What could be causing the canvas circle to appear distorted and not truly circular?

My simple code is intended to draw a circle, but it's not appearing as expected. The coordinates seem to be shifted oddly. The canvas size is specified with 

style="width: 600px; height: 600px;"
. I've tested it on both Chrome and Safari, yet the results are the same so it doesn't appear to be a browser issue. So here are my questions (which likely have the same answer):

  1. If I place the center at (100, 100), why isn't the circle equidistant from the left and top borders?
  2. Why does the point (300, 300) fall outside the canvas instead of being in the center?

Here's the code snippet:

var context = document.getElementById('c').getContext("2d");
context.fillStyle = 'black';
context.fill();
context.beginPath();
context.arc(100, 100, 30, 0, 2 * Math.PI, true);
context.stroke();

Current rendering:

Edit

After discovering a comment, I realized that using 

<canvas id="myCanvas" style="width: 578px; height: 200px;"></canvas>
was causing the problem, whereas changing it to 
<canvas id="myCanvas" width="578" height="200"></canvas>
solved the issue. Does anyone know why this is the case?

javascripthtml5-canvas

Answer №1

The details of this can be found in the HTML5 Canvas specification.

The canvas's drawing area is defined by the HTML attributes width="x" height="y", which default to 300 × 150 px. These attributes also determine the default visible size of the canvas.

Applying the CSS properties width: x; height: y; to the canvas can stretch or compact the drawing area without actually changing its size.

In the scenario presented, the browser expands the default drawing area (300 × 150 px) to match the specified CSS dimensions of 600 × 600 px.

Answer №2

To learn how to create a circle on canvas, check out this helpful tutorial:

Remember to specify the width and height attributes directly in the canvas element rather than using the style attribute, like this:

<canvas id="c" width="600" height="600" style="background-color:yellow;"></canvas>

Similar questions

If you have not found the answer to your question or you are interested in this topic, then look at other similar questions below or use the search

Can jQuery help me identify which <input type='image> was clicked within a form containing several submit images?

Consider this hypothetical scenario: <form> <input type="text" name="some_name" value="val" id="some_name"> <input type="image" value="action" alt="Add To Cart" name="add" src="/images/submit.gif"> <input type="image" value="act ...

javascriptjqueryformsform-submit

Can you provide instructions on utilizing the async .update() function for DataTables within MDBootstrap?

I am just starting to explore MDBootstrap and I'm currently focused on grasping how to utilize the DataTables. While I've browsed through the examples on their website regarding Async table updates, I've found it a bit challenging to adapt i ...

javascriptjsontwitter-bootstrapbootstrap-5mdbootstrap

Importing a library dynamically in Next.js

I'm currently facing a challenge in dynamically importing a library into one of my next.js projects. The issue arises when I don't receive the default export from the library as expected. Initially, I attempted to import it the next.js way: impo ...

javascriptreactjslazy-loadingnext.jsdynamic-import

Managing errors through middleware functions

Currently, I've been studying node.js on and off. I came across this question: Middleware 1: app.use(function(req, res, next) { db.load(function(err, session) { if (err) { return next(err); } ... }); }); Middleware 2: app.u ...

javascriptnode.jsexpress

What is the best way to convert the data stored in an object to an array?

I have a function that is constantly checking for temperature data: {"a":"43", "b":"43", "c":"42", "d":"43", "e":"40", "f":"41", "g":"100", "h":"42.6"} My goal is to graph this data over time, but I'm struggling with how to structure it to fit the f ...

javascriptvue.js

Merge the chosen values from the drop-down menu into one string

Any suggestions would be greatly appreciated! I am currently developing an application using ASP.NET web forms that consists of a dropdown list and two list boxes. I want these elements to be cloned whenever a specific button is clicked. However, my issue ...

javascriptjqueryeach

Invoke a parent method from a nested child component in Vue

After setting up a project with vue-cli using the webpack template, I decided to incorporate a reusable bootstrap modal dialog in the App component. To achieve this, I created a method called showMessage in the App component that handles displaying the mod ...

