. I mobile app that recently got a lot of attending was Instagram, which sold to Facebook for the ~~bat shit crazy~~ price of one billion dollars. Since I wouldn't mind having a neb in my dorsum business relationship, I decided to create an Instagram-fashion app (which I'll share with you in the future). This mail service details how you can catechumen an image to canvass and convert a canvas back to an paradigm.

Catechumen an Image to Canvas with JavaScript

To convert an paradigm to canvass, you use a canvas chemical element'southward context's drawImage method:

// Converts paradigm to sheet; returns new canvas element function convertImageToCanvas(image) { 	var canvas = document.createElement("canvass"); 	canvas.width = image.width; 	canvas.elevation = epitome.height; 	sheet.getContext("2d").drawImage(image, 0, 0);  	return sail; }

The 0, 0 arguments map to coordinates on the sheet where the prototype data should be placed.

Convert Canvas to an Image with JavaScript

Assuming modifications to the prototype accept been made, you lot can easily convert the canvas data to paradigm data with the following snippet:

// Converts canvas to an image office convertCanvasToImage(canvass) { 	var image = new Prototype(); 	paradigm.src = canvas.toDataURL("image/png"); 	return image; }

The lawmaking above magically converts the sheet to a PNG information URI!

Alas, converting an image to sheet and canvass to an paradigm is probably much easier than you think. In future posts, I'll detail how you tin employ unlike image filters to your canvased image. In the mean time, beginning buying fancy cars and houses with the futurity billion y'all'll have!

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