应用程序应“更快”呈现滚动窗格内容以提高滚动速度。
您可以减少要渲染的对象数量或/和减少“重绘”方法调用的数量（JFX 中的 layoutChildren）。据我对代码 sn-p 的理解，您即将减少重绘次数，因为更改增量参数可以减少重绘内容的次数。
-
blockIncrement（如果栏的轨迹被点击）
-
unitIncrement（如果单击了上、下、右、左按钮）
当您单击滚动窗格按钮时，将调用方法 ScrollPane.layoutChildren()。
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：
<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 -> 滚动到 10%
- 0.5 -> 滚动到 50%
- 1.0 -> 100% 滚动
-
Screencast
PS。
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
- 在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，在完成滚动时显示带有新坐标的滚动窗格节点