Image Cache
The image-cache
module contains the
Cache
class, which handles image download requests
and caches the already downloaded images.
Basics
Using Cache
objects requires the
tns-core-modules/ui/image-cache
module.
const Cache = require("tns-core-modules/ui/image-cache").Cache;
import { Cache } from "tns-core-modules/ui/image-cache";
Requesting and caching images with
image-cache
module while using a placeholder image.
const cache = new Cache();
cache.placeholder = fromFile("~/images/logo.png");
cache.maxRequests = 5;
// set the placeholder while the desired image is downloaded
viewModel.set("imageSource", cache.placeholder);
// Enable download while not scrolling
cache.enableDownload();
let cachedImageSource;
const url = "https://avatars1.githubusercontent.com/u/7392261?v=4";
// Try to read the image from the cache
const image = cache.get(url);
if (image) {
// If present -- use it.
cachedImageSource = imageSource.fromNativeSource(image);
viewModel.set("imageSource", cachedImageSource);
} else {
// If not present -- request its download + put it in the cache.
cache.push({
key: url,
url: url,
completed: (image, key) => {
if (url === key) {
cachedImageSource = fromNativeSource(image);
viewModel.set("imageSource", cachedImageSource); // set the downloaded image
}
}
});
}
// Disable download while scrolling
cache.disableDownload();
const cache = new Cache();
cache.placeholder = fromFile("~/images/logo.png");
cache.maxRequests = 5;
// set the placeholder while the desired image is donwloaded
viewModel.set("imageSource", cache.placeholder);
// Enable download while not scrolling
cache.enableDownload();
let cachedImageSource;
const url = "https://avatars1.githubusercontent.com/u/7392261?v=4";
// Try to read the image from the cache
const myImage = cache.get(url);
if (myImage) {
// If present -- use it.
cachedImageSource = fromNativeSource(myImage);
viewModel.set("imageSource", cachedImageSource);
} else {
// If not present -- request its download + put it in the cache.
cache.push({
key: url,
url: url,
completed: (image, key) => {
if (url === key) {
cachedImageSource = fromNativeSource(image);
viewModel.set("imageSource", cachedImageSource); // set the downloaded iamge
}
}
});
}
// Disable download while scrolling
cache.disableDownload();
<Image src="{{ imageSource }}" stretch="aspectFill" />
API Reference for
See Also Android Image Optimization