Skip to main content

preloadImage()

此函数是 @remotion/preload 包的一部分。

此函数预加载图像，以便在挂载 <Img> 标签时，可以立即显示。

虽然预加载对于渲染并非必需，但它可以帮助在 <Player /> 和 Studio 中实现无缝播放。

preloadImage() 的替代方案是 prefetch() API。请参阅 @remotion/preload vs prefetch() 来决定哪个更适合您的用例。

用法​

tsx
import { preloadImage } from "@remotion/preload";
 
const unpreload = preloadImage(
  "https://images.unsplash.com/photo-1561336313-0bd5e0b27ec8?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=1740&q=80"
);
 
// If you want to un-preload the image later
unpreload();
tsx
import { preloadImage } from "@remotion/preload";
 
const unpreload = preloadImage(
  "https://images.unsplash.com/photo-1561336313-0bd5e0b27ec8?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=1740&q=80"
);
 
// If you want to un-preload the image later
unpreload();

工作原理​

一个 <link rel="preload" as="image"> 标签会被添加到文档的 head 元素中。

处理重定向​

如果图像 URL 重定向到另一个 URL，则预加载原始 URL 将无效。

如果您包含的 URL 是未知的，请使用 resolveRedirect() 来以编程方式获取遵循潜在重定向的最终 URL。

如果资源不支持 CORS，resolveRedirect() 将失败。如果资源重定向，并且不支持 CORS，则无法预加载该资产。

此代码片段尝试尽最大努力预加载图像。如果无法解析重定向，则尝试预加载原始 URL。

tsx
import { preloadImage, resolveRedirect } from "@remotion/preload";
import { Img } from "remotion";
 
// This code gets executed immediately once the page loads
let urlToLoad =
  "https://images.unsplash.com/photo-1561336313-0bd5e0b27ec8?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=1740&q=80";
 
resolveRedirect(urlToLoad)
  .then((resolved) => {
    // Was able to resolve a redirect, setting this as the image to load
    urlToLoad = resolved;
  })
  .catch((err) => {
    // Was unable to resolve redirect e.g. due to no CORS support
    console.log("Could not resolve redirect", err);
  })
  .finally(() => {
    // In either case, we try to preload the original or resolved URL
    preloadImage(urlToLoad);
  });
 
// This code only executes once the component gets mounted
const MyComp: React.FC = () => {
  // If the component did not mount immediately, this will be the resolved URL.
 
  // If the component mounted immediately, this will be the original URL.
  // In that case preloading is ineffective anyway.
  return <Img src={urlToLoad}></Img>;
};
tsx
import { preloadImage, resolveRedirect } from "@remotion/preload";
import { Img } from "remotion";
 
// This code gets executed immediately once the page loads
let urlToLoad =
  "https://images.unsplash.com/photo-1561336313-0bd5e0b27ec8?ixlib=rb-4.0.3&ixid=MnwxMjA3fDB8MHxwaG90by1wYWdlfHx8fGVufDB8fHx8&auto=format&fit=crop&w=1740&q=80";
 
resolveRedirect(urlToLoad)
  .then((resolved) => {
    // Was able to resolve a redirect, setting this as the image to load
    urlToLoad = resolved;
  })
  .catch((err) => {
    // Was unable to resolve redirect e.g. due to no CORS support
    console.log("Could not resolve redirect", err);
  })
  .finally(() => {
    // In either case, we try to preload the original or resolved URL
    preloadImage(urlToLoad);
  });
 
// This code only executes once the component gets mounted
const MyComp: React.FC = () => {
  // If the component did not mount immediately, this will be the resolved URL.
 
  // If the component mounted immediately, this will be the original URL.
  // In that case preloading is ineffective anyway.
  return <Img src={urlToLoad}></Img>;
};

参见​