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
The problem was the way that I was loading my Images, I should’ve been doing: var image = new Image(); image.src = “https://stackoverflow.com/questions/22430671/imagesource.jpg”; But instead I was get the elements by id from the document page. Resources: Explanation on loading images Explanation on how html loads images
Don’t forget to add an event listener to the image’s load event. Image loading is something that happens in the background, so when the JavaScript interpreter gets to the canvas.drawImage part it is most likely the image probably will not have loaded yet and is just an empty image object, without content. drawing = new … Read more
Staring with 1.0.x the best way to achieve it is to use the Coil-Compose library. Add in your build.gradle the dependency dependencies { implementation(“io.coil-kt:coil-compose:1.3.1”) } Then just use: Image( painter = rememberImagePainter(“your url”), contentDescription = “My content description”, ) This loads the url passed in with rememberImagePainter, and then displays the resulting image using the … Read more
You almost have it… You just have to give the image time to load before drawing it. You give an image time to load with this code: var logoImg = new Image(); logoImg.onload = function() { // At this point, the image is fully loaded // So do your thing! }; logoImg.src = “https://stackoverflow.com/questions/15048279/myPic.png”; Here … Read more
[Edit ~5 years later: some of this is beginning to change, and there are new web platform features that actually allow rendering to a canvas from a Worker! See this blog for more info: https://hacks.mozilla.org/2016/01/webgl-off-the-main-thread/ – the rest of the answer is provided for 2011-era information ;)] Web workers can only calculate, not modify the … Read more
You need to modify the transformation matrix before drawing the image that you want rotated. Assume image points to an HTMLImageElement object. var x = canvas.width / 2; var y = canvas.height / 2; var width = image.width; var height = image.height; context.translate(x, y); context.rotate(angleInRadians); context.drawImage(image, -width / 2, -height / 2, width, height); context.rotate(-angleInRadians); … Read more
You have a File instance which is not an image. To get an image, use new Image(). The src needs to be an URL referencing to the selected File. You can use URL.createObjectURL to get an URL referencing to a Blob (a File is also a Blob): http://jsfiddle.net/t7mv6/86/. var ctx = document.getElementById(‘canvas’).getContext(‘2d’); var img = … Read more
context.drawImage(imageObj, 0, 0, 100, 100 * imageObj.height / imageObj.width)
You’ll need to read the exif data and check if exif.Orientation is one of the following: fileReader.onloadend = function() { var exif = EXIF.readFromBinaryFile(new BinaryFile(this.result)); switch(exif.Orientation){ case 8: ctx.rotate(90*Math.PI/180); break; case 3: ctx.rotate(180*Math.PI/180); break; case 6: ctx.rotate(-90*Math.PI/180); break; } };