Bug Fix, Added Some More Calculation Features in Calculator Part.

# Conflicts:
#	app/src/main/java/devs/org/calculator/activities/MainActivity.kt

README.md

@@ -54,11 +54,10 @@ Welcome to the **Calculator Hide File App**! This app is a unique and secure way
 
 1. **Calculator Mode**:
    - Perform basic arithmetic operations just like any regular calculator.
-2. **Setup Password**:
-   - Enter `123456=` to setup your password. 
-3. **Hidden Mode**:
+2. **Hidden Mode**:
+   - Enter `123456` and hit the `=` button to setup your password. 
    - Enter your secret passcode and hit the `=` button to unlock the hidden file manager.
-5. **File Management**:
+4. **File Management**:
    - Add files to hide them securely.
    - Retrieve or unhide files as needed.
 
@@ -70,9 +69,9 @@ Support My development by donating money. Thank you very much for your help! ❤
 
 [<img src="https://img.shields.io/badge/sponsor-30363D?style=for-the-badge&logo=GitHub-Sponsors&logoColor=#EA4AAA"
 alt="Sponsor the project on GitHub"
-height="40">](https://github.com/sponsors/Binondi/Calculator-Hide-Files) [<img src="https://img.shields.io/badge/PayPal-00457C?style=for-the-badge&logo=paypal&logoColor=white"
+height="40">](https://github.com/sponsors/Binondi) [<img src="https://img.shields.io/badge/PayPal-00457C?style=for-the-badge&logo=paypal&logoColor=white"
 alt="Donate with PayPal"
-height="40">](https://www.paypal.me/BinondiBorthakur56) [<img src="https://img.shields.io/badge/Buy%20Me%20a%20Coffee-ffdd00?style=for-the-badge&logo=buy-me-a-coffee&logoColor=black"
+height="40">](https://paypal.me/BinondiBorthakur56) [<img src="https://img.shields.io/badge/Buy%20Me%20a%20Coffee-ffdd00?style=for-the-badge&logo=buy-me-a-coffee&logoColor=black"
 alt="Donate with buymeacoffee"
 height="40">](https://buymeacoffee.com/binondi)
 

app/build.gradle.kts

@@ -11,15 +11,22 @@ android {
         applicationId = "devs.org.calculator"
         minSdk = 26
         targetSdk = 34
-        versionCode = 1
-        versionName = "1.0"
+        versionCode = 2
+        versionName = "1.1"
 
         testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
     }
 
     buildTypes {
         release {
-            isMinifyEnabled = false
+            isMinifyEnabled = true
+            proguardFiles(
+                getDefaultProguardFile("proguard-android-optimize.txt"),
+                "proguard-rules.pro"
+            )
+        }
+        debug {
+            isMinifyEnabled = true
             proguardFiles(
                 getDefaultProguardFile("proguard-android-optimize.txt"),
                 "proguard-rules.pro"
@@ -45,15 +52,16 @@ dependencies {
     implementation(libs.material)
     implementation(libs.androidx.activity)
     implementation(libs.androidx.constraintlayout)
+    implementation(libs.androidx.gridlayout)
     testImplementation(libs.junit)
     androidTestImplementation(libs.androidx.junit)
     androidTestImplementation(libs.androidx.espresso.core)
 
     //custom dependencies
     implementation(libs.exp4j)
-    implementation("com.github.bumptech.glide:glide:4.16.0")
-    implementation("androidx.documentfile:documentfile:1.0.1")
-    implementation("com.github.chrisbanes:PhotoView:2.3.0")
-    implementation("androidx.viewpager:viewpager:1.0.0")
-    implementation("com.jsibbold:zoomage:1.3.1")
+    implementation(libs.glide)
+    implementation(libs.androidx.documentfile)
+    implementation(libs.photoview)
+    implementation(libs.androidx.viewpager)
+    implementation(libs.zoomage)
 }

app/proguard-rules.pro

@@ -1,21 +1,70 @@
-# Add project specific ProGuard rules here.
-# You can control the set of applied configuration files using the
-# proguardFiles setting in build.gradle.
-#
-# For more details, see
-#   http://developer.android.com/guide/developing/tools/proguard.html
+# Keep your MainActivity and Application class
+-keep public class devs.org.calculator.activities.MainActivity
+-keep public class devs.org.calculator.activities.SetupPasswordActivity
+-keep public class devs.org.calculator.activities.HiddenVaultActivity
+-keep public class devs.org.calculator.** { *; }
 
-# If your project uses WebView with JS, uncomment the following
-# and specify the fully qualified class name to the JavaScript interface
-# class:
-#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
-#   public *;
-#}
+# Keep exp4j library since it's used for expression evaluation
+-keep class net.objecthunter.exp4j.** { *; }
+-dontwarn net.objecthunter.exp4j.**
 
-# Uncomment this to preserve the line number information for
-# debugging stack traces.
-#-keepattributes SourceFile,LineNumberTable
+# Keep Google Material components
+-keep class com.google.android.material.** { *; }
+-dontwarn com.google.android.material.**
 
-# If you keep the line number information, uncomment this to
-# hide the original source file name.
-#-renamesourcefileattribute SourceFile
+# Keep Android X components
+-keep class androidx.** { *; }
+-keep interface androidx.** { *; }
+
+# Keep any classes with ViewBinding
+-keep class devs.org.calculator.databinding.** { *; }
+
+# Keep any callback interfaces
+-keep class devs.org.calculator.callbacks.** { *; }
+-keep interface devs.org.calculator.callbacks.** { *; }
+
+# Keep classes used for regex pattern matching
+-keep class java.util.regex.** { *; }
+
+# Keep annotation classes
+-keepattributes *Annotation*
+-keepattributes Signature
+-keepattributes SourceFile,LineNumberTable
+
+# Keep Parcelable classes (might be needed for Intent extras)
+-keep class * implements android.os.Parcelable {
+  public static final android.os.Parcelable$Creator *;
+}
+
+# Keep FileManager classes since they work with storage permissions
+-keep class devs.org.calculator.utils.FileManager { *; }
+
+# Keep DialogUtil since it's used for permission dialogs
+-keep class devs.org.calculator.utils.DialogUtil { *; }
+
+# Keep PrefsUtil since it's used for password validation
+-keep class devs.org.calculator.utils.PrefsUtil { *; }
+
+# General Android rules
+-keepclassmembers class * extends android.app.Activity {
+   public void *(android.view.View);
+}
+
+# Keep any classes that use reflection
+-keepattributes InnerClasses
+
+# Keep R classes and their fields
+-keepclassmembers class **.R$* {
+    public static <fields>;
+}
+
+# Keep enums
+-keepclassmembers enum * {
+    public static **[] values();
+    public static ** valueOf(java.lang.String);
+}
+
+# Keep specific activities with special code in onCreate
+-keepclassmembers class * extends android.app.Activity {
+    public void onCreate(android.os.Bundle);
+}

app/src/main/java/devs/org/calculator/activities/AudioGalleryActivity.kt

@@ -78,7 +78,7 @@ class AudioGalleryActivity : BaseGalleryActivity(), FileProcessCallback {
     }
 
     override fun openPreview() {
-        // Implement audio preview
+        // Not implemented audio preview
     }
 
