Improve Matrix animation

app/src/main/AndroidManifest.xml

@@ -21,6 +21,8 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <activity android:name=".LoginActivity" />
+        <activity android:name=".MatrixActivity" />
     </application>
 
 </manifest>

app/src/main/java/com/example/codexthree/LoginActivity.kt

@@ -0,0 +1,36 @@
+package com.example.codexthree
+
+import android.os.Bundle
+import android.widget.Button
+import android.widget.EditText
+import android.widget.Toast
+import androidx.activity.enableEdgeToEdge
+import androidx.appcompat.app.AppCompatActivity
+import androidx.core.view.ViewCompat
+import androidx.core.view.WindowInsetsCompat
+
+class LoginActivity : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)
+        enableEdgeToEdge()
+        setContentView(R.layout.activity_login)
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.login_root)) { v, insets ->
+            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars())
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
+            insets
+        }
+
+        val emailField = findViewById<EditText>(R.id.email_field)
+        val passwordField = findViewById<EditText>(R.id.password_field)
+        findViewById<Button>(R.id.login_button).setOnClickListener {
+            val email = emailField.text.toString().trim()
+            val password = passwordField.text.toString()
+            if (email.isNotEmpty() && password.isNotEmpty()) {
+                Toast.makeText(this, "Logged in as $email", Toast.LENGTH_SHORT).show()
+                finish()
+            } else {
+                Toast.makeText(this, "Please enter email and password", Toast.LENGTH_SHORT).show()
+            }
+        }
+    }
+}

app/src/main/java/com/example/codexthree/MainActivity.kt

@@ -1,11 +1,15 @@
 package com.example.codexthree
 
+import android.content.Intent
 import android.os.Bundle
+import android.widget.Button
 import androidx.activity.enableEdgeToEdge
 import androidx.appcompat.app.AppCompatActivity
 import androidx.core.view.ViewCompat
 import androidx.core.view.WindowInsetsCompat
 
+import com.example.codexthree.MatrixActivity
+
 class MainActivity : AppCompatActivity() {
 
     private val justASimpleTemporaryName : String = "GoBig"
@@ -18,5 +22,12 @@ class MainActivity : AppCompatActivity() {
             v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom)
             insets
         }
+        findViewById<Button>(R.id.open_login_button).setOnClickListener {
+            startActivity(Intent(this, LoginActivity::class.java))
+        }
+
+        findViewById<Button>(R.id.open_matrix_button).setOnClickListener {
+            startActivity(Intent(this, MatrixActivity::class.java))
+        }
     }
 }

app/src/main/java/com/example/codexthree/MatrixActivity.kt

@@ -0,0 +1,22 @@
+package com.example.codexthree // App package
+
+import android.os.Bundle                       // To receive savedInstanceState
+import androidx.activity.enableEdgeToEdge      // Utility for drawing edge-to-edge
+import androidx.appcompat.app.AppCompatActivity // Base class for activities
+import androidx.core.view.ViewCompat            // Compat helpers for views
+import androidx.core.view.WindowInsetsCompat    // For handling system insets
+
+// Activity that hosts the MatrixView animation
+class MatrixActivity : AppCompatActivity() {
+    override fun onCreate(savedInstanceState: Bundle?) {
+        super.onCreate(savedInstanceState)                 // Call parent implementation
+        enableEdgeToEdge()                                 // Draw under system bars
+        setContentView(R.layout.activity_matrix)           // Use layout containing MatrixView
+        // Adjust padding so content isn't obscured by system bars
+        ViewCompat.setOnApplyWindowInsetsListener(findViewById(R.id.matrix_root)) { v, insets ->
+            val systemBars = insets.getInsets(WindowInsetsCompat.Type.systemBars()) // Areas occupied by status/navigation bars
+            v.setPadding(systemBars.left, systemBars.top, systemBars.right, systemBars.bottom) // Apply padding
+            insets
+        }
+    } // End onCreate
+} // End of MatrixActivity

