如何複製圖片

Thomas Steiner

許多現代瀏覽器都支援將圖片複製到剪貼簿，並以 PNG 和 SVG 格式儲存。基於安全考量，目前不支援其他格式。

現代做法

使用 Async Clipboard API

Clipboard.write() 方法會採用 ClipboardItem 物件陣列，並在圖片成功寫入剪貼簿時傳回 Promise。Clipboard.write() 只能從具有焦點的 window 物件使用。

Browser Support

  • Chrome: 76.
  • Edge: 79.
  • Firefox: 127.
  • Safari: 13.1.

Source

傳統做法

使用navigator.clipboard.writeText()

雖然並非所有瀏覽器都支援二進位資料的 navigator.clipboard.write()，但都支援 navigator.clipboard.writeText()。如要複製可擴充向量圖形圖片，可以複製可擴充向量圖形原始碼，而非圖片本身。很抱歉，PNG 圖片無法使用這項功能。

Browser Support

  • Chrome: 66.
  • Edge: 79.
  • Firefox: 63.
  • Safari: 13.1.

Source

漸進增強

const button = document.querySelector('button');
const img = document.querySelector('img');

button.addEventListener('click', async () => {
  const responsePromise = fetch(img.src);
  try {
    if ('write' in navigator.clipboard) {
      await navigator.clipboard.write([
        new ClipboardItem({
          'image/svg+xml': new Promise(async (resolve) => {
            const blob = await responsePromise.then(response => response.blob());
            resolve(blob);
          }),
        }),
      ]);
      // Image copied as image.
    } else {
      const text = await responsePromise.then(response => response.text());
      await navigator.clipboard.writeText(text);
      // Image copied as source code.
    }
  } catch (err) {
    console.error(err.name, err.message);
  }
});

延伸閱讀

示範

HTML

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1" />
    <link
      rel="icon"
      href="data:image/svg+xml,<svg xmlns=%22http://www.w3.org/2000/svg%22 viewBox=%220 0 100 100%22><text y=%22.9em%22 font-size=%2290%22>🎉</text></svg>"
    />
    <title>How to copy images</title>
  </head>
  <body>
    <h1>How to copy images</h1>
    <img src="assets/fugu.svg" alt="Fugu fish." width="128" height="128">
    <button type="button">Copy</button>
  </body>
</html>

CSS


        :root {
  color-scheme: dark light;
}

html {
  box-sizing: border-box;
}

*,
*:before,
*:after {
  box-sizing: inherit;
}

body {
  margin: 1rem;
  font-family: system-ui, sans-serif;
}

button {
  display: block;
}

JS


        const button = document.querySelector('button');
const img = document.querySelector('img');

button.addEventListener('click', async () => {
  const responsePromise = fetch(img.src);

  try {
    if ('write' in navigator.clipboard) {
      await navigator.clipboard.write([
        new ClipboardItem({
          'image/svg+xml': new Promise(async (resolve) => {
            const blob = await responsePromise.then(response => response.blob());
            resolve(blob);
          }),
        }),
      ]);
      // Image copied as image.
    } else {
      const text = await responsePromise.then(response => response.text());
      await navigator.clipboard.writeText(text);
      // Image copied as source code.
    }
  } catch (err) {
    console.error(err.name, err.message);
  }
});