html5 canvas手写字代码(兼容手机端)
画板实验
清 空
生成图片
var canvas,board,img;
canvas = document.getElementById(‘myCanvas‘);
img= document.getElementById(‘img‘);
canvas.height = 300;
canvas.width = 300;
board = canvas.getContext(‘2d‘);
var mousePress = false;
var last = null;
function beginDraw(){
mousePress = true;
}
function drawing(event){
event.preventDefault();
if(!mousePress)return;
var xy = pos(event);
if(last!=null){
board.beginPath();
board.moveTo(last.x,last.y);
board.lineTo(xy.x,xy.y);
board.stroke();
}
last = xy;
}
function endDraw(event){
mousePress = false;
event.preventDefault();
last = null;
}
function pos(event){
var x,y;
if(isTouch(event)){
x = event.touches[0].pageX;
y = event.touches[0].pageY;
}else{
x = event.offsetX+event.target.offsetLeft;
y = event.offsetY+event.target.offsetTop;
}
// log(‘x=‘+x+‘ y=‘+y);
return {x:x,y:y};
}
function log(msg){
var log = document.getElementById(‘log‘);
var val = log.value;
log.value = msg+‘
‘+val;
}
function isTouch(event){
var type = event.type;
if(type.indexOf(‘touch‘)>=0){
return true;
}else{
return false;
}
}
function save(){
//base64
var dataUrl = canvas.toDataURL();
img.src = dataUrl;
}
function clean(){
board.clearRect(0,0,canvas.width,canvas.height);
}
board.lineWidth = 1;
board.strokeStyle="#0000ff";
canvas.onmousedown = beginDraw;
canvas.onmousemove = drawing;
canvas.onmouseup = endDraw;
canvas.addEventListener(‘touchstart‘,beginDraw,false);
canvas.addEventListener(‘touchmove‘,drawing,false);
canvas.addEventListener(‘touchend‘,endDraw,false);
