Add support for Web Share Target API

It is possible to register a PWA (WebAPK) as share target (it happens automatically if share_target is specified in manifest.json) but it does not seem to be supported in TWA at the moment. This is a huge bummer for us because share data with our PWA/TWA is a central feature.

[flunderpero]

Two and a half months and a PR later and still there is no progress on this. We cannot release our app, because its main benefit is being a share-target, which works absolutely great as a PWA. But our customers demand an app (and we want to have the benefits of being listed in the Play Store).

I am a bit baffled that we seem to be the only ones desperately missing this feature.

I don’t want to sound pi**ed or blame anyone for anything, but I need a perspective going forward. Had I known 2.5 months ago, that support for WebShareTargetV2 is not coming for months, I would have decided to use Cordova or write a wrapper on my own.

It would be great if you could just give me feedback, whether you plan to work on this in the next couple of weeks. I would love to help out (more), but my knowledge of the inner workings of this project and androidx is at its limit. 😃

[AliasIO]

@andreban I noticed that share_target.params.files is required in manifest.json (I believe this should be optional). Adding that, shareTarget is correctly added to twa-manifest.json using @bubblewrap/cli@1.8.0.

However, after installing the app on my phone I still can’t share to it. When I install the app as a PWA from Chrome, it works fine.

{
  "packageId": "com.wappalyzer.twa",
  "host": "twa.wappalyzer.com",
  "name": "Wappalyzer",
  "launcherName": "Wappalyzer",
  "display": "standalone",
  "themeColor": "#32067C",
  "navigationColor": "#000000",
  "navigationColorDark": "#000000",
  "navigationDividerColor": "#000000",
  "navigationDividerColorDark": "#000000",
  "backgroundColor": "#FFFFFF",
  "enableNotifications": false,
  "startUrl": "/?standalone=true",
  "iconUrl": "https://twa.wappalyzer.com/images/logo/icon_512.png",
  "maskableIconUrl": "https://twa.wappalyzer.com/images/logo/icon_mask_512.png",
  "monochromeIconUrl": "https://twa.wappalyzer.com/images/logo/icon_white_512.png",
  "splashScreenFadeOutDuration": 300,
  "signingKey": {
    "path": "***",
    "alias": "android"
  },
  "appVersionName": "1",
  "appVersionCode": 1,
  "shortcuts": [],
  "generatorApp": "bubblewrap-cli",
  "webManifestUrl": "https://twa.wappalyzer.com/manifest.json",
  "fallbackType": "customtabs",
  "features": {},
  "alphaDependencies": {
    "enabled": false
  },
  "enableSiteSettingsShortcut": true,
  "isChromeOSOnly": false,
  "shareTarget": {
    "action": "https://twa.wappalyzer.com/",
    "params": {
      "title": "title",
      "text": "text",
      "url": "url",
      "files": []
    }
  },
  "orientation": "default",
  "appVersion": "1"
}