canvas

问题 So I wanna create glitch effect on canvas, that get every frame from webcam. Code below. Here the code, which works only if width: 200px height: 200px if change this value to width: 600px height: 400px (container size), glitch effect stops working. Here's code where you can change value canvas.width, canvas.height, and see it by yourself CodePen. Does someone know, what a reason for that and how fix it? Or it's some kinda limitations on feTurbulence? const addEffect = (element, filter) => {

问题 I try to copy a certain part of a canvas, then write the copied part in an image. Here is my (wrong) approach: var c = document.getElementById('MyCanvas'), ctx = c.getContext('2d'); var ImageData = ctx.getImageData( 25, 25, 150, 150 ); var MyImage = new Image(); MyImage.src = ImageData ; // <-- This is wrong, but I mean something like this Do you know how can I do it? Thank you in advance. ps: I don't want to copy the whole canvas, but a certain part of it. 回答1: You could accomplish that in

问题 In my Android app, I am trying to show letters one by one with a short delay between each, while also playing a sound for each letter. I have everything working, and the sounds play with the correct delay, but the text always prints to the screen far too fast. The canvas seems to be updated even when i am not specifically invalidating the view. Here is what I have so far - I also tried a variant of this based on the "snake" example and had the same results... any help would be appreciated!

问题 I have product images and each image has two configurable areas as below: 1. background 2. Foreground I have to develop a feature where customer can change the color of both areas and save the design. My problem is, i am traversing the image to read old pixel value and change it with new selected color. Bit old pixel values are not consistent. There is textured effect on the image, which is causing the pixel value to be changed at every pixel. How can i achieve the desired the functionality?

问题 This question already has an answer here : HTML Canvas: Drawing grid below a plot (1 answer) Closed 3 years ago . I have a canvas, and I want to use drawImage to draw an image behind the current content on the canvas. Due to the fact that there is content already on the canvas (I'm using Literally Canvas to create a canvas containing an image, so I can't really draw the image first), I cannot use drawImage before I render the rest of my content. Is it possible to drawImage behind all other

问题 I want to play youtube video inside canvas,I use fabric.js and youtube-api my video tag code looks like this <video id="youtube1" width="640" height="360"> <source src="https://www.youtube.com/watch?v=V6DWnVm0Ufk" type="video/youtube" > </video> it works like expected video appears in dom but I want to add this video inside canvas too. my canvas code looks like this: canvas = this.__canvas = new fabric.Canvas('canvas'); var youtube=$('#youtube1')[0]; var video1 = new fabric.Image(youtube, {

问题 hey i am trying to create android app where i can draw on canvas with two buttons on the bottom i managed to get the drawing to work however right now i need to add two buttons(one is for saving the drawing canvas into database (Sqlite if possible) or bitmap and the other one to import the image from the sqlite and display it into the graphicview) right now i have no idea what code i have to put into it to make the save and display button works so please help me with the code and thank you

问题 hey i am trying to create android app where i can draw on canvas with two buttons on the bottom i managed to get the drawing to work however right now i need to add two buttons(one is for saving the drawing canvas into database (Sqlite if possible) or bitmap and the other one to import the image from the sqlite and display it into the graphicview) right now i have no idea what code i have to put into it to make the save and display button works so please help me with the code and thank you

问题 hey i am trying to create android app where i can draw on canvas with two buttons on the bottom i managed to get the drawing to work however right now i need to add two buttons(one is for saving the drawing canvas into database (Sqlite if possible) or bitmap and the other one to import the image from the sqlite and display it into the graphicview) right now i have no idea what code i have to put into it to make the save and display button works so please help me with the code and thank you

问题 I'm using an HTML5 canvas to create a series of trees and their corresponding shadows. I want each shadow to be based on the position of a light source. I can draw each tree and it's shadow as well as skew all the shadows at once, but trying to skew each shadow individually eludes me. Here's my code: var ctx = cvs[0].getContext('2d'); ctx.save(); //skew the canvas ctx.transform(1,0,0.3,-1,0,0); ctx.drawImage(tree1,74,-117,20,40); ctx.drawImage(tree1,126,-125,20,40); var imgd = ctx