Path2D.addPath() 是 Canvas 2D API 根据指定路径变量添加路径的方法。
语法
void path.addPath(path [, transform]);参数
path
需要添加的 Path2D 路径。transform 可选。
SVGMatrix 作为新增路径的变换矩阵。
示例
使用 addPath 方法
这是一段使用 addPath 方法的简单的代码片段。
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// Create a new path with a rect
var p1 = new Path2D();
p1.rect(0,0,100,100);
// Create another path with a rect
var p2 = new Path2D();
p2.rect(0,0,100,100);
// Create transformation matrix that moves vertically 300 points to the right
var m = document.createElementNS("http://www.w3.org/2000/svg", "svg").createSVGMatrix();
m.a = 1; m.b = 0;
m.c = 0; m.d = 1;
m.e = 300; m.f = 0;
// add the second path to the first path
p1.addPath(p2, m);
// Finally, fill the first path onto the canvas
ctx.fill(p1);
修改下面的代码并在线查看 canvas 的变化 (查看浏览器兼容性列表，确定你目前的浏览器是否支持这个方法)：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>Path2D.addPath() | Web176教程www.web176.com</title>
<meta name="robots" content="noindex, nofollow">
<style>
body {
padding: 0;
margin: 0;
}
svg:not(:root) {
display: block;
}
.playable-code {
background-color: #f4f7f8;
border: none;
border-left: 6px solid #558abb;
border-width: medium medium medium 6px;
color: #4d4e53;
height: 100px;
width: 90%;
padding: 10px 10px 0;
}
.playable-canvas {
border: 1px solid #4d4e53;
border-radius: 2px;
}
.playable-buttons {
text-align: right;
width: 90%;
padding: 5px 10px 5px 26px;
}
</style>
</head>
<body>
<canvas id="canvas" width="400" height="200" class="playable-canvas"></canvas>
<div class="playable-buttons">
<input id="edit" type="button" value="Edit" />
<input id="reset" type="button" value="Reset" />
</div>
<textarea id="code" class="playable-code" style="height:220px;">
var p1 = new Path2D();
p1.rect(0,0,100,100);
var p2 = new Path2D();
p2.rect(0,0,100,100);
var m = document.createElementNS("http://www.w3.org/2000/svg", "svg").createSVGMatrix();
m.a = 1; m.b = 0;
m.c = 0; m.d = 1;
m.e = 300; m.f = 0;
p1.addPath(p2, m);
ctx.fill(p1);</textarea>
<script>
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
// Create a new path with a rect
var p1 = new Path2D();
p1.rect(0,0,100,100);
// Create another path with a rect
var p2 = new Path2D();
p2.rect(0,0,100,100);
// Create transformation matrix that moves vertically 300 points to the right
var m = document.createElementNS("http://www.w3.org/2000/svg", "svg").createSVGMatrix();
m.a = 1; m.b = 0;
m.c = 0; m.d = 1;
m.e = 300; m.f = 0;
// add the second path to the first path
p1.addPath(p2, m);
// Finally, fill the first path onto the canvas
ctx.fill(p1);
var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");
var textarea = document.getElementById("code");
var reset = document.getElementById("reset");
var edit = document.getElementById("edit");
var code = textarea.value;
function drawCanvas() {
ctx.clearRect(0, 0, canvas.width, canvas.height);
eval(textarea.value);
}
reset.addEventListener("click", function() {
textarea.value = code;
drawCanvas();
});
edit.addEventListener("click", function() {
textarea.focus();
})
textarea.addEventListener("input", drawCanvas);
window.addEventListener("load", drawCanvas);
</script>
</body>
</html>作者：terry，如若转载，请注明出处：https://www.web176.com/canvas_api/7737.html
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