如何提高ScrollPane JavaFX的滚动速度

Question

嗨，有什么方法可以提高滚动速度。我找到了一些解决方案，但没有一个适合我。那就是我尝试过的：

@FXML
private ScrollPane scrollPane;

@FXML
public void initialize() {
    Platform.runLater(() -> setFasterScroller(scrollPane));
}

private static void setFasterScroller(ScrollPane scrollPane) {
    ScrollBar verticalScrollbar = (ScrollBar) scrollPane.lookup(".scroll-bar:vertical");
    double defaultUnitIncrement = verticalScrollbar.getUnitIncrement();
    verticalScrollbar.setUnitIncrement(defaultUnitIncrement * 3);
}

或者使用CSS：

.scroll-pane .scroll-bar:vertical {
    -fx-unit-increment: 10 ;
    -fx-block-increment: 50 ;
}

.scroll-pane .scroll-bar:horizontal {
    -fx-unit-increment: 5 ;
    -fx-block-increment: 20 ;
}

还有其他办法吗？编辑：上面的解决方案都没有工作，我试图使用疯狂的大数字，但滚动速度仍然相同

Answer 1

应用程序应该“更快”地渲染滚动窗格内容，以提高滚动速度。您可以通过减少要渲染的对象数量或/和减少“重绘”方法调用（JFX 中的layoutChildren）数量来实现此目的。据我了解代码片段，您将减少重绘次数，因为更改增量参数可以减少重绘内容的次数。

• blockIncrement（如果点击栏的轨道）
• unitIncrement（如果单击向上、向下、向右、向左按钮）

ScrollPane.layoutChildren()当您单击滚动窗格按钮时，将调用该方法。它使 ScrollBar 重置增量 ( ScrollPaneSkin.updateVerticalSB(), ScrollPaneSkin.updateHorizontalSB())。因此，您需要存储以前的增量值并过滤“开箱即用”的滚动事件。

来源：

public class UnitIncrementScrollPaneSkin extends ScrollPaneSkin {

    private double prevVerticalBlockIncrement;
    private double prevHorizontalBlockIncrement;
    private double prevVerticalUnitIncrement;
    private double prevHorizontalUnitIncrement;

    public UnitIncrementScrollPaneSkin(final ScrollPane scrollPane) {
        super(scrollPane);
        filterScrollEvents();
    }

    @Override
    protected void layoutChildren(final double x, final double y, final double w, final double h) {
        prevVerticalUnitIncrement = getVerticalScrollBar().getUnitIncrement();
        prevHorizontalUnitIncrement = getHorizontalScrollBar().getUnitIncrement();
        prevVerticalBlockIncrement = getVerticalScrollBar().getBlockIncrement();
        prevHorizontalBlockIncrement = getHorizontalScrollBar().getBlockIncrement();
        super.layoutChildren(x, y, w, h);
        getVerticalScrollBar().setUnitIncrement(prevVerticalUnitIncrement);
        getHorizontalScrollBar().setUnitIncrement(prevHorizontalUnitIncrement);
        getVerticalScrollBar().setBlockIncrement(prevVerticalBlockIncrement);
        getHorizontalScrollBar().setBlockIncrement(prevHorizontalBlockIncrement);
    }

    private void filterScrollEvents() {
        getSkinnable().addEventFilter(ScrollEvent.SCROLL, event -> {

            if (event.getDeltaX() < 0) {
                getHorizontalScrollBar().increment();
            } else if (event.getDeltaX() > 0) {
                getHorizontalScrollBar().decrement();
            }

            if (event.getDeltaY() < 0) {
                getVerticalScrollBar().increment();
            } else if (event.getDeltaY() > 0) {
                getVerticalScrollBar().decrement();
            }

            event.consume();
        });
    }

    public ScrollBar getVerticalScrollBar() {
        return vsb;
    }

    public ScrollBar getHorizontalScrollBar() {
        return hsb;
    }
}

用法：

@FXML
public void initialize() {
    final double initialInc = 0.2;
    UnitIncrementScrollPaneSkin skin = new UnitIncrementScrollPaneSkin(scrollPane);
    skin.getVerticalScrollBar().setUnitIncrement(initialInc);
    skin.getVerticalScrollBar().setBlockIncrement(initialInc);
    skin.getHorizontalScrollBar().setUnitIncrement(initialInc);
    skin.getHorizontalScrollBar().setBlockIncrement(initialInc);
    scrollPane.setSkin(skin);
}

