improve threading at the file editor to better handle large files

app/src/main/kotlin/com/simplemobiletools/filemanager/pro/activities/ReadTextActivity.kt

@@ -16,6 +16,7 @@ import androidx.core.view.MenuItemCompat
 import com.simplemobiletools.commons.extensions.*
 import com.simplemobiletools.commons.helpers.PERMISSION_WRITE_STORAGE
 import com.simplemobiletools.commons.helpers.REAL_FILE_PATH
+import com.simplemobiletools.commons.helpers.ensureBackgroundThread
 import com.simplemobiletools.commons.models.FileDirItem
 import com.simplemobiletools.filemanager.pro.R
 import com.simplemobiletools.filemanager.pro.dialogs.SaveAsDialog
@@ -41,7 +42,9 @@ class ReadTextActivity : SimpleActivity() {
 
         handlePermission(PERMISSION_WRITE_STORAGE) {
             if (it) {
+                read_text_view.onGlobalLayout {
                     checkIntent()
+                }
             } else {
                 toast(R.string.no_storage_permissions)
                 finish()
@@ -160,6 +163,7 @@ class ReadTextActivity : SimpleActivity() {
             return
         }
 
+        ensureBackgroundThread {
             originalText = if (uri.scheme == "file") {
                 filePath = uri.path
                 val file = File(filePath)
@@ -175,10 +179,11 @@ class ReadTextActivity : SimpleActivity() {
                 } catch (e: Exception) {
                     showErrorToast(e)
                     finish()
-                return
+                    return@ensureBackgroundThread
                 }
             }
 
+            runOnUiThread {
                 read_text_view.setText(originalText)
                 if (originalText.isNotEmpty()) {
                     hideKeyboard()
@@ -187,3 +192,5 @@ class ReadTextActivity : SimpleActivity() {
                 }
             }
         }
+    }
+}