我正在尝试创建一个连续的颜色过渡,就像在 Windows 8 安装中那样,We're getting your PC ready .
我不知道如何编写 shift
函数。检查所有 R、G、B 值并将当前颜色与下一种颜色匹配。
谁能帮我解决这个问题?或者让我知道是否有比这更好的方法?
function switchColor(id) {
var elm = document.getElementById(id);
// getting elm's current rgb values
var elmColor = window.getComputedStyle(elm).getPropertyValue("background");
var startIndex = elmColor.indexOf("(");
var finishIndex = elmColor.indexOf(")");
var elmRGB = elmColor.substring(startIndex + 1, finishIndex);
var currentColor = elmRGB.split(",");
for (var i = 0; i<3; i++) { currentColor[i] = currentColor[i].trim(); }
// generating a random color => [r, g, ,b]
var nextColor = [];
for (var i = 0; i < 3; i++) {
nextColor[i] = Math.floor(Math.random()*250);
}
// function to convert rgb array to hex color => [r, g, b] = #rgb
function rgbToHex(clr) {
var rgb = clr;
var hex;
var hex1 = rgb[0].toString(16);
var hex2 = rgb[1].toString(16);
var hex3 = rgb[2].toString(16);
if (hex1.length < 2) { hex1 = "0" + hex1; }
if (hex2.length < 2) { hex2 = "0" + hex2; }
if (hex3.length < 2) { hex3 = "0" + hex3; }
return hex = "#" + hex1 + hex2 + hex3;
}
// checking if nextColor rgb values are greater than current rgb's
// so we can increase or decrease for smooth transition
var status = [];
for (var i = 0; i < 3; i++) {
if (nextColor[i] > currentColor[i]) { status.push(1); }
else { status.push(0); }
}
// this isn't part of the code, just testing
elm.style.background = rgbToHex(nextColor);
function shift() {
// shift between colors
// modify currentColor's rgb values and apply it to the elm
// elm.style.background = rgbToHex(currentColor);
}
var handler = setInterval(shift, 100);
}
setInterval(function() { switchColor("sandbox"); }, 2000);
最佳答案
检查这个JSFiddle用于带有精美图形的转换。
/* ==================== Required Functions ==================== */
// This is required to get the initial background-color of an element.
// The element might have it's bg-color already set before the transition.
// Transition should continue/start from this color.
// This will be used only once.
function getElementBG(elm) {
var bg = getComputedStyle(elm).backgroundColor;
bg = bg.match(/\((.*)\)/)[1];
bg = bg.split(",");
for (var i = 0; i < bg.length; i++) {
bg[i] = parseInt(bg[i], 10);
}
if (bg.length > 3) { bg.pop(); }
return bg;
}
// A function to generate random numbers.
// Will be needed to generate random RGB value between 0-255.
function random() {
if (arguments.length > 2) {
return 0;
}
switch (arguments.length) {
case 0:
return Math.random();
case 1:
return Math.round(Math.random() * arguments[0]);
case 2:
var min = arguments[0];
var max = arguments[1];
return Math.round(Math.random() * (max - min) + min);
}
}
// Generates a random RGB value.
function generateRGB(min, max) {
var min = min || 0;
var max = min || 255;
var color = [];
for (var i = 0; i < 3; i++) {
var num = random(min, max);
color.push(num);
}
return color;
}
// Calculates the distance between the RGB values.
// We need to know the distance between two colors
// so that we can calculate the increment values for R, G, and B.
function calculateDistance(colorArray1, colorArray2) {
var distance = [];
for (var i = 0; i < colorArray1.length; i++) {
distance.push(Math.abs(colorArray1[i] - colorArray2[i]));
}
return distance;
}
// Calculates the increment values for R, G, and B using distance, fps, and duration.
// This calculation can be made in many different ways.
function calculateIncrement(distanceArray, fps, duration) {
var fps = fps || 30;
var duration = duration || 1;
var increment = [];
for (var i = 0; i < distanceArray.length; i++) {
var incr = Math.abs(Math.floor(distanceArray[i] / (fps * duration)));
if (incr == 0) {
incr = 1;
}
increment.push(incr);
}
return increment;
}
// Converts RGB array [32,64,128] to HEX string #204080
// It's easier to apply HEX color than RGB color.
function rgb2hex(colorArray) {
var color = [];
for (var i = 0; i < colorArray.length; i++) {
var hex = colorArray[i].toString(16);
if (hex.length < 2) { hex = "0" + hex; }
color.push(hex);
}
return "#" + color.join("");
}
/* ==================== Setup ==================== */
// Duration is not what it says. It's a multiplier in the calculateIncrement() function.
// duration = 1-4, fast-to-slow
var fps = 30;
var duration = 3;
var transElement = document.body;
var currentColor = getElementBG(transElement);
var transHandler = null;
startTransition();
/* ==================== Transition Initiator ==================== */
function startTransition() {
clearInterval(transHandler);
targetColor = generateRGB();
distance = calculateDistance(currentColor, targetColor);
increment = calculateIncrement(distance, fps, duration);
transHandler = setInterval(function() {
transition();
}, 1000/fps);
}
/* ==================== Transition Calculator ==================== */
function transition() {
// checking R
if (currentColor[0] > targetColor[0]) {
currentColor[0] -= increment[0];
if (currentColor[0] <= targetColor[0]) {
increment[0] = 0;
}
} else {
currentColor[0] += increment[0];
if (currentColor[0] >= targetColor[0]) {
increment[0] = 0;
}
}
// checking G
if (currentColor[1] > targetColor[1]) {
currentColor[1] -= increment[1];
if (currentColor[1] <= targetColor[1]) {
increment[1] = 0;
}
} else {
currentColor[1] += increment[1];
if (currentColor[1] >= targetColor[1]) {
increment[1] = 0;
}
}
// checking B
if (currentColor[2] > targetColor[2]) {
currentColor[2] -= increment[2];
if (currentColor[2] <= targetColor[2]) {
increment[2] = 0;
}
} else {
currentColor[2] += increment[2];
if (currentColor[2] >= targetColor[2]) {
increment[2] = 0;
}
}
// applying the new modified color
transElement.style.backgroundColor = rgb2hex(currentColor);
// transition ended. start a new one
if (increment[0] == 0 && increment[1] == 0 && increment[2] == 0) {
startTransition();
}
}
body {
background: white;
}
关于javascript - 连续颜色过渡,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/19639506/