我是第一次使用 JavaFX,到目前为止,我设法将我想要的其他所有事情都做好了,但现在我陷入了死胡同。我正在使用Treeview
来显示对象列表,每个对象都有一个数值(使用了多少次),并且我想根据使用计数器在树视图上单独更改每个对象的背景颜色。
也就是说,如果一个物体被使用了100次,它应该是红色的,而一个较少使用的物体应该是黄色的,类似于温度读取器。
任何帮助将不胜感激!
谢谢Andreas
使用单元工厂创建树单元,其styleProperty
绑定到树中显示的项的值:
import java.util.Random;
import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.IntegerProperty;
import javafx.beans.property.SimpleIntegerProperty;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.TreeCell;
import javafx.scene.control.TreeItem;
import javafx.scene.control.TreeView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.HBox;
import javafx.stage.Stage;
public class TreeViewChangeBackgroundOnItem extends Application {
private TreeView<Item> tree;
@Override
public void start(Stage primaryStage) {
tree = new TreeView<>();
tree.setRoot(new TreeItem<>(new Item(0)));
tree.getRoot().setExpanded(true);
Random rng = new Random();
for (int i = 0 ; i < 10 ; i++) {
tree.getRoot().getChildren().add(
new TreeItem<>(new Item(rng.nextInt(100))));
}
tree.setCellFactory(tv -> new TreeCell<Item>() {
@Override
protected void updateItem(Item item, boolean empty) {
super.updateItem(item, empty);
styleProperty().unbind();
textProperty().unbind();
if (empty) {
setText("");
setStyle("");
} else {
textProperty().bind(item.valueProperty().asString("Value: %d"));
styleProperty().bind(Bindings.createStringBinding(() ->
String.format("-fx-background: #ff%02x00;",
computeGreen(item.getValue())),
item.valueProperty()));
}
}
});
Button inc = createAdjustButton("Increment", 1);
Button dec = createAdjustButton("Decrement", -1);
HBox buttons = new HBox(5, inc, dec);
buttons.setAlignment(Pos.CENTER);
buttons.setPadding(new Insets(10));
BorderPane root = new BorderPane(tree, null, null, buttons, null);
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}
private int computeGreen(int value) {
int clamped = Math.max(0, Math.min(value, 100));
return 255-255*clamped/100 ;
}
private Button createAdjustButton(String text, int delta) {
Button button = new Button(text);
button.setOnAction(e -> adjust(delta));
button.disableProperty().bind(tree.getSelectionModel().selectedItemProperty().isNull());
return button ;
}
private void adjust(int delta) {
Item selected = tree.getSelectionModel().getSelectedItem().getValue();
selected.setValue(selected.getValue()+delta);
}
public static class Item {
private final IntegerProperty value = new SimpleIntegerProperty();
public Item(int value) {
setValue(value);
}
public final IntegerProperty valueProperty() {
return this.value;
}
public final int getValue() {
return this.valueProperty().get();
}
public final void setValue(final int value) {
this.valueProperty().set(value);
}
}
public static void main(String[] args) {
launch(args);
}
}
自定义cellFactory
可用于根据显示的项目更改Background
。为简单起见,这假设树项包含 IntegerProperty
s:
private final static double FACTOR = -Math.log(5d) * 0.01;
treeView.setCellFactory((t) -> new TreeCell<IntegerProperty>() {
@Override
protected void updateItem(IntegerProperty item, boolean empty) {
super.updateItem(item, empty);
if (empty || item == null) {
textProperty().unbind();
backgroundProperty().unbind();
setText(null);
setBackground(null);
} else {
textProperty().bind(item.asString());
backgroundProperty().bind(Bindings.createObjectBinding(()
-> new Background(new BackgroundFill(
Color.color(1, Math.exp(FACTOR * item.get()), 0, 1),
CornerRadii.EMPTY, Insets.EMPTY)), item));
}
}
});
我还对绿色通道的值使用指数函数来允许所有非负int
值。
有关更复杂的颜色选择算法,您可以参考此页面 http://www.tannerhelland.com/4435/convert-temperature-rgb-algorithm-code/