MainActivity: increase velocity threshold for viewPager

app/src/main/java/com/keylesspalace/tusky/MainActivity.java

@@ -57,6 +57,7 @@ import com.keylesspalace.tusky.pager.MainPagerAdapter;
 import com.keylesspalace.tusky.util.CustomEmojiHelper;
 import com.keylesspalace.tusky.util.NotificationHelper;
 import com.keylesspalace.tusky.util.ShareShortcutHelper;
+import com.keylesspalace.tusky.util.ViewPager2Fix;
 import com.mikepenz.google_material_typeface_library.GoogleMaterial;
 import com.mikepenz.materialdrawer.AccountHeader;
 import com.mikepenz.materialdrawer.AccountHeaderBuilder;
@@ -196,6 +197,7 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
         composeButton = findViewById(R.id.floating_btn);
         tabLayout = findViewById(R.id.tab_layout);
         viewPager = findViewById(R.id.pager);
+        ViewPager2Fix.reduceVelocity(viewPager, 2.0f);
 
         composeButton.setOnClickListener(v -> {
             Intent composeIntent = new Intent(getApplicationContext(), ComposeActivity.class);
@@ -660,4 +662,4 @@ public final class MainActivity extends BottomSheetActivity implements ActionBut
     public AndroidInjector<Object> androidInjector() {
         return androidInjector;
     }
-}
+}

app/src/main/java/com/keylesspalace/tusky/util/ViewPager2Fix.java

@@ -0,0 +1,40 @@
+package com.keylesspalace.tusky.util;
+
+import androidx.viewpager2.widget.ViewPager2;
+import androidx.recyclerview.widget.RecyclerView;
+import java.lang.reflect.*;
+import java.lang.*;
+
+/**
+ * ViewPager2 written by monkeys!
+ */
+public class ViewPager2Fix {
+	/**
+	 * Thanks to @al.e.shevelev@medium.com for solution
+	 */
+	public static Field getViewPagerRecyclerViewField() throws NoSuchFieldException {
+		Field f = ViewPager2.class.getDeclaredField("mRecyclerView");
+		f.setAccessible(true);
+		return f;
+	}
+	
+	public static Field getRecyclerViewTouchSlopField() throws NoSuchFieldException {
+		Field f = RecyclerView.class.getDeclaredField("mTouchSlop");
+		f.setAccessible(true);
+		return f;
+	}
+	 
+	public static void reduceVelocity(ViewPager2 pager, float val) {
+		try {
+			Field recyclerViewField = getViewPagerRecyclerViewField();
+			Field touchSlopField = getRecyclerViewTouchSlopField();
+
+			RecyclerView recyclerView = (RecyclerView)recyclerViewField.get(pager);
+			int touchSlop = (int)touchSlopField.get(recyclerView);
+			touchSlopField.setInt(recyclerView, (int)(touchSlop*val));
+		} catch(Exception e) {
+			// all possible exceptions must be caught during tests
+			;
+		}
+	}
+}

app/src/test/java/com/keylesspalace/tusky/util/ViewPager2FixTest.java

@@ -0,0 +1,34 @@
+package com.keylesspalace.tusky.util;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.Assert;
+import org.junit.runner.RunWith;
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import androidx.viewpager2.widget.ViewPager2;
+import androidx.recyclerview.widget.RecyclerView;
+import org.junit.runners.Parameterized;
+import java.lang.reflect.*;
+import java.lang.*;
+import com.keylesspalace.tusky.util.ViewPager2Fix;
+
+public class ViewPager2FixTest {	
+	@Test
+	public void getViewPagerRecyclerViewFieldTest() {
+		try {
+			Field f = ViewPager2Fix.getViewPagerRecyclerViewField();
+		} catch(Exception e) {
+			Assert.fail("asdf");
+		}
+	}
+	
+	@Test
+	public void getRecyclerViewTouchSlopFieldTest() {
+		try {
+			Field f = ViewPager2Fix.getRecyclerViewTouchSlopField();
+		} catch(Exception e) {
+			Assert.fail("asdf");
+		}
+	}
+}
+