visual enhancements and documentation changes.

README.md

@@ -3,12 +3,12 @@
 A minimal Android application that demonstrates a simple countdown functionality with an audible alert.
 
 ## Description
-The Countdown Timer app is a lightweight utility that launches a modal dialog to count down from 10 seconds. Once the timer reaches zero, the app plays a system error tone and closes the dialog. This project serves as a basic example of using `CountDownTimer`, `ToneGenerator`, and custom `Dialog` implementation in Android.
+The Countdown Timer app is a lightweight utility that launches a modal dialog to count down from a user-selected duration (5s, 10s, 15s, or 30s). Once the timer reaches zero, the app plays a confirmation tone and vibration, then shows a dismiss button. This project serves as a basic example of using `CountDownTimer`, `ToneGenerator`, and custom `Dialog` implementation in Android.
 
 ## Key Features
-- **Single-Action Interface**: A simple main screen with a start button.
-- **Modal Countdown**: A non-cancelable dialog that prevents user interference during the countdown.
-- **Audible Alert**: Integration with Android's `ToneGenerator` to play `TONE_SUP_ERROR` upon completion.
+- **Selectable Duration**: A main screen with a duration picker (chip group) and a start button.
+- **Modal Countdown**: A full-screen dialog with circular progress ring, stop/restart buttons, and a confirmation tone during the final 3 seconds.
+- **Haptic Feedback**: Vibration on the last 3 seconds and on completion (configurable via shared preferences).
 - **Real-time Updates**: UI updates every second to reflect the remaining time.
 
 ## Getting Started
@@ -25,19 +25,46 @@ To build the debug APK from the command line:
 ```
 
 ### Running the App
+
+#### Via Android Studio
 1. Open the project in Android Studio.
 2. Select your target device/emulator.
 3. Click the **Run** button or press `Shift + F10`.
 
+#### Via ADB
+First, ensure your device or emulator is connected (`adb devices`). Then install the debug APK and launch the app:
+
+```bash
+# Install the debug APK
+adb install -r app/build/outputs/apk/debug/app-debug.apk
+
+# Launch the app
+adb shell am start -n com.example.countdowntimer.debug/com.example.countdowntimer.MainActivity
+```
+
+#### Taking a Screenshot via ADB
+To capture a screenshot of the app from your host machine:
+
+```bash
+# Take the screenshot on the device
+adb shell screencap -p /sdcard/screenshot.png
+
+# Pull it to your host machine
+adb pull /sdcard/screenshot.png screenshots/
+```
+
 ## Project Structure
 ```text
 app/
 ├── src/
 │   └── main/
 │       ├── java/com/example/countdowntimer/
-│       │   ├── MainActivity.kt      # Main entry point; launches the timer
-│       │   └── CountdownDialog.kt   # Logic for the 10s countdown and tone
-│       ├── res/                     # UI layouts and resources
-│       └── AndroidManifest.xml      # Application manifest
-└── build.gradle                     # App-level build configuration
+│       │   ├── MainActivity.kt          # Main entry point; duration picker and timer trigger
+│       │   ├── CountdownDialog.kt       # Countdown logic, tone, and vibration
+│       │   └── CountdownCanvasView.kt   # Custom circular progress ring view
+│       ├── res/layout/                  # UI layouts
+│       │   ├── activity_main.xml
+│       │   └── dialog_countdown.xml
+│       └── AndroidManifest.xml          # Application manifest
+└── build.gradle                         # App-level build configuration
 ```