canvas

问题 Yes theres a few threads on this, but not many using angles and I'm really trying to figure it out this way, I'm now stuck on setting the new velocity angles for the circles. I have been looking at: http://www.hoomanr.com/Demos/Elastic2/ as a reference to it, but I'm stuck now. Can anybody shed some light? cx/cy/cx2/cy2 = center x/y for balls 1 and 2. vx/vy/vx2/vy2 = velocities for x/y for balls 1 and 2 function checkCollision() { var dx = cx2 - cx; //distance between x var dy = cy2 - cy; //

问题 I am able to draw lines around a circle. I have the basic implementation of the AudioContext API setup. The problem I am facing is when calling lineTo the line will only grow but not shrink. I am inspired by this https://www.kkhaydarov.com/audio-visualizer/. I am translating this code over into https://codesandbox.io/s/hungry-tereshkova-1pf0c?runonclick=1&file=/src/Visualizer.js:713-725 which is a React.js version. If you run that code you will see the music play, then the bars will grow once

问题 I have to draw a curved line on the left side of recycler view ( which connect all the item in the recyclerview).But i cant get all of the position of recyclerview item to start draw my custom view.I tryed to get the x,y position inside onBindViewHolder but it not work ( i though when inside nestedscrollview it just like a tableview).So how can i get all the position of recyclerview's items after set it adapter Here is the screen shot of what i have to do: https://imgur.com/a/C1jTNKr 回答1: If

问题 So I got this painter to draw a minimap for my game: class MiniMapPainter extends CustomPainter { final GameMap map; final double tileSize; final List<ui.Image> images; MiniMapPainter( {@required this.images, @required this.map, @required this.tileSize}); @override void paint(Canvas canvas, Size size) { var row = 0; var column = 0; map.encodedMap.runes.forEach((charCode) { final character = String.fromCharCode(charCode); if (character == map.rowSeparator) { row++; column = 0; } else if

问题 I am trying to capture the screenshot of a portion of the web-page in my web app using the following code. function getScreenshot(){ var content = document.querySelectorAll("div.class")[0]; setTimeout(function(){captureScreenshot()},10); function captureScreenshot() { html2canvas(content, { onrendered: function(canvas) { var newImg = document.createElement("img"); newImg.src = canvas.toDataURL(); var newAnchor = document.createElement("a"); newAnchor.href = newImg.src; newAnchor.download =

问题 I have a virtual canvas with a drawn icon. This icon is dynamic so I can't make a motion blurred variant of this icon in Photoshop. I render this icon on the scene by this code: function render (context) { context.drawImage(this.bufferedIcon, 0, 0); } Could you tell me if there is a simple way for creating the motion blur of this icon? 回答1: To do a simple motion blur use the globalAlpha var ctx = document.getElementById("can").getContext("2d"); // dx and dy is the direction and speed of the

问题 I am using following javascript algorithm to draw dashed line on canvas. this algo draws horizontal line correctly but unable to draw vertical line: g.dashedLine = function (x, y, x2, y2, dashArray) { this.beginPath(); this.lineWidth = "2"; if (!dashArray) dashArray = [10, 5]; if (dashLength == 0) dashLength = 0.001; // Hack for Safari var dashCount = dashArray.length; this.moveTo(x, y); var dx = (x2 - x); var dy = (y2 - y); var slope = dy / dx; var distRemaining = Math.sqrt(dx * dx + dy * dy

问题 I want to fill no color to canvas i.e. I want the background div color should keep on displaying in the div. I have googled it but didn't find any solution to keep fillStyle as no color. Also I tried omitting the fillStyle but it leave me with black color. Any options available? Thanks 回答1: You need to use this to clear the canvas: context.clearRect(0, 0, canvas.width, canvas.height); (or the rectangle you need). Also make sure you have no CSS rules set for the canvas element's background

问题 I want to fill no color to canvas i.e. I want the background div color should keep on displaying in the div. I have googled it but didn't find any solution to keep fillStyle as no color. Also I tried omitting the fillStyle but it leave me with black color. Any options available? Thanks 回答1: You need to use this to clear the canvas: context.clearRect(0, 0, canvas.width, canvas.height); (or the rectangle you need). Also make sure you have no CSS rules set for the canvas element's background

问题 I have a stacklayout with a canvas and an image. my image has a size_hint of .1 and I want my canvas to have the same height as my image. .kv file: StackLayout: orientation: 'lr-tb' canvas: Color: rgba: 1,1,1,1 Rectangle: pos: self.pos size: self.size Image: size_hint_y: .1 source: 'Images\login\cptbanner.jpg' allow_stretch: True keep_ratio: True what can I do to get the desired effect? 回答1: A Kivy canvas is not a widget or the space in which you paint. It is only a set of instructions. You