Android: Create AutofitGridLayoutManager

Extends GridLayoutManager to make span changes much more responsive.

2 files changed, 75 insertions, 37 deletions

diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/layout/AutofitGridLayoutManager.kt b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/layout/AutofitGridLayoutManager.kt
new file mode 100644
index 0000000000..8fc52e756e
--- /dev/null
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/layout/AutofitGridLayoutManager.kt
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+package org.dolphinemu.dolphinemu.layout
+
+import android.content.Context
+import androidx.recyclerview.widget.GridLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import androidx.recyclerview.widget.RecyclerView.Recycler
+import org.dolphinemu.dolphinemu.R
+
+/**
+  *  Cut down version of the solution provided here
+  *  https://stackoverflow.com/questions/26666143/recyclerview-gridlayoutmanager-how-to-auto-detect-span-count
+  */
+class AutofitGridLayoutManager(
+    context: Context,
+    columnWidth: Int
+) : GridLayoutManager(context, 1) {
+    private var columnWidth = 0
+    private var isColumnWidthChanged = true
+    private var lastWidth = 0
+    private var lastHeight = 0
+
+    init {
+        setColumnWidth(checkedColumnWidth(context, columnWidth))
+    }
+
+    private fun checkedColumnWidth(context: Context, columnWidth: Int): Int {
+        var newColumnWidth = columnWidth
+        if (newColumnWidth <= 0) {
+            newColumnWidth = context.resources.getDimensionPixelSize(R.dimen.spacing_xtralarge)
+        }
+        return newColumnWidth
+    }
+
+    fun setColumnWidth(newColumnWidth: Int) {
+        if (newColumnWidth > 0 && newColumnWidth != columnWidth) {
+            columnWidth = newColumnWidth
+            isColumnWidthChanged = true
+        }
+    }
+
+    override fun onLayoutChildren(recycler: Recycler, state: RecyclerView.State) {
+        val width = width
+        val height = height
+        if (columnWidth > 0 && width > 0 && height > 0 && (isColumnWidthChanged || lastWidth != width || lastHeight != height)) {
+            val totalSpace: Int = if (orientation == VERTICAL) {
+                width - paddingRight - paddingLeft
+            } else {
+                height - paddingTop - paddingBottom
+            }
+            val spanCount = 1.coerceAtLeast(totalSpace / columnWidth)
+            setSpanCount(spanCount)
+            isColumnWidthChanged = false
+        }
+        lastWidth = width
+        lastHeight = height
+        super.onLayoutChildren(recycler, state)
+    }
+}
diff --git a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/platform/PlatformGamesFragment.java b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/platform/PlatformGamesFragment.java
index d76ffce3c5..10dbf10c00 100644
--- a/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/platform/PlatformGamesFragment.java
+++ b/Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/ui/platform/PlatformGamesFragment.java
@@ -6,7 +6,6 @@ import android.os.Bundle;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
-import android.view.ViewTreeObserver;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
@@ -14,7 +13,7 @@ import androidx.core.graphics.Insets;
 import androidx.core.view.ViewCompat;
 import androidx.core.view.WindowInsetsCompat;
 import androidx.fragment.app.Fragment;
-import androidx.recyclerview.widget.GridLayoutManager;
+import androidx.recyclerview.widget.RecyclerView;
 import androidx.swiperefreshlayout.widget.SwipeRefreshLayout;
 
 import com.google.android.material.color.MaterialColors;
@@ -22,13 +21,13 @@ import com.google.android.material.color.MaterialColors;
 import org.dolphinemu.dolphinemu.R;
 import org.dolphinemu.dolphinemu.adapters.GameAdapter;
 import org.dolphinemu.dolphinemu.databinding.FragmentGridBinding;
+import org.dolphinemu.dolphinemu.layout.AutofitGridLayoutManager;
 import org.dolphinemu.dolphinemu.services.GameFileCacheManager;
 
 public final class PlatformGamesFragment extends Fragment implements PlatformGamesView
 {
   private static final String ARG_PLATFORM = "platform";
 
-  private GameAdapter mAdapter;
   private SwipeRefreshLayout mSwipeRefresh;
   private SwipeRefreshLayout.OnRefreshListener mOnRefreshListener;
 
@@ -64,37 +63,12 @@ public final class PlatformGamesFragment extends Fragment implements PlatformGam
   public void onViewCreated(@NonNull View view, Bundle savedInstanceState)
   {
     mSwipeRefresh = mBinding.swipeRefresh;
-    mAdapter = new GameAdapter(requireActivity());
-
-    // Here we have to make sure the fragment is attached to an activity, wait for the layout
-    // to be drawn, and make sure it is drawn with a width > 0 before finding the correct
-    // span for our grid layout. Once drawn correctly, we can stop listening for layout changes.
-    if (isAdded())
-    {
-      view.getViewTreeObserver()
-              .addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener()
-              {
-                @Override
-                public void onGlobalLayout()
-                {
-                  if (mBinding.getRoot().getMeasuredWidth() == 0)
-                  {
-                    return;
-                  }
-
-                  int columns = mBinding.getRoot().getMeasuredWidth() /
-                          requireContext().getResources().getDimensionPixelSize(R.dimen.card_width);
-                  if (columns == 0)
-                  {
-                    columns = 1;
-                  }
-                  view.getViewTreeObserver().removeOnGlobalLayoutListener(this);
-                  GridLayoutManager layoutManager = new GridLayoutManager(getActivity(), columns);
-                  mBinding.gridGames.setLayoutManager(layoutManager);
-                  mBinding.gridGames.setAdapter(mAdapter);
-                }
-              });
-    }
+    GameAdapter adapter = new GameAdapter(requireActivity());
+    adapter.setStateRestorationPolicy(
+            RecyclerView.Adapter.StateRestorationPolicy.PREVENT_WHEN_EMPTY);
+    mBinding.gridGames.setAdapter(adapter);
+    mBinding.gridGames.setLayoutManager(new AutofitGridLayoutManager(requireContext(),
+            getResources().getDimensionPixelSize(R.dimen.card_width)));
 
     // Set theme color to the refresh animation's background
     mSwipeRefresh.setProgressBackgroundColorSchemeColor(
@@ -133,17 +107,21 @@ public final class PlatformGamesFragment extends Fragment implements PlatformGam
   @Override
   public void showGames()
   {
-    if (mAdapter != null)
+    if (mBinding == null)
+      return;
+
+    if (mBinding.gridGames.getAdapter() != null)
     {
       Platform platform = (Platform) getArguments().getSerializable(ARG_PLATFORM);
-      mAdapter.swapDataSet(GameFileCacheManager.getGameFilesForPlatform(platform));
+      ((GameAdapter) mBinding.gridGames.getAdapter()).swapDataSet(
+              GameFileCacheManager.getGameFilesForPlatform(platform));
     }
   }
 
   @Override
   public void refetchMetadata()
   {
-    mAdapter.refetchMetadata();
+    ((GameAdapter) mBinding.gridGames.getAdapter()).refetchMetadata();
   }
 
   public void setOnRefreshListener(@Nullable SwipeRefreshLayout.OnRefreshListener listener)