[英]Why doesn't this control update its contents while the background thread is executing?
[英]Why custom control doesn't resize with its children?
考慮以下最小的可重現示例:
public class Launcher extends Application {
public static final double SCENE_SIZE = 500;
@Override
public void start(Stage primaryStage) {
GridPane grid = new GridPane();
grid.setHgap(10);
grid.setVgap(10);
grid.setGridLinesVisible(true);
grid.getColumnConstraints().setAll(
new ColumnConstraints(USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, Priority.NEVER, HPos.LEFT, false),
new ColumnConstraints(USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, Priority.ALWAYS, HPos.LEFT, false)
);
grid.getRowConstraints().setAll(
new RowConstraints(USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, Priority.NEVER, VPos.TOP, false),
new RowConstraints(USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, Priority.NEVER, VPos.TOP, false),
new RowConstraints(USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, USE_COMPUTED_SIZE, Priority.NEVER, VPos.TOP, false)
);
CustomControl customControl = new CustomControl("Lorem Ipsum ".repeat(10));
customControl.prefWidthProperty().bind(grid.widthProperty());
TextFlow textFlow = new TextFlow(new Text("Lorem Ipsum ".repeat(10)));
textFlow.prefWidthProperty().bind(grid.widthProperty());
grid.add(new Label("0"), 0, 0);
grid.add(customControl, 1, 0);
grid.add(new Label("1"), 0, 1);
grid.add(textFlow, 1, 1);
grid.add(new Label("2"), 0, 2);
grid.add(new Label("..."), 1, 2);
Scene scene = new Scene(grid, SCENE_SIZE, SCENE_SIZE);
primaryStage.setTitle("Demo");
primaryStage.setScene(scene);
primaryStage.setOnCloseRequest(t -> Platform.exit());
primaryStage.show();
}
static class CustomControl extends Control {
private final StringProperty text = new SimpleStringProperty();
public CustomControl(String text) { setText(text); }
public String getText() { return text.get(); }
public StringProperty textProperty() { return text; }
public void setText(String text) { this.text.set(text); }
@Override
protected Skin<?> createDefaultSkin() { return new CustomControlSkin(this); }
}
static class CustomControlSkin extends SkinBase<CustomControl> {
TextFlow textFlow;
public CustomControlSkin(CustomControl control) {
super(control);
textFlow = new TextFlow();
textFlow.getChildren().setAll(new Text(control.getText()));
control.textProperty().addListener(
(obs, old, value) -> textFlow.getChildren().setAll(new Text(control.getText()))
);
control.heightProperty().addListener((observable, oldValue, newValue) -> System.out.println("control = " + newValue));
textFlow.heightProperty().addListener((observable, oldValue, newValue) -> { System.out.println("textFlow = " + newValue); });
getChildren().setAll(textFlow);
}
}
}
Window 調整大小會觸發 TextFlow 自動換行,因此 TextFlow 會更改其高度。 問題是它不會導致 CustomControl 高度變化,它保持不變(注意控制台輸出)。
同時,下一個網格行上的“純”TextFlow 的行為正是 CustomControl 所期望的。 當 window 調整大小時,它會來回更改其高度(以及 GridPane 行高)。
我認為任何控件都會根據孩子的高度自動改變自己的高度(SkinBase 包含很多方法),但似乎我錯了。 簡單地在 TextFlow 監聽器中設置控制高度是沒有幫助的,因為這樣只能增加它。
更新:
好的,我找到了問題所在。 發生這種情況是因為 TextFlow 需要實際寬度來計算其首選高度,但 SkinBase 使用負寬度值。 解決方案:
control.widthProperty().addListener((observable, oldValue, newValue) -> {
control.setPrefHeight(textFlow.prefHeight(newValue.doubleValue()));
});
如果有更好的方法歡迎分享:)
更新 2:
根據@Slaw 的建議,這個也可以。 奇怪的是width
arg 值總是-1
,所以我們必須從 skinnable 中獲取寬度值。
static class CustomControlSkin extends SkinBase<CustomControl> {
// ...
@Override
protected double computePrefHeight(double width, double topInset, double rightInset, double bottomInset,
double leftInset) {
return textFlow.prefHeight(getSkinnable().getWidth() != 0 ? getSkinnable().getWidth() : -1);
}
@Override
protected double computeMaxHeight(double width, double topInset, double rightInset, double bottomInset,
double leftInset) {
return computePrefHeight(width, topInset, rightInset, bottomInset, leftInset);
}
}
根據@Slaw 的建議,這是一種可能的解決方案。 奇怪的是width
arg 值總是-1
,所以我們必須從 skinnable 中獲取寬度值。
static class CustomControlSkin extends SkinBase<CustomControl> {
// ...
@Override
protected double computePrefHeight(double width, double topInset, double rightInset, double bottomInset,
double leftInset) {
return textFlow.prefHeight(getSkinnable().getWidth() != 0 ? getSkinnable().getWidth() : -1);
}
@Override
protected double computeMaxHeight(double width, double topInset, double rightInset, double bottomInset,
double leftInset) {
return computePrefHeight(width, topInset, rightInset, bottomInset, leftInset);
}
}
每次 Control 寬度更改時,它都會調用computeMaxHeight()
,它只是將計算委托給SkinBase
。 然后我們只是強制 Control 始終使用 TextFlow 首選項高度。
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