evolute_printer_flutter

A Flutter plugin for Evolute handheld devices with integrated thermal printer.

Wraps the Evolute SDK AIDL service (com.evolute.sdkservice) to expose a clean, async Dart API for printing text, images, and QR codes on Evolute handheld hardware.

Platform Support

Android	iOS
✅	❌ (Evolute is Android-only hardware)

Minimum Android SDK: 21

Prerequisites

This plugin requires the Evolute SDK JAR — a proprietary vendor library that cannot be distributed via pub.flutter-io.cn.

Because the JAR is referenced directly inside the plugin's native Kotlin code, it must live inside the package itself, not in your app. Follow these steps:

1. Clone the package repo:

git clone https://github.com/haelalhsen/evolute_printer_flutter.git

2. Place the JAR inside the cloned package:

evolute_printer_flutter/
└── android/
    └── libs/
        └── Evolute_SDK_Service_V02.09.00-01.aidl.jar  ← here

3. Reference the package locally in your app's pubspec.yaml:

dependencies:
  evolute_printer_flutter:
    path: /path/to/evolute_printer_flutter

The package android/build.gradle is already configured to pick up the JAR automatically — no extra Gradle changes needed in your app.

Installation

Because the Evolute SDK JAR must be present inside the package (see Prerequisites above), use a local path dependency instead of pub.flutter-io.cn:

dependencies:
  evolute_printer_flutter:
    path: /path/to/evolute_printer_flutter

Quick Start

import 'package:evolute_printer_flutter/evolute_printer_flutter.dart';

final printer = EvolutePrinter();

// 1. Connect — bind to the Evolute SDK service (call in initState)
await printer.connect();

// 2. Set style and buffer text
await printer.setProperties(
  alignment: PrintAlignment.center,
  fontSize: PrintFontSize.normal,
);
await printer.appendText('\nHello World\n');

// 3. Print
await printer.startPrinting();

// 4. Feed paper
await printer.feedLines(5);

// 5. Disconnect (call in dispose)
await printer.disconnect();

API Reference

Lifecycle

await printer.connect();         // Bind to Evolute SDK printer service
await printer.disconnect();      // Unbind and release service
bool ready = printer.isConnected;

Buffer Management

// Set style — applies to all subsequent appendText() calls
await printer.setProperties(
  alignment: PrintAlignment.center,   // left | center | right
  fontSize: PrintFontSize.normal,     // see PrintFontSize enum
);

await printer.appendText('\nYour text');  // Buffer text (\n = line break)
await printer.flushBuffer();              // Clear buffer without printing
await printer.startPrinting();            // Send buffer to printer

Rich Content

// Print image from Flutter assets
final bytes = await rootBundle.load('assets/logo.png');
await printer.printImage(bytes.buffer.asUint8List());

// Print QR code
await printer.printQRCode(
  data: 'https://example.com',
  width: QRWidth.inch2,
  alignment: PrintAlignment.center,
);

// Feed paper lines
await printer.feedLines(9);

Status

final PrinterStatus status = await printer.getStatus();

if (status.isSuccess) {
  print('Printed OK');
} else {
  print('Error: ${status.message}');
}

Error Handling

All methods throw PrinterException on failure:

try {
  await printer.startPrinting();
} on PrinterException catch (e) {
  print('Status : ${e.status}');   // PrinterStatus enum value
  print('Message: ${e.message}');  // Human-readable description
}

Enums

PrintAlignment

Value	Description
`left`	Left-align
`center`	Center
`right`	Right-align

PrintFontSize

Verified against ESDKConstant.FontSize from SDK V02.09:

Value	SDK Enum	Description
`normal`	`Width_x_Height_1x1`	Standard size
`doubleWidth`	`Width_x_Height_2x1`	Double width
`height2`	`Width_x_Height_1x2`	Double height
`doubleSize`	`Width_x_Height_2x2`	Double width & height
`tripleWidth`	`Width_x_Height_3x1`	Triple width
`tripleSize`	`Width_x_Height_3x3`	Triple width & height
`quadSize`	`Width_x_Height_4x4`	Maximum size
(+ 9 more combinations)

PrinterStatus

Value	SDK Code	Meaning
`success`	0	Print completed
`paperOut`	-51	Paper tray empty
`lowPower`	-52	Battery critically low
`busy`	-53	Printer busy
`failure`	-54	Hardware failure
`printLimitExceeded`	-55	Print limit reached
`noResponse`	-56	Not responding
`imageSizeNotSupported`	-57	Image too large
`aborted`	-5	Job aborted

QRWidth

Value	Description
`inch1`	1-inch QR code
`inch2`	2-inch QR code (recommended, max for SDK V02.09)

Full Ticket Example

Future<void> printValetTicket({
  required String plateNumber,
  required String ticketNumber,
  required String inTime,
}) async {
  // Header
  await printer.setProperties(alignment: PrintAlignment.center);
  await printer.appendText('\nValet Parking Ticket No:');
  await printer.startPrinting();

  // Logo
  final bytes = await rootBundle.load('assets/logo.png');
  await printer.printImage(bytes.buffer.asUint8List());

  // Ticket details
  await printer.flushBuffer();
  await printer.setProperties(alignment: PrintAlignment.center);
  await printer.appendText('\n$ticketNumber');
  await printer.appendText('\n\nLocation: EMAAR BUSINESS PARK');
  await printer.startPrinting();

  // Vehicle info
  await printer.flushBuffer();
  await printer.setProperties(alignment: PrintAlignment.left);
  await printer.appendText('\nIN TIME : $inTime');
  await printer.appendText('\nPLATE No: $plateNumber');
  await printer.startPrinting();

  // Paper feed & status check
  await printer.feedLines(9);
  final status = await printer.getStatus();
  if (status.isError) {
    throw PrinterException(status: status, message: status.message);
  }
}

Notes

Android 11+: The plugin's AndroidManifest.xml already declares the required <queries> entry for com.evolute.sdkservice — no extra setup needed in your app.
Single instance: Create one EvolutePrinter per screen and always call disconnect() in dispose() to avoid service leaks.
Images: Pass as Uint8List (PNG or JPEG). The plugin decodes to Bitmap natively. Keep images under 100KB for reliable thermal printing.
SDK version: Developed and tested against Evolute_SDK_Service_V02.09.00-01.

Repository

https://github.com/haelalhsen/evolute_printer_flutter

License

MIT