react-native/Libraries/Image/AssetSourceResolver.js

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/**
* Copyright (c) 2015-present, Facebook, Inc.
*
* This source code is licensed under the MIT license found in the
* LICENSE file in the root directory of this source tree.
*
* @flow
* @format
*/
'use strict';
export type ResolvedAssetSource = {|
+__packager_asset: boolean,
+width: ?number,
+height: ?number,
+uri: string,
+scale: number,
|};
import type {PackagerAsset} from 'AssetRegistry';
const PixelRatio = require('PixelRatio');
const Platform = require('Platform');
const assetPathUtils = require('../../local-cli/bundle/assetPathUtils');
const invariant = require('fbjs/lib/invariant');
/**
* Returns a path like 'assets/AwesomeModule/icon@2x.png'
*/
function getScaledAssetPath(asset): string {
const scale = AssetSourceResolver.pickScale(asset.scales, PixelRatio.get());
const scaleSuffix = scale === 1 ? '' : '@' + scale + 'x';
const assetDir = assetPathUtils.getBasePath(asset);
return assetDir + '/' + asset.name + scaleSuffix + '.' + asset.type;
}
/**
* Returns a path like 'drawable-mdpi/icon.png'
*/
function getAssetPathInDrawableFolder(asset): string {
const scale = AssetSourceResolver.pickScale(asset.scales, PixelRatio.get());
const drawbleFolder = assetPathUtils.getAndroidResourceFolderName(
asset,
scale,
);
const fileName = assetPathUtils.getAndroidResourceIdentifier(asset);
return drawbleFolder + '/' + fileName + '.' + asset.type;
}
class AssetSourceResolver {
serverUrl: ?string;
// where the jsbundle is being run from
jsbundleUrl: ?string;
// the asset to resolve
asset: PackagerAsset;
constructor(serverUrl: ?string, jsbundleUrl: ?string, asset: PackagerAsset) {
this.serverUrl = serverUrl;
this.jsbundleUrl = jsbundleUrl;
this.asset = asset;
}
isLoadedFromServer(): boolean {
return !!this.serverUrl;
}
isLoadedFromFileSystem(): boolean {
return !!(this.jsbundleUrl && this.jsbundleUrl.startsWith('file://'));
}
defaultAsset(): ResolvedAssetSource {
if (this.isLoadedFromServer()) {
return this.assetServerURL();
}
if (Platform.OS === 'android') {
return this.isLoadedFromFileSystem()
? this.drawableFolderInBundle()
: this.resourceIdentifierWithoutScale();
} else {
return this.scaledAssetURLNearBundle();
}
}
/**
* Returns an absolute URL which can be used to fetch the asset
* from the devserver
*/
assetServerURL(): ResolvedAssetSource {
invariant(!!this.serverUrl, 'need server to load from');
return this.fromSource(
this.serverUrl +
getScaledAssetPath(this.asset) +
'?platform=' +
Platform.OS +
'&hash=' +
this.asset.hash,
);
}
/**
* Resolves to just the scaled asset filename
* E.g. 'assets/AwesomeModule/icon@2x.png'
*/
scaledAssetPath(): ResolvedAssetSource {
return this.fromSource(getScaledAssetPath(this.asset));
}
/**
* Resolves to where the bundle is running from, with a scaled asset filename
* E.g. 'file:///sdcard/bundle/assets/AwesomeModule/icon@2x.png'
*/
scaledAssetURLNearBundle(): ResolvedAssetSource {
const path = this.jsbundleUrl || 'file://';
return this.fromSource(path + getScaledAssetPath(this.asset));
}
/**
* The default location of assets bundled with the app, located by
* resource identifier
* The Android resource system picks the correct scale.
* E.g. 'assets_awesomemodule_icon'
*/
resourceIdentifierWithoutScale(): ResolvedAssetSource {
invariant(
Platform.OS === 'android',
'resource identifiers work on Android',
);
return this.fromSource(
assetPathUtils.getAndroidResourceIdentifier(this.asset),
);
}
/**
* If the jsbundle is running from a sideload location, this resolves assets
* relative to its location
* E.g. 'file:///sdcard/AwesomeModule/drawable-mdpi/icon.png'
*/
drawableFolderInBundle(): ResolvedAssetSource {
const path = this.jsbundleUrl || 'file://';
return this.fromSource(path + getAssetPathInDrawableFolder(this.asset));
}
fromSource(source: string): ResolvedAssetSource {
return {
__packager_asset: true,
width: this.asset.width,
height: this.asset.height,
uri: source,
scale: AssetSourceResolver.pickScale(this.asset.scales, PixelRatio.get()),
};
}
static pickScale(scales: Array<number>, deviceScale: number): number {
// Packager guarantees that `scales` array is sorted
for (let i = 0; i < scales.length; i++) {
if (scales[i] >= deviceScale) {
return scales[i];
}
}
// If nothing matches, device scale is larger than any available
// scales, so we return the biggest one. Unless the array is empty,
// in which case we default to 1
return scales[scales.length - 1] || 1;
}
}
module.exports = AssetSourceResolver;