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CanvasRenderingContext2D.shadowOffsetX - Web API 接口参考编辑

CanvasRenderingContext2D.shadowOffsetX 是 Canvas 2D API 描述阴影水平偏移距离的属性。

Syntax

ctx.shadowOffsetX = offset;

offset: 阴影水平偏移距离的float类型的值。默认值是 0。 Infinity 或者NaN都会被忽略。

示例

使用 shadowOffsetX 属性

这是一段简单的代码片段，使用 shadowOffsetX 属性设置阴影的水平偏移量。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.shadowOffsetX = 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.shadowOffsetX = 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.shadowOffsetX	Living Standard

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