react-native/Libraries/Image/resolveAssetSource.js

141 lines
3.7 KiB
JavaScript

/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule resolveAssetSource
*
* Resolves an asset into a `source` for `Image`.
*/
'use strict';
var AssetRegistry = require('AssetRegistry');
var PixelRatio = require('PixelRatio');
var Platform = require('Platform');
var SourceCode = require('NativeModules').SourceCode;
var _serverURL;
function getDevServerURL() {
if (!__DEV__) {
// In prod we want assets to be loaded from the archive
return null;
}
if (_serverURL === undefined) {
var scriptURL = SourceCode.scriptURL;
var match = scriptURL && scriptURL.match(/^https?:\/\/.*?\//);
if (match) {
// Bundle was loaded from network
_serverURL = match[0];
} else {
// Bundle was loaded from file
_serverURL = null;
}
}
return _serverURL;
}
/**
* Returns the path at which the asset can be found in the archive
*/
function getPathInArchive(asset) {
if (Platform.OS === 'android') {
var assetDir = getBasePath(asset);
// E.g. 'assets_awesomemodule_icon'
// The Android resource system picks the correct scale.
return (assetDir + '/' + asset.name)
.toLowerCase()
.replace(/\//g, '_') // Encode folder structure in file name
.replace(/([^a-z0-9_])/g, '') // Remove illegal chars
.replace(/^assets_/, ''); // Remove "assets_" prefix
} else {
// E.g. 'assets/AwesomeModule/icon@2x.png'
return getScaledAssetPath(asset);
}
}
/**
* Returns an absolute URL which can be used to fetch the asset
* from the devserver
*/
function getPathOnDevserver(devServerUrl, asset) {
return devServerUrl + getScaledAssetPath(asset) + '?platform=' + Platform.OS +
'&hash=' + asset.hash;
}
/**
* Returns a path like 'assets/AwesomeModule'
*/
function getBasePath(asset) {
// TODO(frantic): currently httpServerLocation is used both as
// path in http URL and path within IPA. Should we have zipArchiveLocation?
var path = asset.httpServerLocation;
if (path[0] === '/') {
path = path.substr(1);
}
return path;
}
/**
* Returns a path like 'assets/AwesomeModule/icon@2x.png'
*/
function getScaledAssetPath(asset) {
var scale = pickScale(asset.scales, PixelRatio.get());
var scaleSuffix = scale === 1 ? '' : '@' + scale + 'x';
var assetDir = getBasePath(asset);
return assetDir + '/' + asset.name + scaleSuffix + '.' + asset.type;
}
function pickScale(scales, deviceScale) {
// Packager guarantees that `scales` array is sorted
for (var 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;
}
function resolveAssetSource(source) {
if (typeof source === 'object') {
return source;
}
var asset = AssetRegistry.getAssetByID(source);
if (asset) {
return assetToImageSource(asset);
}
return null;
}
function assetToImageSource(asset) {
var devServerURL = getDevServerURL();
if (devServerURL) {
return {
width: asset.width,
height: asset.height,
uri: getPathOnDevserver(devServerURL, asset),
isStatic: false,
};
} else {
return {
width: asset.width,
height: asset.height,
uri: getPathInArchive(asset),
isStatic: true,
};
}
}
module.exports = resolveAssetSource;
module.exports.pickScale = pickScale;