测试应用程序：

<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="226.0" prefWidth="215.0" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="com.stackoverflow.app.scrollpane.SpeedUpScrollPaneController">
   <children>
      <ScrollPane fx:id="scrollPane" fitToHeight="true" fitToWidth="true" hbarPolicy="ALWAYS" prefHeight="200.0" prefWidth="200.0" vbarPolicy="ALWAYS">
         <content>
            <GridPane>
              <rowConstraints>
                <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
              </rowConstraints>
            </GridPane>
         </content>
      </ScrollPane>
      <HBox alignment="CENTER" prefHeight="100.0" prefWidth="200.0">
         <children>
            <Label text="V:" />
            <Spinner fx:id="spinnerVertical" prefHeight="25.0" prefWidth="85.0">
                 <valueFactory>
                    <SpinnerValueFactory.DoubleSpinnerValueFactory amountToStepBy="0.1" max="1.0" min="0" />
                 </valueFactory>
            </Spinner>
         </children>
      </HBox>
      <HBox alignment="CENTER" prefHeight="100.0" prefWidth="200.0">
         <children>
            <Label text="H:" />
            <Spinner fx:id="spinnerHorizontal" prefHeight="25.0" prefWidth="85.0">
                <valueFactory>
                    <SpinnerValueFactory.DoubleSpinnerValueFactory amountToStepBy="0.1" max="1.0" min="0" />
                 </valueFactory>
            </Spinner>
         </children>
      </HBox>
      <ListView fx:id="listViewLog" prefHeight="200.0" prefWidth="200.0" />
   </children>
</VBox>

public class SpeedUpScrollPaneController {

    @FXML
    private ListView<String> listViewLog;
    @FXML
    private Spinner<Double> spinnerVertical;
    @FXML
    private Spinner<Double> spinnerHorizontal;
    @FXML
    private ScrollPane scrollPane;

    @FXML
    public void initialize() {
        mockScrollPane();
        initScrollPane();
    }

    private void mockScrollPane() {
        for (int i = 0; i < 100; i++) {
            for (int j = 0; j < 100; j++) {
                final Label label = new Label(i + "," + j);
                label.setMinWidth(60);
                label.setMinHeight(30);
                ((GridPane) scrollPane.getContent()).add(label, i, j);
            }
        }
    }

    private void initScrollPane() {
        final UnitIncrementScrollPaneSkin skin = new UnitIncrementScrollPaneSkin(scrollPane);
        scrollPane.setSkin(skin);
        initIncrement(0.2, spinnerHorizontal, skin.getHorizontalScrollBar());
        initIncrement(0.2, spinnerVertical, skin.getVerticalScrollBar());
    }

    private void initIncrement(final double increment, final Spinner<Double> spinner, final ScrollBar scrollBar) {
        scrollBar.unitIncrementProperty().addListener((source, prev, curr) -> {
            final String vLog = String.format("%tr: %s unitIncrement=%f", Calendar.getInstance(),
                    scrollBar.getOrientation(), curr);
            listViewLog.getItems().add(vLog);
            listViewLog.scrollTo(vLog);
        });
        scrollBar.blockIncrementProperty().addListener((source, prev, curr) -> {
            final String vLog = String.format("%tr: %s blockIncrement=%f", Calendar.getInstance(),
                    scrollBar.getOrientation(), curr);
            listViewLog.getItems().add(vLog);
            listViewLog.scrollTo(vLog);
        });
        spinner.valueProperty().addListener((source, prev, curr) -> {
            scrollBar.setUnitIncrement(curr);
            scrollBar.setBlockIncrement(curr);

        });

        Platform.runLater(() -> {
            scrollBar.setUnitIncrement(increment);
            scrollBar.setBlockIncrement(increment);
            spinner.getValueFactory().setValue(scrollBar.getUnitIncrement());
        });
    }
}

• 0.0 -> 不滚动
• 0.1 -> 滚动 10%
• 0.5 -> 滚动 50%
• 1.0 -> 100% 滚动
• 截屏视频

附言。如果您有很多要滚动的对象，您可以尝试以下方法：

• 创建表示滚动窗格内容的图像位图
• 开始滚动时显示图像位图
• 在 X,Y 处移动图像（基于ScrollEvent.getDeltaX(), ScrollEvent.getDeltaY()）
• 隐藏图像，在完成滚动时显示具有新坐标的滚动窗格节点