fix: remove extra space under the input window (#1930)

Author: FlyingpigNZ

app/src/main/java/com/osfans/trime/ime/core/BaseInputView.kt

@@ -70,15 +70,16 @@ abstract class BaseInputView(
             return 0
         }
         val insets = WindowInsetsCompat.toWindowInsetsCompat(windowInsets)
-        // use navigation bar insets when available
         val navBars = insets.getInsets(WindowInsetsCompat.Type.navigationBars())
-        // in case navigation bar insets goes wrong (eg. on LineageOS 21+ with gesture navigation)
-        // use mandatory system gesture insets
         val mandatory = insets.getInsets(WindowInsetsCompat.Type.mandatorySystemGestures())
+        // If navBars is 0 but mandatory is non-zero, likely gesture nav - don't add inset
+        if (navBars.bottom == 0 && mandatory.bottom > 0) {
+            return 0
+        }
         var insetsBottom = max(navBars.bottom, mandatory.bottom)
         if (insetsBottom <= 0) {
-            // check system gesture insets and fallback to navigation_bar_frame_height just in case
-            val gesturesBottom = insets.getInsets(WindowInsetsCompat.Type.systemGestures()).bottom
+            val gestures = insets.getInsets(WindowInsetsCompat.Type.systemGestures())
+            val gesturesBottom = gestures.bottom
             if (gesturesBottom > 0) {
                 insetsBottom = max(gesturesBottom, navBarFrameHeight)
             }

app/src/main/java/com/osfans/trime/ime/core/TrimeInputMethodService.kt

@@ -32,6 +32,7 @@ import android.widget.FrameLayout
 import androidx.annotation.Keep
 import androidx.annotation.RequiresApi
 import androidx.core.content.ContextCompat
+import androidx.core.view.WindowInsetsCompat
 import androidx.core.view.updateLayoutParams
 import androidx.lifecycle.lifecycleScope
 import com.osfans.trime.core.KeyModifiers
@@ -449,8 +450,12 @@ open class TrimeInputMethodService : LifecycleInputMethodService() {
                 touchableInsets = Insets.TOUCHABLE_INSETS_VISIBLE
             }
         } else {
-            val n = decorView.findViewById<View>(android.R.id.navigationBarBackground)?.height ?: 0
-            val h = decorView.height - n
+            val insets = WindowInsetsCompat.toWindowInsetsCompat(decorView.rootWindowInsets)
+            val navBarHeight = insets?.getInsets(WindowInsetsCompat.Type.navigationBars())?.bottom ?: 0
+            val mandatoryHeight = insets?.getInsets(WindowInsetsCompat.Type.mandatorySystemGestures())?.bottom ?: 0
+            // If navBarHeight is 0 but mandatory is non-zero, likely gesture nav - don't add inset
+            val finalNavHeight = if (navBarHeight == 0 && mandatoryHeight > 0) 0 else maxOf(navBarHeight, mandatoryHeight)
+            val h = decorView.height - finalNavHeight
             outInsets.apply {
                 contentTopInsets = h
                 visibleTopInsets = h