 

app/src/main/java/devs/org/calculator/activities/BaseGalleryActivity.kt

@@ -13,6 +13,7 @@ import androidx.activity.result.IntentSenderRequest
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.appcompat.app.AppCompatActivity
 import androidx.recyclerview.widget.GridLayoutManager
+import devs.org.calculator.R
 import devs.org.calculator.adapters.FileAdapter
 import devs.org.calculator.databinding.ActivityGalleryBinding
 import devs.org.calculator.utils.FileManager
@@ -20,9 +21,9 @@ import java.io.File
 
 abstract class BaseGalleryActivity : AppCompatActivity() {
     protected lateinit var binding: ActivityGalleryBinding
-    protected lateinit var fileManager: FileManager
-    protected lateinit var adapter: FileAdapter
-    protected lateinit var files: List<File>
+    private lateinit var fileManager: FileManager
+    private lateinit var adapter: FileAdapter
+    private lateinit var files: List<File>
 
     private lateinit var intentSenderLauncher: ActivityResultLauncher<IntentSenderRequest>
     private val storagePermissionLauncher = registerForActivityResult(
@@ -48,16 +49,16 @@ abstract class BaseGalleryActivity : AppCompatActivity() {
 
         binding.fabAdd.text = when(fileType){
             FileManager.FileType.IMAGE -> {
-                 "Add Image"
+                getString(R.string.add_image)
             }
             FileManager.FileType.AUDIO -> {
-                "Add Audio"
+                getString(R.string.add_audio)
             }
             FileManager.FileType.VIDEO -> {
-                "Add Video"
+                getString(R.string.add_video)
             }
             FileManager.FileType.DOCUMENT -> {
-                "Add Files"
+                getString(R.string.add_files)
             }
         }
         binding.recyclerView.setOnScrollChangeListener { _, _, scrollY, _, oldScrollY ->
@@ -128,6 +129,7 @@ abstract class BaseGalleryActivity : AppCompatActivity() {
         // permission denied
     }
 
+    @Deprecated("This method has been deprecated in favor of using the Activity Result API\n      which brings increased type safety via an {@link ActivityResultContract} and the prebuilt\n      contracts for common intents available in\n      {@link androidx.activity.result.contract.ActivityResultContracts}, provides hooks for\n      testing, and allow receiving results in separate, testable classes independent from your\n      activity. Use\n      {@link #registerForActivityResult(ActivityResultContract, ActivityResultCallback)}\n      with the appropriate {@link ActivityResultContract} and handling the result in the\n      {@link ActivityResultCallback#onActivityResult(Object) callback}.")
     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
         super.onActivityResult(requestCode, resultCode, data)
         if (requestCode == 2296 && Build.VERSION.SDK_INT >= Build.VERSION_CODES.R) {

app/src/main/java/devs/org/calculator/activities/DocumentsActivity.kt

@@ -7,6 +7,7 @@ import android.widget.Toast
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.lifecycle.lifecycleScope
+import devs.org.calculator.R
 import devs.org.calculator.utils.FileManager
 import devs.org.calculator.callbacks.FileProcessCallback
 import kotlinx.coroutines.launch
@@ -15,7 +16,6 @@ import java.io.File
 class DocumentsActivity : BaseGalleryActivity(), FileProcessCallback {
     override val fileType = FileManager.FileType.DOCUMENT
     private lateinit var pickLauncher: ActivityResultLauncher<Intent>
-    private var selectedUri: Uri? = null
 
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
@@ -40,19 +40,21 @@ class DocumentsActivity : BaseGalleryActivity(), FileProcessCallback {
                         FileManager(this@DocumentsActivity, this@DocumentsActivity).processMultipleFiles(uriList, fileType,this@DocumentsActivity )
                     }
                 } else {
-                    Toast.makeText(this, "No files selected", Toast.LENGTH_SHORT).show()
+                    Toast.makeText(this, getString(R.string.no_files_selected), Toast.LENGTH_SHORT).show()
                 }
             }
         }
     }
 
     override fun onFilesProcessedSuccessfully(copiedFiles: List<File>) {
-        Toast.makeText(this@DocumentsActivity, "${copiedFiles.size} Documents hidden successfully", Toast.LENGTH_SHORT).show()
+        Toast.makeText(this@DocumentsActivity,copiedFiles.size.toString() +
+            getString(R.string.documents_hidden_successfully ), Toast.LENGTH_SHORT).show()
         loadFiles()
     }
 
     override fun onFileProcessFailed() {
-        Toast.makeText(this@DocumentsActivity, "Failed to hide Documents", Toast.LENGTH_SHORT).show()
+        Toast.makeText(this@DocumentsActivity,
+            getString(R.string.failed_to_hide_documents), Toast.LENGTH_SHORT).show()
     }
 
     private fun setupFabButton() {
@@ -70,6 +72,6 @@ class DocumentsActivity : BaseGalleryActivity(), FileProcessCallback {
     }
 
     override fun openPreview() {
-        // Implement document preview
+        //Not implemented document preview
     }
 }

app/src/main/java/devs/org/calculator/activities/ImageGalleryActivity.kt

@@ -18,6 +18,7 @@ import devs.org.calculator.utils.FileManager
 import kotlinx.coroutines.launch
 import java.io.File
 import android.Manifest
+import devs.org.calculator.R
 import devs.org.calculator.callbacks.FileProcessCallback
 
 class ImageGalleryActivity : BaseGalleryActivity(), FileProcessCallback  {
@@ -33,7 +34,8 @@ class ImageGalleryActivity : BaseGalleryActivity(), FileProcessCallback  {
         setupFabButton()
 
         intentSenderLauncher = registerForActivityResult(ActivityResultContracts.StartIntentSenderForResult()){
-            if (it.resultCode != RESULT_OK) Toast.makeText(this, "Failed to hide/unhide photo", Toast.LENGTH_SHORT).show()
+            if (it.resultCode != RESULT_OK) Toast.makeText(this,
+                getString(R.string.failed_to_hide_unhide_photo), Toast.LENGTH_SHORT).show()
         }
 
