我从一个canvas元素开始。我让左半边是红色，右边是蓝色。每半秒，setInterval调用一个函数，即扰乱，它将RHS和LHS分成几部分，并将它们混洗。
这是一个小提琴：https://jsfiddle.net/aeq1g3yb/
代码如下。我使用window.onload的原因是因为这个东西应该扰乱图片，我希望首先加载图片。我正在使用颜色 here 因为我不太了解的跨领域业务，所以这是我的住所。
var n = 1;
var v = 1;
function scramble() {
//get the canvas and change its width
var c = document.getElementById("myCanvas");
c.width = 600;
var ctx = c.getContext("2d");
//drawing 2 different colors side by side
ctx.fillStyle = "red";
ctx.fillRect(0, 0, c.width/2, c.height);
ctx.fillStyle = "blue";
ctx.fillRect(c.width/2, 0, c.width/2, c.height);
//how big will each shuffled chunk be
var stepsA = (c.width/2) / n;
var stepsB = (c.width/2) / n;
var step = stepsA + stepsB;
var imgDataA = [];
var imgDataB = [];
for (var i = 0; i < n; i++) {
var imgDataElementA = ctx.getImageData(stepsA*i, 0, stepsA, c.height);
var imgDataElementB = ctx.getImageData(c.width/2+stepsB*i, 0, stepsB, c.height);
imgDataA.push(imgDataElementA);
imgDataB.push(imgDataElementB);
}
//clearing out the canvas before laying on the new stuff
ctx.fillStyle = "white";
ctx.fillRect(0, 0, c.width, c.height);
//put the images back
for (var i = 0; i < n; i++) {
ctx.putImageData(imgDataA[i], step*i, 0);
ctx.putImageData(imgDataB[i], step*i+stepsA, 0);
}
//gonna count the steps
var count = document.getElementById("count");
count.innerHTML = n;
n += v;
if (n >= 100 || n <= 1) {
v *= -1;
}
}; //closing function scramble
window.onload = function() { //gotta do this bc code executes before image loads
scramble();
};
window.setInterval(scramble, 500);
或多或少，这个东西按照我想要的方式工作。但有一个问题：有时候会有垂直的白线。
我的问题是：
为什么会出现白线？如果您查看小提琴，您将看到这会损害随机播放效果的程度。
答案 0 :(得分：1)
问题可以解决，但会引入一些其他的工件，因为你不能将整数像素分成几部分。
现有代码的以下解决方案向下舍入以显示部分的开头，向上舍入为宽度。
for (var i = 0; i < n; i++) {
var imgDataElementA = ctx.getImageData(
Math.floor(stepsA * i), 0,
Math.ceil(stepsA + stepsA * i) - Math.floor(stepsA * i), c.height
);
var imgDataElementB = ctx.getImageData(
Math.floor(c.width / 2 + stepsB * i), 0,
Math.ceil(c.width / 2 + stepsB * i + stepsB) - Math.floor(c.width / 2 + stepsB * i), c.height);
imgDataA.push(imgDataElementA);
imgDataB.push(imgDataElementB);
}
但是通过像素图像数据执行此操作是您可以找到的最慢的方法。您可以使用2D context.imageDraw函数为您进行移动。或者，如果你想要在性能方面做得最好，那么片段着色器作为并行解决方案为你加扰时，WebGL解决方案将是最好的。
但最终你不能将一个像素切成两半，有很多方法可以尝试解决这个问题，但每种方法都有自己的工件。理想情况下，如果规则image.width % slices === 0在所有其他情况下您将有一个或多个不适合整数像素的切片，则应该只对图像进行切片。
该演示展示了4种不同的方法和2种颜色。将鼠标移到查看更近的视图。每种方法都用白线水平分开。按住鼠标按钮可增加切片计数器。
顶部是您的原件。 接下来的三种处理分数像素宽度的方法有三种。
const mouse = {x : 0, y : 0, button : false}
function mouseEvents(e){
const m = mouse;
if(m.element){
m.bounds = m.element.getBoundingClientRect();
m.x = e.pageX - m.bounds.left - scrollX;
m.y = e.pageY - m.bounds.top - scrollY;
m.button = e.type === "mousedown" ? true : e.type === "mouseup" ? false : m.button;
}
}
["down","up","move"].forEach(name => document.addEventListener("mouse"+name,mouseEvents));
const counterElement = document.getElementById("count");
// get constants for the demo
const c = document.getElementById("myCanvas");
mouse.element = c;
// The image with the blue and red
const img = document.createElement("canvas");
// the zoom image overlay
const zoom = document.createElement("canvas");
// the scrambled image
const scram = document.createElement("canvas");
// Set sizes and get context
const w = scram.width = zoom.width = img.width = c.width = 500;
const h = scram.height = zoom.height = img.height = c.height;
const dCtx = c.getContext("2d"); // display context
const iCtx = img.getContext("2d"); // source image context
const zCtx = zoom.getContext("2d"); // zoom context
const sCtx = scram.getContext("2d"); // scrambled context
// some constants
const zoomAmount = 4;
const zoomRadius = 60;
const framesToStep = 10;
function createTestPattern(ctx){
ctx.fillStyle = "red";
ctx.fillRect(0, 0, c.width/2, c.height/2);
ctx.fillStyle = "blue";
ctx.fillRect(c.width/2, 0, c.width/2, c.height/2);
ctx.fillStyle = "black";
ctx.fillRect(0, c.height/2, c.width/2, c.height/2);
ctx.fillStyle = "#CCC";
ctx.fillRect(c.width/2, c.height/2, c.width/2, c.height/2);
}
createTestPattern(iCtx);
sCtx.drawImage(iCtx.canvas, 0, 0);
// Shows a zoom area so that blind men like me can see what is going on.