app/src/main/java/com/example/codexthree/MatrixView.kt

@@ -0,0 +1,62 @@
+package com.example.codexthree // App's package name
+
+import android.content.Context       // Provides access to application-specific resources
+import android.graphics.Canvas       // Canvas to draw on the screen
+import android.graphics.Color        // Utility for colors
+import android.graphics.Paint        // Paint object describes how to draw
+import android.graphics.Typeface     // Allows selecting font family
+import android.util.AttributeSet     // For XML attributes
+import android.view.View             // Base class for custom views
+import kotlin.random.Random          // Random number generator
+
+// Custom view that draws the Matrix rain effect
+class MatrixView @JvmOverloads constructor(
+    context: Context,               // Context from the parent view or activity
+    attrs: AttributeSet? = null     // Optional attributes from XML
+) : View(context, attrs) {          // Extends Android's View class
+
+    // Paint object for drawing the characters
+    private val paint = Paint(Paint.ANTI_ALIAS_FLAG).apply {
+        color = Color.GREEN                     // Use a classic Matrix green
+        textSize = 32f                          // Size of each character
+        typeface = Typeface.MONOSPACE          // Monospace font for uniform width
+    } // End Paint configuration
+
+    // Y positions for each column of text
+    private var columnY = FloatArray(0)
+
+    // Pool of characters to randomly display
+    private val charPool = """ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789@#$%^&*(){}[]<>?/|+-="""
+
+    // Called whenever the view size changes
+    override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
+        val textHeight = paint.textSize                 // Height of one character
+        val columnCount = (w / textHeight).toInt() + 1  // How many columns fit on screen
+        // Start each column at a random vertical position above the screen
+        columnY = FloatArray(columnCount) { Random.nextInt(h) * -1f }
+    } // End onSizeChanged
+
+    // Draw one frame of the animation
+    override fun onDraw(canvas: Canvas) {
+        super.onDraw(canvas)                       // Let the parent do its work
+        canvas.drawColor(Color.BLACK)              // Clear the screen with black
+        val textHeight = paint.textSize            // Character height used for spacing
+        for (i in columnY.indices) {               // Loop over each text column
+            var y = columnY[i]                     // Current Y position for this column
+            val x = i * textHeight                 // X coordinate based on column index
+            while (y < height) {                   // Draw characters down the screen
+                // Pick a random character from our pool
+                val ch = charPool[Random.nextInt(charPool.length)].toString()
+                // Random alpha value for fading effect
+                paint.color = Color.argb(Random.nextInt(50, 256), 0, 255, 0)
+                canvas.drawText(ch, x, y, paint)   // Draw the character
+                y += textHeight / 2                // Move down half a char height (slower)
+            } // End while loop
+            columnY[i] += textHeight / 2           // Advance the starting Y position
+            if (columnY[i] > height) {             // If we've moved past bottom
+                columnY[i] = 0f                    // Reset to top
+            } // End if
+        } // End for loop
+        postInvalidateOnAnimation()                // Schedule next frame
+    } // End onDraw
+} // End of MatrixView class

app/src/main/res/layout/activity_login.xml

@@ -0,0 +1,45 @@
+<?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"
+    android:id="@+id/login_root"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent">
+
+    <EditText
+        android:id="@+id/email_field"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:hint="Email"
+        android:inputType="textEmailAddress"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.5"
+        android:layout_marginStart="16dp"
+        android:layout_marginEnd="16dp"
+        android:layout_marginTop="32dp"/>
+
+    <EditText
+        android:id="@+id/password_field"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:hint="Password"
+        android:inputType="textPassword"
+        app:layout_constraintTop_toBottomOf="@id/email_field"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        android:layout_marginStart="16dp"
+        android:layout_marginEnd="16dp"
+        android:layout_marginTop="16dp"/>
+
+    <Button
+        android:id="@+id/login_button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/login"
+        app:layout_constraintTop_toBottomOf="@id/password_field"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        android:layout_marginTop="24dp" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_main.xml

@@ -8,12 +8,31 @@
     tools:context=".MainActivity">
 
     <TextView
+        android:id="@+id/hello_text"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content"
         android:text="Hello World!"
-        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintBottom_toTopOf="@id/open_login_button"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toTopOf="parent" />
 
+    <Button
+        android:id="@+id/open_login_button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/login"
+        app:layout_constraintTop_toBottomOf="@id/hello_text"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent" />
+
+    <Button
+        android:id="@+id/open_matrix_button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:text="@string/open_matrix"
+        app:layout_constraintTop_toBottomOf="@id/open_login_button"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/layout/activity_matrix.xml

@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/matrix_root"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@android:color/black">
+
+    <com.example.codexthree.MatrixView
+        android:id="@+id/matrix_view"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent" />
+
+</FrameLayout>

app/src/main/res/values/strings.xml

@@ -1,3 +1,5 @@
 <resources>
     <string name="app_name">CodexThree</string>
+    <string name="login">Login</string>
+    <string name="open_matrix">Matrix Animation</string>
 </resources>