         pickImageLauncher = registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
@@ -56,7 +58,7 @@ class ImageGalleryActivity : BaseGalleryActivity(), FileProcessCallback  {
                             .processMultipleFiles(uriList, fileType,this@ImageGalleryActivity )
                     }
                 } else {
-                    Toast.makeText(this, "No files selected", Toast.LENGTH_SHORT).show()
+                    Toast.makeText(this, getString(R.string.no_files_selected), Toast.LENGTH_SHORT).show()
                 }
             }
         }
@@ -64,12 +66,14 @@ class ImageGalleryActivity : BaseGalleryActivity(), FileProcessCallback  {
     }
 
     override fun onFilesProcessedSuccessfully(copiedFiles: List<File>) {
-        Toast.makeText(this@ImageGalleryActivity, "${copiedFiles.size} Images hidden successfully", Toast.LENGTH_SHORT).show()
+        Toast.makeText(this@ImageGalleryActivity,  copiedFiles.size.toString() +
+            getString(R.string.images_hidden_successfully), Toast.LENGTH_SHORT).show()
         loadFiles()
     }
 
     override fun onFileProcessFailed() {
-        Toast.makeText(this@ImageGalleryActivity, "Failed to hide images", Toast.LENGTH_SHORT).show()
+        Toast.makeText(this@ImageGalleryActivity,
+            getString(R.string.failed_to_hide_images), Toast.LENGTH_SHORT).show()
     }
 
     private fun setupIntentSenderLauncher() {
@@ -125,9 +129,11 @@ class ImageGalleryActivity : BaseGalleryActivity(), FileProcessCallback  {
         super.onRequestPermissionsResult(requestCode, permissions, grantResults)
         if (requestCode == STORAGE_PERMISSION_CODE) {
             if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
-                Toast.makeText(this, "Storage permissions granted", Toast.LENGTH_SHORT).show()
+                Toast.makeText(this,
+                    getString(R.string.storage_permissions_granted), Toast.LENGTH_SHORT).show()
             } else {
-                Toast.makeText(this, "Storage permissions denied", Toast.LENGTH_SHORT).show()
+                Toast.makeText(this,
+                    getString(R.string.storage_permissions_denied), Toast.LENGTH_SHORT).show()
             }
         }
     }

app/src/main/java/devs/org/calculator/activities/MainActivity.kt

@@ -1,5 +1,6 @@
 package devs.org.calculator.activities
 
+import android.annotation.SuppressLint
 import android.content.Intent
 import android.content.pm.PackageManager
 import android.net.Uri
@@ -20,12 +21,14 @@ import devs.org.calculator.utils.DialogUtil
 import devs.org.calculator.utils.FileManager
 import devs.org.calculator.utils.PrefsUtil
 import net.objecthunter.exp4j.ExpressionBuilder
+import java.util.regex.Pattern
 
 class MainActivity : AppCompatActivity(), DialogActionsCallback {
     private lateinit var binding: ActivityMainBinding
     private var currentExpression = "0"
     private var lastWasOperator = false
     private var hasDecimal = false
+    private var lastWasPercent = false
     private lateinit var launcher: ActivityResultLauncher<Intent>
     private lateinit var baseDocumentTreeUri: Uri
     private val dialogUtil = DialogUtil(this)
@@ -71,7 +74,7 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
         binding.btnClear.setOnClickListener { clearDisplay() }
         binding.btnDot.setOnClickListener { addDecimal() }
         binding.btnEquals.setOnClickListener { calculateResult() }
-        binding.btnPercent.setOnClickListener { calculatePercentage() }
+        binding.btnPercent.setOnClickListener { addPercentage() }
         binding.cut.setOnClickListener { cutNumbers() }
     }
 
@@ -98,41 +101,57 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
                 currentExpression += number
             }
             lastWasOperator = false
+            lastWasPercent = false
             updateDisplay()
         }
     }
 
     private fun setupOperatorButton(button: MaterialButton, operator: String) {
         button.setOnClickListener {
-            if (!lastWasOperator) {
+            if (lastWasOperator) {
+                currentExpression = currentExpression.substring(0, currentExpression.length - 1) +
+                        when (operator) {
+                            "×" -> "*"
+                            else -> operator
+                        }
+            } else if (!lastWasPercent) {
                 currentExpression += when (operator) {
                     "×" -> "*"
                     else -> operator
                 }
                 lastWasOperator = true
+                lastWasPercent = false
                 hasDecimal = false
             }
             updateDisplay()
         }
     }
 
-
     private fun clearDisplay() {
         currentExpression = "0"
         binding.total.text = ""
         lastWasOperator = false
+        lastWasPercent = false
         hasDecimal = false
         updateDisplay()
     }
 
     private fun addDecimal() {
-        if (!hasDecimal && !lastWasOperator) {
+        if (!hasDecimal && !lastWasOperator && !lastWasPercent) {
             currentExpression += "."
             hasDecimal = true
             updateDisplay()
         }
     }
 
+    private fun addPercentage() {
+        if (!lastWasOperator && !lastWasPercent) {
+            currentExpression += "%"
+            lastWasPercent = true
+            updateDisplay()
+        }
+    }
+
     private fun calculatePercentage() {
         try {
             val value = currentExpression.toDouble()
@@ -143,6 +162,126 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
         }
     }
 
