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.

app/src/main/java/protect/card_locker/LoyaltyCardCursorAdapter.java

@@ -6,6 +6,8 @@ import android.database.Cursor;
 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 class LoyaltyCardCursorAdapter extends BaseCursorAdapter<LoyaltyCardCurso
         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 class LoyaltyCardCursorAdapter extends BaseCursorAdapter<LoyaltyCardCurso
             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());

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"