CanvasGradient.addColorStop()

CanvasGradient.addColorStop() 方法添加一个由偏移值和颜色值指定的断点到渐变。如果偏移值不在0到1之间，将抛出INDEX_SIZE_ERR错误，如果颜色值不能被解析为有效的CSS颜色值 <color>，将抛出SYNTAX_ERR错误。

语法

void gradient.addColorStop(offset, color);

参数

offset: 0到1之间的值，超出范围将抛出INDEX_SIZE_ERR错误
color: CSS颜色值 <color>。如果颜色值不能被解析为有效的CSS颜色值 <color>，将抛出SYNTAX_ERR错误。

示例

使用`addColorStop`方法

一个使用CanvasGradient对象的addColorStop 方法的简单例子

HTML

 <canvas id="canvas"></canvas>

JavaScript

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

var gradient = ctx.createLinearGradient(0,0,200,0);
gradient.addColorStop(0,"green");
gradient.addColorStop(1,"white");
ctx.fillStyle = gradient;
ctx.fillRect(10,10,200,100);

编辑以下代码可看到画布变化:

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">
var gradient = ctx.createLinearGradient(0,0,200,0);
gradient.addColorStop(0,"green");
gradient.addColorStop(1,"white");
ctx.fillStyle = gradient;
ctx.fillRect(10,10,200,100);</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);

标准

标准	状态	备注
HTML Living Standard CanvasGradient.addColorStop	Living Standard
Unknown CanvasGradient.addColorStop	Recommendation

浏览器兼容性

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Desktop
Mobile

功能	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
基本支持	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

功能	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
基本支持	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)