+    private fun preprocessExpression(expression: String): String {
+        val percentagePattern = Pattern.compile("(\\d+\\.?\\d*)%")
+        val operatorPercentPattern = Pattern.compile("([+\\-*/])(\\d+\\.?\\d*)%")
+
+        var processedExpression = expression
+
+        // Replace standalone percentages (like "50%") with their decimal form (0.5)
+        val matcher = percentagePattern.matcher(processedExpression)
+        while (matcher.find()) {
+            val fullMatch = matcher.group(0)
+            val number = matcher.group(1)
+
+            // Check if it's a standalone percentage or part of an operation
+            val start = matcher.start()
+            if (start == 0 || !isOperator(processedExpression[start-1].toString())) {
+                val percentageValue = number.toDouble() / 100
+                processedExpression = processedExpression.replace(fullMatch, percentageValue.toString())
+            }
+        }
+
+        // Handle operator-percentage combinations (like "100-20%")
+        val opMatcher = operatorPercentPattern.matcher(processedExpression)
+        val sb = StringBuilder(processedExpression)
+
+        // We need to process matches from right to left to maintain indices
+        val matches = mutableListOf<Triple<Int, Int, String>>()
+
+        while (opMatcher.find()) {
+            val operator = opMatcher.group(1)
+            val percentValue = opMatcher.group(2)!!.toDouble()
+            val start = opMatcher.start()
+            val end = opMatcher.end()
+
+            matches.add(Triple(start, end, "$operator$percentValue%"))
+        }
+
+        // Process matches from right to left
+        for (match in matches.reversed()) {
+            val (start, end, fullMatch) = match
+
+            // Find the number before this operator
+            var leftNumberEnd = start
+            var leftNumberStart = start - 1
+
+            // Skip parentheses and move to the actual number
+            if (leftNumberStart >= 0 && sb[leftNumberStart] == ')') {
+                var openParens = 1
+                leftNumberStart--
+
+                while (leftNumberStart >= 0 && openParens > 0) {
+                    if (sb[leftNumberStart] == ')') openParens++
+                    else if (sb[leftNumberStart] == '(') openParens--
+                    leftNumberStart--
+                }
+
+                // Now we need to find the start of the expression
+                if (leftNumberStart >= 0) {
+                    while (leftNumberStart >= 0 && (isDigit(sb[leftNumberStart].toString()) || sb[leftNumberStart] == '.' || sb[leftNumberStart] == '-')) {
+                        leftNumberStart--
+                    }
+                    leftNumberStart++
+                } else {
+                    leftNumberStart = 0
+                }
+            } else {
+                // For simple numbers, just find the start of the number
+                while (leftNumberStart >= 0 && (isDigit(sb[leftNumberStart].toString()) || sb[leftNumberStart] == '.')) {
+                    leftNumberStart--
+                }
+                leftNumberStart++
+            }
+
+            if (leftNumberStart < leftNumberEnd) {
+                val leftPart = sb.substring(leftNumberStart, leftNumberEnd)
+
+                try {
+                    // Extract the numerical values
+                    val baseNumber = evaluateExpression(leftPart)
+                    val operator = fullMatch.substring(0, 1)
+                    val percentNumber = fullMatch.substring(1, fullMatch.length - 1).toDouble()
+
+                    // Calculate the percentage of the base number
+                    val percentValue = baseNumber * (percentNumber / 100)
+
+                    // Calculate the new value based on the operator
+                    val newValue = when (operator) {
+                        "+" -> baseNumber + percentValue
+                        "-" -> baseNumber - percentValue
+                        "*" -> baseNumber * (percentNumber / 100)
+                        "/" -> baseNumber / (percentNumber / 100)
+                        else -> baseNumber
+                    }
+
+                    // Replace the entire expression "number operator percent%" with the result
+                    sb.replace(leftNumberStart, end, newValue.toString())
+                } catch (e: Exception) {
+                    Log.e("Calculator", "Error processing percentage expression: $e")
+                }
+            }
+        }
+
+        return sb.toString()
+    }
+
+    private fun isOperator(char: String): Boolean {
+        return char == "+" || char == "-" || char == "*" || char == "/"
+    }
+
+    private fun isDigit(char: String): Boolean {
+        return char.matches(Regex("[0-9]"))
+    }
+
+    private fun evaluateExpression(expression: String): Double {
+        return try {
+            ExpressionBuilder(expression).build().evaluate()
+        } catch (e: Exception) {
+            expression.toDouble()
+        }
+    }
+
     private fun calculateResult() {
         if (currentExpression == "123456") {
             val intent = Intent(this, SetupPasswordActivity::class.java)
@@ -161,8 +300,15 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
         }
 
         try {
-            currentExpression = currentExpression.replace("×", "*")
-            val expression = ExpressionBuilder(currentExpression).build()
+            // Replace '×' with '*' for the expression evaluator
+            var processedExpression = currentExpression.replace("×", "*")
+
+            // Process percentages in the expression
+            if (processedExpression.contains("%")) {
+                processedExpression = preprocessExpression(processedExpression)
+            }
+
+            val expression = ExpressionBuilder(processedExpression).build()
             val result = expression.evaluate()
 
             currentExpression = if (result.toLong().toDouble() == result) {
@@ -172,16 +318,17 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
             }
 
             lastWasOperator = false
+            lastWasPercent = false
             hasDecimal = currentExpression.contains(".")
 
             updateDisplay()
             binding.total.text = ""
         } catch (e: Exception) {
-            binding.display.text = getString(R.string.invalid_message)
+            e.printStackTrace()
         }
     }
 
-
+    @SuppressLint("DefaultLocale")
     private fun updateDisplay() {
         binding.display.text = currentExpression.replace("*", "×")
 
@@ -191,8 +338,24 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
         }
 
         try {
-            val expression = ExpressionBuilder(currentExpression).build()
+            // Don't show preview result if the expression ends with an operator
+            // (but allow percentage at the end)
+            if (currentExpression.isEmpty() ||
+                (isOperator(currentExpression.last().toString()) && currentExpression.last() != '%')) {
+                binding.total.text = ""
+                return
+            }
+
+            // Process the expression for preview calculation
+            var processedExpression = currentExpression.replace("×", "*")
+
+            if (processedExpression.contains("%")) {
+                processedExpression = preprocessExpression(processedExpression)
+            }
+
+            val expression = ExpressionBuilder(processedExpression).build()
             val result = expression.evaluate()
+
             val formattedResult = if (result.toLong().toDouble() == result) {
                 result.toLong().toString()
             } else {
@@ -205,16 +368,27 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
         }
     }
 
-
     private fun cutNumbers() {
         if (currentExpression.isNotEmpty()){
             if (currentExpression.length == 1){
-                currentExpression = currentExpression.substring(0, currentExpression.length - 1)
                 currentExpression = "0"
-            }else currentExpression = currentExpression.substring(0, currentExpression.length - 1)
-        }else currentExpression = "0"
-        updateDisplay()
+            } else {
+                val lastChar = currentExpression.last()
+                currentExpression = currentExpression.substring(0, currentExpression.length - 1)
 
+                // Update flags based on what was removed
+                if (lastChar == '%') {
+                    lastWasPercent = false
+                } else if (isOperator(lastChar.toString())) {
+                    lastWasOperator = false
+                } else if (lastChar == '.') {
+                    hasDecimal = false
+                }
+            }
+        } else {
+            currentExpression = "0"
+        }
+        updateDisplay()
     }
 
     override fun onPositiveButtonClicked() {
@@ -239,6 +413,4 @@ class MainActivity : AppCompatActivity(), DialogActionsCallback {
             }
         }
     }
-}
-
-
+}

app/src/main/java/devs/org/calculator/activities/PreviewActivity.kt

@@ -4,8 +4,8 @@ import android.net.Uri
 import android.os.Bundle
 import androidx.appcompat.app.AppCompatActivity
 import androidx.lifecycle.lifecycleScope
-import androidx.viewpager.widget.ViewPager
 import androidx.viewpager2.widget.ViewPager2
+import devs.org.calculator.R
 import devs.org.calculator.adapters.ImagePreviewAdapter
 import devs.org.calculator.callbacks.DialogActionsCallback
 import devs.org.calculator.databinding.ActivityPreviewBinding
@@ -13,7 +13,6 @@ import devs.org.calculator.utils.DialogUtil
 import devs.org.calculator.utils.FileManager
 import kotlinx.coroutines.launch
 import java.io.File
-import devs.org.calculator.R
 
