I'm seeing an odd issue with using CSS to colour a Shape when I have it as
a child of a TextFlow.
My use case is a "rich" text Cell in a tree or list. I want to have the
text portion in multiple colours and so instead of using the graphic and
text parts of a typical Cell, I'm using only the Graphic and setting it to
a TextFlow to get the text colours. This means that I lose the ability to
set a graphic independen to the text, and so the graphic is also added to
the TextFlow.
To style the graphics, which are made of simple shapes, I'm using CSS. It
makes it easy to adapt the colours for when a cell is selected etc. What
I've noticed is that as the cell selection moves around the Shape component
of the TextFlow flickers, as if it is drawn first using default colours and
then the CSS is applied afterward. I tried working around this by
explicitly calling applyCss() on the Shape from the Cell's update method,
but it did not help. If I explicitly set the Stroke and Fill via the Shape
API the flickering does not occur. If I use CSS, but set the Shape as the
Cell's graphic and resort to only having plain text, there is no flickering.
A test program that demonstrates this is below.
Bug or known limitation?
Scott
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package bugs;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.CheckBox;
import javafx.scene.control.ContentDisplay;
import javafx.scene.control.Label;
import javafx.scene.control.ListCell;
import javafx.scene.control.ListView;
import javafx.scene.control.Tab;
import javafx.scene.control.TabPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Rectangle;
import javafx.scene.shape.Shape;
import javafx.scene.text.Text;
import javafx.scene.text.TextFlow;
import javafx.stage.Stage;
public class CSSFlickerInTextFlow extends Application {
public static void main(String[] args) {
launch(args);
}
private CheckBox onlyCssCB;
@Override
public void start(Stage stage) throws Exception {
ListView<String> list1 = new ListView<>();
ListView<String> list2 = new ListView<>();
var items1 = list1.getItems();
var items2 = list2.getItems();
for (int i = 1; i < 23; i++) {
var x = "Item #"+i;
items1.add(x);
items2.add(x);
}
list1.setCellFactory(t -> new MyCell1());
list2.setCellFactory(t -> new MyCell2());
onlyCssCB = new CheckBox("Use only CSS (shapes will flicker in
TextFlow)");
HBox buttons = new HBox(8, onlyCssCB);
buttons.setPadding(new Insets(4));
Tab custom = new Tab("Everything in Graphic", list1);
Tab withoutColoredText = new Tab("Graphic + Text", list2);
TabPane tabs = new TabPane(custom, withoutColoredText);
VBox root = new VBox(
new Label("""
Focus in list, cursor up and down, pay attention
to the circle.
Try the same with the box checked - circle
flickers.
Doesn't happen when not using the TextFlow.
"""),
buttons, tabs);
root.setPadding(new Insets(4));
var scene = new Scene(root);
stage.setScene(scene);
stage.setTitle("Flickering with CSS in TextFlow");
stage.show();
}
private Shape makeGraphic() {
Shape graphic = new Circle(6);
if (!onlyCssCB.isSelected()) {
graphic.setFill(Color.SALMON); // CSS overrides these but
causes flickering if not the same
graphic.setStroke(Color.BLACK);
}
graphic.setStyle("-fx-fill: salmon; -fx-stroke: black;");
return graphic;
}
class MyCell1 extends ListCell<String> {
@Override
protected void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
setText(null);
if (!empty && item != null) {
TextFlow flow = new TextFlow();
Shape graphic = makeGraphic();
graphic.setTranslateY(2);
var nodeList = flow.getChildren();
Text name = new Text(item + " : ");
name.setStyle("-fx-fill: -fx-text-background-color;");
Text extra = new Text("with Color");
extra.setStyle("-fx-fill:ladder(-fx-background, white 49%,
salmon 50%);");
nodeList.add(graphic);
nodeList.add(new Rectangle(4,0)); // gap
nodeList.add(name);
nodeList.add(extra);
setGraphic(flow);
} else {
setGraphic(null);
}
}
}
class MyCell2 extends ListCell<String> {
@Override
protected void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
if (!empty && item != null) {
setGraphic(makeGraphic());
setText(item);
} else {
setText(null);
setGraphic(null);
}
}
}
}
