The code you are showing introduces an asynchronous primitive, Promise, which can be passed around and used to access a resource that hasn’t been populated yet. In this case, you want an Image that is fully loaded and has image data that you can use. However, you can’t access the image data until a network … Read more
Like almost all Javascript functions, drawImage is synchronous, i.e. it’ll only return once it has actually done what it’s supposed to do. That said, what it’s supposed to do, like most other DOM calls, is queue-up lists of things to be repainted next time the browser gets into the event loop. There’s no event you … Read more
Use the transform to move the path Using CanvasRenderingContext2D.translate const canvas = document.getElementById(‘canvas’); const ctx = canvas.getContext(‘2d’); let p = new Path2D(‘M10 10 h 80 v 80 h -80 Z’); ctx.translate(100, 100); ctx.fill(p); or using CanvasRenderingContext2D.setTransform let p = new Path2D(‘M10 10 h 80 v 80 h -80 Z’); ctx.setTransform(1, 0, 0, 1, 100, 100); … Read more
SVG might be a good fit for your text pagination SVG text is actually text — unlike canvas which displays just a picture of text. SVG text is readable, selectable, searchable. SVG text does not auto-wrap natively, but this is easily remedied using javascript. Flexible page sizes are possible because page formatting is done in … Read more
Demo: http://jsfiddle.net/m1erickson/2Us2S/ Use jquery-ui to create draggable elements. $(“#myToolbarImageElement”).draggable(); Load these elements with data payloads which are key-value pairs. In your case this might be an image object that you want drawn on the canvas. $(“#myToolbarImageElement”).data(“image”,myImageObject); Set your canvas as a drop zone: $(“#myCanvas”).droppable({drop:myDropHandler}); When you drop the elements on canvas you can read the … Read more
Axonometric rendering The best way to handle axonometric (commonly called isometric) rendering is via a projection matrix. A projection object as follows can describe all you need to do any form of axonometric projection The object has 3 transforms for the x,y and z axis with each describing the scale and direction in the 2D … Read more
I used this in the end: function draw(imgData, frameCount) { var r = new FileReader(); r.readAsBinaryString(imgData); r.onload = function(){ var img=new Image(); img.onload = function() { cxt.drawImage(img, 0, 0, canvas.width, canvas.height); } img.src = “data:image/jpeg;base64,”+window.btoa(r.result); }; } I needed to read the bytes into a string before using btoa().
are you setting the crossOrigin attribute on your img before requesting it? var img = new Image(); img.crossOrigin = “anonymous”; img.src = “https://graph.facebook.com/1387819034852828/picture?width=150&height=150”; It’s was working for me when this question was asked. Unfortunately the URL above no longer points to anything so I’ve changed it in the example below var img = new Image(); … Read more
If you don’t mind having the calendar icon inside the date input field then a cross browser alternative would be to position a calendar icon over top of the triangle calendar picker indicator and then set the calendar icon to pointer-events: none which will cause all click events to be passed through to the triangle … Read more
You made the error, for the second call, to set the size of source to the size of the target. Anyway i bet that you want the same aspect ratio for the scaled image, so you need to compute it : var hRatio = canvas.width / img.width ; var vRatio = canvas.height / img.height ; … Read more