 class PreviewActivity : AppCompatActivity() {
 
@@ -55,19 +54,19 @@ class PreviewActivity : AppCompatActivity() {
         when (type) {
             "IMAGE" -> {
                 filetype = FileManager.FileType.IMAGE
-                binding.title.text = "Preview Images"
+                binding.title.text = getString(R.string.preview_images)
             }
             "VIDEO" -> {
                 filetype = FileManager.FileType.VIDEO
-                binding.title.text = "Preview Videos"
+                binding.title.text = getString(R.string.preview_videos)
             }
             "AUDIO" -> {
                 filetype = FileManager.FileType.AUDIO
-                binding.title.text = "Preview Audios"
+                binding.title.text = getString(R.string.preview_audios)
             }
             else -> {
                 filetype = FileManager.FileType.DOCUMENT
-                binding.title.text = "Preview Documents"
+                binding.title.text = getString(R.string.preview_documents)
             }
         }
     }
@@ -107,10 +106,10 @@ class PreviewActivity : AppCompatActivity() {
             val fileUri = FileManager.FileManager().getContentUriImage(this, files[binding.viewPager.currentItem], filetype)
             if (fileUri != null) {
                 dialogUtil.showMaterialDialog(
-                    "Delete File",
-                    "Are you sure to Delete this file permanently?",
-                    "Delete Permanently",
-                    "Cancel",
+                    getString(R.string.delete_file),
+                    getString(R.string.are_you_sure_to_delete_this_file_permanently),
+                    getString(R.string.delete_permanently),
+                    getString(R.string.cancel),
                     object : DialogActionsCallback{
                         override fun onPositiveButtonClicked() {
                             lifecycleScope.launch {
@@ -136,10 +135,10 @@ class PreviewActivity : AppCompatActivity() {
             val fileUri = FileManager.FileManager().getContentUriImage(this, files[binding.viewPager.currentItem], filetype)
             if (fileUri != null) {
                 dialogUtil.showMaterialDialog(
-                    "Unhide File",
-                    "Are you sure you want to Unhide this file?",
-                    "Unhide",
-                    "Cancel",
+                    getString(R.string.un_hide_file),
+                    getString(R.string.are_you_sure_you_want_to_un_hide_this_file),
+                    getString(R.string.un_hide),
+                    getString(R.string.cancel),
                     object : DialogActionsCallback{
                         override fun onPositiveButtonClicked() {
                             lifecycleScope.launch {
@@ -168,7 +167,7 @@ class PreviewActivity : AppCompatActivity() {
         adapter.images = updatedFiles // Update adapter with the new list
 
         // Update the ViewPager's position
-        if (!updatedFiles.isNotEmpty()) finish()
+        if (updatedFiles.isEmpty()) finish()
 
     }
 

app/src/main/java/devs/org/calculator/activities/SetupPasswordActivity.kt

@@ -45,28 +45,28 @@ class SetupPasswordActivity : AppCompatActivity() {
             val securityAnswer = binding.etSecurityAnswer.text.toString()
 
             if (password.isEmpty()){
-                binding.etPassword.error = "Enter password"
+                binding.etPassword.error = getString(R.string.enter_password)
                 return@setOnClickListener
             }
             if (confirmPassword.isEmpty()){
-                binding.etConfirmPassword.error = "Confirm password"
+                binding.etConfirmPassword.error = getString(R.string.confirm_password)
                 return@setOnClickListener
             }
             if (securityQuestion.isEmpty()){
-                binding.etSecurityQuestion.error = "Enter security question"
+                binding.etSecurityQuestion.error = getString(R.string.enter_security_question)
                 return@setOnClickListener
             }
             if (securityAnswer.isEmpty()){
-                binding.etSecurityAnswer.error = "Enter security answer"
+                binding.etSecurityAnswer.error = getString(R.string.enter_security_answer)
                 return@setOnClickListener
             }
             if (password != confirmPassword) {
-                binding.etPassword.error = "Passwords don't match"
+                binding.etPassword.error = getString(R.string.passwords_don_t_match)
                 return@setOnClickListener
             }
             prefsUtil.savePassword(password)
             prefsUtil.saveSecurityQA(securityQuestion, securityAnswer)
-            Toast.makeText(this, "Password set successfully", Toast.LENGTH_SHORT).show()
+            Toast.makeText(this, getString(R.string.password_set_successfully), Toast.LENGTH_SHORT).show()
             startActivity(Intent(this, MainActivity::class.java))
             finish()
         }
@@ -75,40 +75,43 @@ class SetupPasswordActivity : AppCompatActivity() {
             // Implement password reset logic
             // Could use security questions or email verification
             if (prefsUtil.getSecurityQuestion() != null) showSecurityQuestionDialog(prefsUtil.getSecurityQuestion().toString())
-            else Toast.makeText(this, "Security question not set yet.", Toast.LENGTH_SHORT).show()
+            else Toast.makeText(this,
+                getString(R.string.security_question_not_set_yet), Toast.LENGTH_SHORT).show()
 
         }
         binding2.btnChangePassword.setOnClickListener{
             val oldPassword = binding2.etOldPassword.text.toString()
             val newPassword = binding2.etNewPassword.text.toString()
             if (oldPassword.isEmpty()) {
-                binding2.etOldPassword.error = "This field can't be empty"
+                binding2.etOldPassword.error = getString(R.string.this_field_can_t_be_empty)
                 return@setOnClickListener
             }
             if (newPassword.isEmpty()) {
-                binding2.etNewPassword.error = "This field can't be empty"
+                binding2.etNewPassword.error = getString(R.string.this_field_can_t_be_empty)
                 return@setOnClickListener
             }
 
             if (prefsUtil.validatePassword(oldPassword)){
                 if (oldPassword != newPassword){
                     prefsUtil.savePassword(newPassword)
-                    Toast.makeText(this, "Password reset successfully", Toast.LENGTH_SHORT).show()
+                    Toast.makeText(this,
+                        getString(R.string.password_reset_successfully), Toast.LENGTH_SHORT).show()
                     startActivity(Intent(this, MainActivity::class.java))
                     finish()
 
