Javascript 以烧瓶形式提交画布绘图
我已经在Flask中创建了表单,我正在使用引导来帮助呈现文件。我的表单工作正常,但现在我想让用户画出他们的签名,并将签名与表单一起提交。但我一直很难做到这一点,因为当我将canvas标记放在表单标记中时,用户无法在画布中绘制任何东西。如果我将canvas标记放在表单标记之外,我就能够在其上进行绘制Javascript 以烧瓶形式提交画布绘图,javascript,html,jquery,flask,canvas,Javascript,Html,Jquery,Flask,Canvas,我已经在Flask中创建了表单,我正在使用引导来帮助呈现文件。我的表单工作正常,但现在我想让用户画出他们的签名,并将签名与表单一起提交。但我一直很难做到这一点,因为当我将canvas标记放在表单标记中时,用户无法在画布中绘制任何东西。如果我将canvas标记放在表单标记之外,我就能够在其上进行绘制 {% extends "base.html" %} {% import 'wtf.html' as wtf %} <html> <body> {% block app_cont
{% extends "base.html" %}
{% import 'wtf.html' as wtf %}
<html>
<body>
{% block app_content %}
{% block content %}
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.0/jquery.min.js"></script>
<script>
$(document).ready(function() {
var flag, dot_flag = false,
prevX, prevY, currX, currY = 0,
color = 'black', thickness = 2;
var $canvas = $('#canvas');
var ctx = $canvas[0].getContext('2d');
$canvas.on('mousemove mousedown mouseup mouseout', function(e) {
prevX = currX;
prevY = currY;
currX = e.clientX - $canvas.offset().left;
currY = e.clientY - $canvas.offset().top;
if (e.type == 'mousedown') {
flag = true;
}
if (e.type == 'mouseup' || e.type == 'mouseout') {
flag = false;
}
if (e.type == 'mousemove') {
if (flag) {
ctx.beginPath();
ctx.moveTo(prevX, prevY);
ctx.lineTo(currX, currY);
ctx.strokeStyle = color;
ctx.lineWidth = thickness;
ctx.stroke();
ctx.closePath();
}
}
});
$('.canvas-clear').on('click', function(e) {
c_width = $canvas.width();
c_height = $canvas.height();
ctx.clearRect(0, 0, c_width, c_height);
$('#canvasimg').hide();
});
});
</script>
//When canvas placed here, the canvas shows up, and it works fine as user can write to it
<canvas id="canvas" width="300" height="50" style="border:2px solid;"></canvas>
<input type="button" value="Clear" class="canvas-clear" />
<script>
function delete_flash(flash){$(flash).parent().remove()}
</script>
<div class="container">
{% with messages = get_flashed_messages(with_categories=true) %}
{% if messages %}
{% for category, message in messages %}
<div class="alert alert-{{ category }}" role="alert" onclick=delete_flash(this)>
{{ message }}
<button type="button" class="close" data-dismiss="alert" aria-label="Close">
<span aria-hidden="true">×</span>
</button>
</div>
{% endfor %}
{% endif %}
{% endwith %}
</div>
<h1><center>Visitor Check In</center></h1>
<form action="" method="post" novalidate>
{{ form.hidden_tag() }}
<h5>  <b>3. </b>{{ form.question1.label }}</h5>
{% for subfield in form.question1%}
<tr> 
<td>{{ subfield }}</td>
<td>{{ subfield.label }}</td>  
</tr>
{% endfor %}
{% for error in form.question1.errors %}
<span style="color: red;">[{{ error }}]</span>
{% endfor %}
<h5> <b>4. </b>{{ form.question2.label }}</h5>
{% for subfield in form.question2%}
<tr> 
<td>{{ subfield }}</td>
<td>{{ subfield.label }}</td>  
</tr>
{% endfor %}
{% for error in form.question2.errors %}
<span style="color: red;">[{{ error }}]</span>
{% endfor %}
//When canvas placed here, the canvas shows up, but user cannot write anything to it
<canvas id="canvas" width="300" height="50" style="border:2px solid;"></canvas>
<input type="button" value="Clear" class="canvas-clear" />
<p>{{ form.submit() }}</p>
</form>
{% endblock %}
{% endblock %}
</body>
</html>
{%extends“base.html”%}
{%import'wtf.html'作为wtf%}
{%block app_content%}
{%block content%}
$(文档).ready(函数(){
var标志,dot_标志=false,
prevX,prevY,currX,currY=0,
颜色=黑色,厚度=2;
var$canvas=$(“#canvas”);
var ctx=$canvas[0]。getContext('2d');
$canvas.on('mousemove mousedown mouseup mouseout',函数(e){
prevX=currX;
prevY=咖喱;
currX=e.clientX-$canvas.offset().left;
currY=e.clientY-$canvas.offset().top;
如果(e.type=='mousedown'){
flag=true;
}
如果(e.type=='mouseup'| | e.type=='mouseout'){
flag=false;
}
如果(e.type==“mousemove”){
国际单项体育联合会(旗){
ctx.beginPath();
ctx.moveTo(prevX,prevY);
ctx.lineTo(咖喱,咖喱);
ctx.strokeStyle=颜色;
ctx.线宽=厚度;
ctx.stroke();
ctx.closePath();
}
}
});
$('.canvas clear')。在('click',函数(e)上{
c_width=$canvas.width();
c_height=$canvas.height();
ctx.clearRect(0,0,c_宽度,c_高度);
$('#canvasimg').hide();
});
});
//当画布放在这里时,画布就会显示出来,用户可以对其进行写入,它工作得很好
函数delete_flash(flash){$(flash.parent().remove()}
{%with messages=get\u flashed\u messages(with\u categories=true)%}
{%if消息%}
{%对于类别,消息中的消息%}
{{message}}
&时代;
{%endfor%}
{%endif%}
{%endwith%}
访客登记
{{form.hidden_tag()}}
&emsp;3.{{form.question1.label}
{表单中的子字段为%1%}
&emsp;
{{子字段}}
{{subfield.label}}&emsp;
{%endfor%}
{form.question1.errors%}中的错误为%
[{{error}}]
{%endfor%}
&emsp;4.{{form.question2.label}
{form.question2%}中的子字段为%
&emsp;
{{子字段}}
{{subfield.label}}&emsp;
{%endfor%}
{form.question2.errors%}中的错误为%
[{{error}}]
{%endfor%}
//当画布放置在这里时,画布显示出来,但用户不能向其中写入任何内容
{{form.submit()}}
{%endblock%}
{%endblock%}
也许将画布放在表单标签中的问题是,我在后端没有任何东西可以提交画布上绘制的内容。因此,我还想知道,当用户单击submit按钮时,如何才能将绘制的内容保存到画布上