Load thumbnails on main screen asynchronously

Decoding a bitmap can be slow. On slow devices, loading all the images as soon as the card should be shown can lead to UI freezes. By loading the thumbnail asynchronously, scrolling quickly remains smooth even on slow devices.
CatimaLoyalty · Jun 27, 2024 · 0431803 · 0431803
1 parent 5f5280e
commit 0431803
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Showing 2 changed files with 24 additions and 8 deletions.
diff --git a/app/src/main/java/protect/card_locker/LoyaltyCardCursorAdapter.java b/app/src/main/java/protect/card_locker/LoyaltyCardCursorAdapter.java
@@ -6,6 +6,8 @@
 import android.graphics.Bitmap;
 import android.graphics.Color;
 import android.graphics.drawable.Drawable;
+import android.os.Handler;
+import android.os.Looper;
 import android.util.SparseBooleanArray;
 import android.util.TypedValue;
 import android.view.HapticFeedbackConstants;
@@ -88,9 +90,29 @@ public void onBindViewHolder(LoyaltyCardListItemViewHolder inputHolder, Cursor i
         inputHolder.mDivider.setVisibility(View.GONE);
 
         LoyaltyCard loyaltyCard = LoyaltyCard.toLoyaltyCard(inputCursor);
-        Bitmap icon = Utils.retrieveCardImage(mContext, loyaltyCard.id, ImageLocationType.icon);
 
-        if (mLoyaltyCardListDisplayOptions.showingNameBelowThumbnail() && icon != null) {
+        inputHolder.mCardIcon.setContentDescription(loyaltyCard.store);
+
+        // Default header at first, real icon will be retrieved asynchronously if it exists to ensure
+        // smooth scrolling even on slower devices
+        Utils.setIconOrTextWithBackground(mContext, loyaltyCard, null, inputHolder.mCardIcon, inputHolder.mCardText);
+        inputHolder.toggleCardStateIcon(loyaltyCard.starStatus != 0, loyaltyCard.archiveStatus != 0, itemSelected(inputCursor.getPosition()));
+        boolean hasIcon = Utils.retrieveCardImageAsFile(mContext, loyaltyCard.id, ImageLocationType.icon).exists();
+        if (hasIcon) {
+            new Thread() {
+                @Override
+                public void run() {
+                    Bitmap icon = Utils.retrieveCardImage(mContext, loyaltyCard.id, ImageLocationType.icon);
+
+                    new Handler(Looper.getMainLooper()).post(() -> {
+                        inputHolder.mIconBackgroundColor = Utils.setIconOrTextWithBackground(mContext, loyaltyCard, icon, inputHolder.mCardIcon, inputHolder.mCardText);
+                        inputHolder.toggleCardStateIcon(loyaltyCard.starStatus != 0, loyaltyCard.archiveStatus != 0, itemSelected(inputHolder.getAdapterPosition()));
+                    });
+                }
+            }.start();
+        }
+
+        if (mLoyaltyCardListDisplayOptions.showingNameBelowThumbnail() && hasIcon) {
             showDivider = true;
             inputHolder.setStoreField(loyaltyCard.store);
         } else {
@@ -122,11 +144,6 @@ public void onBindViewHolder(LoyaltyCardListItemViewHolder inputHolder, Cursor i
             inputHolder.setExtraField(inputHolder.mExpiryField, null, null, false);
         }
 
-        inputHolder.mCardIcon.setContentDescription(loyaltyCard.store);
-        inputHolder.mIconBackgroundColor = Utils.setIconOrTextWithBackground(mContext, loyaltyCard, icon, inputHolder.mCardIcon, inputHolder.mCardText);
-
-        inputHolder.toggleCardStateIcon(loyaltyCard.starStatus != 0, loyaltyCard.archiveStatus != 0, itemSelected(inputCursor.getPosition()));
-
         inputHolder.itemView.setActivated(mSelectedItems.get(inputCursor.getPosition(), false));
         applyIconAnimation(inputHolder, inputCursor.getPosition());
         applyClickEvents(inputHolder, inputCursor.getPosition());

diff --git a/app/src/main/res/layout/loyalty_card_layout.xml b/app/src/main/res/layout/loyalty_card_layout.xml
@@ -29,7 +29,6 @@
                 android:layout_height="match_parent"
                 android:contentDescription="@string/thumbnailDescription"
                 android:scaleType="fitCenter"
-                android:src="@mipmap/ic_launcher"
                 app:layout_constraintBottom_toBottomOf="parent"
                 app:layout_constraintEnd_toEndOf="parent"
                 app:layout_constraintStart_toStartOf="parent"