                 }else {
-                    Toast.makeText(this, "Old Password And New Password Not Be Same", Toast.LENGTH_SHORT).show()
-                    binding2.etNewPassword.error = "Old Password And New Password Not Be Same"
+                    Toast.makeText(this,
+                        getString(R.string.old_password_and_new_password_not_be_same), Toast.LENGTH_SHORT).show()
+                    binding2.etNewPassword.error = getString(R.string.old_password_and_new_password_not_be_same)
                 }
             }else {
-                Toast.makeText(this, "Wrong password entered", Toast.LENGTH_SHORT).show()
-                binding2.etOldPassword.error = "Old Password Not Matching"
+                Toast.makeText(this, getString(R.string.wrong_password_entered), Toast.LENGTH_SHORT).show()
+                binding2.etOldPassword.error = getString(R.string.old_password_not_matching)
             }
         }
         binding2.btnResetPassword.setOnClickListener{
             if (prefsUtil.getSecurityQuestion() != null) showSecurityQuestionDialog(prefsUtil.getSecurityQuestion().toString())
-            else Toast.makeText(this, "Security question not set yet.", Toast.LENGTH_SHORT).show()
+            else Toast.makeText(this, getString(R.string.this_field_can_t_be_empty), Toast.LENGTH_SHORT).show()
         }
     }
 
@@ -120,26 +123,28 @@ class SetupPasswordActivity : AppCompatActivity() {
 
 
         MaterialAlertDialogBuilder(this)
-            .setTitle("Answer the Security Question!")
+            .setTitle(getString(R.string.answer_the_security_question))
             .setView(dialogView)
-            .setPositiveButton("Verify") { dialog, _ ->
+            .setPositiveButton(getString(R.string.verify)) { dialog, _ ->
                 val inputEditText: TextInputEditText = dialogView.findViewById(R.id.text_input_edit_text)
                 val userAnswer = inputEditText.text.toString().trim()
 
                 if (userAnswer.isEmpty()) {
-                    Toast.makeText(this, "Answer cannot be empty!", Toast.LENGTH_SHORT).show()
+                    Toast.makeText(this,
+                        getString(R.string.answer_cannot_be_empty), Toast.LENGTH_SHORT).show()
                 } else {
                     if (prefsUtil.validateSecurityAnswer(userAnswer)){
                         prefsUtil.resetPassword()
-                        Toast.makeText(this, "Password successfully reset.", Toast.LENGTH_SHORT).show()
+                        Toast.makeText(this,
+                            getString(R.string.password_successfully_reset), Toast.LENGTH_SHORT).show()
                         dialog.dismiss()
                     }else {
-                        Toast.makeText(this, "Invalid answer!", Toast.LENGTH_SHORT).show()
+                        Toast.makeText(this, getString(R.string.invalid_answer), Toast.LENGTH_SHORT).show()
                     }
 
                 }
             }
-            .setNegativeButton("Cancel") { dialog, _ ->
+            .setNegativeButton(getString(R.string.cancel)) { dialog, _ ->
 
                 dialog.dismiss()
             }

app/src/main/java/devs/org/calculator/activities/VideoGalleryActivity.kt

@@ -7,6 +7,7 @@ import android.widget.Toast
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.contract.ActivityResultContracts
 import androidx.lifecycle.lifecycleScope
+import devs.org.calculator.R
 import devs.org.calculator.utils.FileManager
 import devs.org.calculator.callbacks.FileProcessCallback
 import kotlinx.coroutines.launch
@@ -15,7 +16,6 @@ import java.io.File
 class VideoGalleryActivity : BaseGalleryActivity(), FileProcessCallback {
     override val fileType = FileManager.FileType.VIDEO
     private lateinit var pickLauncher: ActivityResultLauncher<Intent>
-    private var selectedUri: Uri? = null
 
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -42,19 +42,21 @@ class VideoGalleryActivity : BaseGalleryActivity(), FileProcessCallback {
                             .processMultipleFiles(uriList, fileType,this@VideoGalleryActivity )
                     }
                 } else {
-                    Toast.makeText(this, "No files selected", Toast.LENGTH_SHORT).show()
+                    Toast.makeText(this, getString(R.string.no_files_selected), Toast.LENGTH_SHORT).show()
                 }
             }
         }
     }
 
     override fun onFilesProcessedSuccessfully(copiedFiles: List<File>) {
-        Toast.makeText(this@VideoGalleryActivity, "${copiedFiles.size} Videos hidden successfully", Toast.LENGTH_SHORT).show()
+        Toast.makeText(this@VideoGalleryActivity, copiedFiles.size.toString() +
+            getString(R.string.videos_hidden_successfully), Toast.LENGTH_SHORT).show()
         loadFiles()
     }
 
     override fun onFileProcessFailed() {
-        Toast.makeText(this@VideoGalleryActivity, "Failed to hide videos", Toast.LENGTH_SHORT).show()
+        Toast.makeText(this@VideoGalleryActivity,
+            getString(R.string.failed_to_hide_videos), Toast.LENGTH_SHORT).show()
     }
 
     private fun setupFabButton() {

app/src/main/java/devs/org/calculator/adapters/FileAdapter.kt

@@ -13,7 +13,6 @@ import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListAdapter
 import androidx.recyclerview.widget.RecyclerView
 import com.bumptech.glide.Glide
-import com.google.android.material.dialog.MaterialAlertDialogBuilder
 import devs.org.calculator.R
 import devs.org.calculator.activities.PreviewActivity
 import devs.org.calculator.callbacks.DialogActionsCallback
@@ -35,18 +34,18 @@ class FileAdapter(
     private var fileTypes = when (fileType) {
 
         FileManager.FileType.IMAGE -> {
-            "IMAGE"
+            context.getString(R.string.image)
         }
 
         FileManager.FileType.VIDEO -> {
-            "VIDEO"
+            context.getString(R.string.video)
         }
 
         FileManager.FileType.AUDIO -> {
-            "AUDIO"
+            context.getString(R.string.audio)
         }
 
-        else -> "DOCUMENT"
+        else -> context.getString(R.string.document)
 
     }
 
@@ -93,7 +92,8 @@ class FileAdapter(
                         try {
                             context.startActivity(intent)
                         } catch (e: Exception) {
-                            Toast.makeText(context, "No audio player found!", Toast.LENGTH_SHORT).show()
+                            Toast.makeText(context,
+                                context.getString(R.string.no_audio_player_found), Toast.LENGTH_SHORT).show()
                         }
                     }
 
@@ -106,7 +106,8 @@ class FileAdapter(
                         try {
                             context.startActivity(intent)
                         } catch (e: Exception) {
-                            Toast.makeText(context, "No suitable app found to open this document!", Toast.LENGTH_SHORT).show()
+                            Toast.makeText(context,
+                                context.getString(R.string.no_suitable_app_found_to_open_this_document), Toast.LENGTH_SHORT).show()
                         }
                     }
                     else -> {
@@ -131,14 +132,14 @@ class FileAdapter(
 
                 }
                 fileName = FileManager.FileName(context).getFileNameFromUri(fileUri)?.toString()
-                    ?: "Unknown File"
+                    ?: context.getString(R.string.unknown_file)
 
