add rtl support to rectangle indicator

sample/src/main/java/io/github/vejei/viewpagerindicator/sample/MainFragment.java

@@ -35,5 +35,10 @@ public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceStat
         rectIndicatorButton.setOnClickListener(v -> {
             activity.addFragment(new RectIndicatorFragment());
         });
+
+        Button rectIndicatorRtlButton = view.findViewById(R.id.button_main_rect_indicator_rtl);
+        rectIndicatorRtlButton.setOnClickListener(v -> {
+            activity.addFragment(new RectIndicatorRtlFragment());
+        });
     }
 }

sample/src/main/java/io/github/vejei/viewpagerindicator/sample/RectIndicatorRtlFragment.java

@@ -0,0 +1,50 @@
+package io.github.vejei.viewpagerindicator.sample;
+
+
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+
+import java.util.Arrays;
+import java.util.List;
+
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.fragment.app.Fragment;
+import androidx.viewpager2.widget.ViewPager2;
+import io.github.vejei.viewpagerindicator.indicator.RectIndicator;
+
+public class RectIndicatorRtlFragment extends Fragment {
+    @Nullable
+    @Override
+    public View onCreateView(@NonNull LayoutInflater inflater, @Nullable ViewGroup container,
+            @Nullable Bundle savedInstanceState) {
+        return inflater.inflate(R.layout.fragment_rect_indecator_rtl, container, false);
+    }
+
+    @Override
+    public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
+        super.onViewCreated(view, savedInstanceState);
+
+        MainActivity activity = (MainActivity) getActivity();
+        if (activity == null) return;
+
+        PageAdapter pageAdapter = new PageAdapter();
+        ViewPager2 viewPager2 = view.findViewById(R.id.view_pager2);
+        viewPager2.setAdapter(pageAdapter);
+        pageAdapter.setData(Arrays.asList(activity.data));
+
+        RectIndicator rectIndicator = view.findViewById(R.id.rect_indicator);
+        rectIndicator.setWithViewPager2(viewPager2);
+
+        RectIndicator squareIndicator = view.findViewById(R.id.square_indicator);
+        squareIndicator.setWithViewPager2(viewPager2);
+
+        RectIndicator stadiumIndicator = view.findViewById(R.id.stadium_indicator);
+        stadiumIndicator.setWithViewPager2(viewPager2);
+
+        List<String> newData = Arrays.asList("Seventh", "Eighth", "Ninth");
+        pageAdapter.append(newData);
+    }
+}

sample/src/main/res/layout/fragment_main.xml

@@ -19,4 +19,10 @@
         android:layout_height="wrap_content"
         android:text="@string/main_rect_indicator_button_text"/>
 
+    <Button
+        android:id="@+id/button_main_rect_indicator_rtl"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:text="@string/main_rect_indicator_rtl_button_text"/>
+
 </LinearLayout>

sample/src/main/res/layout/fragment_rect_indecator_rtl.xml

@@ -0,0 +1,65 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:background="@android:color/white"
+    tools:context=".CircleIndicatorFragment"
+    android:layoutDirection="rtl">
+
+    <androidx.viewpager2.widget.ViewPager2
+        android:id="@+id/view_pager2"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        tools:layout_height="200dp"/>
+
+    <io.github.vejei.viewpagerindicator.indicator.RectIndicator
+        android:id="@+id/rect_indicator"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="16dp"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/view_pager2"
+        app:indicatorColor="@android:color/darker_gray"
+        app:indicatorSelectedColor="@color/colorAccent"
+        app:indicatorGap="8dp"
+        app:indicatorWidth="20dp"
+        app:indicatorHeight="5dp"
+        app:indicatorCornerRadius="0dp" />
+
+    <io.github.vejei.viewpagerindicator.indicator.RectIndicator
+        android:id="@+id/square_indicator"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="16dp"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/rect_indicator"
+        app:indicatorColor="@android:color/darker_gray"
+        app:indicatorSelectedColor="@color/colorAccent"
+        app:indicatorGap="8dp"
+        app:indicatorWidth="10dp"
+        app:indicatorHeight="10dp"
+        app:indicatorCornerRadius="0dp" />
+
+    <io.github.vejei.viewpagerindicator.indicator.RectIndicator
+        android:id="@+id/stadium_indicator"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="16dp"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toBottomOf="@id/square_indicator"
+        app:indicatorColor="@android:color/darker_gray"
+        app:indicatorSelectedColor="@color/colorAccent"
+        app:indicatorGap="8dp"
+        app:indicatorWidth="20dp"
+        app:indicatorHeight="5dp"
+        app:indicatorCornerRadius="10dp" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

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

@@ -2,4 +2,5 @@
     <string name="app_name">ViewPagerIndicator</string>
     <string name="main_circle_indicator_button_text">Circle Indicator</string>
     <string name="main_rect_indicator_button_text">Rect Indicator</string>
+    <string name="main_rect_indicator_rtl_button_text">Rect Indicator Rtl</string>
 </resources>

viewpagerindicator/src/main/java/io/github/vejei/viewpagerindicator/indicator/RectIndicator.java

@@ -150,11 +150,14 @@ protected int measureHeight() {
     @Override
     public int getCoordinateX(int position) {
         int coordinate = getPaddingLeft();
+        if(isRtl()) coordinate = getMeasuredWidth() - indicatorWidth;
+
         for (int i = 0; i < getItemCount(); i++) {
-            if (i == position) {
-                return coordinate;
-            }
-            coordinate += indicatorWidth + indicatorGap;
+            if (i == position) return coordinate;
+
+            if(isRtl()) coordinate -= indicatorWidth + indicatorGap;
+            else coordinate += indicatorWidth + indicatorGap;
+
         }
         return coordinate;
     }

viewpagerindicator/src/main/java/io/github/vejei/viewpagerindicator/indicator/ViewPagerIndicator.java

@@ -283,6 +283,9 @@ protected void onPageScrolled(int position, float positionOffset) {
         }
     }
 
+    protected boolean isRtl() {
+        return getLayoutDirection() == View.LAYOUT_DIRECTION_RTL;
+    }
     public int getCoordinateX(int position) {
         return 0;
     }
@@ -292,4 +295,5 @@ public int getCoordinateY() {
 
     abstract protected int measureWidth();
     abstract protected int measureHeight();
+
 }