html5-canvas

update canvas element with a DOM canvas

由 走远了吗. 提交于 2021-01-27 06:42:23
问题 let's say I have var myCanvas = document.createElement('canvas'); and I do myCanvas.setAttribute("id", "my-canvas"); document.body.appendChild(myCanvas); Afterwords I make change to myCanvas and want to replace the html-canvas with my updated DOM canvas. The following works: document.getElementById("my-canvas").innerHTML = myCanvas; but the html (via inspector) looks like <canvas id="my-canvas">[object HTMLCanvasElement]</canvas> When it should look like <canvas id="my-canvas"></canvas> How

How to calculate the color of the selected color in a color palette?

由 一曲冷凌霜 提交于 2021-01-24 09:48:08
问题 This is a follow-up to this question I asked earlier Previously, I was using getImageData on the selected pixel in the color palette to determine what the color is. However, the gradient will not always be perfectly accurate. This is even the case with Google's color picker. Their palette isn't entirely accurate, but the color they return based on your selected position in the color palette is . So, assuming this code is generating the palette: function drawPalette(hue) { var ctx = document

How to calculate the color of the selected color in a color palette?

由 邮差的信 提交于 2021-01-24 09:46:04
问题 This is a follow-up to this question I asked earlier Previously, I was using getImageData on the selected pixel in the color palette to determine what the color is. However, the gradient will not always be perfectly accurate. This is even the case with Google's color picker. Their palette isn't entirely accurate, but the color they return based on your selected position in the color palette is . So, assuming this code is generating the palette: function drawPalette(hue) { var ctx = document

How to scrape json data from an interactive chart?

由 爱⌒轻易说出口 提交于 2021-01-21 05:48:28
问题 I have a specific section of a website that I want to scrape data from and here's the screenshot of the section - I inspected the elements of that particular section and noticed that it's within a canvas tag. However, I also checked the source code of the website and I found that the data lies within the source code in a format I'm not familiar with. Here's a sample of that data JSON.parse('\x5B\x7B\x22id\x22\x3A\x2232522\x22,\x22minute\x22\x3A\x2222\x22,\x22result\x22\x3A\x22MissedShots\x22,

How to scrape json data from an interactive chart?

由 天大地大妈咪最大 提交于 2021-01-21 05:47:07
问题 I have a specific section of a website that I want to scrape data from and here's the screenshot of the section - I inspected the elements of that particular section and noticed that it's within a canvas tag. However, I also checked the source code of the website and I found that the data lies within the source code in a format I'm not familiar with. Here's a sample of that data JSON.parse('\x5B\x7B\x22id\x22\x3A\x2232522\x22,\x22minute\x22\x3A\x2222\x22,\x22result\x22\x3A\x22MissedShots\x22,

Does using percentages instead of pixels change an html 5 canvas change its properties?

由 血红的双手。 提交于 2021-01-03 06:28:09
问题 I am practicing javascript and I am trying to make a game. I want the canvas element to be fullscreen, so I used percentages for the height and width attribute, but when I do, it doesn't behave like it normally does. When I run my debug code, it is supposed to make a box that is 50px by 50px, but the graphics look bigger than normal. I've tried getting the canvas height and width in pixels, but that did not work. It does not report any error messages, but it is still too big. <!DOCTYPE html>

CSS linear-gradient and Canvas linear-gradient aren't the same with opacity settings

由 我与影子孤独终老i 提交于 2021-01-02 20:51:34
问题 I want to achieve the same linear gradient look defined by CSS on a canvas. Used a method that works great until no transparency setting is used. When there are rgba color values defined with the same linear gradient color settings the results doesn't look the same, please see the following link: JSFiddle: Example var canvas = document.getElementById("myCanvas"); var ctx = document.getElementById("myCanvas").getContext("2d"); var w = canvas.width; var h = canvas.height; var cssAng = Math.PI;

How to position Path2D SVG element in canvas?

由 自古美人都是妖i 提交于 2021-01-01 18:41:23
问题 I'm drawing a path2D SVG shape on canvas. The problem is that the moveTo function does not seem to work when using SVG data. The problem is illustrated in this codepen. https://codepen.io/grasmachien/pen/rNaJeBN const canvas = document.getElementById('canvas'); const ctx = canvas.getContext('2d'); let p = new Path2D('M10 10 h 80 v 80 h -80 Z'); p.moveTo(100,100) ctx.fill(p); Is there a way to move the path without moving the canvas? 回答1: Use the transform to move the path Using

How to position Path2D SVG element in canvas?

由 99封情书 提交于 2021-01-01 18:36:30
问题 I'm drawing a path2D SVG shape on canvas. The problem is that the moveTo function does not seem to work when using SVG data. The problem is illustrated in this codepen. https://codepen.io/grasmachien/pen/rNaJeBN const canvas = document.getElementById('canvas'); const ctx = canvas.getContext('2d'); let p = new Path2D('M10 10 h 80 v 80 h -80 Z'); p.moveTo(100,100) ctx.fill(p); Is there a way to move the path without moving the canvas? 回答1: Use the transform to move the path Using

What is the indexing logic in the ImageData array?

由 吃可爱长大的小学妹 提交于 2020-12-31 14:59:45
问题 This question is for a deeper understanding of my previous question about large size Canvas animation. The question is here: Repeat HTML canvas element (box) to fill whole viewport I am trying to understand the logic behind the TypedArray - Uint8ClampedArray. I will first start with my research and get to the question itself later. So, ImageData represents the pixel data of the HTML5 Canvas. It allows for much faster performance and is good for heavy animations. After we have our ImageData
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