                 DialogUtil(context).showMaterialDialogWithNaturalButton(
-                    "$fileTypes DETAILS",
-                    "File Name: $fileName\n\nFile Path: $file\n\nYou can permanently delete or unhide this file.",
-                    "Delete Permanently",
-                    "Unhide",
-                    "Cancel",
+                    context.getString(R.string.details, fileTypes),
+                    "File Name: $fileName\n\nFile Path: $file\n\nYou can permanently delete or un-hide this file.",
+                    context.getString(R.string.delete_permanently),
+                    context.getString(R.string.un_hide),
+                    context.getString(R.string.cancel),
                     object : DialogActionsCallback {
                         override fun onPositiveButtonClicked() {
                             lifecycleOwner.lifecycleScope.launch {

app/src/main/java/devs/org/calculator/utils/DialogUtil.kt

@@ -1,22 +1,10 @@
 package devs.org.calculator.utils
 
-import android.app.RecoverableSecurityException
 import android.content.Context
-import android.net.Uri
-import android.os.Build
-import android.provider.MediaStore
-import android.view.View
-import android.widget.Toast
 import androidx.activity.result.ActivityResultLauncher
 import androidx.activity.result.IntentSenderRequest
-import androidx.documentfile.provider.DocumentFile
-import androidx.lifecycle.LifecycleOwner
 import com.google.android.material.dialog.MaterialAlertDialogBuilder
-import com.google.android.material.textfield.TextInputEditText
-import devs.org.calculator.R
 import devs.org.calculator.callbacks.DialogActionsCallback
-import kotlinx.coroutines.Dispatchers
-import kotlinx.coroutines.withContext
 
 class DialogUtil(private val context: Context) {
     private lateinit var intentSenderLauncher: ActivityResultLauncher<IntentSenderRequest>
@@ -57,7 +45,7 @@ class DialogUtil(private val context: Context) {
         MaterialAlertDialogBuilder(context)
             .setTitle(title)
             .setMessage(message)
-            .setPositiveButton(positiveButton) { dialog, _ ->
+            .setPositiveButton(positiveButton) { _, _ ->
                 // Handle positive button click
                 callback.onPositiveButtonClicked()
             }

app/src/main/java/devs/org/calculator/utils/FileManager.kt

@@ -188,7 +188,7 @@ class FileManager(private val context: Context, private val lifecycleOwner: Life
                 withContext(Dispatchers.Main) {
                     Toast.makeText(
                         context,
-                        "Error hiding/unhiding file: ${e.message}",
+                        "Error hiding/un-hiding file: ${e.message}",
                         Toast.LENGTH_LONG
                     ).show()
                 }

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

@@ -1,39 +1,45 @@
 <?xml version="1.0" encoding="utf-8"?>
-<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<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:id="@+id/main"
     android:layout_width="match_parent"
-    android:orientation="vertical"
     android:layout_height="match_parent"
     tools:context=".activities.MainActivity">
 
     <!-- Calculator Display -->
-    <LinearLayout
-        android:layout_width="match_parent"
-        android:layout_height="160dp"
+    <androidx.constraintlayout.widget.ConstraintLayout
+        android:id="@+id/displayContainer"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
         android:layout_margin="16dp"
-        android:layout_weight="3"
-        android:layout_marginTop="0dp"
-        android:orientation="vertical"
-        android:gravity="right|bottom">
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHeight_percent="0.3">
+
         <TextView
             android:id="@+id/display"
-            android:layout_width="match_parent"
+            android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:gravity="end|bottom"
             android:padding="10dp"
             android:text="0"
             android:textSize="48sp"
             android:autoSizeTextType="uniform"
-            android:autoSizeMinTextSize="20sp"
+            android:autoSizeMinTextSize="16sp"
             android:autoSizeMaxTextSize="48sp"
             android:autoSizeStepGranularity="2sp"
+            app:layout_constraintBottom_toTopOf="@+id/total"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintVertical_chainStyle="packed"
             tools:ignore="Suspicious0dp" />
 
         <TextView
             android:id="@+id/total"
-            android:layout_width="match_parent"
+            android:layout_width="0dp"
             android:layout_height="wrap_content"
             android:gravity="end|bottom"
             android:paddingRight="10dp"
@@ -41,279 +47,265 @@
             android:text=""
             android:textSize="26sp"
             android:autoSizeTextType="uniform"
-            android:autoSizeMinTextSize="20sp"
-            android:autoSizeMaxTextSize="48sp"
+            android:autoSizeMinTextSize="12sp"
+            android:autoSizeMaxTextSize="26sp"
             android:autoSizeStepGranularity="2sp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toBottomOf="@+id/display"
             tools:ignore="Suspicious0dp" />
-    </LinearLayout>
-
-
-
-
+    </androidx.constraintlayout.widget.ConstraintLayout>
 
     <!-- Calculator Buttons -->
-    <GridLayout
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
+    <androidx.gridlayout.widget.GridLayout
+        android:id="@+id/buttonGrid"
+        android:layout_width="0dp"
+        android:layout_height="0dp"
         android:layout_margin="8dp"
-        android:columnCount="4"
-        android:layout_weight="4"
-        android:rowCount="5">
+        app:columnCount="4"
+        app:rowCount="5"
+        app:layout_constraintTop_toBottomOf="@id/displayContainer"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent">
 
         <!-- Row 1 -->
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnClear"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:layout_margin="4dp"
             android:textSize="30sp"
             android:text="C"
-            app:layout_constraintDimensionRatio="1:1"
             app:cornerRadius="15dp"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnPercent"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="%"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnDivide"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="÷"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/cut"
-            android:layout_height="70dp"
-            android:layout_width="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:gravity="center"
             android:layout_margin="4dp"
             app:icon="@drawable/backspace"
             android:textAlignment="center"
-            app:layout_constraintDimensionRatio="1:1"
             app:iconSize="32dp"
             app:cornerRadius="15dp"/>
+
         <!-- Row 2 -->
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn7"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="7"
-            app:layout_constraintDimensionRatio="1:1"
             app:cornerRadius="15dp"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn8"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="8"
-            app:layout_constraintDimensionRatio="1:1"
             app:cornerRadius="15dp"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn9"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:layout_margin="4dp"
             android:textSize="30sp"
             android:text="9"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnMultiply"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:layout_margin="4dp"
             android:textSize="30sp"
             android:text="×"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button"/>
 
         <!-- Row 3 -->
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn4"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             app:cornerRadius="15dp"
             android:text="4"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn5"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="5"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn6"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="6"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnMinus"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="-"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button"/>
 
         <!-- Row 4 -->
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn1"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="1"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn2"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
-            android:layout_columnWeight="1"
             android:layout_margin="4dp"
             android:text="2"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn3"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
-            android:layout_columnWeight="1"
             android:layout_margin="4dp"
             android:text="3"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnPlus"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="+"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button"/>
 
