CanvasRenderingContext2D.shadowOffsetY

CanvasRenderingContext2D.shadowOffsetY 是 Canvas 2D API 描述阴影垂直偏移距离的属性。

语法

ctx.shadowOffsetY = offset;

offset: 阴影垂直偏移距离的float类型的值。默认值是 0。 Infinity 或者NaN 都会被忽略。

示例

使用 shadowOffsetY 属性

这是一段简单的代码片段，使用 shadowOffsetY 属性绘制阴影垂直偏移量。注意：将shadowColor属性设置成不透明，阴影才会被绘制。

HTML

<canvas id="canvas"></canvas>

JavaScript

var canvas = document.getElementById("canvas");
var ctx = canvas.getContext("2d");

ctx.shadowColor = "black";
ctx.shadowOffsetY = 10;
ctx.shadowBlur = 10;

ctx.fillStyle = "green";
ctx.fillRect(10, 10, 100, 100);

修改下面的代码并在线查看 canvas 的变化：

Playable code

<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">
ctx.shadowColor = "black";
ctx.shadowOffsetY = 10;
ctx.shadowBlur = 10;
ctx.fillStyle = "green";
ctx.fillRect(10, 10, 100, 100);</textarea>

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);

规范描述

Specification	Status	Comment
HTML Living Standard CanvasRenderingContext2D.shadowOffsetY	Living Standard

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

Desktop
Mobile

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

Feature	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

语法

示例