LeetCode Heatmap Android Widget

A Flutter application that fetches a user's LeetCode submission history and renders it as a native Android Home Screen widget.

🚀 Getting Started

Follow these simple steps to run the application on your device.

1. Clone the Repository

Open your terminal and clone the project:

git clone https://github.com/Dikshant005/Leet_code_widget
cd leet_code_widget

2. Install Dependencies

Download the required Flutter packages:

flutter pub get

3. Configure Your Username

To display your own LeetCode stats, you need to update the username in the main file.

1. Open lib/main.dart.
2. Scroll to the MyApp class inside the build method.
3. Locate the LeetCodeHeatMapWidget and change the string:

// lib/main.dart

home: const Scaffold(
  body: SafeArea(
    child: Center(
      // Change "krish_Agarwal-" to your LeetCode username
      child: LeetCodeHeatMapWidget(username: "YOUR_USERNAME_HERE"), 
    ),
  ),
),

4. Run the App

Connect your Android device (or start an emulator) and run:

flutter run

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🛠 Project Challenges & Solutions

During the development of this widget, several technical challenges were encountered. Here is how they were resolved:

1. Widget Image Not Fetching ("Image not on disk")

The Problem: Even though the Flutter app was running, the Android widget remained empty or displayed errors in Logcat stating that the image file path was null or the file did not exist.

The Solution:

• Path Synchronization: We moved away from guessing directory paths in Kotlin. Instead, we used HomeWidget.saveWidgetData in Flutter to save the absolute path of the generated image.
• Kotlin Update: We updated LeetCodeWidgetProvider.kt to read this exact path string from SharedPreferences instead of looking in hardcoded folders.
• Trigger Logic: We added a WidgetsBinding.instance.addPostFrameCallback inside the Flutter app. This ensures the widget update is triggered immediately after the API data is successfully fetched, rather than waiting for a manual refresh.

2. Widget Overflow (99,850 Pixel Overflow)

The Problem: When generating the snapshot for the widget in the background, the app crashed with RenderFlex overflowed by 99850 pixels. This happened because the background rendering engine has an effectively infinite height, and standard Flutter widgets like Scaffold or Column (without constraints) tried to expand to fill it.

The Solution:

• Constraint Management: We removed Scaffold and MaterialApp from the widget generation code (StaticHeatMap) as they are designed for full-screen apps.
• Fixed Size: We wrapped the entire layout in a SizedBox(width: 300, height: 150) and used a FittedBox. This forces the content to scale down to fit the specific box size, preventing it from trying to expand indefinitely into the void.

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📦 Tech Stack

• Flutter: UI and Business Logic.
• Home Widget: Plugin for bridging Flutter and Android Widgets.
• GraphQL: Used to communicate with the LeetCode API.
• Kotlin: Used for the native Android Broadcast Receiver to update the widget image.