admin管理员组文章数量:1323330
I need to draw a polygon on my canvas but i have to make it with clicks of mouse. For exemple: click one click two tree and so... max of ten clicks and apper a line to fill all clicked points. Pure JS.
function drawPolygon(position, sides, angle) {
var coordinates = [],
radius = Math.sqrt(Math.pow((dragStartLocation.x - position.x), 2) + Math.pow((dragStartLocation.y - position.y), 2)),
index = 0;
for (index = 0; index < sides; index++) {
coordinates.push({x: dragStartLocation.x + radius * Math.cos(angle), y: dragStartLocation.y - radius * Math.sin(angle)});
angle += (2 * Math.PI) / sides;
}
context.beginPath();
context.moveTo(coordinates[0].x, coordinates[0].y);
for (index = 1; index < sides; index++) {
context.lineTo(coordinates[index].x, coordinates[index].y);
}
context.closePath();
}
I need to draw a polygon on my canvas but i have to make it with clicks of mouse. For exemple: click one click two tree and so... max of ten clicks and apper a line to fill all clicked points. Pure JS.
function drawPolygon(position, sides, angle) {
var coordinates = [],
radius = Math.sqrt(Math.pow((dragStartLocation.x - position.x), 2) + Math.pow((dragStartLocation.y - position.y), 2)),
index = 0;
for (index = 0; index < sides; index++) {
coordinates.push({x: dragStartLocation.x + radius * Math.cos(angle), y: dragStartLocation.y - radius * Math.sin(angle)});
angle += (2 * Math.PI) / sides;
}
context.beginPath();
context.moveTo(coordinates[0].x, coordinates[0].y);
for (index = 1; index < sides; index++) {
context.lineTo(coordinates[index].x, coordinates[index].y);
}
context.closePath();
}
Share
Improve this question
asked Apr 4, 2015 at 0:18
Wesley HeronWesley Heron
4233 gold badges13 silver badges27 bronze badges
1 Answer
Reset to default 6All you have to do is add a mousedown event handler. In mousedown, push the mouse coordinates into the coordinates[] array.
var canvas=document.getElementById("canvas");
var context=canvas.getContext("2d");
var cw=canvas.width;
var ch=canvas.height;
function reOffset(){
var BB=canvas.getBoundingClientRect();
offsetX=BB.left;
offsetY=BB.top;
}
var offsetX,offsetY;
reOffset();
window.onscroll=function(e){ reOffset(); }
context.lineWidth=2;
context.strokeStyle='blue';
var coordinates = [];
var isDone=false;
$('#done').click(function(){
isDone=true;
});
$("#canvas").mousedown(function(e){handleMouseDown(e);});
function handleMouseDown(e){
if(isDone || coordinates.length>10){return;}
// tell the browser we're handling this event
e.preventDefault();
e.stopPropagation();
mouseX=parseInt(e.clientX-offsetX);
mouseY=parseInt(e.clientY-offsetY);
coordinates.push({x:mouseX,y:mouseY});
drawPolygon();
}
function drawPolygon(){
context.clearRect(0,0,cw,ch);
context.beginPath();
context.moveTo(coordinates[0].x, coordinates[0].y);
for(index=1; index<coordinates.length;index++) {
context.lineTo(coordinates[index].x, coordinates[index].y);
}
context.closePath();
context.stroke();
}
body{ background-color: ivory; }
#canvas{border:1px solid red;}
<script src="https://ajax.googleapis./ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<h4>Click to assign polygon vertices</h4>
<button id=done>Click when done assigning points</button>
<br><canvas id="canvas" width=300 height=300></canvas>
本文标签: javascripthow to draw polygon on canvas with mouse clicks Pure JSStack Overflow
版权声明:本文标题:javascript - how to draw polygon on canvas with mouse clicks? Pure JS - Stack Overflow 内容由网友自发贡献,该文观点仅代表作者本人, 转载请联系作者并注明出处:http://www.betaflare.com/web/1742128453a2422050.html, 本站仅提供信息存储空间服务,不拥有所有权,不承担相关法律责任。如发现本站有涉嫌抄袭侵权/违法违规的内容,一经查实,本站将立刻删除。
发表评论