perf: avoid repeated allocations in RTL pager

Agent-Logs-Url: https://github.com/ArcaneChat/android/sessions/3fcef4ec-8b52-4a73-a2d3-393e224f7da1

Co-authored-by: adbenitez <24558636+adbenitez@users.noreply.github.com>

src/main/java/org/thoughtcrime/securesms/components/viewpager/RtlSafeViewPager.java

@@ -0,0 +1,78 @@
+package org.thoughtcrime.securesms.components.viewpager;
+
+import android.content.Context;
+import android.graphics.Matrix;
+import android.util.AttributeSet;
+import android.view.MotionEvent;
+import androidx.annotation.NonNull;
+import androidx.annotation.Nullable;
+import androidx.core.view.ViewCompat;
+
+public class RtlSafeViewPager extends HackyViewPager {
+  private final Matrix mirrorMatrix = new Matrix();
+  private boolean rtl;
+
+  public RtlSafeViewPager(@NonNull Context context) {
+    super(context);
+  }
+
+  public RtlSafeViewPager(@NonNull Context context, @Nullable AttributeSet attrs) {
+    super(context, attrs);
+  }
+
+  @Override
+  protected void onAttachedToWindow() {
+    super.onAttachedToWindow();
+    updateLayoutDirection();
+  }
+
+  @Override
+  public void onRtlPropertiesChanged(int layoutDirection) {
+    super.onRtlPropertiesChanged(layoutDirection);
+    updateLayoutDirection();
+  }
+
+  @Override
+  public boolean onInterceptTouchEvent(MotionEvent ev) {
+    if (!isRtl()) {
+      return super.onInterceptTouchEvent(ev);
+    }
+
+    MotionEvent mirrored = getMirroredMotionEvent(ev);
+    try {
+      return super.onInterceptTouchEvent(mirrored);
+    } finally {
+      mirrored.recycle();
+    }
+  }
+
+  @Override
+  public boolean onTouchEvent(MotionEvent ev) {
+    if (!isRtl()) {
+      return super.onTouchEvent(ev);
+    }
+
+    MotionEvent mirrored = getMirroredMotionEvent(ev);
+    try {
+      return super.onTouchEvent(mirrored);
+    } finally {
+      mirrored.recycle();
+    }
+  }
+
+  private boolean isRtl() {
+    return rtl;
+  }
+
+  private MotionEvent getMirroredMotionEvent(@NonNull MotionEvent ev) {
+    MotionEvent mirrored = MotionEvent.obtain(ev);
+    mirrorMatrix.reset();
+    mirrorMatrix.setScale(-1f, 1f, getWidth() / 2f, 0f);
+    mirrored.transform(mirrorMatrix);
+    return mirrored;
+  }
+
+  private void updateLayoutDirection() {
+    rtl = ViewCompat.getLayoutDirection(this) == ViewCompat.LAYOUT_DIRECTION_RTL;
+  }
+}

src/main/res/layout/activity_qr.xml

@@ -37,7 +37,7 @@
 
     </com.google.android.material.appbar.AppBarLayout>
 
-    <androidx.viewpager.widget.ViewPager
+    <org.thoughtcrime.securesms.components.viewpager.RtlSafeViewPager
         android:id="@+id/pager"
         android:layout_width="match_parent"
         android:layout_height="match_parent"

src/main/res/layout/all_media_activity.xml

@@ -37,7 +37,7 @@
 
     </com.google.android.material.appbar.AppBarLayout>
 
-    <androidx.viewpager.widget.ViewPager
+    <org.thoughtcrime.securesms.components.viewpager.RtlSafeViewPager
         android:id="@+id/pager"
         android:layout_width="match_parent"
         android:layout_height="match_parent"

src/main/res/layout/scribble_select_sticker_activity.xml

@@ -21,7 +21,7 @@
         app:tabSelectedTextColor="@color/white"
         app:tabMode="fixed" />
 
-    <androidx.viewpager.widget.ViewPager
+    <org.thoughtcrime.securesms.components.viewpager.RtlSafeViewPager
         android:id="@+id/camera_sticker_pager"
         android:layout_width="match_parent"
         android:layout_height="0px"