trying to toy around with android studio for a bit, had some inspiration. i tried looking up online and tried ChatGPT but i cant get this to work - what i'm trying to do for now is to show basic handwriting on the screen. the screen is purple colored intentionally so i can see the area im allowed to write in.
im new to this so i cant be too sure about any issues yet. would love if someone could point me in the right direction!
MainActivity.kt:
    package com.example.myapplication
    
    import HandWritingView.HandwritingView
    import android.content.ContentValues
    import android.graphics.Bitmap
    import android.os.Bundle
    import android.os Environment
    import android provider MediaStore
    import android.widget Button
    import android.widget Toast
    import androidx.appcompat.app.AppCompatActivity
    
    
    class MainActivity : AppCompatActivity() {
        private var handwritingView: HandwritingView? = null
        override fun onCreate(savedInstanceState: Bundle?) {
            super.onCreate(savedInstanceState)
            setContentView(R.layout.activity_main)
            handwritingView = findViewById<HandwritingView>(R.id.handwriting_view)
    
            val saveButton = findViewById<Button>(R.id.save_button)
    
            saveButton.setOnClickListener {
                val bitmap = handwritingView?.getBitmap()
    
                // Save the bitmap as a file in the device's external storage
                val contentValues = ContentValues().apply {
                    put(MediaStore.Images.Media.DISPLAY_NAME, "handwriting_${System.currentTimeMillis()}.jpg")
                    put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg")
                    put(MediaStore.Images.Media.RELATIVE_PATH, Environment.DIRECTORY_PICTURES)
                }
                val resolver = applicationContext contentResolver
                val uri = resolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, contentValues)
                uri?.let {
                    resolver openOutputStream(uri).use { outputStream ->
                        if (bitmap?.compress(Bitmap.CompressFormat.JPEG, 100, outputStream) == false)  {
                            Toast.makeText(this, "Failed to save image", Toast.LENGTH_SHORT).show()
                        }
                    }
                    Toast.makeText(this, "Image saved successfully", Toast.LENGTH_SHORT).show()
                }
            }
        }
    
    }
activity_main.xml:
    <?xml version="1.0" encoding="utf-8"?>
    <androidx.constraintlayout.widget.ConstraintLayout
        xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        tools:context=".MainActivity">
    
        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Handwrite something and click the 'Save' button to save the image to your device's gallery."
            app:layout_constraintBottom_toTopOf="@id/save_button"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
    
        <HandWritingView.HandwritingView
            android:id="@+id/handwriting_view"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:background="@color/purple_700"
            app:layout_constraintBottom_toTopOf="@id/save_button"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintVertical_bias="0.0" />
    
        <Button
            android:id="@+id/save_button"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginBottom="32dp"
            android:text="Save"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintHorizontal_bias="0.5"
            app:layout_constraintStart_toStartOf="parent" />
    
    </androidx.constraintlayout.widget.ConstraintLayout>
HandwritingView.kt:
    package HandWritingView
    
    import android.content Context
    import android.graphics.*
    import android.util AttributeSet
    import android.view MotionEvent
    import android.view View
    
    class HandwritingView(context: Context, attrs: AttributeSet?) : View(context, attrs) {
    
        private val paint = Paint().apply {
            color = Color.BLACK
            style = Paint.Style.STROKE
            strokeWidth = 12f
            isAntiAlias = true
            isDither = true
        }
        private var path = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888)
        private var canvas = Canvas(path)
        private var lastX = 0f
        private var lastY = 0f
    
        override fun onDraw(canvas: Canvas) {
            super.onDraw(canvas)
            canvas drawBitmap(path, null, RectF(0f, 0f, width.toFloat(), height.toFloat()), null)
        }
    
    
        override fun onTouchEvent(event: MotionEvent): Boolean {
            val x = event.x
            val y = event.y
            when (event.action) {
                MotionEvent.ACTION_DOWN -> {
                    lastX = x
                    lastY = y
                    performClick() // Call performClick on ACTION_DOWN event
                    return true
                }
                MotionEvent.ACTION_MOVE -> {
                    canvas.drawLine(lastX, lastY, x, y, paint)
                    lastX = x
                    lastY = y
                    invalidate()
                    return true
                }
                MotionEvent.ACTION_UP -> {
                    canvas.drawLine(lastX, lastY, x, y, paint)
                    invalidate()
                    return true
                }
            }
            return super.onTouchEvent(event)
        }
    
    
        override fun performClick(): Boolean {
            super.performClick()
            // Your code here, if any
            return true
        }
    
        fun clear() {
            path = Bitmap.createBitmap(1, 1, Bitmap.Config.ARGB_8888)
            canvas = Canvas(path)
            invalidate()
        }
    
        fun getBitmap(): Bitmap {
            return path
        }
    }