Add lastSaveExtension to config

This allow to keep the preferred user file extension like save folder

app/src/main/kotlin/com/simplemobiletools/draw/pro/activities/MainActivity.kt

@@ -73,6 +73,7 @@ class MainActivity : SimpleActivity(), CanvasListener {
         setBackgroundColor(config.canvasBackgroundColor)
         setColor(config.brushColor)
         defaultPath = config.lastSaveFolder
+        defaultExtension = config.lastSaveExtension
 
         brushSize = config.brushSize
         updateBrushSize()
@@ -395,6 +396,7 @@ class MainActivity : SimpleActivity(), CanvasListener {
             defaultFilename = filename
             defaultExtension = extension
             config.lastSaveFolder = defaultPath
+            config.lastSaveExtension = defaultExtension
         }
     }
 

app/src/main/kotlin/com/simplemobiletools/draw/pro/helpers/Config.kt

@@ -30,6 +30,10 @@ class Config(context: Context) : BaseConfig(context) {
         get() = prefs.getString(LAST_SAVE_FOLDER, "")!!
         set(lastSaveFolder) = prefs.edit().putString(LAST_SAVE_FOLDER, lastSaveFolder).apply()
 
+    var lastSaveExtension: String
+        get() = prefs.getString(LAST_SAVE_EXT, "")!!
+        set(lastSaveExtension) = prefs.edit().putString(LAST_SAVE_EXT, lastSaveExtension).apply()
+
     var allowZoomingCanvas: Boolean
         get() = prefs.getBoolean(ALLOW_ZOOMING_CANVAS, false)
         set(allowZoomingCanvas) = prefs.edit().putBoolean(ALLOW_ZOOMING_CANVAS, allowZoomingCanvas).apply()

app/src/main/kotlin/com/simplemobiletools/draw/pro/helpers/Constants.kt

@@ -5,6 +5,7 @@ const val CANVAS_BACKGROUND_COLOR = "canvas_background_color"
 const val SHOW_BRUSH_SIZE = "show_brush_size"
 const val BRUSH_SIZE = "brush_size_2"
 const val LAST_SAVE_FOLDER = "last_save_folder"
+const val LAST_SAVE_EXT = "last_save_ext"
 const val ALLOW_ZOOMING_CANVAS = "allow_zooming_canvas"
 const val FORCE_PORTRAIT_MODE = "force_portrait_mode"