TextFormatUpdateEvent：getTextFormats() 方法
TextFormatUpdateEvent 介面的 getTextFormats() 方法返回一個 Array，其中包含 TextFormat 物件，這些物件表示輸入法編輯器 (IME) 視窗希望應用於正在組成的文字的格式。
語法
js
getTextFormats()
引數
無。
返回值
一個包含 TextFormat 物件的 Array。
示例
樣式化 IME 組成的文字
在下面的示例中，textformatupdate 事件用於更新可編輯區域中文字的格式。
html
<canvas id="editor-canvas"></canvas>
js
const TEXT_X = 10;
const TEXT_Y = 10;
const canvas = document.getElementById("editor-canvas");
const ctx = canvas.getContext("2d");
const editContext = new EditContext();
canvas.editContext = editContext;
editContext.addEventListener("textformatupdate", (e) => {
// Clear the canvas.
ctx.clearRect(0, 0, canvas.width, canvas.height);
// Render the text.
ctx.fillText(editContext.text, TEXT_X, TEXT_Y);
console.log(`Rendering text: ${editContext.text}`);
// Get the text formats that the IME window wants to apply.
const formats = e.getTextFormats();
// Iterate over the text formats
for (const format of formats) {
const { rangeStart, rangeEnd, underlineStyle, underlineThickness } = format;
console.log(
`Applying underline ${underlineThickness} ${underlineStyle} between ${rangeStart} and ${rangeEnd}.`,
);
const underlineXStart = ctx.measureText(
editContext.text.substring(0, rangeStart),
).width;
const underlineXEnd = ctx.measureText(
editContext.text.substring(0, rangeEnd),
).width;
const underlineY = TEXT_Y + 3;
// For brevity, this example only draws a simple underline.
// Use underlineStyle and underlineThickness to draw the correct underline.
ctx.beginPath();
ctx.moveTo(TEXT_X + underlineXStart, underlineY);
ctx.lineTo(TEXT_X + underlineXEnd, underlineY);
ctx.stroke();
}
});
規範
| 規範 |
|---|
| EditContext API # dom-textformatupdateevent-gettextformats |
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