Use LiveData for empty content view

Signed-off-by: Stefan Niedermann <info@niedermann.it>

2 files changed, 29 insertions, 14 deletions

diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java
index cfab75a32..d062bc827 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentAdapter.java
@@ -14,6 +14,8 @@ import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
 import androidx.core.app.ActivityOptionsCompat;
 import androidx.fragment.app.FragmentManager;
+import androidx.lifecycle.LiveData;
+import androidx.lifecycle.MutableLiveData;
 import androidx.recyclerview.widget.RecyclerView;
 
 import java.util.ArrayList;
@@ -28,6 +30,7 @@ import it.niedermann.nextcloud.deck.ui.attachments.AttachmentsActivity;
 import it.niedermann.nextcloud.deck.ui.branding.Branded;
 import it.niedermann.nextcloud.deck.util.MimeTypeUtil;
 
+import static androidx.lifecycle.Transformations.distinctUntilChanged;
 import static androidx.recyclerview.widget.RecyclerView.NO_ID;
 import static it.niedermann.nextcloud.deck.util.AttachmentUtil.openAttachmentInBrowser;
 
@@ -37,6 +40,9 @@ public class CardAttachmentAdapter extends RecyclerView.Adapter<AttachmentViewHo
     public static final int VIEW_TYPE_DEFAULT = 2;
     public static final int VIEW_TYPE_IMAGE = 1;
 
+    @NonNull
+    private MutableLiveData<Boolean> isEmpty = new MutableLiveData<>(true);
+    @NonNull
     private final MenuInflater menuInflater;
     @ColorInt
     private int mainColor;
@@ -126,22 +132,34 @@ public class CardAttachmentAdapter extends RecyclerView.Adapter<AttachmentViewHo
         return attachments.size();
     }
 
+    private void updateIsEmpty() {
+        this.isEmpty.postValue(getItemCount() <= 0);
+    }
+
+    @NonNull
+    public LiveData<Boolean> isEmpty() {
+        return distinctUntilChanged(this.isEmpty);
+    }
+
     public void setAttachments(@NonNull List<Attachment> attachments, @Nullable Long cardRemoteId) {
         this.cardRemoteId = cardRemoteId;
         this.attachments.clear();
         this.attachments.addAll(attachments);
         notifyDataSetChanged();
+        this.updateIsEmpty();
     }
 
     public void addAttachment(Attachment a) {
         this.attachments.add(0, a);
         notifyItemInserted(this.attachments.size());
+        this.updateIsEmpty();
     }
 
     public void removeAttachment(Attachment a) {
         final int index = this.attachments.indexOf(a);
         this.attachments.remove(a);
         notifyItemRemoved(index);
+        this.updateIsEmpty();
     }
 
     public void replaceAttachment(Attachment toReplace, Attachment with) {
diff --git a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentsFragment.java b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentsFragment.java
index d3441b998..d528dc903 100644
--- a/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentsFragment.java
+++ b/app/src/main/java/it/niedermann/nextcloud/deck/ui/card/attachments/CardAttachmentsFragment.java
@@ -54,6 +54,8 @@ import static android.app.Activity.RESULT_OK;
 import static android.os.Build.VERSION.SDK_INT;
 import static android.os.Build.VERSION_CODES.LOLLIPOP;
 import static android.os.Build.VERSION_CODES.M;
+import static android.view.View.GONE;
+import static android.view.View.VISIBLE;
 import static androidx.core.content.PermissionChecker.PERMISSION_GRANTED;
 import static androidx.core.content.PermissionChecker.checkSelfPermission;
 import static it.niedermann.nextcloud.deck.persistence.sync.adapters.db.util.LiveDataHelper.observeOnce;
@@ -106,7 +108,15 @@ public class CardAttachmentsFragment extends BrandedFragment implements Attachme
                 viewModel.getFullCard().getLocalId());
         binding.attachmentsList.setAdapter(adapter);
 
-        updateEmptyContentView();
+        adapter.isEmpty().observe(getViewLifecycleOwner(), (isEmpty) -> {
+            if (isEmpty) {
+                this.binding.emptyContentView.setVisibility(VISIBLE);
+                this.binding.attachmentsList.setVisibility(GONE);
+            } else {
+                this.binding.emptyContentView.setVisibility(GONE);
+                this.binding.attachmentsList.setVisibility(VISIBLE);
+            }
+        });
 
         final DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
         int spanCount = (int) ((displayMetrics.widthPixels / displayMetrics.density) / getResources().getInteger(R.integer.max_dp_attachment_column));
@@ -138,7 +148,6 @@ public class CardAttachmentsFragment extends BrandedFragment implements Attachme
                 }
             });
             adapter.setAttachments(viewModel.getFullCard().getAttachments(), viewModel.getFullCard().getId());
-            updateEmptyContentView();
         }
 
         if (viewModel.canEdit()) {
@@ -287,7 +296,6 @@ public class CardAttachmentsFragment extends BrandedFragment implements Attachme
                         }
                     });
                 }
-                updateEmptyContentView();
                 break;
             }
             default: {
@@ -344,7 +352,6 @@ public class CardAttachmentsFragment extends BrandedFragment implements Attachme
                 }
             });
         }
-        updateEmptyContentView();
     }
 
     @Override
@@ -352,16 +359,6 @@ public class CardAttachmentsFragment extends BrandedFragment implements Attachme
         this.clickedItemPosition = position;
     }
 
-    private void updateEmptyContentView() {
-        if (this.adapter == null || this.adapter.getItemCount() == 0) {
-            this.binding.emptyContentView.setVisibility(View.VISIBLE);
-            this.binding.attachmentsList.setVisibility(View.GONE);
-        } else {
-            this.binding.emptyContentView.setVisibility(View.GONE);
-            this.binding.attachmentsList.setVisibility(View.VISIBLE);
-        }
-    }
-
     @Override
     public void applyBrand(int mainColor) {
         applyBrandToFAB(mainColor, binding.fab);