Async file loading in file viewers

app/src/main/java/sushi/hardcore/droidfs/BaseActivity.kt

@@ -1,10 +1,7 @@
 package sushi.hardcore.droidfs
 
-import android.content.Intent
 import android.content.SharedPreferences
-import android.os.Build
 import android.os.Bundle
-import android.os.Parcelable
 import android.view.WindowManager
 import androidx.appcompat.app.AppCompatActivity
 import androidx.preference.PreferenceManager
@@ -17,8 +14,8 @@ open class BaseActivity: AppCompatActivity() {
 
     override fun onCreate(savedInstanceState: Bundle?) {
         sharedPrefs = PreferenceManager.getDefaultSharedPreferences(this)
+        themeValue = sharedPrefs.getString(ConstValues.THEME_VALUE_KEY, ConstValues.DEFAULT_THEME_VALUE)!!
         if (shouldCheckTheme && applyCustomTheme) {
-            themeValue = sharedPrefs.getString(ConstValues.THEME_VALUE_KEY, ConstValues.DEFAULT_THEME_VALUE)!!
             when (themeValue) {
                 "black_green" -> setTheme(R.style.BlackGreen)
                 "dark_red" -> setTheme(R.style.DarkRed)

app/src/main/java/sushi/hardcore/droidfs/file_viewers/FileViewerActivity.kt

@@ -6,6 +6,11 @@ import androidx.activity.addCallback
 import androidx.core.content.ContextCompat
 import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.WindowInsetsControllerCompat
+import androidx.lifecycle.lifecycleScope
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.isActive
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
 import sushi.hardcore.droidfs.BaseActivity
 import sushi.hardcore.droidfs.ConstValues
 import sushi.hardcore.droidfs.R
@@ -81,22 +86,29 @@ abstract class FileViewerActivity: BaseActivity() {
         }
     }
 
-    protected fun loadWholeFile(path: String, fileSize: Long? = null): ByteArray? {
+    protected fun loadWholeFile(path: String, fileSize: Long? = null, callback: (ByteArray) -> Unit) {
-        val result = encryptedVolume.loadWholeFile(path, size = fileSize)
+        lifecycleScope.launch(Dispatchers.IO) {
-        if (result.second != 0) {
+            val result = encryptedVolume.loadWholeFile(path, size = fileSize)
-            val dialog = CustomAlertDialogBuilder(this, themeValue)
+            if (isActive) {
-                .setTitle(R.string.error)
+                withContext(Dispatchers.Main) {
-                .setCancelable(false)
+                    if (result.second == 0) {
-                .setPositiveButton(R.string.ok) { _, _ -> goBackToExplorer() }
+                        callback(result.first!!)
-            when (result.second) {
+                    } else {
-                1 -> dialog.setMessage(R.string.get_size_failed)
+                        val dialog = CustomAlertDialogBuilder(this@FileViewerActivity, themeValue)
-                2 -> dialog.setMessage(R.string.outofmemoryerror_msg)
+                            .setTitle(R.string.error)
-                3 -> dialog.setMessage(R.string.read_file_failed)
+                            .setCancelable(false)
-                4 -> dialog.setMessage(R.string.io_error)
+                            .setPositiveButton(R.string.ok) { _, _ -> goBackToExplorer() }
+                        when (result.second) {
+                            1 -> dialog.setMessage(R.string.get_size_failed)
+                            2 -> dialog.setMessage(R.string.outofmemoryerror_msg)
+                            3 -> dialog.setMessage(R.string.read_file_failed)
+                            4 -> dialog.setMessage(R.string.io_error)
+                        }
+                        dialog.show()
+                    }
+                }
             }
-            dialog.show()
         }
-        return result.first
     }
 
     protected fun createPlaylist() {

app/src/main/java/sushi/hardcore/droidfs/file_viewers/ImageViewer.kt

@@ -163,13 +163,13 @@ class ImageViewer: FileViewerActivity() {
     }
 
     private fun loadImage(){
+        fileName = File(filePath).name
+        binding.textFilename.text = fileName
         requestBuilder = null
-        loadWholeFile(filePath)?.let {
+        loadWholeFile(filePath) {
             originalOrientation = 0f
             requestBuilder = Glide.with(this).load(it)
             requestBuilder?.into(binding.imageViewer)
-            fileName = File(filePath).name
-            binding.textFilename.text = fileName
             rotationAngle = originalOrientation
         }
     }

app/src/main/java/sushi/hardcore/droidfs/file_viewers/PdfViewer.kt

@@ -22,7 +22,7 @@ class PdfViewer: FileViewerActivity() {
         val fileName = File(filePath).name
         title = fileName
         val fileSize = encryptedVolume.getAttr(filePath)?.size
-        loadWholeFile(filePath, fileSize)?.let {
+        loadWholeFile(filePath, fileSize) {
             pdfViewer.loadPdf(ByteArrayInputStream(it), fileName, fileSize)
         }
     }

app/src/main/java/sushi/hardcore/droidfs/file_viewers/TextEditor.kt

@@ -23,8 +23,10 @@ class TextEditor: FileViewerActivity() {
     }
 
     override fun viewFile() {
-        loadWholeFile(filePath)?.let {
+        fileName = File(filePath).name
-            fileName = File(filePath).name
+        title = fileName
+        supportActionBar?.setDisplayHomeAsUpEnabled(true)
+        loadWholeFile(filePath) {
             try {
                 loadLayout(String(it))
             } catch (e: OutOfMemoryError){
@@ -43,8 +45,6 @@ class TextEditor: FileViewerActivity() {
         } else {
             setContentView(R.layout.activity_text_editor)
         }
-        title = fileName
-        supportActionBar?.setDisplayHomeAsUpEnabled(true)
         editor = findViewById(R.id.text_editor)
         editor.setText(fileContent)
         editor.addTextChangedListener(object: TextWatcher {