本文目录一览：
Unity3d如何实现滚动文本框
一、在Canvas新建一个Panel，add scroll Rect和mask组件，Rect Transform设成 middle-center，因为这样才能设置大小和text控件相同大小
二、Panel下新建一个Text，Vertical Overflow设置成Overflow，然后add Content Size Fitter这个Layout，该Layout的Vertical Fit设置为Perferred Size，然后调整大小和在Panel中的位置
三、新建一个ScrollBar，不在Panel之下，和Panel并列，Direction设置成Bottan to Top。设置成Panel同样的高度，并挨在一起，这样看起来就是一个文本框右边带着一个垂直滚动条
四、Panel的Scroll Rect组件的Content指定Text，Vertical Scrollbar指定上面新建的ScrollBar。
如何实现canvas的图片轮播
图片自动滑动效果很多网站都要用，最近在学html5就拿这个练练手，发现用canvas实现起来其实很简单。代码比较粗糙，有很多改进的地方，不过还是先记录一下。
一. html文件
[html] view
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!DOCTYPE html
html lang="en"
head
meta charset="utf-8"/
titleHTML5 Images Slider/title
script src=""/script
script src="test.js"/script
link href="style.css" rel="stylesheet" /
/head
body
div id="container"
canvas id="imgs" width="500" height="300" onclick="canvasClick()"/canvas
/div
div class="imgGallery"
span class="cover"img src="1.jpg" id="img1" width="125" height="150" onclick="iconClick(this.id)"/span
img src="2.jpg" id="img2" width="125" height="150" onclick="iconClick(this.id)"
img src="3.jpg" id="img3" width="125" height="150" onclick="iconClick(this.id)"
img src="4.jpg" id="img4" width="125" height="150" onclick="iconClick(this.id)"
/div
/body
footer
/footer
/html
二. js文件，名字test.js
[javascript] view
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var images = new Array();
var cIndex = 0;
var speed = 5;
var context;
var canvas;
var currentImage;
var width=300;
var height=300;
var stopX = 95;
var stopY = 0;
var autoTimeout;
var manuTimeout;
var interval;
var img1;
var img2;
var img3;
var img4;
var timeoutInterval = 5;
function slideImage(id,x,y,imgObj){
this.speed = speed;
this.preImage = null;
this.nextImage = null;
this.imgObj=imgObj;
this.x=x;
this.y=y;
this.direction="right";
this.id = id;
}
function buttonNext(x,y,bwidth,bheight){
this.x = x;
this.y = y;
this.width = bwidth;
this.height = bheight;
}
$(document).ready(
function(){
InitImages();
canvas = document.getElementById("imgs");
context = canvas.getContext("2d");
//移动图片
context.drawImage(currentImage.imgObj,currentImage.x,currentImage.y,width,height);
context.drawImage(currentImage.preImage.imgObj,currentImage.preImage.x,currentImage.preImage.y,width,height);
context.drawImage(currentImage.nextImage.imgObj,currentImage.nextImage.x,currentImage.nextImage.y,width,height);
context.fillStyle="rgba(100,150,185,0.5)";
context.fillRect(0,0,100,height);
context.fillRect(400,0,100,height);
interval = setTimeout("intervalSlide()", 20);
}
);
function drawFrame(){
context.clearRect(0,0,canvas.width,canvas.height);
//调用beginPath()确保不会接着上次绘制的图形绘制
context.beginPath();
context.drawImage(currentImage.imgObj,currentImage.x,currentImage.y,width,height);
context.drawImage(currentImage.preImage.imgObj,currentImage.preImage.x,currentImage.preImage.y,width,height);
context.drawImage(currentImage.nextImage.imgObj,currentImage.nextImage.x,currentImage.nextImage.y,width,height);
context.drawImage(currentImage.preImage.preImage.imgObj,currentImage.preImage.preImage.x,currentImage.preImage.preImage.y,width,height);
//遮罩
context.fillStyle="rgba(100,150,185,0.5)";
context.fillRect(0,0,100,height);
context.fillRect(400,0,100,height);
//每一帧的位置变动
currentImage.x -= speed;
currentImage.preImage.x -= speed;
currentImage.nextImage.x -= speed;
currentImage.preImage.preImage.x -= speed;
if(currentImage.x == 200){
currentImage.nextImage.x = 500;
}
//到达指定位置停止变动
if(currentImage.x != stopX){
autoTimeout = setTimeout("drawFrame()",timeoutInterval);
}
else{
}
}
function InitImages(){
img1 = new slideImage("img1",-200,0,document.getElementById("img1"));
img2 = new slideImage("img2",100,0,document.getElementById("img2"));
img3 = new slideImage("img3",400,0,document.getElementById("img3"));
img4 = new slideImage("img4",700,0,document.getElementById("img4"));
img1.preImage = img4;
img1.nextImage = img2;
img2.preImage= img1;
img2.nextImage= img3;
img3.preImage=img2;
img3.nextImage=img4;
img4.preImage = img3;
img4.nextImage = img1;
currentImage=img2;
hilightSelectedImg();
}
function canvasClick(){
currentImage = currentImage.nextImage;
manuTimeout = setTimeout("drawFrame()",timeoutInterval);
}
function intervalSlide(){
currentImage = currentImage.nextImage;
hilightSelectedImg();
autoTimeout = setTimeout("drawFrame()", timeoutInterval);
setTimeout("intervalSlide()", 5000)
}
function iconClick(obj){
if(obj == "img1"){
currentImage = img1;
}
else if(obj == "img2"){
currentImage = img2;
}
else if(obj == "img3"){
currentImage = img3;
}
else if(obj == "img4"){
currentImage = img4;
}
currentImage.preImage.x = 100;
currentImage.preImage.preImage.x = -200;
currentImage.x = 400;
hilightSelectedImg();
manuTimeout = setTimeout("drawFrame()",timeoutInterval);
}
function hilightSelectedImg(){
img1.imgObj.width = 125;
img1.imgObj.height = 150;
img1.imgObj.style.opacity = 0.5;
img2.imgObj.width = 125;
img2.imgObj.height = 150;
img2.imgObj.style.opacity = 0.5;
img3.imgObj.width = 125;
img3.imgObj.height = 150;
img3.imgObj.style.opacity = 0.5;
img4.imgObj.width = 125;
img4.imgObj.height = 150;
img4.imgObj.style.opacity = 0.5
currentImage.imgObj.width = 150;
currentImage.imgObj.height = 175;
currentImage.imgObj.style.opacity = 1;
}
三. css文件。style.css
[css] view
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canvas {
border:1px dashed black;
}
.imgGallery{
width:550px;
position:absolute;
height:170px
}
img{
opacity:0.5;
}
怎样canvas画布上添加滚动条，显示更多数据
canvas是不能添加滚动条，
可以把canvas画布放在一个层里，再给这个层添加滚动条，
div style="width:300px; height:200px; overflow:auto"
canvas id="idline" width="750" height="400" style="border:2px solid gray"/canvas
/div
HTML5 在CANVAS标签里面增加滚动条
使用缓存Canvas，将中间的部分缓存，然后drawImage将缓存canvas画到主画布上，这样你可以使用drawImage的剪切方法来模拟滚动了。
