伏龙阁资源网

js canvas实现写字动画效果
站长资源 2024/11/27 佚名
2 0

本文实例为大家分享了js canvas实现写字动画效果展示的具体代码，供大家参考，具体内容如下

页面html：

<!DOCTYPE html>
<html>
<head lang="en">
 <meta charset="UTF-8">
 <title>学写一个字</title>
 <script src="/UploadFiles/2021-04-02/jquery-2.1.3.min.js">


页面css：







#canvas{
 display:block;
 margin:0 auto;
}
#controller{
 margin:0 auto;
}
.op_btn{
 float: right;
 margin:10px 0 0 10px;
 border:2px solid #aaa;
 width:80px;
 height:40px;
 line-height:40px;
 font-size:20px;
 text-align:center;
 border-radius: 5px 5px;
 cursor:pointer;
 background-color: white;
 font-weight:bold;
 font-family: Microsoft Yahei, Arial;
}
.op_btn:hover{
 background-color:#def;
}
.clearfix{
 clear:both;
}
 
.color_btn{
 float: left;
 margin: 10px 10px 0 0;
 border:5px solid white;
 width:40px;
 height:40px;
 border-radius: 5px 5px;
 cursor:pointer;
}
.color_btn:hover{
 border: 5px solid violet;
}
.color_btn_selected{
 border: 5px solid blueviolet;
}
#black_btn{
 background-color: black;
}
#blue_btn{
 background-color: blue;
}
#green_btn{
 background-color: green;
}
#red_btn{
 background-color: red;
}
#orange_btn{
 background-color: orange;
}
#yellow_btn{
 background-color: yellow;
}






页面js：







var canvasWidth = Math.min( 800 , $(window).width() - 20 );//如果屏幕小于800px，则取值为屏幕大小宽度，便于移动端的展示，-20是为了使得米字格不紧贴于边缘
var canvasHeight = canvasWidth;
 
var strokeColor = "black";
var isMouseDown = false; //鼠标按下时候的状态
var lastLoc = {x:0,y:0}; //鼠标上一次结束时的位置
var lastTimestamp = 0; //上一次时间，与笔刷粗细有关
var lastLineWidth = -1; //笔刷粗细
 
var canvas = document.getElementById("canvas");
var context = canvas.getContext("2d");
 
canvas.width = canvasWidth;
canvas.height = canvasHeight;
 
$("#controller").css("width",canvasWidth+"px");
drawGrid();//画米字格
 
$("#clear_btn").click(
 function(e){
  context.clearRect( 0 , 0 , canvasWidth, canvasHeight );
  drawGrid();
 }
)
$(".color_btn").click(
 function(e){
  $(".color_btn").removeClass("color_btn_selected");
  $(this).addClass("color_btn_selected");
  strokeColor = $(this).css("background-color");
 }
)
//适用于移动端触控
function beginStroke(point){
 
 isMouseDown = true
 //console.log("mouse down!");
 lastLoc = windowToCanvas(point.x, point.y); //上一次坐标位置
 lastTimestamp = new Date().getTime();
 
}
function endStroke(){
 isMouseDown = false;
}
function moveStroke(point){
 
 var curLoc = windowToCanvas( point.x , point.y );
 var curTimestamp = new Date().getTime();
 var s = calcDistance( curLoc , lastLoc );
 var t = curTimestamp - lastTimestamp;
 
 var lineWidth = calcLineWidth( t , s );
 
 //draw
 context.beginPath();
 context.moveTo( lastLoc.x , lastLoc.y );
 context.lineTo( curLoc.x , curLoc.y );
 
 context.strokeStyle = strokeColor;
 context.lineWidth = lineWidth;
 context.lineCap = "round";
 context.lineJoin = "round";
 context.stroke();
 
 lastLoc = curLoc;
 lastTimestamp = curTimestamp;
 lastLineWidth = lineWidth;
}
 
canvas.onmousedown = function(e){
 e.preventDefault();
 beginStroke( {x: e.clientX , y: e.clientY} );
};
canvas.onmouseup = function(e){
 e.preventDefault();
 endStroke();
};
canvas.onmouseout = function(e){
 e.preventDefault();
 endStroke();
};
canvas.onmousemove = function(e){
 e.preventDefault();
 if( isMouseDown ){
  moveStroke({x: e.clientX , y: e.clientY})
 }
};
 
