[release/3.9] 优化 JFXListView 的平滑滚动效果 (#5228)

#5052

Author: Glavo

HMCL/src/main/java/org/jackhuang/hmcl/ui/ScrollUtils.java

@@ -25,7 +25,6 @@
 import javafx.animation.KeyFrame;
 import javafx.animation.Timeline;
 import javafx.event.EventHandler;
-import javafx.scene.control.IndexedCell;
 import javafx.scene.control.ScrollPane;
 import javafx.scene.control.skin.VirtualFlow;
 import javafx.scene.input.MouseEvent;
@@ -226,15 +225,13 @@ private static void smoothScroll(VirtualFlow<?> virtualFlow, double speed, doubl
         final double[] derivatives = new double[FRICTIONS.length];
 
         Timeline timeline = new Timeline();
-        Holder<ScrollDirection> scrollDirectionHolder = new Holder<>();
         final EventHandler<MouseEvent> mouseHandler = event -> timeline.stop();
         final EventHandler<ScrollEvent> scrollHandler = event -> {
             if (event.getEventType() == ScrollEvent.SCROLL) {
                 ScrollDirection scrollDirection = determineScrollDirection(event);
                 if (scrollDirection == ScrollDirection.LEFT || scrollDirection == ScrollDirection.RIGHT) {
                     return;
                 }
-                scrollDirectionHolder.value = scrollDirection;
                 double currentSpeed = isTrackPad(event, scrollDirection) ? speed / trackPadAdjustment : speed;
 
                 derivatives[0] += scrollDirection.intDirection * currentSpeed;
@@ -256,15 +253,7 @@ private static void smoothScroll(VirtualFlow<?> virtualFlow, double speed, doubl
             }
 
             double dy = derivatives[derivatives.length - 1];
-
-            int cellCount = virtualFlow.getCellCount();
-            IndexedCell<?> firstVisibleCell = virtualFlow.getFirstVisibleCell();
-            double height = firstVisibleCell != null ? firstVisibleCell.getHeight() * cellCount : 0.0;
-
-            double delta = height > 0.0
-                    ? dy / height
-                    : (scrollDirectionHolder.value == ScrollDirection.DOWN ? 0.001 : -0.001);
-            virtualFlow.setPosition(Math.min(Math.max(virtualFlow.getPosition() + delta, 0), 1));
+            virtualFlow.scrollPixels(dy);
 
             if (Math.abs(dy) < 0.001) {
                 timeline.stop();