I want to create an undo button for my web application using javascript. Can someone please help. Basically i got an web app which has got features such as Drawing, Image effect, and Drag and Drop. These functionality are performed on one canvas. All i need is an #Undo button so that if i do a mistake i can go one step backwards. I cant use Jquery. I am looking for a pure javascript to implement that function.
You haven't given much info, so I'll make assumptions.
Assumption 1: all you user drawing interactions are recorded in an array.
If this is true then simply clear the canvas and redraw the interactions from the array to interactionArray.length -1;
Assumption 2: You're using multiple canvas.
If this is true, hide/remove the last (most top) canvas element.
If you're not using either of these methods, maybe look into these methods. Or give us more information on the the method you're currently using.
Note: There are certainly not the only methods to including an "undo" feature!)
Depends on your web application, but shouldn't this do?
<button type="reset">Click Me!</button>
or in js:
Reset Form
Related
I'm looking to implement a video editing feature like that of featured here https://clideo.com/video-editor.
I'm planning to use Vue 3 with a Laravel backend, but is there an ideal framework to use for a web application like this, or should I just try to reverse engineer/hack my way to a working implementation?
Sorry if this is the wrong place to ask, I just haven't been able to find an answer.
Thanks
Video editor consist of two important parts
1)A Timeline that represents sequence.
2)A Output window to show output of timeline.
-Clideo uses div and html elements positioning to generate timeline but a better alternative is to use Canvas and draw a timeline on it just like in veed.io
-For video output again you have to use canvas and webGL to draw each and every frame one by one.
you wont be able to edit video on backend and send edited multimedia for each change user makes you need to find a way to do in on client using webcodec.
For the choice of framework if you are having canvas and webGL do all the rendering of timeline and output then it dosent matters you will spend more time with drawing functions.
Almost every video editor has a timeline. But only in some of it (https://wave.video/tools/video-marketing/promo-video-maker) is divided into several ranges. An additional advantage will be the grid on the line. You can also easily manage layers and frames.
I am building a web based chess game in Javascript. I'm using the HTML5 canvas to display the board by drawing rectangles.
I am trying to implement the move logic. So when a chess piece is clicked, and then they click on an empty block, I want to move it. However, it is quite tedious using the canvas. I need to do the following:
Update my 2D grid of objects to reflect the change, I set the current
square to undefined and set the new square to the object being moved
clearRect(..) which I still haven't got to work
Redraw the image at the new position
Is there a better way?
Also, how do I deal with the 'double click'. I currently using a boolean that holds if the piece was pressed, and if it was and they click on an empty square I call the move function. Are there any other ways of doing this? Additionally, are there any tools for making it seem like the chess piece is being dragged?
I appreciate any help. Thanks guys.
Over the years I've written a lot of chessboards for HTML. In the end the simplest approach I think is:
Keep an array (either 1d or 2d, both have pros and cons) with just piece names (e.g. "wp"=white pawn, "bn"=black night, "--" empty). Nothing to be gained with an OO-approach or even a generic piece object.
Use one single canvas for the board, drawing the pieces on them with drawImage.
Write a function that just draws everything and call it when needed (don't bother erasing/drawing single pieces).
For piece dragging empty the square and create a separate dragged div containing just the dragged piece (redrawing the full board during drag can be slow for low-end mobile devices).
For dragging attach move and up handlers to the document and not to the canvas, so that you won't miss up events when the mouse is outside of the browser window.
Start dragging on mousedown and attach events for mousemove and mouseup. This will work both on computers and on mobile phones without having to handle specific cases. Always call preventDefault and stopPropagation.
Make full-page view with no overflow and handle resize yourself (you'll need to add some mobile-specific metas to stop phones messing up with the page).
HTML can really do impressive things with just 2d canvas, as an example see this 2d/3d chessboard. One single file less than 300k (200k zipped).
Easiest you say?
Using chessboard.js has to be the easiest way and it is 2D.
HTML
<div id="board1" style="width: 400px"></div>
JavaScript
var board1 = ChessBoard('board1', 'start');
It has very good documentation and tons of different examples (customization) and can be downloaded here.
Learning by coding -- Good for you!
Here are a few tips to get you started:
A reusable structure for your game:
Create a JS object for each of your chess pieces and save those piece-objects in an array.
// an example piece object
var blackKing={
player:'black',
pieceType:'king',
image:blackKingImageObject,
currentSquare:['E','1'],
isCaptured: false,
// etc...
}
// a pieces-array
var pieces=[];
pieces.push(blackKing);
Create a function that does all of these things:
clearRect the entire canvas,
redraw the chess board,
use the piece-array to redraw all the pieces onto the chessboard.
About click vs double-click vs dragging:
Yes, that's troublesome and requires special handling.
Many coders handle it this way:
Listen for mousedown and save that timestamp and initial mouse position.
If a mouseup plus another mousedown occurs quickly it's a double-click.
If a mousemove of more than a few pixels occurs then it's the start of a drag.
Otherwise, it's a single-click.
I want to put textboxes (that can be edited) on a HTML5 canvas.
(Example : like in a "Paint" software, you can create textboxes).
Is it really needed to use third-party libraries such as
https://github.com/claydotio/Canvas-Input in order to do such a basic thing?
Isn't there no simple solution for creating textboxes in a HTML5 canvas?
If so, is there are a library (for Textbox inside ) that is considered as standard?
No, canvas is a bitmap and has no support for controls or DOM elements such as input boxes.
All the logic for that must be made manually by simulating such a functionality.
You can take a look at my previous answer for one way of doing this.
Are there any lightweight frameworks out there for this task. I have a collection of divs, that I want to be able to save positions when dragged/resized/pushed etc.
I was going to build one, to my spec, but if there is a lightweight one out there that might save me a lot of time. I've seen some jQuery plugins that push divs around a page fluidly.
I want to be able to save positions, but also snap divs to each other and save all news positions for divs moved or re-sized. I've looked briefly at shindig, but seems a bit heavy... at least I wanted to see if there are any lightweight front end alternatives.
I will be using php for my backend.
Consider midorijs (www.midorijs.com). It is lightweight and contains a simple drag and drop interface complete with a default drop callback function. You can also define your own. You mentioned you wanted a callback for position save, Midori's callback function does pass the x,y coordinates of the object.
Chceck out more drag and drop callback details at the bottom of this page: http://www.midorijs.com/midoriDragDrop.html
Another benefit since you mentioned you are using php is Midori's convertToFields function which converts javascript object to php.
Good luck!
Why not using jQuery ui? You can customize a bundle to fit your needs + when delivering from googlecode you can get sure that a huge amount of users already have that in their cache. And you can easily get the positionings and push them to your server.
http://jqueryui.com/download
I'd like to be able to write an application in HTML5 that is similar to the following.
HTML5 Canvas Animals on the Beach Game with KineticJS
The problem with that demo though is the mouse over event is only accurate to the rectangle surrounding the animal. Is there any way to do this with more accuracy, be it in KinectJS or otherwise?
There are generally two ways:
Using custom paths with each image as hitboxes (that you manually define) then using an is-point-in-path algorithm
Using a ghost-canvas (or whatever you like to call it) as I detailed in this old tutorial. Ignore the link to the new tutorial, the old one uses what you'd want.
The first method here is much faster but requires a lot more code and manual work. The second method is pixel-perfect but much slower. Still, if you don't have an enormous amount of objects it may suit your needs.