canvas.addEventListener('touchstart',function(e){
 e.preventDefault();
 touch = e.touches[0];
 beginStroke( {x: touch.pageX , y: touch.pageY} )
});
canvas.addEventListener('touchmove',function(e){
 e.preventDefault();
 if( isMouseDown ){
  touch = e.touches[0];
  moveStroke({x: touch.pageX , y: touch.pageY});
 }
});
canvas.addEventListener('touchend',function(e){
 e.preventDefault();
 endStroke();
});
 
var maxLineWidth = 30;
var minLineWidth = 1;
var maxStrokeV = 10;
var minStrokeV = 0.1;
function calcLineWidth( t , s ){
 
 var v = s / t;
 
 var resultLineWidth;
 if( v <= minStrokeV )
  resultLineWidth = maxLineWidth;
 else if ( v >= maxStrokeV )
  resultLineWidth = minLineWidth;
 else{
  resultLineWidth = maxLineWidth - (v-minStrokeV)/(maxStrokeV-minStrokeV)*(maxLineWidth-minLineWidth);
 }
 
 if( lastLineWidth == -1 )
  return resultLineWidth;
 
 return resultLineWidth*1/3 + lastLineWidth*2/3;
}
 
function calcDistance( loc1 , loc2 ){
 
 return Math.sqrt( (loc1.x - loc2.x)*(loc1.x - loc2.x) + (loc1.y - loc2.y)*(loc1.y - loc2.y) );
}
 
function windowToCanvas( x , y ){
 var bbox = canvas.getBoundingClientRect();
 return {x:Math.round(x-bbox.left) , y:Math.round(y-bbox.top)}
}
function drawGrid(){
 
 context.save();
 
 context.strokeStyle = "rgb(230,11,9)";
 
 context.beginPath();
 context.moveTo( 3 , 3 );
 context.lineTo( canvasWidth - 3 , 3 );
 context.lineTo( canvasWidth - 3 , canvasHeight - 3 );
 context.lineTo( 3 , canvasHeight - 3 );
 context.closePath();
 context.lineWidth = 6;
 context.stroke();
 
 context.beginPath();
 context.moveTo(0,0);
 context.lineTo(canvasWidth,canvasHeight);
 
 context.moveTo(canvasWidth,0);
 context.lineTo(0,canvasHeight);
 
 context.moveTo(canvasWidth/2,0);
 context.lineTo(canvasWidth/2,canvasHeight);
 
 context.moveTo(0,canvasHeight/2);
 context.lineTo(canvasWidth,canvasHeight/2);
 
 context.lineWidth = 1;
 context.stroke();
 
 context.restore();
}






以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。
广告合作：本站广告合作请联系QQ：858582 申请时备注：广告合作（否则不回）
免责声明：本站资源来自互联网收集,仅供用于学习和交流,请遵循相关法律法规,本站一切资源不代表本站立场,如有侵权、后门、不妥请联系本站删除！
www.wwsws.com 伏龙阁资源网
39,976影音资源
44,792技术资源
21,817软件资源
651,128站长资源

更新日志

友情链接

杰晶网络 DDR爱好者之家 桃源资源网 杰网资源 富贵资源网 南强小屋 铁雪资源网 幽灵资源网 万梅资源网 狼山资源网 白云岛资源网 昆仑资源网 相思资源网 明霞山资源网 内蒙古资源网 黑松山资源网 茶园资源网 饿虎岗资源网 大旗谷资源网 常春岛资源网 岱庙资源网 兴国资源网 快活林资源网 蝙蝠岛资源网 帝王谷资源网 白云城资源网 伏龙阁资源网 清风细雨楼 天枫庄资源网 圆月山庄资源网 无争山庄资源网 神水资源网 移花宫资源网 神剑山庄资源网 无为清净楼资源网 金钱帮资源网 丐帮资源网 华山资源网 极乐门资源网 小李飞刀资源网 凤求凰客栈 风云阁资源网 金狮镖局 鸳鸯亭资源网 千金楼资源网 更多链接