add-pen-input

📋 Shared instructions: shared-instructions.md — read first.

Add Pen Input

Internal helper. Users should invoke /add-native pen-input, /add-native signature, or /add-native @microsoft/power-apps-native-pen-input; /add-native routes here after resolving the capability.

Generate or verify the native pen input wrapper and show how to call its native React Native API. Do not use the HostingSDK / PCF path from the package README; that is for a different use case.

Steps

1. Verify app

test -f app.config.js && test -f power.config.json && test -f package.json && test -d src

If this fails, tell the user to run /create-mobile-app first and STOP.

2. Verify package is already present

node -e "const p=require('./package.json'); const m='@microsoft/power-apps-native-pen-input'; if (!p.dependencies?.[m]) { console.error('MISSING: ' + m + ' is not in package.json. The template/app must already ship this native extension. This skill will not install it or edit native config.'); process.exit(1); } console.log('OK: pen input package present');"

If the check fails, STOP. Do not run npm install, npx expo install, pod install, or edit app.config.js. This package contains native iOS/Android code and must already be part of the app's native build.

3. Write or verify src/native/penInput.ts

Create src/native/penInput.ts if it does not exist. If it already exists, inspect it and patch only if cancellation is treated as an error or the wrapper can throw.

The wrapper MUST:

• Return a discriminated union and never throw.
• Return { ok: false, reason: 'USER_CANCELLED' } for user cancellation; this is a non-error path.
• Return NATIVE_MODULE_MISSING when the extension is installed in JS but unavailable in the native build.
• Return a PNG data URI (data:image/png;base64,...) on success.

// src/native/penInput.ts
import {
  PenInputNative,
  PenInputStatus,
  PenInputErrorCode,
} from '@microsoft/power-apps-native-pen-input';

export type PenInputResult =
  | { ok: true; dataUri: string }
  | { ok: false; reason: 'USER_CANCELLED' | 'NATIVE_MODULE_MISSING' | 'CAPTURE_FAILED'; message?: string };

export async function captureSignature(options?: {
  backgroundColor?: string;
  strokeColor?: string;
  strokeWidth?: number;
}): Promise<PenInputResult> {
  if (!PenInputNative?.capturePenInput) {
    return { ok: false, reason: 'NATIVE_MODULE_MISSING', message: 'Pen input module is not available in this build.' };
  }

  try {
    const result = await PenInputNative.capturePenInput({
      backgroundColor: '#ffffff',
      strokeColor: '#0078d4',
      strokeWidth: 2,
      ...options,
    });

    if (result.status === PenInputStatus.Ok && result.result) {
      return { ok: true, dataUri: result.result };
    }

    if (result.error === PenInputErrorCode.UserCancelled) {
      return { ok: false, reason: 'USER_CANCELLED' };
    }

    return { ok: false, reason: 'CAPTURE_FAILED', message: result.error };
  } catch (error: any) {
    return { ok: false, reason: 'CAPTURE_FAILED', message: error?.message ?? String(error) };
  }
}

export function stripDataUriPrefix(dataUri: string): string {
  return dataUri.replace(/^data:image\/png;base64,/, '');
}