center the drawing canvas at the editor

app/src/main/kotlin/com/simplemobiletools/gallery/pro/activities/EditActivity.kt

@@ -85,6 +85,7 @@ class EditActivity : SimpleActivity(), CropImageView.OnCropImageCompleteListener
     private var isCropIntent = false
     private var isEditingWithThirdParty = false
     private var isSharingBitmap = false
+    private var wasDrawCanvasPositioned = false
     private var oldExif: ExifInterface? = null
     private var filterInitialBitmap: Bitmap? = null
 
@@ -246,10 +247,14 @@ class EditActivity : SimpleActivity(), CropImageView.OnCropImageCompleteListener
         default_image_view.beGone()
         crop_image_view.beGone()
         editor_draw_canvas.beVisible()
-        editor_draw_canvas.onGlobalLayout {
-            Thread {
-                fillCanvasBackground()
-            }.start()
+
+        if (!wasDrawCanvasPositioned) {
+            wasDrawCanvasPositioned = true
+            editor_draw_canvas.onGlobalLayout {
+                Thread {
+                    fillCanvasBackground()
+                }.start()
+            }
         }
     }
 
@@ -275,7 +280,7 @@ class EditActivity : SimpleActivity(), CropImageView.OnCropImageCompleteListener
                     updateBackgroundBitmap(bitmap)
                     layoutParams.width = bitmap.width
                     layoutParams.height = bitmap.height
-                    (layoutParams as RelativeLayout.LayoutParams).removeRule(RelativeLayout.ABOVE)
+                    y = (height - bitmap.height) / 2f
                     requestLayout()
                 }
             }

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

@@ -17,8 +17,7 @@
         android:id="@+id/crop_image_view"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:layout_above="@+id/bottom_editor_crop_rotate_actions"
-        android:layout_marginBottom="@dimen/bottom_actions_height"
+        android:layout_marginBottom="@dimen/bottom_actions_height_bigger"
         android:visibility="gone"
         app:cropBackgroundColor="@color/crop_image_view_background"
         app:cropInitialCropWindowPaddingRatio="0"/>
@@ -27,10 +26,8 @@
         android:id="@+id/editor_draw_canvas"
         android:layout_width="match_parent"
         android:layout_height="match_parent"
-        android:layout_above="@+id/bottom_editor_crop_rotate_actions"
-        android:layout_alignParentTop="true"
-        android:layout_centerInParent="true"
-        android:layout_marginBottom="@dimen/bottom_actions_height"
+        android:layout_centerHorizontal="true"
+        android:layout_marginBottom="@dimen/bottom_actions_height_double"
         android:background="@android:color/transparent"
         android:visibility="gone"/>
 

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

@@ -12,6 +12,8 @@
     <dimen name="instant_change_bar_width">50dp</dimen>
     <dimen name="list_view_folder_thumbnail_size">72dp</dimen>
     <dimen name="bottom_actions_height">64dp</dimen>
+    <dimen name="bottom_actions_height_double">128dp</dimen>
+    <dimen name="bottom_actions_height_bigger">164dp</dimen>
     <dimen name="bottom_editor_color_picker_size">48dp</dimen>
     <dimen name="bottom_filters_thumbnail_size">76dp</dimen>
     <dimen name="bottom_filters_height">90dp</dimen>