         <!-- Row 5 -->
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btn0"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnSpan="2"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnSpan="2"
+            app:layout_columnWeight="2"
             android:textSize="30sp"
-            android:layout_columnWeight="2"
             android:layout_margin="4dp"
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             android:text="0" />
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnDot"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
-            android:layout_columnWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
             android:layout_margin="4dp"
             android:text="."
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button.OutlinedButton"/>
 
         <com.google.android.material.button.MaterialButton
             android:id="@+id/btnEquals"
-            android:layout_width="70dp"
-            android:layout_height="70dp"
-            android:layout_rowWeight="1"
+            android:layout_width="0dp"
+            android:layout_height="0dp"
+            app:layout_rowWeight="1"
+            app:layout_columnWeight="1"
             android:textSize="30sp"
-            android:layout_columnWeight="1"
             android:layout_margin="4dp"
             android:text="="
             app:cornerRadius="15dp"
-            app:layout_constraintDimensionRatio="1:1"
             style="@style/Widget.MaterialComponents.Button"/>
 
-    </GridLayout>
+    </androidx.gridlayout.widget.GridLayout>
 
-</LinearLayout>
+</androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -1,4 +1,54 @@
 <resources>
     <string name="app_name">Calculator</string>
     <string name="invalid_message">Invalid Value Entered</string>
+    <string name="add_image">Add Image</string>
+    <string name="add_audio">Add Audio</string>
+    <string name="add_video">Add Video</string>
+    <string name="add_files">Add Files</string>
+    <string name="failed_to_hide_documents">Failed to hide Documents</string>
+    <string name="no_files_selected">No files selected</string>
+    <string name="documents_hidden_successfully">%1$s Documents hidden successfully</string>
+    <string name="failed_to_hide_unhide_photo">Failed to hide/unhide photo</string>
+    <string name="images_hidden_successfully">%1$s Images hidden successfully</string>
+    <string name="failed_to_hide_images">Failed to hide images</string>
+    <string name="storage_permissions_granted">Storage permissions granted</string>
+    <string name="storage_permissions_denied">Storage permissions denied</string>
+    <string name="preview_images">Preview Images</string>
+    <string name="preview_videos">Preview Videos</string>
+    <string name="preview_audios">Preview Audios</string>
+    <string name="preview_documents">Preview Documents</string>
+    <string name="delete_file">Delete File</string>
+    <string name="are_you_sure_to_delete_this_file_permanently">Are you sure to Delete this file permanently?</string>
+    <string name="delete_permanently">Delete Permanently</string>
+    <string name="cancel">Cancel</string>
+    <string name="un_hide_file">Un-hide File</string>
+    <string name="are_you_sure_you_want_to_un_hide_this_file">Are you sure you want to Un-hide this file?</string>
+    <string name="un_hide">Un-hide</string>
+    <string name="enter_password">Enter password</string>
+    <string name="confirm_password">Confirm password</string>
+    <string name="enter_security_question">Enter security question</string>
+    <string name="enter_security_answer">Enter security answer</string>
+    <string name="passwords_don_t_match">Passwords don\'t match</string>
+    <string name="password_set_successfully">Password set successfully</string>
+    <string name="security_question_not_set_yet">Security question not set yet.</string>
+    <string name="this_field_can_t_be_empty">This field can\'t be empty</string>
+    <string name="password_reset_successfully">Password reset successfully</string>
+    <string name="old_password_and_new_password_not_be_same">Old Password And New Password Not Be Same</string>
+    <string name="wrong_password_entered">Wrong password entered</string>
+    <string name="old_password_not_matching">Old Password Not Matching</string>
+    <string name="answer_the_security_question">Answer the Security Question!</string>
+    <string name="verify">Verify</string>
+    <string name="answer_cannot_be_empty">Answer cannot be empty!</string>
+    <string name="password_successfully_reset">Password successfully reset.</string>
+    <string name="invalid_answer">Invalid answer!</string>
+    <string name="videos_hidden_successfully">%1$s Videos hidden successfully</string>
+    <string name="failed_to_hide_videos">Failed to hide videos</string>
+    <string name="image">IMAGE</string>
+    <string name="video">VIDEO</string>
+    <string name="audio">AUDIO</string>
+    <string name="document">DOCUMENT</string>
+    <string name="no_audio_player_found">No audio player found!</string>
+    <string name="no_suitable_app_found_to_open_this_document">No suitable app found to open this document!</string>
+    <string name="unknown_file">Unknown File</string>
+    <string name="details">%1$s DETAILS</string>
 </resources>

gradle/libs.versions.toml

@@ -1,6 +1,8 @@
 [versions]
-agp = "8.7.2"
+agp = "8.7.3"
+documentfile = "1.0.1"
 exp4j = "0.4.8"
+glide = "4.16.0"
 kotlin = "1.9.24"
 coreKtx = "1.15.0"
 junit = "4.13.2"
@@ -11,10 +13,17 @@ material = "1.12.0"
 activity = "1.9.3"
 constraintlayout = "2.2.0"
 materialColorUtilities = "1.3.0"
+gridlayout = "1.0.0"
+photoview = "2.3.0"
+viewpager = "1.1.0"
+zoomage = "1.3.1"
 
 [libraries]
 androidx-core-ktx = { group = "androidx.core", name = "core-ktx", version.ref = "coreKtx" }
+androidx-documentfile = { module = "androidx.documentfile:documentfile", version.ref = "documentfile" }
+androidx-viewpager = { module = "androidx.viewpager:viewpager", version.ref = "viewpager" }
 exp4j = { module = "net.objecthunter:exp4j", version.ref = "exp4j" }
+glide = { module = "com.github.bumptech.glide:glide", version.ref = "glide" }
 junit = { group = "junit", name = "junit", version.ref = "junit" }
 androidx-junit = { group = "androidx.test.ext", name = "junit", version.ref = "junitVersion" }
 androidx-espresso-core = { group = "androidx.test.espresso", name = "espresso-core", version.ref = "espressoCore" }
@@ -23,6 +32,9 @@ material = { group = "com.google.android.material", name = "material", version.r
 androidx-activity = { group = "androidx.activity", name = "activity", version.ref = "activity" }
 androidx-constraintlayout = { group = "androidx.constraintlayout", name = "constraintlayout", version.ref = "constraintlayout" }
 material-color-utilities = { module = "com.google.android.material:material-color-utilities", version.ref = "materialColorUtilities" }
+androidx-gridlayout = { group = "androidx.gridlayout", name = "gridlayout", version.ref = "gridlayout" }
+photoview = { module = "com.github.chrisbanes:PhotoView", version.ref = "photoview" }
+zoomage = { module = "com.jsibbold:zoomage", version.ref = "zoomage" }
 
 [plugins]
 android-application = { id = "com.android.application", version.ref = "agp" }