javascriptvue.jsvue-cli

Rendering images from Laravel's storage folder in a React component

When uploading an image from a React frontend to a Laravel backend, I encountered an issue where the uploaded image path was saved in the database but the image wouldn't display. React code ` useEffect(() => { axiosClient .g ...

javascriptphpreactjslaravel

Adding two comparable Objects in Javascript / vuejs

I have two objects and I want to add the values of each key separately with another object. Here's an example: CharacterStats: { a: 0, b: 2, c: 0, d: 0 } ItemStats: { a: 0, b: -1, c: 4, d: 0 } The expected result is: CharacterStats: { a: 0, b: 1, c: ...

javascriptvue.jsobject

Populating a clickable list and form with a complex JavaScript object

I have a code snippet that takes an unstructured String and parses it into a JavaScript object. My next step is to integrate it into a web form. You can check out the demo here. The demo displays the structured object hierarchy and showcases an example of ...

javascriptjqueryjsonforms

Difficulty in detecting state changes without refreshing the component when using Redux and React

I'm encountering difficulties detecting state changes from my Redux reducer in a React application. When I modify the state within one component, the other component in the app does not get the update unless the component is reloaded or refreshed. Let ...

javascriptreactjsredux

Testing actual HTTP requests in unit and integration tests with AngularJS

Attempting a request that was not mocked using $httpBackend.when in an Angular 1.x unit/integration test will lead to an error: Error: Unexpected request: GET /real-request Is there a way to perform actual HTTP requests with ngMock and the Karma+Jasmin ...

javascriptangularjsunit-testingjasmineintegration-testing

Javascript AppendChild Problem with Internet Explorer

When it comes to this particular snippet of code, everything seems to run smoothly in Firefox and Chrome. However, Internet Explorer is causing some major headaches. var anotherDiv= document.getElementById("anotherDiv"); var destination = document.getElem ...

javascriptinternet-explorerhtmlinternet-explorer-8appendchild

Error: The request was denied by the operating system. Issue encountered while attempting to build a new React application

I recently installed the LTS version 14.17.3 of Node (npm version 6.14.13). Following that, I successfully globally installed create-react-app using the command "npm install -g create-react-app" (version 4.0.3). However, when attempting to create a new R ...

javascriptnode.jsreactjsnpm

How can I effectively refresh the provider_token / access token for Discord in NextJS with Supabase Auth?

Currently, I have encountered an issue with my NextJs project using Supabase Auth for authentication. I am currently utilizing the Discord provider and everything works fine initially. However, after a few minutes, the session object gets updated and the p ...

javascriptsessionnext.jsoauth-2.0supabase

When the Angular script is executed, the variable is not defined

One of my custom directives receives an object named 'vm' in its scope, which contains a property/value pair (ccirCategoryIncidentI : 3) that I need to access. When I try to log this value with console.log(scope.vm.ccirCategoryIncidentI), it init ...

javascriptjqueryangularjsd3.jsnvd3.js

Change the rectangle's position by rotating another rectangle

I am facing a challenge with two rectangles that have pivots attached to them, The task at hand is to align the green rectangle's position based on the rotation of the red rectangle. The desired outcome should resemble the image provided: Despite t ...

javascriptmath2dtrigonometry

Navigate to a particular section, initially gliding smoothly before suddenly lurching downwards on the screen

I am currently working on improving the functionality of my fixed navigation bar at the top of the screen. When a link in the nav bar is clicked, it scrolls to a specific section using this code: $('a[href^="#"]').bind('click.smoothscrol ...

javascriptjqueryhtmlcssanimation

Is it possible to have an icon change color in a TableRow column when hovering over any part of that particular row?

I am currently using material-ui version 4.9.5. To illustrate my issue, I have created a simplified example here. I have a Table that is populated with basic JSON data. Each row in the table consists of an icon element along with its corresponding color a ...

javascripthtmlcssreactjsmaterial-ui

Using MongoDB to restrict fields and slice the projection simultaneously

I have a User object with the following details: { "_id" : ObjectId("someId"), "name" : "Bob", "password" : "fakePassword", "follower" : [...], "following" : [..] } My goal is to paginate over the follower list using the slice projection operat ...

javascriptnode.jsmongodbmongoosemongodb-query