canvas

问题 Basically I want to be able to perform effectively this same code: const video = document.getElementById('video'); const canvas = document.getElementById('canvas'); const context = canvas.getContext('2d'); const draw = () => { context.drawImage(video, 0, 0); requestAnimationFrame(draw); } video.onplay = () => { requestAnimationFrame(draw); } only using an offscreen canvas. I can send images over messages to the worker the offscreen canvas is on, but not video as it's directly tied to an

问题 Basically I want to be able to perform effectively this same code: const video = document.getElementById('video'); const canvas = document.getElementById('canvas'); const context = canvas.getContext('2d'); const draw = () => { context.drawImage(video, 0, 0); requestAnimationFrame(draw); } video.onplay = () => { requestAnimationFrame(draw); } only using an offscreen canvas. I can send images over messages to the worker the offscreen canvas is on, but not video as it's directly tied to an

问题 I'm trying to capture the contents of a canvas element with alpha channel. When I do it I get the RGB values correctly but the Alpha channel seems to get dropped when playing back the resulting video. Is there a way to achieve this? I'm running the following code: var stream = canvas.captureStream(60); var recorder = new MediaRecorder(stream); recorder.addEventListener('dataavailable', finishCapturing); recorder.addEventListener('stop', function(e) { video.oncanplay = video.play; video.src =

问题 I'm trying to capture the contents of a canvas element with alpha channel. When I do it I get the RGB values correctly but the Alpha channel seems to get dropped when playing back the resulting video. Is there a way to achieve this? I'm running the following code: var stream = canvas.captureStream(60); var recorder = new MediaRecorder(stream); recorder.addEventListener('dataavailable', finishCapturing); recorder.addEventListener('stop', function(e) { video.oncanplay = video.play; video.src =

问题 I'm a total beginner to Rust and WebAssembly. I was trying to find a way to draw on a canvas element with performance in mind. To draw on a canvas using Rust and WebAssembly I usually find examples in which they would use the browser's CanvasRenderingContext2D interface and draw data on it they will receive from WASM const canvasContext = canvasElement.getContext("2d"); const canvasImageData = canvasContext.createImageData(width, height); const imageDataArray = getWasmImageDataArray()

问题 I'm a total beginner to Rust and WebAssembly. I was trying to find a way to draw on a canvas element with performance in mind. To draw on a canvas using Rust and WebAssembly I usually find examples in which they would use the browser's CanvasRenderingContext2D interface and draw data on it they will receive from WASM const canvasContext = canvasElement.getContext("2d"); const canvasImageData = canvasContext.createImageData(width, height); const imageDataArray = getWasmImageDataArray()

问题 I'm a total beginner to Rust and WebAssembly. I was trying to find a way to draw on a canvas element with performance in mind. To draw on a canvas using Rust and WebAssembly I usually find examples in which they would use the browser's CanvasRenderingContext2D interface and draw data on it they will receive from WASM const canvasContext = canvasElement.getContext("2d"); const canvasImageData = canvasContext.createImageData(width, height); const imageDataArray = getWasmImageDataArray()

问题 This function shuffles only matrix[y], but I want it to shuffle matrix[y][x] But it doesn't want to shuffle correctly. The code what I used: function Shuffle(arguments) { for (var k = 0; k < arguments.length; k++) { var i = arguments[k].length; if (i == 0) return false; else { while (--i) { var j = Math.floor(Math.random() * (i + 1)); var tempi = arguments[k][i]; var tempj = arguments[k][j]; arguments[k][i] = tempj; arguments[k][j] = tempi; } return arguments; } } return arguments } var

问题 Update - Here is my final jsfiddle working version using Kinetic. I'm trying to show text with two different shadows to create an "embossed" look. I'm using this jsfiddle as a model of the result I'd like to get which uses CSS. Here is the jsfiddle of what I'm working on currently with Kinetic JS. var stage = new Kinetic.Stage({ container: 'stage-container', width: 400, height: 200 }); var layer = new Kinetic.Layer(); stage.add(layer); var darkShadow = new Kinetic.Text({ text: 'Hello', x: 140

问题 I was writing a function to shrink a source image (JPG file) according to a 170 x 200px picture. The source JPG image was loaded into a TImage (Image1, fixed size of 400 x 400px, stretched to fit with aspect ration maintained), then the user will make a selection rectangle to set the area to copy, and then the image will be copied using CopyRect() onto the destination TImage (Image2). void __fastcall TSizePhotoForm::Button3Click(TObject *Sender) { float scale, base = 400.0f; TRect crect; //