function showMouseZoom(src,dest,zoom = zoomAmount,radius = zoomRadius){
dest.clearRect(0,0,w,h);
dest.imageSmoothingEnabled = false;
if(mouse.x >= 0 && mouse.y >= 0 && mouse.x < w && mouse.y < h){
dest.setTransform(zoom,0,0,zoom,mouse.x,mouse.y)
dest.drawImage(src.canvas, -mouse.x, -mouse.y);
dest.setTransform(1,0,0,1,0,0);
dest.globalCompositeOperation = "destination-in";
dest.beginPath();
dest.arc(mouse.x,mouse.y,radius,0,Math.PI * 2);
dest.fill();
dest.globalCompositeOperation = "source-over";
dest.lineWidth = 4;
dest.strokeStyle = "black";
dest.stroke();
}
}
function scramble(src,dest,y,height) {
const w = src.canvas.width;
const h = src.canvas.height;
const steps = (w/2) / slices;
dest.fillStyle = "white";
dest.fillRect(0, y, w, height);
for (var i = 0; i < slices * 2; i++) {
dest.drawImage(src.canvas,
((i / 2) | 0) * steps + (i % 2) * (w / 2)- 0.5, y,
steps + 1, height,
i * steps - 0.5, y,
steps+ 1, height
);
}
}
function scrambleFloor(src,dest,y,height) {
const w = src.canvas.width;
const h = src.canvas.height;
const steps = (w/2) / slices;
dest.fillStyle = "white";
dest.fillRect(0, y, w, height);
for (var i = 0; i < slices * 2; i++) {
dest.drawImage(src.canvas,
(((i / 2) | 0) * steps + (i % 2) * (w / 2)- 0.5) | 0, y,
steps + 1, height,
(i * steps - 0.5) | 0, y,
steps + 1, height
);
}
}
function scrambleNoOverlap(src,dest,y,height) {
const w = src.canvas.width;
const h = src.canvas.height;
const steps = (w / 2) / slices;
dest.fillStyle = "white";
dest.fillRect(0, y, w, height);
for (var i = 0; i < slices * 2; i++) {
dest.drawImage(src.canvas,
((i / 2) | 0) * steps + (i % 2) * (w / 2), y,
steps, height,
i * steps - 0.5, y,
steps, height
);
}
}
function scrambleOriginal(src,dest,y,height) {
const w = src.canvas.width;
const h = src.canvas.height;
//how big will each shuffled chunk be
var stepsA = (w/2) / slices;
var stepsB = (w/2) / slices;
var step = stepsA + stepsB;
var imgDataA = [];
var imgDataB = [];
for (var i = 0; i < slices; i++) {
var imgDataElementA = src.getImageData(stepsA*i, y, stepsA, height);
var imgDataElementB = src.getImageData(w/2+stepsB*i, y, stepsB, height);
imgDataA.push(imgDataElementA);
imgDataB.push(imgDataElementB);
}
//clearing out the canvas before laying on the new stuff
dest.fillStyle = "white";
dest.fillRect(0, y, w, height);
//put the images back
for (var i = 0; i < slices; i++) {
dest.putImageData(imgDataA[i], step*i, y);
dest.putImageData(imgDataB[i], step*i+stepsA, y);
}
}; //closing function scramble
const scrambleMethods = [scrambleOriginal,scramble,scrambleFloor,scrambleNoOverlap];
var frameCount = 0;
var sliceStep = 1;
var slices = 1;
function mainLoop(){
if(mouse.button){
if(frameCount++ % framesToStep === framesToStep-1){ // every 30 Frames
slices += sliceStep;
if(slices > 150 || slices < 2){ sliceStep = -sliceStep }
counterElement.textContent = slices; // Prevent reflow by using textContent
sCtx.clearRect(0,0,w,h);
sCtx.imageSmoothingEnabled = true;
const len = scrambleMethods.length;
for(var i = 0; i < len; i ++){
scrambleMethods[i](iCtx,sCtx,(128/len) * i, 128/len-2);
scrambleMethods[i](iCtx,sCtx,(128/len) * i + 128, 128/len-2);
}
}
}
dCtx.fillStyle = "white";
dCtx.fillRect(0,0,w,h);
dCtx.drawImage(sCtx.canvas,0,0);
showMouseZoom(dCtx,zCtx);
dCtx.drawImage(zCtx.canvas,0,0);
requestAnimationFrame(mainLoop);
}
//scramble(iCtx,sCtx);
requestAnimationFrame(mainLoop);canvas {
border: 1px solid black;
}
#count {
position : absolute;
top : 0px;
left : 10px;
font-family: monospace;
font-size: 20px;
}<canvas id="myCanvas" height = "256" title="Hold mouse button to chance slice count"></canvas>
<p id="count"></p>