var SVG = function() {
this.element = document.getElementsByTagName("svg")[0];
this.namespace = "http://www.w3.org/2000/svg";
this.width = 400;
this.height = 400;
}
/****Let's initialise our SVG ready to draw our shape****/
var svg = new SVG();
/****This sets up the user interface - we've included the script for this as an external library for the codepen****/
var gui = new dat.GUI();
/****Here's where the code to create the shape begins!****/
var Teardrop = function() {
this.x = svg.width * 0.5;
this.y = svg.height * 0.1;
this.width = svg.width * 0.4;
this.triangleHeight = svg.height * 0.5;
this.yCP1 = svg.height * 0.2;
this.yCP2 = svg.height * 0.45;
this.element = null;
this.ctrlPoints = [];
this.anchors = [];
this.fill = "none";
this.stroke = "#333";
this.strokeWidth = 2;
this.showCtrlPoints = true;
this.init();
}
Teardrop.prototype.init = function() {
this.element = document.createElementNS(svg.namespace, "path");
svg.element.appendChild(this.element);
this.element.setAttribute("fill", this.fill);
this.element.setAttribute("stroke", this.stroke);
this.element.setAttribute("stroke-width", this.strokeWidth);
for (var i = 0; i < 3; i++) {
this.ctrlPoints.push(document.createElementNS(svg.namespace, "circle"));
svg.element.appendChild(this.ctrlPoints[i]);
this.ctrlPoints[i].setAttribute("fill", this.fill);
this.ctrlPoints[i].setAttribute("stroke", 'red');
this.ctrlPoints[i].setAttribute("stroke-width", 1);
this.anchors.push(document.createElementNS(svg.namespace, "line"));
svg.element.appendChild(this.anchors[i]);
this.anchors[i].setAttribute("stroke-width", 1);
this.anchors[i].setAttribute("stroke", this.stroke);
this.anchors[i].setAttribute("stroke-dasharray", "3,2");
}
this.draw();
}
Teardrop.prototype.draw = function() {
this.radius = this.width / 2;
path = [
"M", this.x, ",", this.y,
"C", this.x, ",", this.yCP1, " ", this.x + this.width / 2, ",", this.yCP2, " ", this.x + this.width / 2, ",", this.y + this.triangleHeight,
"A", this.radius, ",", this.radius, ",", "0 0,1,", this.x - this.width / 2, ",", this.y + this.triangleHeight,
"C", this.x - this.width / 2, ",", this.yCP2, " ", this.x, ",", this.yCP1, " ", this.x, ",", this.y
];
this.element.setAttribute("d", path.join(""));
cpCoords = [];
cpCoords[0] = [this.x, this.yCP1];
cpCoords[1] = [this.x - this.width / 2, this.yCP2];
cpCoords[2] = [this.x + this.width / 2, this.yCP2];
anchorCoords = [];
anchorCoords[0] = [this.x, this.y];
anchorCoords[1] = [this.x - this.width / 2, this.y + this.triangleHeight];
anchorCoords[2] = [this.x + this.width / 2, this.y + this.triangleHeight];
for (var i = 0; i < 3; i++) {
this.ctrlPoints[i].setAttribute("cx", cpCoords[i][0]);
this.ctrlPoints[i].setAttribute("cy", cpCoords[i][1]);
this.anchors[i].setAttribute("x1", cpCoords[i][0]);
this.anchors[i].setAttribute("x2", anchorCoords[i][0]);
this.anchors[i].setAttribute("y1", cpCoords[i][1]);
this.anchors[i].setAttribute("y2", anchorCoords[i][1]);
if (this.showCtrlPoints) {
this.ctrlPoints[i].setAttribute("r", 2);
this.anchors[i].setAttribute("stroke-width", 1);
} else {
this.ctrlPoints[i].setAttribute("r", 0);
this.anchors[i].setAttribute("stroke-width", 0);
}
}
}
var teardrop = new Teardrop();
gui.add(teardrop, 'triangleHeight', 0, svg.height * 0.75);
gui.add(teardrop, 'width', 0, 200);
gui.add(teardrop, 'yCP1', 0, svg.height);
gui.add(teardrop, 'yCP2', 0, svg.height);
gui.add(teardrop, 'showCtrlPoints', 0, svg.height);
for (var i in gui.__controllers) {
gui.__controllers[i].onChange(function() {
teardrop.draw();
});
}
html,
body {
height: 100%;
}
svg {
display: block;
margin: 0 auto;
background: url('http://unitedshapes.com/images/graph-paper/graph-paper.png');
}
<script src="//cdnjs.cloudflare.com/ajax/libs/dat-gui/0.5/dat.gui.min.js"></script>
<svg width='400px' height='400px'></svg>
[srcset]หรือ<picture>องค์ประกอบ ยังดีกว่าเพียงเชื่อมโยงไปยังภาพ svg:<img src="tear.svg" alt="Teardrop"/>