improve long fade out animation efficiency

src/main/java/com/sparrowwallet/sparrow/control/AnimationUtil.java

@@ -0,0 +1,20 @@
+package com.sparrowwallet.sparrow.control;
+
+import javafx.animation.KeyFrame;
+import javafx.animation.Timeline;
+import javafx.scene.Node;
+import javafx.util.Duration;
+
+public class AnimationUtil {
+    public static Timeline getSlowFadeOut(Node node, Duration duration, double fromValue, int numIncrements) {
+        Timeline fadeTimeline = new Timeline();
+        Duration incrementDuration = duration.divide(numIncrements);
+        for(int i = 0; i < numIncrements; i++) {
+            double normalized = ((double)numIncrements - i - 1) / numIncrements;
+            double opacity = normalized * fromValue;
+            fadeTimeline.getKeyFrames().add(new KeyFrame(incrementDuration.multiply(i+1), event -> node.setOpacity(opacity)));
+        }
+
+        return fadeTimeline;
+    }
+}

src/main/java/com/sparrowwallet/sparrow/control/ConfirmationProgressIndicator.java

@@ -86,10 +86,10 @@ public class ConfirmationProgressIndicator extends StackPane {
                     upTickLineTimeline.getKeyFrames().add(upTickLineFrame);
                     sequence.getChildren().add(upTickLineTimeline);
 
-                    FadeTransition groupFadeOut = new FadeTransition(Duration.minutes(10), confirmationGroup);
-                    groupFadeOut.setFromValue(1);
-                    groupFadeOut.setToValue(0);
+                    Timeline groupFadeOut = AnimationUtil.getSlowFadeOut(confirmationGroup, Duration.minutes(10), 1.0, 10);
                     sequence.getChildren().add(groupFadeOut);
+
+                    confirmationsProperty().unbind();
                 }
 
                 sequence.play();

src/main/java/com/sparrowwallet/sparrow/control/MixStatusCell.java

@@ -10,7 +10,7 @@ import com.sparrowwallet.sparrow.wallet.Entry;
 import com.sparrowwallet.sparrow.wallet.UtxoEntry;
 import com.sparrowwallet.sparrow.whirlpool.Whirlpool;
 import com.sparrowwallet.sparrow.whirlpool.WhirlpoolException;
-import javafx.animation.FadeTransition;
+import javafx.animation.Timeline;
 import javafx.geometry.Pos;
 import javafx.scene.control.*;
 import javafx.util.Duration;
@@ -84,13 +84,13 @@ public class MixStatusCell extends TreeTableCell<Entry, UtxoEntry.MixStatus> {
                     "\nTo prevent sleeping, use the " + getPlatformSleepConfig() + " or enable the function in the Tools menu.");
             setTooltip(tt);
 
-            FadeTransition ft = new FadeTransition(Duration.millis(ERROR_DISPLAY_MILLIS - elapsed), failGlyph);
-            ft.setFromValue(1.0 - ((double)elapsed / ERROR_DISPLAY_MILLIS));
-            ft.setToValue(0.0);
-            ft.setOnFinished(event -> {
+            Duration fadeDuration = Duration.millis(ERROR_DISPLAY_MILLIS - elapsed);
+            double fadeFromValue = 1.0 - ((double)elapsed / ERROR_DISPLAY_MILLIS);
+            Timeline timeline = AnimationUtil.getSlowFadeOut(failGlyph, fadeDuration, fadeFromValue, 10);
+            timeline.setOnFinished(event -> {
                 setTooltip(null);
             });
-            ft.play();
+            timeline.play();
         } else {
             setGraphic(null);
             setTooltip(null);