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 {{cssxref("<color>")}}，将抛出SYNTAX_ERR错误。
void gradient.addColorStop(offset, color);
0到1之间的值，超出范围将抛出INDEX_SIZE_ERR错误<color>，将抛出SYNTAX_ERR错误。addColorStop方法一个使用{{domxref("CanvasGradient")}}对象的addColorStop 方法的简单例子
<canvas id="canvas"></canvas>
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:
<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);
{{ EmbedLiveSample('Playable_code', 700, 360) }}
| 标准 | 状态 | 备注 |
|---|---|---|
| {{SpecName('HTML WHATWG', "scripting.html#dom-canvasgradient-addcolorstop", "CanvasGradient.addColorStop")}} | {{Spec2('HTML WHATWG')}} | |
| {{SpecName('HTML Canvas 2D Context W3C', "#dom-canvasgradient-addcolorstop", "CanvasGradient.addColorStop")}} | {{Spec2('HTML5 W3C')}} |