CanvasRenderingContext2D.shadowOffsetY 是 Canvas 2D API 描述阴影垂直偏移距离的属性。
ctx.shadowOffsetY = offset;
offsetshadowOffsetY 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。
<canvas id="canvas"></canvas>
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：
<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);
{{ EmbedLiveSample('Playable_code', 700, 360) }}
| Specification | Status | Comment |
|---|---|---|
| {{SpecName('HTML WHATWG', "scripting.html#dom-context-2d-shadowoffsety", "CanvasRenderingContext2D.shadowOffsetY")}} | {{Spec2('HTML WHATWG')}} |